Droughts of the Late 1980s in the United States as Derived from NOAA Polar-Orbiting Satellite Data

Drought is one of the most adverse and powerful weather-related disasters that occur every year across a portion of the United States. The consequences of droughts quite often can be devastating. To mitigate these consequences, droughts require careful monitoring. Recently, NOAA's National Environmental Satellite Data and Information Service developed a new Advanced Very High Resolution Radiometer–based vegetation condition index (VCI) that showed good results when it was used for drought detection and tracking. The VCI is a vegetation index with reduced noise and is adjusted for land climate, ecology, and weather conditions. This index provides a quantitative estimate of weather impact on vegetation and also measures vegetation conditions. Several large-area experiments showed that the VCI had excellent ability to detect drought and to measure the time of its onset and its intensity, duration, and impact on vegetation. The VCI provides accurate drought information not only for the cases with well-defined, prolonged, widespread, and very strong droughts, but also for very localized, short-term, and ill-defined droughts. The advantages of this index compared to conventional ground data are in providing more comprehensive, timely, and accurate drought information. This paper describes the methodology and technical principles used to derive the vegetation condition index, explores data processing, and gives many examples of VCI application for drought monitoring in the United States during 1985–90. The spatial and temporal patterns of VCI-derived drought were in a very good agreement with the identical patterns identified from precipitation and yield anomalies.