Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO
In recent years, an increased occurrence of loss and damage of property and human casualties over the southern rim area of the Himalayas, caused by landslides following intense rainfall events, has been reported. An analysis of Tropical Rainfall Measuring Mission (TRMM)-gridded rainfall data shows t...
Main Authors: | , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Stockholm University Press
2015-05-01
|
Series: | Tellus: Series A, Dynamic Meteorology and Oceanography |
Subjects: | |
Online Access: | http://www.tellusa.net/index.php/tellusa/article/view/26031/pdf_33 |
_version_ | 1811291012009558016 |
---|---|
author | Prabhakar Shrestha Ashok Priyadarshan Dimri Annika Schomburg Clemens Simmer |
author_facet | Prabhakar Shrestha Ashok Priyadarshan Dimri Annika Schomburg Clemens Simmer |
author_sort | Prabhakar Shrestha |
collection | DOAJ |
description | In recent years, an increased occurrence of loss and damage of property and human casualties over the southern rim area of the Himalayas, caused by landslides following intense rainfall events, has been reported. An analysis of Tropical Rainfall Measuring Mission (TRMM)-gridded rainfall data shows that events with an exceedance probability of 1.6% for 200 mm/d rainfall are common over this region during the monsoon season. An improved understanding of the mechanisms, which lead to such events, is important for their prediction and to estimate the impact of climate change on their recurrence. In this study, we analyse such an extreme precipitation event, which hit the Uttarakhand region of the central Himalayas on 13 September 2012. We use the operational regional weather forecast model COSMO at a convection-permitting resolution of 2.8 km to simulate this event. The spatial pattern of daily-accumulated precipitation and atmospheric state profiles simulated by the model compared well with the TRMM-gridded data and radiosonde observations, which adds confidence to our model results. Our analysis suggests a three-step mechanism leading to this event: (1) development of an easterly low-level wind along the Gangetic Plain caused by a low pressure system over the central Gangetic Plain; (2) convergence of moisture over the north-western part of India, leading to an increase of potential instability of the air mass along the valley recesses, which is capped by an inversion located above the ridgeline; and (3) strengthening of the north-westerly flow above the ridges, which supports the lifting of the potentially unstable air over the protruding ridge of the foothills of the Himalayas and triggers shallow convection, which on passing through adjacent folds initiates deep convection. |
first_indexed | 2024-04-13T04:23:04Z |
format | Article |
id | doaj.art-616c884284514aad826aa65e86d724cc |
institution | Directory Open Access Journal |
issn | 1600-0870 |
language | English |
last_indexed | 2024-04-13T04:23:04Z |
publishDate | 2015-05-01 |
publisher | Stockholm University Press |
record_format | Article |
series | Tellus: Series A, Dynamic Meteorology and Oceanography |
spelling | doaj.art-616c884284514aad826aa65e86d724cc2022-12-22T03:02:40ZengStockholm University PressTellus: Series A, Dynamic Meteorology and Oceanography1600-08702015-05-0167011310.3402/tellusa.v67.2603126031Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMOPrabhakar Shrestha0Ashok Priyadarshan Dimri1Annika Schomburg2Clemens Simmer3 Meteorological Institute, University of Bonn, Bonn, Germany School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India Deutscher Wetterdienst, Offenbach, Germany Meteorological Institute, University of Bonn, Bonn, GermanyIn recent years, an increased occurrence of loss and damage of property and human casualties over the southern rim area of the Himalayas, caused by landslides following intense rainfall events, has been reported. An analysis of Tropical Rainfall Measuring Mission (TRMM)-gridded rainfall data shows that events with an exceedance probability of 1.6% for 200 mm/d rainfall are common over this region during the monsoon season. An improved understanding of the mechanisms, which lead to such events, is important for their prediction and to estimate the impact of climate change on their recurrence. In this study, we analyse such an extreme precipitation event, which hit the Uttarakhand region of the central Himalayas on 13 September 2012. We use the operational regional weather forecast model COSMO at a convection-permitting resolution of 2.8 km to simulate this event. The spatial pattern of daily-accumulated precipitation and atmospheric state profiles simulated by the model compared well with the TRMM-gridded data and radiosonde observations, which adds confidence to our model results. Our analysis suggests a three-step mechanism leading to this event: (1) development of an easterly low-level wind along the Gangetic Plain caused by a low pressure system over the central Gangetic Plain; (2) convergence of moisture over the north-western part of India, leading to an increase of potential instability of the air mass along the valley recesses, which is capped by an inversion located above the ridgeline; and (3) strengthening of the north-westerly flow above the ridges, which supports the lifting of the potentially unstable air over the protruding ridge of the foothills of the Himalayas and triggers shallow convection, which on passing through adjacent folds initiates deep convection.http://www.tellusa.net/index.php/tellusa/article/view/26031/pdf_33COSMOdeep convectionextreme rainfallorographyNorth-west India |
spellingShingle | Prabhakar Shrestha Ashok Priyadarshan Dimri Annika Schomburg Clemens Simmer Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO Tellus: Series A, Dynamic Meteorology and Oceanography COSMO deep convection extreme rainfall orography North-west India |
title | Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO |
title_full | Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO |
title_fullStr | Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO |
title_full_unstemmed | Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO |
title_short | Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO |
title_sort | improved understanding of an extreme rainfall event at the himalayan foothills a case study using cosmo |
topic | COSMO deep convection extreme rainfall orography North-west India |
url | http://www.tellusa.net/index.php/tellusa/article/view/26031/pdf_33 |
work_keys_str_mv | AT prabhakarshrestha improvedunderstandingofanextremerainfalleventatthehimalayanfoothillsacasestudyusingcosmo AT ashokpriyadarshandimri improvedunderstandingofanextremerainfalleventatthehimalayanfoothillsacasestudyusingcosmo AT annikaschomburg improvedunderstandingofanextremerainfalleventatthehimalayanfoothillsacasestudyusingcosmo AT clemenssimmer improvedunderstandingofanextremerainfalleventatthehimalayanfoothillsacasestudyusingcosmo |