Publications des scientifiques de l'IRD

Samson G., Masson S., Durand Fabien, Terray Pascal, Berthet S., Jullien S. (2017). Roles of land surface albedo and horizontal resolution on the Indian summer monsoon biases in a coupled ocean-atmosphere tropical-channel model. Climate Dynamics, 48 (5-6), p. 1571-1594. ISSN 0930-7575.

Titre du document
Roles of land surface albedo and horizontal resolution on the Indian summer monsoon biases in a coupled ocean-atmosphere tropical-channel model
Année de publication
2017
Type de document
Article référencé dans le Web of Science WOS:000395060900011
Auteurs
Samson G., Masson S., Durand Fabien, Terray Pascal, Berthet S., Jullien S.
Source
Climate Dynamics, 2017, 48 (5-6), p. 1571-1594 ISSN 0930-7575
The Indian summer monsoon (ISM) simulated over the 1989-2009 period with a new 0.75A degrees ocean-atmosphere coupled tropical-channel model extending from 45A degrees S to 45A degrees N is presented. The model biases are comparable to those commonly found in coupled global climate models (CGCMs): the Findlater jet is too weak, precipitations are underestimated over India while they are overestimated over the southwestern Indian Ocean, South-East Asia and the Maritime Continent. The ISM onset is delayed by several weeks, an error which is also very common in current CGCMs. We show that land surface temperature errors are a major source of the ISM low-level circulation and rainfall biases in our model: a cold bias over the Middle-East (ME) region weakens the Findlater jet while a warm bias over India strengthens the monsoon circulation over the southern Bay of Bengal. A surface radiative heat budget analysis reveals that the cold bias is due to an overestimated albedo in this desertic ME region. Two new simulations using a satellite-observed land albedo show a significant and robust improvement in terms of ISM circulation and precipitation. Furthermore, the ISM onset is shifted back by 1 month and becomes in phase with observations. Finally, a supplementary set of simulations at 0.25A degrees-resolution confirms the robustness of our results and shows an additional reduction of the warm and dry bias over India. These findings highlight the strong sensitivity of the simulated ISM rainfall and its onset timing to the surface land heating pattern and amplitude, especially in the ME region. It also illustrates the key-role of land surface processes and horizontal resolution for improving the ISM representation, and more generally the monsoons, in current CGCMs.
Plan de classement
Limnologie physique / Océanographie physique [032]
Description Géographique
OCEAN INDIEN ; ASIE
Localisation
Fonds IRD [F B010069408]
Identifiant IRD
fdi:010069408
Contact