17:15 〜 19:15
[ACG45-P02] Importance of meteorological observations at high altitude in the Himalayas: heavy rainfall event in Nepal at the end of September 2024
キーワード：極端降水、ヒマラヤ、現地気象観測、モンスーン
The hydrological cycle in the Himalayas is characterized by large amounts of precipitation over slopes and glaciers in high-elevation areas. The cycle maintains the headwaters of major rivers such as the Indus, the Ganges, and the Brahmaputra, providing water resources for South Asia's large population. In the central-eastern Himalayas, most of the total annual precipitation falls in summer (June–September), which makes summer precipitation a crucial part of the high-elevation hydroclimate in the Nepal Himalayas. Meteorological observations at more than 4,000 m above sea level (asl) over the Himalayas are still extremely scarce. Therefore, in situ observations with high temporal resolution remain essential.
In order to better understand summer precipitation in the Himalayas and the mechanisms of its variability on the diurnal to seasonal timescale, international collaborative research on precipitation in the Himalayas (HiPRECS: Himalaya precipitation study) has been carried out since 2019. HiPRECS performed comprehensive research based on in-situ observations, including glacier sites, satellite remote sensing (e.g., TRMM, GPM, and Meteosat-IODC), large-scale and regional-scale data analyses (e.g., ERA5), and numerical simulation using cloud-resolving models (e.g, WRF, CReSS and JMA-NHM). We established a rain gauge network in the Rolwaling valley in the eastern Nepal Himalayas, which has eight rain gauge stations covering from ~1,000 m to ~5,500 m asl.
In this presentation, we will present a heavy precipitation event observed by our meteorological observation network in the eastern Nepal Himalayas from 26–28 September 2024. During this period, record-breaking rainfall was observed mainly in the Kathmandu basin of Nepal, causing massive floods and landslides that claimed hundreds of lives. Our rain gauge network also observed intense precipitation at higher elevations, causing landslides and flooding in the surrounding areas. During the period, there was little diurnal variation in precipitation, and intermittent heavy precipitation occurred. The flooding caused by this precipitation washed away the meteorological observation station at Dongang (~2,800 m asl). At higher elevations, Beding (~3,700 m asl) and Na (~4,200 m asl), daily precipitation amounts exceeded 90 mm on the 27th. It snowed at the AWS near the Trakarding glacier (~4,800 m asl), bringing snow accumulation over the glacier. The presentation will also report on the characteristics of the precipitation system and atmospheric circulation field that brought this precipitation event.
In order to better understand summer precipitation in the Himalayas and the mechanisms of its variability on the diurnal to seasonal timescale, international collaborative research on precipitation in the Himalayas (HiPRECS: Himalaya precipitation study) has been carried out since 2019. HiPRECS performed comprehensive research based on in-situ observations, including glacier sites, satellite remote sensing (e.g., TRMM, GPM, and Meteosat-IODC), large-scale and regional-scale data analyses (e.g., ERA5), and numerical simulation using cloud-resolving models (e.g, WRF, CReSS and JMA-NHM). We established a rain gauge network in the Rolwaling valley in the eastern Nepal Himalayas, which has eight rain gauge stations covering from ~1,000 m to ~5,500 m asl.
In this presentation, we will present a heavy precipitation event observed by our meteorological observation network in the eastern Nepal Himalayas from 26–28 September 2024. During this period, record-breaking rainfall was observed mainly in the Kathmandu basin of Nepal, causing massive floods and landslides that claimed hundreds of lives. Our rain gauge network also observed intense precipitation at higher elevations, causing landslides and flooding in the surrounding areas. During the period, there was little diurnal variation in precipitation, and intermittent heavy precipitation occurred. The flooding caused by this precipitation washed away the meteorological observation station at Dongang (~2,800 m asl). At higher elevations, Beding (~3,700 m asl) and Na (~4,200 m asl), daily precipitation amounts exceeded 90 mm on the 27th. It snowed at the AWS near the Trakarding glacier (~4,800 m asl), bringing snow accumulation over the glacier. The presentation will also report on the characteristics of the precipitation system and atmospheric circulation field that brought this precipitation event.