Variations in the cloud-base height over the central Himalayas during GVAX: association with the monsoon rainfall

Singh, Narendra and Solanki, Raman and Ojha, N and Naja, M and Dumka, UC and Phanikumar, DV and Sagar, Ram and Satheesh, SK and Moorthy, K Krishna and Kotamarthi, VR and Dhaka, SK (2016) Variations in the cloud-base height over the central Himalayas during GVAX: association with the monsoon rainfall. In: CURRENT SCIENCE, 111 (1). pp. 109-116.

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Abstract

We present the measurements of cloud-base height variations over Aryabhatta Research Institute of Observational Science, Nainital (79.45 degrees E, 29.37 degrees N, 1958 m amsl) obtained from Vaisala Ceilometer, during the nearly year-long Ganges Valley Aerosol Experiment (GVAX). The cloud-base measurements are analysed in conjunction with collocated measurements of rainfall, to study the possible contributions from different cloud types to the observed monsoonal rainfall during June to September 2011. The summer monsoon of 2011 was a normal monsoon year with total accumulated rainfall of 1035.8 mm during June-September with a maximum during July (367.0 mm) and minimum during September (222.3 mm). The annual mean monsoon rainfall over Nainital is 1440 +/- 430 mm. The total rainfall measured during other months (October 2011-March 2012) was only 9% of that observed during the summer monsoon. The first cloud-base height varied from about 31 m above ground level (AGL) to a maximum of 7.6 km AGL during the summer monsoon period of 2011. It is found that about 70% of the total rain is observed only when the first cloud-base height varies between surface and 2 km AGL, indicating that most of the rainfall at high altitude stations such as Nainital is associated with stratiform low-level clouds. However, about 25% of the total rainfall is being contributed by clouds between 2 and 6 km. The occurrences of high-altitude cumulus clouds are observed to be only 2-4%. This study is an attempt to fill a major gap of measurements over the topographically complex and observationally sparse northern Indian region providing the evaluation data for atmospheric models and therefore, have implications towards the better predictions of monsoon rainfall and the weather components over this region.

Item Type:	Journal Article
Publication:	CURRENT SCIENCE
Publisher:	INDIAN ACAD SCIENCES
Additional Information:	Copy right for this article belongs to the INDIAN ACAD SCIENCES, BANGALORE, INDIA
Keywords:	Ceilometer;central Himalaya;cloud-base;GVAX;monsoon
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	19 Aug 2016 06:45
Last Modified:	19 Aug 2016 06:45
URI:	http://eprints.iisc.ac.in/id/eprint/54401

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