The 2020 fire season includes the single largest fire in California’s history, the August Complex Fire. Ash and soot contained in wildfire smoke have a low albedo and can absorb incoming UV radiation. As a result, one would hypothesize that at a local level the surface UV irradiance dosage would change in areas leeward of large fires. To test this hypothesis, the direct and diffused UV irradiance recorded east of the August Complex Fire at the UVMRP station in Davis, CA were compared between 2020 and 2016. Direct and diffused UV irradiance levels at local noon of an entire year were compared between these two years, trying to identify how wildfire impacts surface UV. Using satellite imagery to determine when smoke was present in the skies over Davis, CA, this study investigated how UV irradiance changes during those time periods.
U.S. Landsat Analysis Ready Data (ARD) recently included the Land Surface Temperature (LST) product, which contains widespread and irregularly-shaped missing pixels due to cloud contamination or incomplete satellite coverage. Many analyses rely on complete LST images therefore techniques that accurately fill data gaps are needed. Here, the development of a partial-convolution based model with the U-Net like architecture to reconstruct the missing pixels in the ARD LST images is discussed. The original partial convolution layer is modified to consider both the convolution kernel weights and the number of valid pixels in the calculation of the mask correction ratio. In addition, the new partial merge layer is developed to merge feature maps according to their masks. Pixel reconstruction using this model was conducted using Landsat 8 ARD LST images in Colorado between 2014 and 2018. Complete LST patches (64x64) for two identical scenes acquired at different dates (up to 48 days apart) were randomly paired with ARD cloud masks to generate the model inputs. The model was trained for 10 epochs and the validation results show that the average RMSE values for a restored LST image in the unmasked, masked, and whole region are 0.29K, 1.00K, and 0.62K, respectively. In general, the model is capable of capturing the high-level semantics from the inputs and bridging the difference in acquisition dates for gap filling. The transition between the masked and unmasked regions (including the edge area of the image) in restored images is smooth and reflects realistic features (e.g., LST gradients). For large masked areas, the reference provides semantics at both low and high levels.
Surface ozone can trigger many health problems for human (e.g. coughing, bronchitis, emphysema, and asthma), especially for children and the elderly. It also has harmful effects on plants (e.g. chlorosis, necrosis, and yield reduction). The United State (U.S.) Environmental Protection Agency (EPA) has been monitoring surface ozone concentrations across the U.S. since 1980s. However, their stations are sparsely distributed and mainly in urban areas. Evaluation of surface ozone effects at any given locations in the U.S. requires spatial interpolation of ozone observations. In this study, we implemented two traditional spatial interpolation methods (i.e. triangulation-based linear interpolation and geostatistics-based method). One limitation of these two methods is their reliance on single-scene observations in constructing the spatial relationship, which is prone to influence of noisy observations and has large uncertainty. Deep learning, on the other hand, is capable of simulating common patterns (including complex spatial patterns) from a large amount of training samples. Therefore, we also implemented three deep learning algorithms for the spatial interpolation problem: mixture model network (MoNet), Convolutional Neural Network for Graphs (ChebNet), and Recurrent Neural Network (RNN). The training and validation data of this study are the 2016 EPA hourly surface ozone observations within ±3-degree box centered at the Billings, Oklahoma station (USDA UV-B Monitoring and Research Program). The results showed that among the five methods, RNN and MoNet outperformed the two traditional spatial interpolation methods and RNN has the lowest validation error (mean absolute error: 2.82 ppb; standard deviation: 2.76 ppb). Finally, we used the integrated gradients method to analyze the attribution of RNN inputs on the surface ozone prediction. The results showed that surface ozone observation is the most important input feature followed by distance and absolute locations (i.e. elevations, longitudes, and latitudes).
Particulate matter (PM) is one of the main pollutants in the atmosphere, which is harmful to human. PM10 and PM2.5 became the main subject attracting more and more interest. To compensate the weakness of conventional observation method, application of remote sensing tools have been widely used in environmental monitoring. The Moderate Resolution Imaging Spectroradiometer (MODIS) data has a high temporal resolution, which, at present, is an ideal data source in simulative monitoring of regional-scale environment changes. In this study, we focused on PM2.5 and AOD (Aerosol Optical Depth) in coastal areas. Correlation between each two of them was analyzed. From the daily average value year of two sites PM2.5, the concentration of air particulate pollutants is low before and after summer, and the heating season is higher in winter and spring. The average PM2.5 concentration value of 2014 and 2015 is 50.11μg/m3 and 41.11μg/m3 respectively in Fushan station, and that of the Laishan station is 45.63μg/m3 and 38.73μg/m3 respectively. From the interannual variation, the concentration of air particulate pollutants in the two regions has a tendency to decrease. According to the new standard of air quality of the PM2.5 monitoring network, the air quality of the vast majority of dates belongs to the excellent grade. In light of the policy of air pollution, the PM2.5 concentration in 2015 was lower than that in 2014. Due to the complexity of atmospheric components and their interactions, and the spatial and temporal constraints of PM2.5 detection resulted in a low correlation between the AOT and PM2.5.
For the past few years, the aerosol pollution in Shanghai is getting worse, leading to the haze weather and air quality deterioration as well. This paper is a comparative study on reliability and applicability of the spatial interpolation methods for the regional air quality evaluation, the daily data of the air quality indices (AQI, PM2.5 and PM10) comes from the Shanghai automatic monitoring stations, which helps us to compare the different interpolation methods in testing and measuring various air pollutants in Shanghai. Inverse Distance Weighted (IDW), Spline and Kriging were respectively used for the calculation of spatial interpolation. With the aforementioned methods we can compare the interpolation methods and gain the four indices, such as the mean error (ME), the mean relative error (MRE), the root mean squared error (RMSIE), and the correlation coefficient (R2) , which help us make a comprehensive comparative analysis of the spatial interpolation methods for the Shanghai regional air quality. The result shows that the IDW method is optimal for PM2.5 concentration and AQI, while Kriging Method is the Best for the concentration of PM10. We can also find that Seasonal characteristics and different spatial aggregation characteristics have a significant impact on the interpolated results of air pollutants.
