Influence of Land Cover and Soil Moisture based Brown Ocean Effect on an Extreme Rainfall Event from a Louisiana Gulf Coast Tropical System

Authors

Udaysankar S. Nair, University of Alabama in HuntsvilleFollow
Eric Rappin, Western Kentucky University
Emily Foshee, University of Alabama in Huntsville
Warren Smith, National Center for Atmospheric Research & University of Colorado- Boulder
Roger A. Pielke Sr., University of Colorado - Boulder
Rezaul Mamood, University of Nebraska-LincolnFollow
Jonathan L. Case, ENSCO, Inc./NASA Short-term Prediction Research and Transition (SPoRT) Center, Huntsville
Clay B. Blankenship, NASA Short-term Prediction Research and Transition (SPoRT) Center
Marshall Shepherd, University of Georgia
Joseph A. Santanello, NASA-GSFC, Hydrological Sciences Laboratory
Dev Niyogi, Purdue University

ORCID IDs

http://orcid.org/0000-0002-3724-9630

Date of this Version

11-20-2019

Citation

The Author(s) 2019

Comments

(2019) 9:17136 | https://doi.org/10.1038/s41598-019-53031-6

Abstract

Extreme flooding over southern Louisiana in mid-August of 2016 resulted from an unusual tropical low that formed and intensified over land. We used numerical experiments to highlight the role of the ‘Brown Ocean’ effect (where saturated soils function similar to a warm ocean surface) on intensification and it’s modulation by land cover change. A numerical modeling experiment that successfully captured the flood event (control) was modified to alter moisture availability by converting wetlands to open water, wet croplands, and dry croplands. Storm evolution in the control experiment with wet antecedent soils most resembles tropical lows that form and intensify over oceans. Irrespective of soil moisture conditions, conversion of wetlands to croplands reduced storm intensity, and also, nonsaturated soils reduced rain by 20% and caused shorter durations of high intensity wind conditions. Developing agricultural croplands and more so restoring wetlands and not converting them into open water can impede intensification of tropical systems that affect the area.