Deviation Correction Scheme of FY-4A SSI Product in the Position of Sparse Radiation Observations

Abstract

As the basis of the forecasting of solar radiation and power generation， the quality of observed radiation data has gradually become the key problem that restricts the forecasts’ level.FY-4A SSI product are tried to apply in order to effectively solve the problem of solar radiation observation data shortage on the location of photovoltaic power stations in the weather forecast service of photovoltaic power generation.In this study， three photovoltaic power stations on the location of sparse ground-based radiation observations are selected as the research areas， where the deviation correction of FY-4A surface solar irradiance is carried out using the probability density function matching method （PDF）.The PDF method adjusts the satellite retrievals through matching it’s probability density function against that based on situ observations.One advantage of this technique is that it is capable of correcting retrieval errors that are range dependent.According to the location of photovoltaic power stations and the temporal and spatial distribution of solar energy resources in Inner Mongolia， the temporal and spatial windows of PDF model are determined and then the PDF model is established.By the tests of basing the observation data on the location of photovoltaic power stations， results indicate that： The correction results of PDF method in the three research areas are similar.It is feasible to correct FY-4A SSI product in the effective area by using ground-based radiation observation.After correction， the correlation coefficients improve from 0.83~0.84 to 0.84~0.85， the mean errors decrease from 50.8~113.5 W·m-2 to 12.6~68.4 W·m-2， the mean absolute errors decrease from 107.8~174.0 W·m-2 to 92.8~135.3 W·m-2， and the mean absolute percentage errors decrease from 44.4%~92.6% to 27.0%~57.4%.The correlation coefficients， mean errors， mean absolute errors and mean absolute percentage errors of the research areas improve in varying degrees after correction， and the improvement effect of mean errors and mean absolute percentage errors is particularly obvious.The PDF method can improve the FY-4A’s overestimations in the range of low value radiations nd underestimations in the range of high value radiations.It has a strong correction ability to FY-4A total irradiance under precipitation and cloudy weather conditions.In these two conditions， the mean absolute errors are reduced by 19.9%~62.2% compared with that before correction.And the PDF method can improve the total irradiance of FY-4A in all seasons， especially in spring， summer and autumn.Affected by the limitations of FY-4A inversion algorithm， the improvement effect is the least obvious in winter.

Keywords

• fy-4a
• solar radiation
• photovoltaic power station
• correction
• the pdf method