Current Science

G. S. Bhat ¹, K. R. Sreenivasan ²

Affiliations
1 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012, IN
2 New York University, New York, US

Abstract

No Abstract.

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G. S. Bhat ¹, J. C. R. Hunt ²

Affiliations
1 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, IN
2 Malaysian Commonwealth Studies Centre, University of Cambridge, Cambridge, GB

Abstract

No Abstract.

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Sachin D. Ghude ¹, G. S. Bhat ², Thara Prabhakaran ¹, R. K. Jenamani ³, D. M. Chate ¹, P. D. Safai ¹, A. K. Karipot ⁴, M. Konwar ¹, Prakash Pithani ¹, V. Sinha ⁵, P. S. P. Rao ¹, S. A. Dixit ¹, S. Tiwari ¹, K. Todekar ¹, S. Varpe ¹, A. K. Srivastava ¹, D. S. Bisht ¹, P. Murugavel ¹, Kaushar Ali ¹, Usha Mina ⁶, M. Dharua ¹, J. Rao ¹, B. Padmakumari ¹, A. Hazra ¹, N. Nigam ³, U. Shende ³, D. M. Lal ¹, B. P. Chandra ⁵, A. K. Mishra ⁵, A. Kumar ⁵, H. Hakkim ⁵, H. Pawar ⁵, P. Acharja ¹, Rachana Kulkarni ¹, C. Subharthi ¹, B. Balaji ¹, M. Varghese ¹, S. Bera ¹, M. Rajeevan ⁷

Affiliations
1 Indian Institute of Tropical Meteorology, Pashan, Pune 411 008, IN
2 Indian Institute of Science, Bengaluru 560 012, IN
3 India Meteorological Department, New Delhi 110 003, IN
4 Savitribai Phule Pune University, Pune 411 007, IN
5 Indian Institute of Science Education and Research Mohali, Mohali 140 306, IN
6 Indian Agricultural Research Institute, Pusa, New Delhi 110 012, IN
7 Ministry of Earth Sciences, Government of India, New Delhi 110 003, IN

Abstract

The objectives of the Winter Fog Experiment (WIFEX) over the Indo-Gangetic Plains of India are to develop better now-casting and forecasting of winter fog on various time- and spatial scales. Maximum fog occurrence over northwest India is about 48 days (visibility <1000 m) per year, and it occurs mostly during the December-February time-period. The physical and chemical characteristics of fog, meteorological factors responsible for its genesis, sustenance, intensity and dissipation are poorly understood. Improved understanding on the above aspects is required to develop reliable forecasting models and observational techniques for accurate prediction of the fog events. Extensive sets of comprehensive ground-based instrumentation were deployed at the Indira Gandhi International Airport, New Delhi. Major in situ sensors were deployed to measure surface micro-meteorological conditions, radiation balance, turbulence, thermodynamical structure of the surface layer, fog droplet and aerosol microphysics, aerosol optical properties, and aerosol and fog water chemistry to describe the complete environmental conditions under which fog develops. In addition, Weather Forecasting Model coupled with chemistry is planned for fog prediction at a spatial resolution of 2 km. The present study provides an introductory overview of the winter fog field campaign with its unique instrumentation.

Keywords

Aerosols, Atmospheric Profiles, Forecasting, Winter Fog.

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Jyotirmayee Satapathy ¹, G. S. Bhat ²

Affiliations
1 Department of Physics, Amrita Vishwa Vidyapeetham, Amritapuri 690 525, IN
2 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, IN

Abstract

Many parts of India experience extreme gust and dust storms during the pre-monsoon months of April and May. These events can cause lot of damage to plants and properties. Despite their annual recurrences, their physical nature (e.g. temporal and spatial scales) and mechanism remain unaddressed in the Indian context. Here we present some case studies of pre-monsoon, damage-causing extreme winds reported from Bengaluru, India, in the media, and explore their nature, initiation and propagation using in situ observations, and INSAT-3D and INSAT-3DR infrared channel imageries. These gust events occurred on 24 April 2018, 7 and 26 May as well as 2 June 2019. Among these, the 24 April event was the strongest and the instantaneous wind speed exceeded 75 kmph. It is shown that all these cases share some common features. The first is the arrival of a pool of cold air with its minimum temperature that is at least 10 K less compared to what was prevailing about 15 min earlier. The second is the high rainfall rate; 1 min accumulation-based rainfall rate exceeds 100 mm h^–1. Extreme winds are short-lived and wind speeds exceeding 50 kmph last for less than 5 min. Satellite imageries of the corresponding period show that the associated clouds were organized with a spatial scale of at least several tens of kilometres.

Keywords

Extreme Gust Storms, Pre-Monsoon Cold Air, Satellite Imageries.

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K. R. Sreenivasan ¹, G. S. Bhat ²

Affiliations
1 University Professor and Eugene Kleiner Chair for Innovation, Physics Department, Courant Institute of Mathematical Sciences, Tandon School of Engineering, and NYU Abu Dhabi, New York University, US
2 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, IN

Abstract

No Abstract.

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