The statistical forecasting model based on time series is one of the main means of sea level forecasting at present stage. However, the mechanism of sea level change is complex. The traditional method has some limitations for non-stationary nonlinear time series forecasting, and the prediction accuracy needs to be further improved. In this paper, we use the monthly mean tide level series from Zhapo Station (1959 ~ 2011), and combine the Ensemble Empirical Mode Decomposition(EEMD), Genetic Algorithm (GA) and Back Propagation (BP) Neural Network to propose a improved EEMD-GA-BP method for regional sea level change prediction. In this study, the EEMD method was used to decompose the original series and generate multiple intrinsic mode functions (IMF) according to different spectral characteristics of signals implied in the tide level series, to stabilize the time series, and improve signal to noise ratio. GA is used to optimize the weights and thresholds of BP Neural Network, due to the difficulty of determining the initial weight and threshold in BP Neural Network. Taking each IMF as the input factor of BP Neural Network, the future trend of each IMF is predicted respectively. Finally, the output of the IMF is reconstructed to obtain the predicted value of the original series. The results show that EEMD can effectively extract multi-time scale signals implicit in the series. BP Neural Network optimized by GA can well predict the future trend of sea level. Compared with the direct use of BP Neural Network algorithm, the use of EEMD for non-stationary non-linear time series smoothing, noise reduction and other processing can effectively improve the prediction accuracy. The use of GA optimize BP Neural Network can improve the accuracy. The EEMD-GA-BP algorithm provides a realistic meaning for the prediction of regional sea level change.
Based on the data of Landsat remote sensing images in 2005 and 2015 in Weihai City, this paper referenced China coastal zone land use classification system and used the Arcgis10.2 software to construct the land use database by visual interpretation , and then analyzed the spatial and temporal changes of land use in Weihai City for 10 years. The results showed that: (1) The total area of the land use in Weihai City had been enlarged, mainly by mariculture expansion with land area of 11.3 thousand hectares.(2) The land use changing rates were fast, among which the unused land attitude was the largest at 24.85%.(3) The area of these land uses change was increased, which are forest land, urban construction land and the independent industrial and mining and traffic construction land. While the arable land and grass land areas decreased. (4) The main driving forces were its economic development and its national economic and social development planning. May this paper provide some references to its regional land use sustainable development.
Based on GOCI data and the built-in CO2 algorithm, this paper investigated the spatial-temporal distribution characteristics of chlorophyll-a in offshore waters of Yantai and Weihai from 2014 to 2016. Results showed: The chlorophyll-a concentration in the study area has a significant spatial-temporal characteristics, showed a decreased tendency from estuary to offshore area in general. While the lowest value major in the north open seas, the highest value appeared in Sishili Bay and the coastal zone along Weihai, even extended to the western coastal area of Shandong Peninsula. The spatial difference of the concentration of chlorophyll-a in summer was significantly higher than that in winter, and the enrichment effect increased with the increase of temperature. From the perspective of temporal distribution, the chlorophyll-a level was highest in August and lowest in February, and there are small but obvious double peaks in the spring and autumn of May and October. Our work indicated that chlorophyll a concentration level in the study area showed a gradual upward trend in recent 3 years.
Air pollutants can cause serious effects on human health, especially fine particles in air, which can easily cause respiratory diseases, such as asthma and bronchitis, and also increase the probability of lung cancer and heart disease. The disease surveillance of the residents around the chemical plant is an effective means to understand the effects of the discharged pollutant on the health of the surrounding residents. The research area, Shanghai Chemical Industry Park is located at the junction of Jinshan and Fengxian, as the South Center of the six industrial bases of Shanghai. Applying the spatial distribution of population obtained from the extraction of residential land by using GF-2 data, and the disease data after cleaning treatment, can reach to the spatial distribution of the above two diseases. Through the integration of spatial characteristics and attribute characteristics, the disease surveillance of the surrounding residents can be realized, which directly reflects the impact of chemical industry on the health of the surrounding residents.
Chinese yam (Dioscorea opposita Thunb.) is consumed and regarded as medicinal food in traditional Chinese herbal medicine, Chinese medicinal yam especially is one of the most important Chinese herbal medicines and its medicinal needs have been increasing in recent decades1. Furthermore, Chinese medicinal yam is susceptible to climate conditions during the growth period. Therefore, a better understanding of the suitability regionalization of Chinese medicinal yam under the impact of climate change is of both scientific and practical importance to spacial development and reasonable layout of Chinese yam in China. In this study, based on the Coupled Model Inter-comparison Project, Phase 5 (CMIP5) climate model projections with 5 Global Circulation Models (GCMs) developed by the Inter-Sectoral Impact Model Inter-comparison Project (ISIMIP) driven by 4 Representative Concentration Pathways (RCPs), we assessed the changes of potential planting area of Chinese medicinal yam between the baseline climatology of 1981-2010 and the future climatology of the 2050s (2041-2070) under the RCP 4.5 scenario by the Geographic Information System (GIS) technology. Results indicate that regions with high ecological similarity to the Geo-authentic producing areas of Chinese medicinal yam include northeastern Henan, southeastern Hebei and western Shandong, mainly distribute in the lower reaches of the Yellow River basin and other major floodplains. In the future, the climate suitability of Chinese medicinal yam in these areas will be weakened, but that will still be the main suitable planting regions.
KEYWORDS: Methane, Data modeling, Atmospheric modeling, Climate change, Climatology, Temperature metrology, Geographic information systems, Systems modeling, Data centers, Agriculture
Paddy field is a major source of methane (CH4) emission. Methane emission in paddy fields accounts for 31.5% of agricultural methane emissions in China. Double-rice cropping system is a part of the major paddy systems in China for rice production, accounting for only 27% of the national rice planting area while CH4 emission accounting for 60% of the national CH4 emission. Given the importance of reducing CH4 emission from double rice to mitigate climate warming, it is necessary to investigate the impact of climate change on CH4 emission of double cropping paddy field in the future. In this study, the denitrification–decomposition (DNDC-a process-based biogeochemistry model) model is employed to simulate the CH4 emission from double-rice cropping system in southern China based on the historical meteorological data of the past 50 years (1966-2015) and the observational data of rice agricultural stations in the study area. Then we combined the outputs with Geographic Information System (GIS) technology to analyze the impact of climate change on CH4 emissions from the double rice paddy. The results indicate that change of the average temperature is associated with the change of CH4 emission across the growing period of double rice paddy. Methane has increased by 8.4% in the main producing provinces of double cropping rice in southern China. Zhejiang has increased by up to 20.8%. Anhui, Hubei, Hunan has increased by 10.6%, 10.2% and 11.4%. The relatively small increase in Fujian and Yunnan is only 5%. However, in the low latitudes of Guangxi, and Guangdong province, there was a slight reduction in CH4 emission.
