Selection of a 1.3758-μm channel for remote sensing of cirrus clouds and stratospheric aerosols from EOS/MODIS

Abstract

Thin cirrus clouds are difficult to detect in visible and thermal infrared images, particularly over land. Using spectral imaging data measured with the airborne visible/infrared imaging spectrometer (AVIRIS) from an ER-2 aircraft, it has been found that narrow channels close to the center of the strong 1.38 micrometers water vapor band are very effective in separating thin cirrus clouds from clear surface areas. Due to the total absorption of solar radiation by atmospheric water vapor, pixels that do not contain cirrus clouds or stratospheric aerosols are black in images around 1.38 micrometers . Pixels containing cirrus clouds appear white in these images because of the scattering of solar radiation by cirrus clouds. We have selected a near- IR channel centered at 1.375 micrometers with a width of 30 nm for the moderate resolution imaging spectrometer (MODIS) for remote sensing of cirrus clouds from space. This channel may also be useful for remote sensing of stratospheric aerosols when cirrus clouds are absent.