Modelling evapotranspiration in provincial regions based on FY-3/VIRR remote sensing data

Abstract: In order to expand meteorological satellite FY-3 in scientific research, the application of remote sensing inversion of the data is needed for evapotranspiration studies. Based on FY-3/VIRR channel characteristics and use of Shandong as a case study area, we proposed to use FY-3 satellite remote sensing data for regional evapotranspiration inversion and to establish a provincial regional daily evapotranspiration estimation system based on the surface energy balance equation in combination with ground meteorological elements ( air temperature and wind speed). To test our newly developed system for estimation of evapotranspiration, we used May 11, August 20, October 16, 2013 as our study dates. The results showed that evapotranspiration estimated from the inversion of the FY-3/VIRR data was respectively -0.19 mm/d, -0.12 mm/d, and 0.16 mm/d difference for the three tested dates as compared to the results obtained from the Penman equation. The relative deviation of the results between the two methods was 10%, 12% and 11% for the three tested dates, respectively. The tested results showed a better FY-3 data quality for the distribution patterns that reflected different types of surface evapotranspiration and features including the daily highest evapotranspiration in a variety of water surfaces. Followed by the types of water surface was the artificial influence of land uses such as arable land, urban, etc. The least affected by human activities for the evapotransiration was mainly natural vegetation and land cover types, such as woodlands, shrubs. The bare land had the lowest evapotranspiration inversion which accurately revealed the different land cover types in the area of evapotranspiration and the space characteristics and differences. Evapotranspiration spatial distribution of farmland has important implications for drought monitoring, irrigation, etc., It is necessary to conduct further analysis of cropland evaporation. Depending on grain yield, farmland can be divided into high, medium and low-yield fields. Evapotranspiration over the different grain yield types showed that amount evapotranspiration was high in the high and middle yield field and low in the low yield field. In the high and middle yield field, paddy water conditions were relatively good, soil water supply was adequate and crop growth was good resulting large amount of actual evapotranspiration. For the low yield field, soil water supply was poor resulting poor crop growth and hence small amount of actual evapotranspiration. The estimated result conformed to the water consumption characteristics of grain filling stage of wheat. The segment EOS/MODIS evapotranspiration product comparison analysis showed that: two kinds of daily ET overall spatial distribution was very similar with correlation coefficients >0.99 and the mean square root difference <0.36 mm. The above analysis showed that in the absence of data for measured evapotranspiration for all land cover types, the estimated daily ET using FY-3/VIRR through mutual comparison and verification of the results of the past studies were reasonable. This study showed a great potential in future evapotranspiration retrieval operation using Chinese FY-3/VIRR satellite data.