Relevance of soil moisture for seasonal climate predictions: a preliminarystudy

Citation
H. Douville et F. Chauvin, Relevance of soil moisture for seasonal climate predictions: a preliminarystudy, CLIM DYNAM, 16(10-11), 2000, pp. 719-736
Citations number
36
Categorie Soggetti
Earth Sciences
Journal title
CLIMATE DYNAMICS
ISSN journal
09307575 → ACNP
Volume
16
Issue
10-11
Year of publication
2000
Pages
719 - 736
Database
ISI
SICI code
0930-7575(200010)16:10-11<719:ROSMFS>2.0.ZU;2-Q
Abstract
In the framework of the Global Soil Wetness Project (GSWP). the ISBA land-s urface scheme of the ARPEGE atmospheric general circulation model has been forced with meteorological observations and analyses in order to produce a two-year (1987-1988) soil moisture climatology at a 1 degrees x 1 degrees h orizontal resolution. This climatology is model dependent, but it is the cl imatology that the ARPEGE model would produce if its precipitation and radi ative fluxes were perfectly simulated. In the present study, ensembles of s easonal simulations (March ch to September) have been performed for 1987 an d 1988, in which the total soil water content simulated by ARPEGE is relaxe d towards the GSWP climatology. The results indicate that the relaxation ha s a positive impact on both the model's climatology and the simulated inter annual variability, thereby confirming the utility of the GSWP soil moistur e data for prescribing initial or boundary conditions in comprehensive clim ate and numerical weather prediction models. They also demonstrated the rel evance of soil moisture for achieving realistic simulations of the Northern hemisphere summer climate. in order to get closer to the framework of seas onal predictions, additional experiments have been performed in which GSWP is only used for initialising soil moisture at the beginning of the summer season (the relaxation towards GSWP is removed on 1st June). The results sh ow a limited improvement of the interannual variability, compared to the si mulations initialised from the ARPEGE climatology. However, some regional p atterns of the precipitation differences between 1987 and 1988 are better c aptured, suggesting that seasonal predictions can benefit from a better ini tialisation of soil moisture.