La Niña's diminishing fingerprint on the central Indian summer monsoon
La Niña years tend to provide increased Indian summer monsoon (ISM) rainfall. However, observations show 6–8% reduction in ISM rainfall during post-1980 La Niñas relative to pre-1980. Using a suite of atmospheric general circulation model experiments, we replicate this observed phenomenon and attrib...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/137838 |
| _version_ | 1826125235234013184 |
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| author | Samanta, Dhrubajyoti Rajagopalan, Balaji Karnauskas, Kristopher B. Zhang, Lei Goodkin, Natalie Fairbank |
| author2 | Asian School of the Environment |
| author_facet | Asian School of the Environment Samanta, Dhrubajyoti Rajagopalan, Balaji Karnauskas, Kristopher B. Zhang, Lei Goodkin, Natalie Fairbank |
| author_sort | Samanta, Dhrubajyoti |
| collection | NTU |
| description | La Niña years tend to provide increased Indian summer monsoon (ISM) rainfall. However, observations show 6–8% reduction in ISM rainfall during post-1980 La Niñas relative to pre-1980. Using a suite of atmospheric general circulation model experiments, we replicate this observed phenomenon and attribute it to a combination of weakening La Niña events themselves plus strongly warming tropical Indian Ocean. We demonstrate that half of the ISM rainfall reduction during post-1980 La Niñas can be attributed to changes in the spatial pattern and intensity of La Niña within the tropical Pacific Ocean. Warmer eastern-equatorial Pacific Ocean temperatures during post-1980 La Niñas weaken the Walker circulation, resulting in large-scale anomalous subsidence over the Indian subcontinent, thereby inhibiting the deep convection that drives ISM rainfall. Further, we demonstrate the declining central ISM rainfall during La Niña years with increasing tropical Indian Ocean warming, which has several serious concerns for regional water resources and stability. |
| first_indexed | 2024-10-01T06:33:23Z |
| format | Journal Article |
| id | ntu-10356/137838 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T06:33:23Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | ntu-10356/1378382023-02-28T16:41:30Z La Niña's diminishing fingerprint on the central Indian summer monsoon Samanta, Dhrubajyoti Rajagopalan, Balaji Karnauskas, Kristopher B. Zhang, Lei Goodkin, Natalie Fairbank Asian School of the Environment Science::Physics::Meteorology and climatology Science::Physics::Geophysics and geomagnetism ISM Rainfall La Niña‐ISM Teleconnection La Niña years tend to provide increased Indian summer monsoon (ISM) rainfall. However, observations show 6–8% reduction in ISM rainfall during post-1980 La Niñas relative to pre-1980. Using a suite of atmospheric general circulation model experiments, we replicate this observed phenomenon and attribute it to a combination of weakening La Niña events themselves plus strongly warming tropical Indian Ocean. We demonstrate that half of the ISM rainfall reduction during post-1980 La Niñas can be attributed to changes in the spatial pattern and intensity of La Niña within the tropical Pacific Ocean. Warmer eastern-equatorial Pacific Ocean temperatures during post-1980 La Niñas weaken the Walker circulation, resulting in large-scale anomalous subsidence over the Indian subcontinent, thereby inhibiting the deep convection that drives ISM rainfall. Further, we demonstrate the declining central ISM rainfall during La Niña years with increasing tropical Indian Ocean warming, which has several serious concerns for regional water resources and stability. MOE (Min. of Education, S’pore) Published version 2020-04-16T02:30:32Z 2020-04-16T02:30:32Z 2020 Journal Article Samanta, D., Rajagopalan, B., Karnauskas, K. B., Zhang, L., & Goodkin, N. F. (2020). La Niña's diminishing fingerprint on the central Indian summer monsoon. Geophysical Research Letters, 47(2), e2019GL086237-. doi:10.1029/2019GL086237 0094-8276 https://hdl.handle.net/10356/137838 10.1029/2019GL086237 2-s2.0-85079754972 2 47 1 11 en Geophysical Research Letters © 2020 The Author(s). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. application/pdf |
| spellingShingle | Science::Physics::Meteorology and climatology Science::Physics::Geophysics and geomagnetism ISM Rainfall La Niña‐ISM Teleconnection Samanta, Dhrubajyoti Rajagopalan, Balaji Karnauskas, Kristopher B. Zhang, Lei Goodkin, Natalie Fairbank La Niña's diminishing fingerprint on the central Indian summer monsoon |
| title | La Niña's diminishing fingerprint on the central Indian summer monsoon |
| title_full | La Niña's diminishing fingerprint on the central Indian summer monsoon |
| title_fullStr | La Niña's diminishing fingerprint on the central Indian summer monsoon |
| title_full_unstemmed | La Niña's diminishing fingerprint on the central Indian summer monsoon |
| title_short | La Niña's diminishing fingerprint on the central Indian summer monsoon |
| title_sort | la nina s diminishing fingerprint on the central indian summer monsoon |
| topic | Science::Physics::Meteorology and climatology Science::Physics::Geophysics and geomagnetism ISM Rainfall La Niña‐ISM Teleconnection |
| url | https://hdl.handle.net/10356/137838 |
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