Origin of cold bias over the Arabian Sea in climate models

S. Sandeep, Ajaya Ravindran

    Research output: Contribution to journalArticle

    Abstract

    Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation.

    Original languageEnglish (US)
    Article number6403
    JournalScientific Reports
    Volume4
    DOIs
    StatePublished - Jan 1 2014

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    climate modeling
    sea surface temperature
    monsoon
    spring (season)
    summer
    temperature gradient
    entropy
    sea
    cold
    subsidence
    desert
    divergence
    winter
    air
    CMIP
    land

    ASJC Scopus subject areas

    • General

    Cite this

    Origin of cold bias over the Arabian Sea in climate models. / Sandeep, S.; Ravindran, Ajaya.

    In: Scientific Reports, Vol. 4, 6403, 01.01.2014.

    Research output: Contribution to journalArticle

    Sandeep, S. ; Ravindran, Ajaya. / Origin of cold bias over the Arabian Sea in climate models. In: Scientific Reports. 2014 ; Vol. 4.
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