Satellite-Based Imagery Techniques for Daytime Cloud/Snow Delineation from MODIS

Abstract

This paper presents two multispectral enhancement techniques for distinguishing between regions of cloud and snow cover using optical spectrum passive radiometer satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS). Fundamental to the techniques are the 1.6- and 2.2-μm shortwave infrared bands that are useful in distinguishing between absorbing snow cover (having low reflectance) and less absorbing liquid-phase clouds (higher reflectance). The 1.38-μm band helps to overcome ambiguities that arise in the case of optically thin cirrus. Designed to provide straightforward, stand-alone environmental characterization for operational forecasters (e.g., military weather forecasters in the context of mission planning), these products portray the information that is contained within complex scenes as value-added, readily interpretable imagery at the highest available spatial resolution. Their utility in scene characterization and quality control of digital snow maps is demonstrated.

Illuminating the Capabilities of the Suomi National Polar-Orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band

“…The ability of multispectral satellite observations to distinguish snow cover from bare land and clouds during the daytime has led to important advances in the capacity of snow field monitoring [16][17][18][19][20][21]. However, challenges exist at night.…”

New Approach for Snow Cover Detection through Spectral Pattern Recognition with MODIS Data

“…Therefore, discrimination between snow and clouds is not simple. In particular, it is extremely difficult to differentiate them using a single channel [42]. In the shortwave band (1.6 m), snow cover has lower reflectance than clouds [21].…”

“…In the shortwave band (1.6 m), snow cover has lower reflectance than clouds [21]. Thus, reflectance at 1.6 m is widely used for discrimination between snow cover, snowfree land, and clouds, including in NDSI calculations with other threshold methods [7,12,18,28,42,43]. As mentioned, threshold methods have been widely used in previous studies for detection of snow cover but can cause errors such as misdetection or false detection, because these methods do not consider the variation in reflectance from snow cover due to sun-target-sensor geometry and the characteristics of snow such as contamination, age, and particle size.…”

Cover. Operation Iraqi Freedom in MODIS collage

“…Miller et al 2005) were designed to support operations near the mountainous northern borders of Iraq with eastern Turkey and western Iran. These specific regions are shown in figure 1, with the transitions into true colour intended to emphasize the ambiguity between clouds and snow in visible imagery.…”