Estimating global solar radiation using a hybrid parametric model from MODIS data over the Tibetan Plateau

Abstract

The Tibetan Plateau plays an important role in global atmospheric circulation with its complex terrain. The downward surface shortwave radiation (DSSR) can be obtained from remote sensing data because of its sparse observations and rugged surface. In this paper, a satellite-based scheme is presented to retrieve all-sky downward surface shortwave radiation, which links a look-up table algorithm and satellite images. The look-up table for clear sky and cloudy sky was created separately using a comprehensive 1D physically based radiative transfer model SBDART to achieve a higher computational accuracy and efficiency compared to the comprehensive radiative transfer model. The estimated DSSR was validated using one year pyranometer measurements from 8 stations in the Tibetan Plateau and compared with GEWEX-SRB data with 1°spatial resolution. The result shows that the largest root mean square error was 60 W/m 2 (32%) at Guoluo station, and the least root mean square error was 13 W/m 2 (13%) at Golmud station. The bias was larger in summer and smaller in winter, which may be caused by uncertainties in the assumption from the 1D radiative transfer model and MODIS cloud properties product for broken and inhomogeneous clouds. The algorithm we proposed can be applied globally without local calibration because it is independent of climate and the surface elevation.

Snow depth variability across the Qinghai Plateau and its influencing factors during 1980–2018

“…A possible explanation for this phenomenon is that high elevation areas in the southeast and east have colder air temperature and more precipitation, contributing snow cover formation (Zhang et al, 2021a). However, lower Moreover, the snowfall is low in many parts of the QP (Su et al, 2022b), and the strong solar radiation makes the newly formed snow sublimation disappear before it can be detected by satellites (Zhang et al, 2015;Shuhai et al, 2017), so the snow depth may not increase with precipitation in these areas. Due to the lack of available and accurate snowfall grid data, we did not utilize snowfall data in the analysis.…”

Process time and MPPT performance analysis of CF, LUT, and ANN control methods for a PMSG-based wind energy generation system

“…The equations for the electromagnetic torque, the electrical speed, and the mechanical speed of the PMSG are given in Eqs. (7), (8), and (9), respectively.…”

“…Based on an evaluation of previous studies performed with the artificial neural network (ANN), look-up table (LUT), and curve-fitting (CF) controllers [1][2][3][4][5][6][7][8][9][10], it is possible to see that Hui et al [1] performed the maximum power point tracking (MPPT) of a low-power PMSG by utilizing the results of a simulation in which wind speed was estimated with an ANN controller. The control method they proposed was then applied to a variable-speed cage induction machine wind generation system.…”

“…They then compared the simulation results for the ANFIS and fuzzy logic controllers. Zhang et al [7] used the LUT algorithm to estimate solar radiation; based on the method they proposed, they were able to significantly develop the downward surface shortwave radiation estimations for regions with periodic meteorological conditions and complex terrain by using LUT controllers. Employing the LUT method, Benammar et al [8] estimated angles based on the sinus and cosine signals generated by the resolver and sinusoidal encoder.…”

Estimation of daily, weekly and monthly global solar radiation using ANNs and a long data set: a case study of Fortaleza, in Brazilian Northeast region

“…Through the last years, a high number of models have been designed to assess the global solar irradiation over a horizontal surface. Among them, it highlights the empirical models [10,11], satellite data based [12,13], stochastic [14,15], heuristics [6,16,17] and statistical [12,18,19] models.…”