Accurate quantification of precipitation partitioning into evapotranspiration and runoff is important for global water balance estimation and water resources managements. The Budyko framework is a simple yet robust solution to parameterize precipitation partitioning and has been widely applied for studying catchment-level water and energy fluxes. However, substantial variations between the observed and Budyko-predicted evaporative indices have been observed. Many studies have attributed the scatter around the Budyko curve to catchment characteristics (e.g., vegetation and soil property), which are not directly accounted for in the Budyko framework. However, modified Budyko-type equations that consider catchment characteristics are not transferable between regions and the interannual catchment behaviours still fail to follow the adjusted Budyko trajectories. To explore if the pronounced Budyko scatter in humid catchments has a systematic pattern caused by measurable catchment properties, this study comprehensively investigated the relationship between Budyko scatter and multiple catchment biophysical features from both spatial and temporal perspectives. Results reveal that for humid catchments, topography and seasonal cumulative moisture surplus can explain the spatial distributions of Budyko scatter with r higher than 0.65, whereas soil properties and vegetation indices explained little of the variance (r≤0.30). Temporally, the interannual variability of Budyko scatter was negatively correlated with annual average vegetation indices, particularly for catchments with relatively low vegetation cover. Overall, this study provides valuable insights to the interpretation of Budyko framework and offers possible solutions to improve its performance to predict the spatio-temporal variability of water balances.
The paper presents the optical power absorption simulation in a silicon solar cell utilizing single and double diffraction gratings at varying locations (depths) within the device. The solar cell under discussion consists of a rectangular top grating, P-type Si, N-type Si, a rectangular bottom grating, and a reflective material on the bottom. We use 3D finite differential time domain (FDTD) simulations to calculate the power at the solar cell PN interface at wavelengths ranging from 300nm to 1100nm. Throughout simulation, the structure of the gratings remains unchanged – only its location within the device varies, which is accomplished by varying the thickness of the P and N regions. The spectrum of incident solar light and the photo-responsivity of silicon are also took into account to obtain a total weighted power factor, allowing comparison between all simulated cases. We find an increase in weighted power absorption (compared to the non-grating case) ranging from 42% to 72% across all simulated grating locations. Overall, our simulations show that varying the location of the grating(s) changes the amount of power absorbed, and that certain device thicknesses correspond to increased power absorption and are preferred in the design.
This study concentrates on solar light absorption power in a silicon solar cell using a double diffraction triangular
nano-grating. The first grating is located on top of the solar cell and the second grating is located on bottom of the
solar cell above a reflective metallic substrate of Ar (Si3 N4 ) (Argon gas mixed with Silicon Nitride). We simulate the
solar cell behavior over varying grating parameters as it absorbs sunlight and compare the average power output
absorbed at the center of the solar cell. Each case simulates a period (At ) that varies from 100nm to 800nm in 100nm
interval for the top lattice, while maintaining the bottom lattice at a constant period (Ab ). We repeat this procedure
for the bottom lattice, changing the lattice period from 100nm to 800nm in 100nm interval in order to find the
optimized case. We also consider solar spectrum irradiation under wavelengths ranging from 300nm to 1100nm in
50nm intervals. The total power absorption improvement is about 170% compared to the non-grating case, occurring
in the weighted solar cell simulation with top grating period greater than 300nm and bottom grating period of
500nm.
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