Fine particles less than 2.5 microns in aerodynamic diameter (PM2.5) has found to threat human health and environment. The formation and diffusion of PM2.5 are closely related to the meteorological elements. Many scholars have studied the influence mechanism of meteorological elements to PM2.5. However, most of these researches mainly focus on some serious short-term atmospheric pollution, long-term research is rare. In addition, the impact of meteorological elements on PM2.5 has regional characteristics. This paper takes Shanghai as study area, applying PM2.5 concentrations from China environmental monitoring stations and reanalysis meteorological data from 2014 to 2016.. Through qualitative and quantitative analysis, this paper got the change characteristics of PM2.5 in Shanghai in recent three years, and the correlation between PM2.5 and relative humidity, temperature, wind and boundary layer height. Relative humidity is positively correlated with PM2.5, while U wind is negatively correlated with PM2.5. And there are seasonal differences in the correlation between PM2.5 and temperature, V wind and boundary layer height.
People in Huaihe River Basin and Shanghai have been suffering from severe air pollution of nitrogen dioxide and sulfur dioxide due to the development of heavy industry. Traditional ambient monitoring station measurements can provide real-time accurate data, but it is limited due to the less number of monitoring sites. Satellite observation data from remote sensing can provide a wide range opollutants concentrations in long-time sequence. Top-down approaches based on satellite data can be effectively applied to estimate the ground concentrations of pollutants. In this paper, the tropospheric pollutants columns from the Ozone Monitoring Instrument(OMI) were used to analyse the seasonal variation of NO2 and SO2 in 2015. Moreover, the ground-level NO2 and SO2 concentrations of the Huaihe River Basin and Shanghai at this time were estimated by the data and meteorological data. The results show that: the concentrations of NO2 and SO2 are highest in winter, and high-value areas are mainly located in Shandong and Northern Henan. Estimating the ground-level NO2 and SO2 concentrations based on satellite observations is reliable with the validation R2 0.48 and 0.47 respectively. Finally, The spatial distribution of satellite-derived annual mean NO2 and SO2 has a similar characteristics to the satellite columns.
KEYWORDS: Calibration, Monte Carlo methods, Data modeling, Roads, Information science, Remote sensing, Climatology, Diffusion, Resistance, Local area networks
With the rapid development of urbanization, the dynamic evolution of urban expansion has become one of the hot topics throughout the world. Thus, modeling and predicting the urban expansion in the future is one of the effective methods for the study of urban growth. Based on the rapid urbanization in Shanghai, our study uses four years of land use data (1995, 2000, 2005 and 2010), DEM and two years of traffic roads data (2005 and 2010) to obtain the optimal parameters of urban growth through model calibration. And the results of calibration were used to simulate and predict the land use change in 2040 under different scenarios of excluded layers. The results show that the urban growth in Shanghai is more often grow along the edge of existing urban centers and the transportation network with the relatively high spread coefficient (43) and road coefficient (66), while the dispersion, breed and slope coefficient are relatively low. The SLEUTH simulation with these five parameters possessed satisfactory capability of predicting land use changes with the kappa coefficient of 0.8628 and an appropriate Lee-Sallee index of 0.8139. The result shows that the urban areas in Shanghai increase significantly in 2040, while the rural area, grass and other construction area are decreased. Therefore, SLEUTH can better predict the spatial changes of land use and provide some theoretical support and decision-making basis for the urban-rural planning in Shanghai.
As an important complement to satellite observation, the technique of Unmanned Aerial Vehicle (UAV) shows great advantages because of its high spatiotemporal resolutions, low cost and risk. With the development of technology related to UAV, its research was increasingly enhanced and has been applied to many fields such as environmental monitoring. Taking a coastal zone of Yantai as test area, this paper studied how to utilize the UAV system to monitor contaminated water in coastal zones. The results show that the contaminated water information can be extracted from the UAV remote sensing image. The multi-time monitoring conducted in this study can monitor the change of polluted water. This will provide technical support for the monitoring and treatment of polluted water bodies.
Since 2008, the Green Tide has been continuously erupted for 10 years in Yellow Sea. Relevant studies have proved that the source of the green tide burst is the laver rafts in the radiated sand area. In this study, UAV (Unmanned Aerial Vehicle ) and S2A (Sentinel Satellite) data were used to monitor and estimate the biomass of Green tide algae on the rafts of seaweed. Using UAV imagery combined with high-resolution satellite data and field survey data, Accurately monitoring and assessing the biomass of green tide algae in the radiation sandy area can provide a scientific basis for the prevention and early warning of the Southern Yellow Sea green tide disasters.
Unmanned aerial vehicle (UAV) have been increasingly used for natural resource applications in recent years as a result of their greater availability, the miniaturization of sensors, and the ability to deploy UAV relatively quickly and repeatedly at low altitudes. In this paper, the wetland vegetation information is extracted from UAV remote sensing images by object-oriented approach. Firstly, the images are segmented and images object are build. Secondly, VDVI, VDWI, spectral information and object geometry information of images objects are comprehensively applied to build wetland vegetation extraction knowledge base. Thirdly, the results of wetland vegetation extraction are improved and completed. The results show that better accuracy of wetland vegetation extraction can be obtained by the proposed method, in contrast to the pixel-oriented method. In this study, the overall accuracy of classified image is 0.968 and Kappa accuracy is 0.934.
Based on the current land uses of 2005 and 2015 in Dongying City, this study obtained the spatial-temporal variation matrix of land use of the two periods with the overlay function in ArcGIS 10.2. The analysis results showed as follows: 1-Agricultural area decrease a little. 2-The urban land area had increased greatly. 3-Coastal aquaculture area increase a lot. The main driving factors were: 1-The policy of farmland protection was carried out in Dongying City. 2-Dongying City economic has developed rapidly in recent 10 years. 3-Driven by higher economic profits. The conclusions were meaningful for the reform of land use structure and the reform of economic structure in the future in Dongying City.
