Professor, Department of Atmospheric, Oceanic, and Earth Sciences
I study the role of the land surface in the climate system. This includes the development and application of land-surface models, studies of the impact of land surface variability on the predictability of climate, interactions between the terrestrial and atmospheric branches of the hydrologic cycle, and the impacts of land use change on regional and global climate. My research spans time scales from the diurnal (daily) cycle to centuries and spatial scales from hundreds of meters to global.
■ To explore how regional changes in land use could alter land-atmosphere interactions against the backdrop of a warming climate. This includes examination of important climate processes over land within observational data and models to quantify (1) the relationships between soil moisture, vegetation, and surface fluxes; (2) the connection between surface fluxes and the development of the atmospheric boundary layer, clouds and precipitation; (3) the role of the biogeophysical elements in these processes. Regions of strong land-atmosphere feedback in the physical climate system will likely evolve and migrate significantly in a changing climate.
■ Research to enhance our understanding of the connection between droughts and heat waves in the US, and to evaluate the ability of forecast models to predict heat wave occurrence. We evaluate multiple operational and research models from the US and overseas for their ability to predict heat waves following drought events, relate forecast performance to coupled land-atmosphere metrics, and assess how land surface states may affect predictions.
■ To improve US capability to predict weather variability on sub-seasonal time scales arising from soil moisture anomalies, and by better using information from ensembles of different numerical model forecasts to increase prediction skill.
■ Dirmeyer, P. A., et al. (2005). The second Global Soil Wetness Project (GSWP-2): multi-model analysis and implications for our perception of the land surface. Bull Amer Meteor Soc, 87, 1381-1397.
■ Koster, R. D., et al. (2004). Regions of strong coupling between soil moisture and precipitation. Science, 305(5687), 1138-1140.
■ Dirmeyer, P. A. (2011). The terrestrial segment of soil moisture–climate coupling. Geophys Res Lett, 38(16).
■ Dirmeyer, P. A., et al. (2012). Simulating the diurnal cycle of rainfall in global climate models: resolution versus parameterization. Clim Dyn, 39(1-2), 399-418.