A powerful computing tool allows scientists to compare two of the most hazardous events in recent U.S. history.
The summer of 1988 saw much of the United States bake in a heat wave that resulted in the worst season of drought since the 1930s. Five years later in 1993, drenching rains in the spring and summer caused historic flooding in Midwest states. A complex combination of weather and climate factors gave rise to these opposing catastrophes. To better understand these events scientists used an integrated record of Earth's weather and climate over the past three decades that combines computer modeling with a broad collection of satellite and meteorological observations. This dataset, called the Modern Era Retrospective-Analysis for Research and Applications (MERRA), allows scientists to pinpoint the unique conditions behind the 1988 drought and 1993 floods. The pattern of air circulation over the middle of the country in 1988 blocked the typical movement of moisture from the Gulf of Mexico northward. Conversely, 1993 saw an extreme intensification of winds pushing rain clouds north from the Gulf of Mexico. In the visualizations below, look for the differences in this recreation of wind patterns over the United States from May 1 to July 31 in 1988 and 1993.