Tidal flats in Rudong county, located at the end of Jiandsu Radail Sand Ridges Area. Plentiful quantities of tidal flat makes this area an important land reserve resource. However, traditional field measurement technology encounters difficult due to special form of geomorphology in Rudong tidal flat, resulting the lack of data support in rational exploitation. In order to obtain the extent of tidal flat with volatile coastal evolution, we proposed a modified method, which based on the previous studies, to map tidal flat area with rare manual intervention. Firstly, a confident low tide image generated under the method of pixel-based NDWI average composite. Then, OSTU method was used to compute threshold, which used to segment image into two value. followed by tideline extraction. Subsequently, the extent of tidal flat in Rudong county was obtained. The study shows that the method can realize the extraction of the tidal flat extent in complex landform quickly and accurately. The research data can be obtained free of charge, which makes the method generalized.
The USDA UV-B Monitoring and Research Program (UVMRP) comprises of 36 climatological sites along with 4 long-duration research sites, in 27 states, one Canadian province, and the south island of New Zealand. Each station is equipped with an Ultraviolet multi-filter rotating shadowband radiometer (UV-MFRSR) which can provide response-weighted irradiances at 7 wavelengths (300, 305.5, 311.4, 317.6, 325.4, and 368 nm) with a nominal full width at half maximun of 2 nm. These UV irradiance data from the long term monitoring station at Mauna Loa, Hawaii, are used as input to a retrieval algorithm in order to derive high time frequency total ozone columns. The sensitivity of the algorithm to the different wavelength inputs is tested and the uncertainty of the retrievals is assessed based on error propagation methods. For the validation of the method, collocated hourly ozone data from the Dobson Network of the Global Monitoring Division (GMD) of the Earth System Radiation Laboratory (ESRL) under the jurisdiction of the US National Oceanic & Atmospheric Administration (NOAA) for the period 2010-2015 were used.
The USDA UV-B Monitoring and Research Program (UVMRP) is an ongoing effort aiming to establish a valuable,
longstanding database of ground-based ultraviolet (UV) solar radiation measurements over the US. Furthermore, the
program aims to achieve a better understanding of UV variations through time, and develop a UV climatology for
the Northern American section. By providing high quality radiometric measurements of UV solar radiation,
UVMRP is also focusing on advancing science for agricultural, forest, and range systems in order to mitigate climate
impacts. Within these foci, the goal of the present study is to investigate, analyze, and validate the accuracy of the
measurements of the UV multi-filter rotating shadowband radiometer (UV-MFRSR) and Yankee (YES) UVB-1
sensor at the high altitude, pristine site at Mauna Loa, Hawaii. The response-weighted irradiances at 7 UV channels
of the UV-MFRSR along with the erythemal dose rates from the UVB-1 radiometer are discussed, and evaluated for
the period 2006-2015. Uncertainties during the calibration procedures are also analyzed, while collocated groundbased
measurements from a Brewer spectrophotometer along with model simulations are used as a baseline for the
validation of the data. Besides this quantitative research, the limitations and merits of the existing UVMRP methods
are considered and further improvements are introduced.
Spartina alterniflora, one of most successful invasive species in the world, was firstly introduced to China in 1979 to accelerate sedimentation and land formation via so-called “ecological engineering”, and it is now widely distributed in coastal saltmarshes in China. A key question is how to retrieve chlorophyll content to reflect growth status, which has important implication of potential invasiveness. In this work, an estimation model of chlorophyll content of S. alterniflora was developed based on hyper-spectral data in the Dongtan Wetland, Yangtze Estuary, China. The spectral reflectance of S. alterniflora leaves and their corresponding chlorophyll contents were measured, and then the correlation analysis and regression (i.e., linear, logarithmic, quadratic, power and exponential regression) method were established. The spectral reflectance was transformed and the feature parameters (i.e., “san bian”, “lv feng” and “hong gu”) were extracted to retrieve the chlorophyll content of S. alterniflora . The results showed that these parameters had a large correlation coefficient with chlorophyll content. On the basis of the correlation coefficient, mathematical models were established, and the models of power and exponential based on SDb had the least RMSE and larger R2 , which had a good performance regarding the inversion of chlorophyll content of S. alterniflora.
Mean Solar Exo-atmospheric Irradiances (ESUN) is an important parameter to calculate the apparent
reflectance based on the satellite sensor measured DN values. GF-4 was launched in 2015, the ESUN
of this satellite has not been officially reported, however. To determine which solar spectrum curve is
best fitted to GF-4, this study calculated the ESUN of GF-1 at first, by using six distinct solar spectrum
curves and spectral response curves of GF-1. Next, the results were validated by comparing with the
operational released values. It indicates that the World Radiation Center (WRC) solar spectrum is the
most accurate and reliable solar spectrum curve for GF-1, with a total error less than 0.1% for 4 bands.
Finally, the ESUN of GF-4 was calculated by making use of the WRC solar spectrum curve.
Peanut is one of the major edible vegetable oil crops in China, whose growth and yield are very sensitive to climate change. In addition, agriculture climate resources are expected to be redistributed under climate change, which will further influence the growth, development, cropping patterns, distribution and production of peanut. In this study, we used the DSSAT-Peanut model to examine the climate change impacts on peanut production, oil industry and oil food security in China. This model is first calibrated using site observations including 31 years’ (1981-2011) climate, soil and agronomy data. This calibrated model is then employed to simulate the future peanut yield based on 20 climate scenarios from 5 Global Circulation Models (GCMs) developed by the InterSectoral Impact Model Intercomparison Project (ISIMIP) driven by 4 Representative Concentration Pathways (RCPs). Results indicate that the irrigated peanut yield will decrease 2.6% under the RCP 2.6 scenario, 9.9% under the RCP 4.5 scenario and 29% under the RCP 8.5 scenario, respectively. Similarly, the rain-fed peanut yield will also decrease, with a 2.5% reduction under the RCP 2.6 scenario, 11.5% reduction under the RCP 4.5 scenario and 30% reduction under the RCP 8.5 scenario, respectively.
Based on the SPOT/ NDVI data and meteorological data of Jianghuai watershed area, the temporal and spatial variation characteristics of NDVI and their correlation with climate factors (temperature and precipitation) are analyzed from 1998 to 2013 by utilizing the maximum value composite and linear regression method. The results showed that the vegetation growth has changed year by year with an overall trend in Jianghuai watershed region, and the number of pixels in the growing area accounts for 85.8% of the total. From the space point of view, expect for some regions in Hefei, Chuzhou and Luan are obviously decreasing, most of the other regions showing a growth trend. Vegetation was not positively correlated with temperature and precipitation, and the correlation between NDVI and temperature was higher than that of precipitation. Due to the differences of topography, geography and human activities, the correlation in different regions is different. In addition, human activities are also the influencing factors of vegetation change.
