Global Microwave Emission Depth Analyses from AMSR-E, SSMI, and MODIS

A global analysis of microwave emission depth signatures shows that the characteristic temporal behaviors associated with subsurface emission in sand deserts carry over to arid and semi-arid regions worldwide. Previous work showed that the greatly reduced diurnal range of SSM/I brightness temperatures compared to skin temperatures in deserts could be explained by microwave effective emission depths that depended on soil type and microwave wavelength. Here, a similar methodology is applied globally with coincident Aqua AMSR-E and MODIS data used in addition to SSM/I, providing a more complete sample of diurnal cycle extremes. The signatures of significant microwave emission depths can be seen to occur in drier regions globally not dominated by dense forest or crop cover-including, for example, the western half of the continental United States, south central Asia, Australia, and southern Africa and South America.