Satellite signatures of the Mississippi Alluvial Valley

May 12th, 2008 |

MODIS images (Animated GIF)

AWIPS images of the MODIS visible channel along with the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) products (above) depicted the areal extent of the Mississippi Alluvial Valley (MAV) on 12 May 2008. This physiographic feature represents the historical flood plain of the lower Mississippi River, which stretches from the confluence of the Ohio River to the Gulf of Mexico. Much of this land has been converted to agricultural use during the past century — because of the marked differences in soil composition and vegetation density between the MAV and the surrounding forest-covered areas, the MAV shows up as a lighter shade of gray on the visible image, with significantly lower NDVI values around 0.2 to 0.3. In addition, significantly warmer LST values were seen in the MAV, which were 20-30 degrees F warmer (darker red colors) compared to the surrounding forested areas (similar warm LST values were also noted over cities and other heavily urbanized locations).