Coastal wetland is a net carbon sink with a high carbon density. However, coastal reclamation
directly changes the structure of coastal wetland ecosystem and consequent carbon sink function.
The aim of this work was to estimate the reclamation-induced carbon loss in coastal wetlands
using time series GF-1 WVF data. For this purpose, GF-1 WVF imageries of 2013 (before
reclamation) and 2017 (after reclamation) in the Yangtze Estuary were collected and analyzed
combined with field monitoring. Results showed that the converted coastal wetland area occupied
up to 61.60% between 2013 and 2017. Carbon estimation indicated that the coastal wetland before
reclamation had greater potential contribution to the global warming mitigation than the wetland
reclamation to other land cover types. Finally the vulnerability of carbon stores and uncertain
analysis with remote sensing technology in coastal wetlands environment were discussed. We
emphasized that long-term monitoring of coastal wetlands and its carbon dynamic are urgently
needed, because so many uncertain factors exist in short-term monitoring.
The accuracy of the temperature and humidity profiles from the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) is evaluated using three month of collocated datasets over East China. The AIRS/AMSU retrievals, radiosonde data (RAOB), and the ERA-Interim data from European Center for medium Range Forecast (ECMWF) are used in this validation. This study also compares the AIRS/AMSU retrieved profiles with it only retrieved by AIRS. Results of the entire intercomparison reveal that the RMSE of temperature profiles are in very good agreement with all cases, whilst the relative humidity RMSE show larger difference. Compared with RAOB for the AIRS/AMSU retrievals and ERA-Interim data, it is found that the ERA-Interim temperature and humidity profiles are superior to AIRS retrievals except the humidity in upper troposphere. The accuracy of AIRS/AMSU retrievals is a little bit better than only AIRS retrieved profile product.
The North China Plain is a major food producing region in China, and climate change could pose
a threat to food production in the region. Based on China Meteorological Forcing Dataset,
simulating the growth of summer maize in North China Plain from 1979 to 2015 with the regional
implementation of crop growth model WOFOST. The results showed that the model can reflect the
potential yield and water-limited yield of Summer Maize in North China Plain through the calibration
and validation of WOFOST model. After the regional implementation of model, combined with the
reanalysis data, the model can better reproduce the regional history of summer maize yield in the North
China Plain. The yield gap in Southeastern Beijing, southern Tianjin, southern Hebei province,
Northwestern Shandong province is significant, these means the water condition is the main factor to
summer maize yield in these regions.
This paper conducted dynamic monitoring over the green tide (large green alga—Ulva prolifera)
occurred in the Yellow Sea in 2014 to 2016 by the use of multi-source remote sensing data, including GF-1
WFV, HJ-1A/1B CCD, CBERS-04 WFI, Landsat-7 ETM+ and Landsta-8 OLI, and by the combination of
VB-FAH (index of Virtual-Baseline Floating macroAlgae Height) with manual assisted interpretation
based on remote sensing and geographic information system technologies. The result shows that unmanned
aerial vehicle (UAV) and shipborne platform could accurately monitor the distribution of Ulva prolifera in
small spaces, and therefore provide validation data for the result of remote sensing monitoring over Ulva
prolifera. The result of this research can provide effective information support for the prevention and
control of Ulva prolifera.
Cloud screening is an essential procedure for in-situ calibration and atmospheric properties retrieval on (UV-)MultiFilter Rotating Shadowband Radiometer [(UV-)MFRSR]. Previous study has explored a cloud screening algorithm for direct-beam (UV-)MFRSR voltage measurements based on the stability assumption on a long time period (typically a half day or a whole day). To design such an algorithm requires in-depth understanding of radiative transfer and delicate data manipulation. Recent rapid developments on deep neural network and computation hardware have opened a window for modeling complicated End-to-End systems with a standardized strategy. In this study, a multi-layer dynamic bidirectional recurrent neural network is built for determining the cloudiness on each time point with a 17-year training dataset and tested with another 1-year dataset. The dataset is the daily 3-minute cosine corrected voltages, airmasses, and the corresponding cloud/clear-sky labels at two stations of the USDA UV-B Monitoring and Research Program. The results show that the optimized neural network model (3-layer, 250 hidden units, and 80 epochs of training) has an overall test accuracy of 97.87% (97.56% for the Oklahoma site and 98.16% for the Hawaii site). Generally, the neural network model grasps the key concept of the original model to use data in the entire day rather than short nearby measurements to perform cloud screening. A scrutiny of the logits layer suggests that the neural network model automatically learns a way to calculate a quantity similar to total optical depth and finds an appropriate threshold for cloud screening.
In neural networks, the training/predicting accuracy and algorithm efficiency can be improved significantly via accurate input feature extraction. In this study, some spatial features of several important factors in retrieving surface ultraviolet (UV) are extracted. An extreme learning machine (ELM) is used to retrieve the surface UV of 2014 in the continental United States, using the extracted features. The results conclude that more input weights can improve the learning capacities of neural networks.
Tidal flat area gains abundant natural resources. With the development of the coastal economy, tidal flat area possesses an unstable nature, thus of significant value for its study. Waterline extracting methods are essential to understand the dynamic change of tidal flat. In order to find a good method, we took Rudong County in Jiangsu Province as the research area, by using the HJ1A/1B images, waterlines are generated under the method of visual interpretation extraction, Canny edge detection, threshold segmentation and object-oriented classification. By contrast, the paper considered object-oriented classification as an effective method to extract waterlines.
Using Landsat 5 Thematic Mapper and Landsat 8 Operational Land Imager and Thermal
Infrared Sensor imagery of the Yellow River Delta, this study analyzed the relationships between
NDVI and LST (land surface temperature). Six Landsat images comprising two time series were
used to calculate the land surface temperature and correlated vegetation indices. The Yellow River
Delta area has expanded substantially because of the deposited sediment carried from upstream
reaches of the river. Between 1986 and 2015, approximately 35% of the land use area of the
Yellow River Delta has been transformed into salterns and aquaculture ponds. Overall, land use
conversion has occurred primarily from poorly utilized land into highly utilized land. To analyze
the variation of land surface temperature, a mono-window algorithm was applied to retrieve the
regional land surface temperature. The results showed bilinear correlation between land surface
temperature and the vegetation indices (i.e., Normalized Difference Vegetation Index,
Adjusted-Normalized Vegetation Index, Soil-Adjusted Vegetation Index, and Modified
Soil-Adjusted Vegetation Index). Generally, values of the vegetation indices greater than the
inflection point mean the land surface temperature and the vegetation indices are correlated
negatively, and vice versa. Land surface temperature in coastal areas is affected considerably by
local seawater temperature and weather conditions.
