NASA Images Show Anatomy of Pakistan Flood Disaster

In late July 2010, flooding caused by heavy monsoon rains began across several regions of Pakistan. According to the Associated Press, the floods have affected about one-fifth of this country of more than 170 million. Tens of thousands of villages have been flooded, more than 1,500 people have been killed, and millions have been left homeless. The floodwaters are not expected to recede fully before late August. NASA's CloudSat satellite captured the genesis of the flooding event as it flew over the region on July 28, 2010. At that time, a large area of intense thunderstorms covered much of Pakistan. Between July 28 and 29, up to 400 millimeters (16 inches) of rain fell from these storm cells, triggering flooding along the Indus and Kabul Rivers.

Storms with similar structures to this one have become common this summer as tropical monsoon moisture, coupled with a strengthening La Nina, dominate this region's weather patterns. The top portion of the second image, from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua spacecraft, reveals the bright white cloud tops of the cluster of thunderstorms. The blue vertical line shows CloudSat's path at the time the MODIS image was acquired. CloudSat's path cut through a large thunderstorm cell in the northern section of the country. The Cloudsat data are shown in the bottom portion of the first image. As seen in the top half of the bottom image, CloudSat classified the majority of the clouds present at the time as deep convective (cumulonimbus) clouds, typical of thunderstorms.

The bottom half of the lower image shows the 3-D vertical structure of the storm along the satellite's flight path, revealing its heavy precipitation. CloudSat measured the cloud heights along the radar's flight path at around 15 kilometers (9.3 miles) in the areas of deepest convection. The next pair of images was taken by the vertical-viewing camera on the Multi-angle Imaging Spectroradiometer (MISR) instrument aboard NASA's Terra spacecraft. The image on the left was taken Aug. 8, 2009, while the one on the right is from Aug. 11, 2010. These false-color views display the instrument's near-infrared, red and green bands as shades of red, green and blue. The colors distinctly highlight the contrast between water and vegetation on the river banks, since vegetation appears bright in the near-infrared portion of the electromagnetic spectrum.