Detection of high clouds in polar regions during the daytime using the MODIS 1.375-μm channel

Identification of clouds over Earth´s polar regions is difficult from satellite radiometric measurements in the visible and infrared (IR) atmospheric window regions because of the high albedos of snow- and ice-covered surfaces in the visible and the low-temperature contrast between the surface and the troposphere in the IR. The Moderate Resolution Imaging SpectroRadiometer (MODIS) on the Terra Spacecraft has a near-IR channel located within the strong water vapor absorption regions close to 1.38 μm. This channel was originally designed for remote sensing of high-altitude clouds in the tropical and mid-latitude regions. In this paper, we report that this channel is also quite useful for detecting high clouds in polar regions during the daytime. Comparisons with IR emission techniques for polar cloud detections are also presented.