COLA / AOES Land Group

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Prof. Paul Dirmeyer
Building: Research Hall
Office: Room 266
Mail stop: 6C5
Phone: +1-703-993-5363
E-mail: pdirmeye~gmu.edu

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JAMES
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The Latest

New textbook is in the works

August 2019: Paul Dirmeyer, with Eleanor Blyth of the Centre for Ecology and Hydrology in Wallingford, UK, will be authoring a textbook on land-atmosphere interactions. The textbook is titled "The Land-Atmosphere System" and will be aimed at advanced undergraduate and graduate students and courses, but should be a resource for anyone in this multidisciplinary field. The book will be published by Cambridge University Press - here is a short version of the book proposal. The final product will undoubtedly deviate from this outline in some details, but the 3-Tier approach is a construct the authors hope will make the book useful to a wide range of readers. The target for publication is 2022.


Recent moves for former staff, students

July 2019: Several recent members of the Land Group have moved on to new positions. In January, Liang Chen took a position in the Climate and Atmospheric Science section of the Illinois State Water Survey. Recent Ph.D graduate Jiexia Wu is now in the Institute of Agricultural Equipment at the Zhejiang Academy of Agricultural Sciences. Two former students are taking positions at NASA Goddard Space Flight Center this Fall in the Hydrologic Sciences Lab: Andrew Badger is finishing his post-doc at U. Colorado and will be working on the Global Precipitaiton Mission with Dalia Kirschbaum. Holly Norton will be working with Augusto Getirana on urban flood modeling. Zhichang Guo has left COLA after 15 years with the Center.


Dirmeyer completes sabbatical

May 2019: But don't call it a "sabbatical" - GMU uses the term "Study Leave". Paul Dirmeyer paid two extended visits to ECMWF: 4 weeks in July 2018, coincidentally during the core of the European heat wave, and 5 weeks during March-April 2019. Gianpaolo Balsamo hosted the visit, which focused on assessment of new improvements to the land surface model, and evaluation of land-atmosphere interactions in IFS and ERA5. Paul also visited NCAR for the month of September 2019. A major goal of the Study Leave was preparation of a textbook proposal and initial writing on the topic of land-atmosphere interactions.


Animation shows seasonal cycle of land-atmosphere coupling

L-A coupling animation

The animation above shows the mean seasonal cycle (moving 30-day window) of global land-atmosphere coupling, estimated from a blend of three reanalyses each covering about 3 decades, and two metrics; one measuring the terrestrial leg and one the atmospheric leg of feedback from land to atmosphere. Green shaded areas show where the link between soil moisture and evaporation is strong, but the atmosphere does not convey the signal from surface fluxes to boundary layer development. Blue areas show the opposite, where the atmospheric link in the feedback loop is in place but the land surface does not convey soil moisture anomalies into surface flux anomalies. Red regions have complete linkage and denote "hot spots" of land-atmosheric coupling, which grow, shrink and migrate during the year.
Fascinating details are evident. L-A coupling over North America expands north from Mexico to Canada in the spring, and retreats slowly in the fall. The onset and disspiation of coupling over Eurasia is much more abrupt. At low latitudes, wet monsoon regions are largely uncoupled (black) but coupling is strong during the dry season. Some areas (e.g., in Queensland, Austalia, Ethiopia or parts of India) remain hot spots throughout the year. Find your favorite corner of the world and stare!