Unmanned aerial vehicle(UAV) have been increasingly used for natural resource applications in
recent years as a result of their greater availability, the miniaturization of sensors, and the ability to
deploy UAV relatively quickly and repeatedly at low altitudes. UAV remote sensing offer rich
contextual information, including spatial, spectral and contextual information. In order to extract the
information from these UAV remote sensing images, we need to utilize the spatial and contextual
information of an object and its surroundings. If pixel based approaches are applied to extract
information from such remotely sensed data, only spectral information is used. Thereby, in Pixel based
approaches, information extraction is based exclusively on the gray level thresholding methods. To
extract the certain features only from UAV remote sensing images, this situation becomes worse. To
overcome this situation an object-oriented approach is implemented. By object-oriented thought, the
coastal windbreak forest information are extracted by the use of UAV remote sensing images. Firstly,
the images are segmented. And then the spectral information and object geometry information of
images objects are comprehensively applied to build the coastal windbreak forest extraction knowledge
base. Thirdly, the results of coastal windbreak forest extraction are improved and completed. The
results show that better accuracy of coastal windbreak forest extraction can be obtained by the
proposed method, in contrast to the pixel-oriented method. In this study, the overall accuracy of
classified image is 0.94 and Kappa accuracy is 0.92.
This paper monitored the outbreak of green tide in the Yellow Sea, China, in 2014 based on GOCI remote sensing image and NDVI extraction method, combined with GIS (Geographical Information System) and visual interpretation technologies. The results show: the green tide is firstly found in the open waters near Yancheng, Jiangsu Province in mid May, and drifted from the southwest to the northeast direction. When reached the neighboring waters between Jiangsu and Shandong in early June, the green tide entered an outbreak stage and reached the maximum coverage area of 2206.54 km2 in 18, June. In early July, the green tide began into a recession stage until all died in early August while its frontline preserved in Yantai – Weihai – Qingdao. Our work shows GOCI image with high temporal resolution is available for the study of migration path and drift speed of green tide.
In recent years, satellite remote sensing have been widely used in dynamic monitoring of Green Tide. However, the images captured by unmanned aerial vehicles (UAV) are rarely used in floating green tide monitoring. In this paper, a quad-rotor unmanned aerial vehicle was used to mapping the coverage of green tide on the seabeach in Haiyang with three algorithms based on RGB image.The conclusions are as follows: there is discrepancy in both maximum value band among RGB and the difference in the green band for a true color aerial photograph taken from a UAV; the best index for floating green tide mapping on seabeach is GLI. It is possible to have a comprehensive, objective and scientific understanding of the floating green tide mapping with aid of UAV based on RGB image in the seabeach.
This study calculated the land water storage using the time-varying monthly gravity data from the GRACE (Gravity Recovery and Climate Experience) gravity satellite combined with Gaussian smoothing filter. The characteristics of spatiotemporal variations of long-term regional land water storage derived from the linear fitting method were then examined from January 2003 to December 2013. The results showed that the water storage over the huang-huai-hai plain showed an overall declining trend from 2003 to 2013 and the average declining rate is about 2.86 mm/a. The comparison between the GEACE calculation results with the soil moisture content products from the global land data assimilation system (GLDAS) showed that they are very highly consistent. The variations of regional mean soil moisture over the huang-huai-hai plain also exhibited a downward trend from 2003 to 2013 with an average declining rate about 0.74 mm/a. Based on water balance equation, we obtained the change of average groundwater storage and it showed a decreasing variability with a general declining trend with an average rate about 2.22 mm/a. In addition, the retrieved groundwater data was proven to be accurate compared to observations from groundwater wells measurement with high consistency and correlations. . Further investigations focused on analyzing the impacts of precipitation factors on groundwater variations, implying that the human influences are the main reasons for the decline in groundwater.
Phragmites australis is a native dominant specie in the Yangtze Estuary, which plays a key role in the structure and function of wetland ecosystem. One key question is how to estimate the Chlorophyll content quickly and effectively at large scales, which could be used to reflect the growth condition and calculate the vegetation productivity. The aim of this work was to estimate Chlorophyll content of P. australis based on the PROSPECT and DART (Discrete Anisotropic Radiative Transfer) model. A total of 6 widely used Vegetation indices (VIs) were chosen (i.e., Normalized Difference Vegetation Index (NDVI), Structure Insensitive Pigment Index (SIPI), Colouration Index (COI), Simple Ratio Index (SR), Cater Index (CAI), and Red-edge Position Linear Interpolation (REP_Li)) and calculated, and then the relationship between VIs and Cab were analyzed. Results showed that COI and SIPI were sensitive to the leaf chlorophyll content as the chlorophyll content changes at the leaf scale. Meanwhile, no obvious saturation phenomenon was observed for these two indices compared to other indices.
The difficulty of in-situ calibration on the 940 nm channel of Multi-Filter Rotating Shadowband Radiometer (MFRSR) stems from the distinctive non-linear relationship between the amount of precipitable water vapor (PW) and its optical depth (i.e. curve of growth) compared to the counterpart of aerosols. Previous approaches, the modified Langley methods (MLM), require exact aerosol optical depth (AOD) values and a constant PW value at all points participating the regression. Instead, we propose a new method that substitutes the PW optical depth derived from collocated GPS zenith wet delay retrieval in conjunction with meteorology data and requires a constant AOD value at all points participating the regression. The main benefits of the new method include: (1) Aerosol stability is easier to fulfill than PW stability; (2) AOD stability could be inferred from adjacent channels (e.g. 672 and 870 nm) of MFRSR itself without measurements of a collocated AERONET sun photometer; and (3) When applicable, the time interval of GPS derived PW (i.e. 3 minutes) is more compatible with the MFRSR sampling interval (i.e. 3 minutes) than AERONET interpolated AOD (i.e. 15 minutes). Both MLM and the new method were applied to the MFRSR of USDA UV-B Monitoring and Research Program at the station in Billings, Oklahoma (active for 18 years so far) on July 28, 2015. The performances of the two methods are compared in order to assess their accuracy and the advantages and disadvantages.
