*2.3. MODIS Data*

NASA's moderate resolution imaging spectroradiometer (MODIS) was launched aboard the Earth observing system (EOS) aqua satellite in May 2002 and provides atmospheric, terrestrial and oceanic data products [30]. With 36 spectral bands, the highest of any global coverage moderate resolution imager, and spatial resolution ranging from 250 m to 1 km, MODIS is able to provide a multitude of global land products [30]. In this study, daily normalized difference vegetation index (NDVI) and land surface temperature (LST) from MODIS were used to downscale SMAP soil moisture estimates. The 1 km daily LST (MYD11A1), 1 km biweekly NDVI (MYD13A2), and 500 m biweekly climate modeling grid (CMG) NDVI (MYD13C1) were utilized in this study.
