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

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 observation...

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Bibliographic Details
Published in:Journal of Geophysical Research: Atmospheres 2012-07, Vol.117 (D13), p.1J-n/a
Main Authors: Saha, Subodh Kumar, Halder, Subhadeep, Suryachandra Rao, A., Goswami, B. N.
Format: Article
Language:English
Subjects:
Atmosphere
Climate models
Earth sciences
Earth, ocean, space
Exact sciences and technology
Geophysics
Hydrologic data
land-atmosphere interaction
monsoon ISOs
Monsoons
Soil moisture
Soil surfaces
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Summary: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. Key Points Indian summer monsoon and ISO interaction through soil moisture memory Mechanism of ISO variability through internal feedback Simulation of monsoon by regional climate model
ISSN:0148-0227
2169-897X
2156-2202
2169-8996
DOI:10.1029/2011JD017291