The Wide Field View (WFV), a space borne multi-spectral sensor onboard the Chinese GaoFen-1 (GF-1) satellite from the China High-resolution Earth Observation System, is operating in orbit dedicating to providing Earth observation with decametric spatial resolution, high temporal resolution and wide coverage for environment monitoring purpose. The objective of this study is to present an integrated image processing and environment monitoring platform specifically for GF-1 WFV data. The platform is developed with a multi-layer architecture and C/S structure, which primarily consists of image pre-processing, environment monitoring, data visualization, and results output modules. The client application was created by using C# whereas IDL was used to develop image processing and other relevant algorithms. This paper focuses mainly on the overall design of the platform and related key techniques. The platform has been implemented as a stand-alone application, and successfully implemented in real world environment monitoring studies.
Multi-Filter Rotating Shadowband Radiometer (MFRSR) and its UV version (UV-MFRSR) are ground-based instruments for measuring solar UV and VIS radiation, deployed together in field at most USDA UV-B Monitoring and Research Program (UVMRP) sites. The performance of the traditional calibration method, Langley Analysis (LA), varies with MFRSR channels and sites, resulting in less confidence in some irradiance products. A two-stage calibration method is developed. We attributed the variation in Langley Analysis performance to the monotonically changing total optical depth (TOD) in the cloud screened points. Constant TOD is an assumption in LA. Since (1) aerosol is the main source of TOD variation at the 368nm channel and (2) UV-MFRSR measures direct normal and diffuse horizontal simultaneously, we used the radiative transfer model (i.e. MODTRAN) to create the look-up table of the ratio of direct normal and diffuse (DDR) with respect to aerosol optical depth (AOD) and solar zenith angle to evaluate the quality of the Langley Offset (VLO) by giving lower weights to VLO generated from points with monotonic AOD variation. With one or two calibrated channels as Reference Channels (RC), the most stable points in RC were selected and LA was applied on those time points to generate VLO at the adjacent un-calibrated channel. The test of this method on the UV-B program site at Homestead, Florida showed that (1) The long-term trend of the original LA VLO is impacted by the monotonic changing in AOD at 368nm channel; and (2) more clustered and abundant VLO at all channels are generated compared with the original Langley method.
Aerosol optical depth (AOD), aerosol single scattering albedo (SSA), and asymmetry factor (g) at seven ultraviolet wavelengths along with total column ozone (TOC) were retrieved based on Bayesian optimal estimation (OE) from the measurements of the UltraViolet Multifilter Rotating Shadowband Radiometer (UV-MFRSR) deployed at the Southern Great Plains (SGP) site during March to November in 2009. To assess the accuracy of the OE technique, the AOD retrievals are compared to both the Beer’s law derived ones and the AErosol RObotic Network (AERONET) AOD product; and the TOC retrievals are compared to both the TOC product of the U.S. Department of Agriculture UV-B Monitoring and Research Program (USDA UVMRP) and the Ozone Monitoring Instrument (OMI) satellite data. The scatterplots of the AOD estimated by the OE method with the Beer’s law derived ones and the collocated AERONET AOD product both show a very good agreement: the correlation coefficients vary between 0.98 and 0.99; the slopes range from 0.95 to 1.0; and the offsets are less than 0.02 at 368 nm. The comparison of TOC also shows a promising accuracy of the OE method: the standard deviations of the difference between the OE derived TOC and other TOC products are about 5 to 6 Dobson Units (DU). The validation of the OE retrievals on the selected dates suggests the OE technique has its merits and is a supplemental tool in analyzing UVMRP data.
In order to improve the accuracy of solar radiation related parameters’ for crop modeling, a new calibration method (Multi-Channel Calibration) for Multi-Filter Rotating Shadow-band Radiometer (MFRSR) is proposed. It uses the Angstrom Law that links aerosol optical depth (AOD) at multiple wavelengths as the primary constraint. It also uses the bi-channel Langley Regression to provide an additional constraint. Starting with any initial guess of calibration coefficient (V0) at 870 nm, two consecutive steps, both involves calling trust region based non-linear optimization module (CONDOR), are implemented to solve (1) the intermediate parameter Angstrom coefficient and the set of biased V0s at other channels corresponding to the initial one at 870 nm channel; and (2) the final V0s of all permissible channels. The result shows that Unlike Langley method, the Multi-Channel Calibration method return V0 at all permissible channels. Besides, the new method can converge to the same (less than 0.5%) final V0s with the starting guess in a wide range. Most important, the comparison between AODs derived from those final V0s and those of AERONET sunphotometers suggests the upper limit of the error of those final V0s is less than 1.03%, which is a great improvement over the Langley V0s (7.45%).
Land is an indispensable natural resource for human, without which we cannot survive and develop. Land-use
change, influenced by both natural environment and human activity, has a close relationship with food security, resource
utilization, biodiversity and climate change. In order to understand the process and driving mechanism of land-use
change, dynamic models were developed in these years, among which Dinamica EGO is a practical one and has been
widely used in the world. In this paper, we aim to use Dinamica EGO to simulate the land-use of China in 2005 with data
extracted from SPOT VGT NDVI. The real land-use map was compared with the simulation result so as to verify the
feasibility of Dinamica EGO. Then we supposed three sceneries under which we could analyze the land-use change of
China in 2020. Results indicated that: on the basis of no extreme natural disasters or exceptional policy fluctuation, the
grassland area would reduce by 22.21 million hectares averagely. However forest would increase by 19.81 billion
hectares on average. Water and unused land would probably remain stable as there was little change in three sceneries.
Farmland areas showed a good agreement under these sceneries whereas the greatest difference in land-use area
estimations lies in built-up with an uncertainty accounting for 1.67%.
Transpiration, an essential component of surface evapotranspiration, is particularly important in the research of surface evapotranspiration in arid areas. The paper explores the spectral information of the arid vegetal evapotranspiration from a semi-empirical perspective by the measured data and the up-scaling method. The paper inverted the transpiration of Haloxylon ammodendronat at the canopy, pixel and regional scales in the southern edge of the Gurbantunggut desert in Xinjiang, China. The results are as follows: At the canopy scale, the optimal exponential model of the sap flow based on the hyperspectrum is Y = 3.65× SR(1580,1600) + 0.76, R2 = 0.72. At the pixel scale, there was a good linear relationship between the sap flow and the SR index, with a linear relationship of Y = 0.0787 X - 0.0724, R2 = 0.604. At the regional scale, based on the optimal exponential model and the EO-1 Hyperion remote sensing data, the transpiration of the study area was inverted. Comparing the results of the SEBAL and SEBS models, the errors of the simulation results were 12.66% and 11.68%. The paper made full use of the knowledge flow at different scales, bridging the scale difference in canopy and remote sensing images to avoid the information bottleneck in the up-scaling. However, there is much limit in the data acquirement, the endmembers determine, the temporal-spatial up-scaling, and the accuracy assessment to be improved in the future studies.
