Alys Thomas

[2011, 2012, 2013]

https://fellowships.nasaprs.com/gsrp/nav/

Location: Goddard Space Flight Center

Advisor: Dr. Matthew Rodell, Hydrological Science Lab

Summary of Research Project

When this project was first proposed, my overarching goal was to investigate/characterize drought using NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite data across a variety of regions throughout the world. Since then, the project has progressed admirably, becoming more defined and focused. The major challenges were developing the proper methodology for drought characterization using the GRACE-observed terrestrial water storage anomalies and determining how other datasets (precipitation, soil moisture, streamflow, temperature, vegetation greenness indices) could be incorporated into the analysis to make the results more robust.

In the first two years, the focus was on researching and applying various statistical methods to the GRACE data to quantify the variability of extremes in the dataset. The secondary objective was determining how to track the propagation of storage anomalies from a spatial perspective. I’ve had the opportunity to present the various stages of this work at several conferences and seminars over the past two years. Highlights include: presenting for a terrestrial water cycle-themed seminar series at GSFC, giving my first talk at the American Meteorological Society Annual Meeting in Austin, TX, and presenting a poster at the American Geophysical Union Annual Meeting a third time. I was also nominated into the 2013 NASA Student Ambassador Virtual Community because the GSRP fellowship gave me the opportunity to work at the GSFC Hydrologic Science Lab.

Recently, I finished writing my first journal article manuscript to be submitted within the next two months. This paper summarizes a majority of the work conducted in the last two years. It discusses how we quantified the severity of GRACE-observed water storage deficits using three metrics: total event severity, severity in terms of accumulated storage deficits, and a severity index based on standardized storage heights. Four regions are highlighted: the Amazon and Zambezi river basins, the Southern Plains (U.S.A.), and the Southeastern United States.

At this moment, I am concentrating on editing my manuscript for publication so that I can move on to exploring other facets of this project that will be incorporated in my dissertation. This includes: spatio-temporal propagation of hydrologic drought, using outputs from hydrologic computer models to augment the GRACE dataset, and the development of a GRACE-based drought index that takes into account anthropogenic influences on the hydrologic system, particularly the increased extraction of groundwater during drought episodes.

Having the GSRP fellowship these past three years gave me the opportunity to travel to several conferences where I presented my research and received vital feedback from scientists and experts in my field. My 10-week stays in Washington, D.C., working at Goddard Space Flight Center (GSFC) were invaluable. I had immediate access to the NASA servers where I worked with computer models. The scientists that created and ran these important global land models (within the GLDAS and NLDAS assimilation systems) made themselves available when I required assistance while learning how to: read and alter the computer code, interpret the outputs, and work through complications. Working down the hall from my NASA Technical Advisor helped me make progress at a faster pace because I did not have to wait for email response when I had questions that needed to be answered. He was also accessible when we needed to discuss data analysis and methodology.