UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Influence of ENSO on Regional Indian Summer Monsoon Precipitation-Local Atmospheric Influences or Remote Influence from Pacific

Roy, I; Tedeschi, RG; (2016) Influence of ENSO on Regional Indian Summer Monsoon Precipitation-Local Atmospheric Influences or Remote Influence from Pacific. Atmosphere , 7 (2) , Article 25. 10.3390/atmos7020025. Green open access

[thumbnail of atmosphere-07-00025.pdf]
Preview
Text
atmosphere-07-00025.pdf - Published Version

Download (3MB) | Preview

Abstract

Using CMIP5 model outputs in different El Niño-Southern Oscillation (ENSO) phases, this work investigates the indicator that could be used as an Index to characterise regional Indian Summer Monsoon (ISM) precipitation. Dividing the Indian subcontinent into five arbitrarily chosen regions, viz. Central North East (CNE) (18˝N–31˝N, 86˝E–75˝E), Hilly (H) (28˝N–38˝N, 85˝E–70˝E), North West (NW) (21˝N–31˝N, 79˝E–67˝E), North East (NE) (21˝N–31˝N, 86˝E–97˝E) and Southern India (S) (18˝N–7˝N, 73˝E–85˝E), local wind field and remote influences from the tropical Pacific are considered to improve understanding of regional monsoon rainfall. Results are also compared with observations/reanalysis data to pinpoint areas of shortcomings and agreements. Model results suggest that regional wind velocity, viz. meridional wind component (V) at 850 mb level (V850) and zonal component at 200 mb (U200) and 850 mb (U850) can yield better estimation of local precipitation in regions CNE, H and NW, agreeing well with earlier proposed monsoon Indices. Such observations are independent of different subcategories of ENSO phases and models show good correspondence with observations. Analyses with V at 200 mb (V200) indicate circulation of the upper branch of Hadley cells in regions CNE and S, though suggest the best agreement among models in comparison with other fields, but there are some deviations from observations, indicating a missing mechanism in the models. Using models, this study identified the best parameter in different regions that could be used for the regional monsoon Index, irrespective of various ENSO subcategories; for CNE it is the U200, for H it is U200 and U850, and for NW it is U850. The current analysis, however, fails to indicate anything clearly about the NE region. When focusing on the remote influence from the eastern Pacific region, it is found that atmospheric contribution to regional ISM precipitation fails to indicate consistent roles among models, but sea surface temperature suggests strong connection. However, remote influence from the Central Pacific is captured uniformly in models via zonal components of wind in the H and NW regions.

Type: Article
Title: Influence of ENSO on Regional Indian Summer Monsoon Precipitation-Local Atmospheric Influences or Remote Influence from Pacific
Open access status: An open access version is available from UCL Discovery
DOI: 10.3390/atmos7020025
Publisher version: https://doi.org/10.3390/atmos7020025
Language: English
Additional information: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited https://creativecommons.org/licenses/by/4.0/
Keywords: Indian Summer Monsoon; ENSO Modoki; Canonical ENSO; CMIP5 models; Monsoon Index; Walker circulation; Hadley circulation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Inst for Risk and Disaster Reduction
URI: https://discovery.ucl.ac.uk/id/eprint/10122767
Downloads since deposit
32Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item