Identification

Title

Attributing the recent weakening of the South Asian subtropical westerlies

Abstract

<p><span style="-webkit-text-stroke-width:0px;background-color:rgb(255, 255, 255);color:rgb(34, 34, 34);display:inline !important;float:none;font-family:-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;font-size:18px;font-style:normal;font-variant-caps:normal;font-variant-ligatures:normal;font-weight:400;letter-spacing:normal;orphans:2;text-align:start;text-decoration-color:initial;text-decoration-style:initial;text-decoration-thickness:initial;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;">Over the last four decades (1980–2020), the summer westerlies that prevail in South Asia along the monsoon trough region have weakened by about 25% based on multiple reanalysis datasets. Trends in a range of climate model simulations suggest that the weakening is driven by multiple anthropogenic forcings. Over the period, sea-level pressure has increased by 0.6–1.0 hPa over South Asia’s northwestern regions, induced by cooling due to aerosol emission and changes in land use and land cover, and has decreased over the Arabian Peninsula mainly due to warming by greenhouse gases. These changes in temperature and pressure act to weaken the regional pressure gradient, deflecting the subtropical westerlies from South Asia toward the Arabian Peninsula and weakening the winds in the monsoon trough and its adjacent region. The slowing down of winds appears to result in an anomalous moisture loading and increase in rainfall over the semi-arid northwestern South Asia. This weakening and its associated changes in regional climate are highly relevant to policymaking across South Asia.</span></p>

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.net/ark:/85065/d79g5s22

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2024-12-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact