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Modulation of ISOs by land-atmosphere feedback and contribution to the interannual variability of Indian summer monsoon

Saha, SK and Halder, S and Suryachandra Rao, A and Goswami, BN (2012) Modulation of ISOs by land-atmosphere feedback and contribution to the interannual variability of Indian summer monsoon. Journal of Geophysical Research D: Atmospheres, 117 (13).

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Abstract

A mechanism of internal variability of Indian summer monsoon through the modulation of intraseasonal oscillation (ISO) by land-atmosphere feedback is proposed. Evidence of feedback between surface soil moisture and ISOs is seen in the soil moisture data from GSWP-2 and rainfall data from observations. Using two sets of internal simulation by a regional climate model (RCM), it is shown that internally generated anomalous soil moisture interacts with the following ISO and generates interannual variability. To gain further insight, 27 years of sensitivity experiment by prescribing wet (dry) soil moisture condition during break (active) period along with a control simulation are carried out. The sensitivity experiment reveals the large-scale nature of soil moisture and ISO feedback which takes place through the changes in atmospheric stability by altering lower-level atmospheric conditions. The feedback is inherent to the monsoon system and a part of it acts through the intraseasonal varying memory of soil moisture. The RCM used to test the hypothesis is constrained by one-way interactions at the lateral boundary. Experiments with a much larger domain upheld the findings and hence suggest the true nature of soil moisture and ISO feedback present in the monsoon system.

Item Type: Article
Additional Information: Copyright of this article belongs to American Geophysical Union.
Uncontrolled Keywords: Atmospheric conditions; Atmospheric stability; Control simulation; Indian summer monsoon; Interannual variability; Internal variability; Intraseasonal oscillations; Lateral boundary; Moisture conditions; Monsoon system; Rainfall data; Regional climate models; Surface soil moisture, Atmospheric thermodynamics; Climate change; Climate models; Experiments; Soil moisture, Tropical engineering, annual variation; atmospheric dynamics; boundary layer; climate modeling; climate oscillation; experimental study; feedback mechanism; hypothesis testing; moisture flux; monsoon; regional climate; soil moisture; summer
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 28 Dec 2013 18:02
Last Modified: 28 Dec 2013 18:02
URI: http://moeseprints.incois.gov.in/id/eprint/470

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