Estimation of near-surface air temperature from HJ-1B satellite data in Northwest China

Abstract: Near-surface air temperature is an important meteorological parameter, and is closely related to agriculture production. In this paper, the temperature-vegetation index method (TVX method, also called contextual method) for the area-wide mapping of instantaneous air temperature was adopted for use with HJ-1B data in Northwest China. The approach was complemented with an iterative filtering routine for eliminating outliers, and an interpolation algorithm for filling in data gaps. The air temperature at the time of satellite passing through was estimated from the maximum and minimum air temperature measured in a meteorological station with a simple sine curve model, and we still labeled it as "measured" air temperature. The improved generalized single-channel algorithm was adopted for retrieved surface temperature, and the results were validated by comparison with MODIS land surface temperature products (MOD11_L2). In addition, the meteorological measured air temperatures and three scenes HJ-1B data on July 20,2010, August 28, 2010, and August 8, 2011 were adopted for parameterization of NDVImax. Then the NDVImax was applied to HJ-1B data on August 28, 2011, and the retrieved air temperatures were validated by the meteorological measured air temperatures. The results showed that the land surface temperature retrieved with the improved algorithm were consistent with those provided by the MODIS product, and that the satellite-derived air temperature also had a consistent distribution with land surface temperature, the satellite-derived air temperatures were in good agreement with the meteorological observed values with MAE=2.16 K, RMSE=2.72 K, and the accuracy was in line with previously reported results for the TVX method. There are difficulties in relating the satellite-derived air temperature to a fixed shelter height, therefore the results of this study showed that the remote sensing approach tends to overestimate the in situ air temperatures. It is concluded that near-surface air temperature can be retrieved effectively from HJ-1B satellite data through the use of the TVX method.