The role of the subtropical jet in deficient winter precipitation across the mid-Holocene Indus basin

Hunt, K. M. R. ORCID: https://orcid.org/0000-0003-1480-3755 and Turner, A. G. ORCID: https://orcid.org/0000-0002-0642-6876 (2019) The role of the subtropical jet in deficient winter precipitation across the mid-Holocene Indus basin. Geophysical Research Letters, 46 (10). pp. 5452-5459. ISSN 0094-8276 doi: 10.1029/2019GL081920

Abstract/Summary

The mid-Holocene (7-5 ka) was a period with an increased seasonal insolation cycle, resulting from decreased insolation during northern hemisphere winter. Here, a set of six CMIP5 models is used to show that the decreased insolation reduced the upper-tropospheric meridional temperature gradient, producing a weaker subtropical jet with less horizontal shear. These effects work to reduce the baroclinic and barotropic instability available for perturbations to grow, and in consequence, storm-tracking results show that there are fewer winter storms over India and Pakistan (known as western disturbances). These western disturbances are weaker, resulting in a reduction in winter precipitation of around 15% in the north Indus Basin. Combined with previous work showing greater northwestward extent of the Indian monsoon during the mid-Holocene, our GCM-derived results are consistent with the Indus Basin changing from a summer-growing season in the mid-Holocene to a winter-growing season in the present day.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/83142
Identification Number/DOI	10.1029/2019GL081920
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Geophysical Union
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