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Onset and withdrawal of the large-scale South Asian monsoon: A dynamical definition using change point detection

Walker, Jennifer M. and Bordoni, Simona (2016) Onset and withdrawal of the large-scale South Asian monsoon: A dynamical definition using change point detection. Geophysical Research Letters, 43 (22). pp. 11815-11822. ISSN 0094-8276. http://resolver.caltech.edu/CaltechAUTHORS:20170119-102522681

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Abstract

We introduce an objective definition for onset and withdrawal of the South Asian summer monsoon (SASM), based on the large-scale atmospheric moisture budget. The change point (CHP) index allows precise characterization of the different stages and timescales of the large-scale SASM and is highly correlated with the local operational index, the monsoon onset over Kerala. The CHP-based onset and withdrawal dates, which capture the expected seasonal transitions in rainfall and winds, correspond with regime changes in the SASM moisture budget between negative and positive net precipitation. Climatological composites reveal that the seasonal transitions in SASM sector mean precipitation and circulation closely resemble those of the zonal mean Hadley circulation. The CHP index at grid points within the SASM domain yields a robust definition of local onset and withdrawal dates, which are well correlated with the large-scale index on interannual timescales, providing insight into the regional variability of the SASM.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/2016GL071026DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2016GL071026/abstractPublisherArticle
ORCID:
AuthorORCID
Bordoni, Simona0000-0003-4771-3350
Additional Information:© 2016 American Geophysical Union. Received 2 SEP 2016; Accepted 4 NOV 2016; Accepted article online 14 NOV 2016; Published online 22 NOV 2016. This work was supported by the Caltech Terrestrial Hazard Observation and Reporting (THOR) Center. We thank Sabin TP for providing MOK data from the IMD. Reanalysis and precipitation data sources are cited in the text and referred to in the references list. MERRA-2 data are available at http://disc.sci.gsfc.nasa.gov/mdisc/. GPCP data are available at http://precip.gsfc.nasa.gov/. All other data and source code necessary to reproduce this analysis are available from the authors upon request (jwalker@caltech.edu).
Funders:
Funding AgencyGrant Number
Caltech Terrestrial Hazard Observation and Reporting (THOR) CenterUNSPECIFIED
Subject Keywords:monsoon; onset
Record Number:CaltechAUTHORS:20170119-102522681
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170119-102522681
Official Citation:Walker, J. M. and S. Bordoni (2016), Onset and withdrawal of the large-scale South Asian monsoon: A dynamical definition using change point detection, Geophys. Res. Lett., 43, 11,815–11,822, doi:10.1002/2016GL071026
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73548
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Jan 2017 18:36
Last Modified:02 Jun 2017 17:33

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