The stem sap flow exhibited a bi-peaked or multi-peaked curve, with lower values at night than
during the day. The ambiguous noon-depression phenomenon usually occurs during 14:00~16:00
from mid-May to the early September. Under the same environmental conditions, the larger the
stem diameter, the larger the stem sap flow, and the more obvious the ambiguous noon-depression
phenomenon. The daily changes of the sap flow were highest in June and lowest in September.
There were differences in the monthly mean value in different plants, which may result from the
differences in the crown and the number of assimilation organ. The daily accumulation showed a
“S” trend between May and the end of August, and showed a straight line with the same slope in
September and October. The larger the stem diameter, the larger the daily water use and the
accumulative rate were. The sap flow was influenced by meterological factors, it was positively
correlated with solar radiation, air temperature and wind speed, and negatively correlated with the
air relative humidity, in which the solar radiation had the greatest impact on the sap flow. Under
the same environmental condition, the larger the stem diameter, the better the correlation was. The
correlation was the largest water use in July, and least in May and October. The larger the stem
diameter, the more the water consumption was.
By using MODIS data products, combined with DEM data, land use data, meteorological data, employed SEBAL model, light use efficiency model, PAR model and the algorithm of vegetation index , the parameters of ET (Evapotranspiration), NPP (Net Primary Product) , PAR (Photosynthetic Active Radiation), NDVI (Normalized Difference Vegetation Index) and EVI (Enhance Vegetation Index) in Haihe River Basin were estimated. The impacts of elevation and land cover change on ET, NPP , PAR , NDVI and EVI are analyzed.
Land-use and land-cover change has been a research focus in global environmental change. Recent research found
that land-use change could influence the structure of biogeochemical spheres as well as material and energy recycle
directly or indirectly. Land-use dynamic models are considered as an effective technique to study the processes of
land-use modification. The objective of this paper is to compare two widely use land-use dynamic models, CLUE-S and
Dinamica EGO, from the perspective of land-use change amount, spatial characteristics, and their utility. A case study
was conducted to examine the ascendants of each model and Kappa coefficient was used to compare the simulation
accuracy. The modelling experiments reflected that the predictions of land-use change based on CLUE-S and Dinamica
EGO matched broadly with actual situation. CLUE-S was better in overall accuracy whereas the Markov process in
Dinamica EGO could precisely predict the amount of land-use change. Moreover, the spatial pattern of simulation map
based on Dinamica EGO was more consistent with empirical result. Both results indicate their possible further
applicability for forecasting future land-use change and corresponding studies.
GEOLUE model was designed with Light Use Efficiency (LUE) mechanism and was validated with
observed data and models comparison (GLOPEM, CASA, and CEVSA). We found that: GEOLUE model
correctly simulates monthly, quarterly and annual variation of Net Primary Product (NPP) in different
vegetation communities under monsoon climate. The spatial distribution of NPP simulated by GEOLUE
matched up to 96.67% with that of forest and shrub land. The GEOLUE model perfectly simulated the
seasonal characteristics and spatial pattern of biomass in different types of vegetation. The total amount
NPP of China simulated by GEOLUE is 0.667GtC in spring, 1.365GtC in summer, 0.587GtC in autumn
and 0.221GtC in winter. The average total NPP of China for 5 years is 2.84GtC / year.
We studied the crop classification in North China using multi-bands MODIS data with time resolution of 8 days and
spatial resolution of 500m in year 2007. Vegetation Index EVI was seen as a robust vegetation indicator and its layers
were stacked in the time dimension to detect the phenology of various vegetation types including our targets crops.
Before classification, a series of data processing steps were performed: first, a comprehensive use of time-frequency
analysis methods such as iterated Savitzky-Golay filtering, multi-resolution analysis and energy threshold based
algorithm was conducted to reduce noises in the EVI series data; second, crop/non-crop boundary was obtained from the
noise reduced data using a binary encoding based algorithm, in which we introduced the concept of "effective width" as
the threshold for crop/non-crop vegetation; third, we analyzed the wave structures including starting/ending/maximum
curvature/minimum curvature/half wave height points and matched them to the typical crops' phenology in North China
to form the training sample sets. The classification methods include ISODATA (unsupervised), SAM (Spectral Angle
Mapper), Minimum Distance and SVM (Support Vector Machine). The results showed that the SVM method had the
highest accuracy: 82.3% in the double-cropping area and 93.4% in the single-cropping area.
Spatial and temporal distribution of vegetation net primary production (NPP) in China was studied using three light-use
efficiency models (CASA, GLOPEM and GEOLUE) and two mechanistic ecological process models (CEVSA GEOPRO).
Based on spatial and temporal analysis (e.g. monthly, seasonally and annually) of simulated results from ecological process
mechanism models of CASA, GLOPEM, and CEVSA, the following conclusions could be made: (1) during the last 20 years,
NPP change in China is followed closely by the seasonal change of climate affected by the monsoon with an overall trend of
increasing. (2) Average annual NPP in China was 2.864±1GtC. All five models were able to simulate spatial features of
biomass for different ecological types in China. This paper provides a baseline for China's total biomass production. It also
offers a means of estimating the NPP change due to afforestation, reforestation, conservation and other human activities and
could aid people in using for-mentioned carbon sinks to fulfill China's commitment of reducing greenhouse gases.
Under the influence of the global change and human activity, the land use/land cover change (LUCC) is remarkable.
The evapotranspiration is one of the key taches of the water cycle. And it's the component of both water balance and
energy balance, which embodiments the balance of the substance, energy and the information system. The
evapotranspiration is closely related to the land use and land cover change. In this paper, we first gives the dynamic
characteristics of the land use and land cover change; and then, the distribution of the land surface water and heat flux
and evapotranspiration, by means of the SEBAL equation, based on the radiation balance equation and energy balance
equation; and finally, based on the tempo-spatial characteristics of evapotranspiration, we discusses the influence of
land use/cover change to the land surface evapotranspiration from two aspects: land use/land cover type and fresh/salt
water.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.