NASA has rolled out a new blog devoted to earth science, entitled "What on Earth", during the 2009 Fall Meeting of the American Geophysical Union (AGU). Despite the fact that NASA has launched and operated numerous Earth observing satellites, including the Terra-Aqua-Aura Earth Observing System, many people are still unfamiliar with NASA's leading role in earth science. Data from NASA's satellites is found in the growing number of interfaces in the GES DISC Giovanni system.
One of the first posts on the "What on Earth" blog highlighted a paper by Marshall Shepherd, Dev Niyogi, and Thomas L. Mote, which examined tornado frequency in spring following autumn and winter seasons with reduced precipitation; this notably occurred in the U.S. Southeast over the past four years. Despite the ocurrence of strong tornadoes in Georgia during this period (particularly the March 14, 2008 twister that wrecked parts of central Atlanta as it rambled through), the researchers found that when autumn and winter precipitation was below normal (especially during droughts), subsequent spring tornado activity appeared to be reduced. It was definitely clear that when autumn-winter precipitation was below normal, spring tornado activity was never above normal.
The researchers used Global Historical Climatological Network (GHCN) data and Legates and Willmott gauge precipitation measurements acquired from the GES DISC. A Giovanni plot of TRMM 3B43 precipitation anomalies, illustrating the drought conditions occurring in the region between February 2006 and February 2008 (utilizing the Willmott–Matsuura rainfall climatology) was overlain with the two study regions considered.
The paper, published in Environmental Research Letters, is available online:
A seasonal-scale climatological analysis correlating spring tornadic activity with antecedent fall–winter drought in the southeastern United States