Land-atmosphere coupling over North America in CRCM5

Diro, G. T.; Sushama, L.; Martynov, Andrey; Jeong, D. I.; Verseghy, D.; Winger, K. (2014). Land-atmosphere coupling over North America in CRCM5. Journal of Geophysical Research: Atmospheres, 119(21), pp. 11955-11972. American Geophysical Union 10.1002/2014JD021677

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Land-atmosphere coupling and its impact on extreme precipitation and temperature events over North America are studied using the fifth generation of the Canadian Regional Climate Model (CRCM5). To this effect, two 30 year long simulations, spanning the 1981–2010 period, with and without land-atmosphere coupling, have been performed with CRCM5, driven by the European Centre for Medium-Range Weather Forecasts reanalysis at the boundaries. In the coupled simulation, the soil moisture interacts freely with the atmosphere at each time step, while in the uncoupled simulation, soil moisture is replaced with its climatological value computed from the coupled simulation, thus suppressing the soil moisture-atmosphere interactions. Analyses of the coupled and uncoupled simulations, for the summer period, show strong soil moisture-temperature coupling over the Great Plains, consistent with previous studies. The maxima of soil moisture-precipitation coupling is more spread out and covers the semiarid regions of the western U.S. and parts of the Great Plains. However, the strength of soil moisture-precipitation coupling is found to be generally weaker than that of soil moisture-temperature coupling. The study clearly indicates that land-atmosphere coupling increases the interannual variability of the seasonal mean daily maximum temperature in the Great Plains. Land-atmosphere coupling is found to significantly modulate selected temperature extremes such as the number of hot days, frequency, and maximum duration of hot spells over the Great Plains. Results also suggest additional hot spots, where soil moisture modulates extreme events. These hot spots are located in the southeast U.S. for the hot days/hot spells and in the semiarid regions of the western U.S. for extreme wet spells. This study thus demonstrates that climatologically wet/dry regions can become hot spots of land-atmosphere coupling when the soil moisture decreases/increases to an intermediate transitional level where evapotranspiration becomes moisture sensitive and large enough to affect the climate.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Impact
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography

UniBE Contributor:

Martynov, Andrey

Subjects:

500 Science > 550 Earth sciences & geology
900 History > 910 Geography & travel

ISSN:

2169-897X

Publisher:

American Geophysical Union

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

05 Jan 2015 15:18

Last Modified:

20 Aug 2015 15:56

Publisher DOI:

10.1002/2014JD021677

Uncontrolled Keywords:

land-atmosphere coupling, North America, hot spell, wet spell, extremes, soil moisture

BORIS DOI:

10.7892/boris.61477

URI:

https://boris.unibe.ch/id/eprint/61477

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