Current Science

D. S. Pai ¹, A. Suryachandra Rao ², Soma Senroy ¹, Maheswar Pradhan ², Prasanth A. Pillai ², M. Rajeevan ³

Affiliations
1 India Meteorological Department, Shivajinagar, Pune 411 005, IN
2 Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pashan, Pune 411 008, IN
3 Ministry of Earth Sciences, Prithvi Bhavan, Opp. India Habitat Centre, Lodhi Road, New Delhi 110 003, IN

Abstract

India experienced deficient monsoon rainfall in 2015 that followed the deficient monsoon of 2014. India Meteorological Department (IMD) correctly predicted the large rainfall deficiency (86% of long period average) in 2015. Incidentally, this was the first ever deficient monsoon forecast issued by IMD, though it had earlier issued below-normal rainfall forecasts in the previous two deficient monsoon years (2009 and 2014) and was partially correct. The fact that there were only three previous occasions of consecutive two deficient monsoon years during the last 114 years (1901-2014) was itself a challenge to IMD to issue the forecast in 2015. It may be mentioned that IMD persisted with the deficient monsoon forecast for 2015, even though there were predictions from private agencies for a normal monsoon and apprehensions from the press and media about the low probability of two consecutive deficient years. IMD was also able to correctly predict the regional distribution of seasonal rainfall during the season. IMD's first deficient monsoon forecast was based on the state-of-the-art operational statistical forecasting system, which was introduced in 2007. IMD was further confident for a deficient monsoon due to the clear indications of a strong El Niño event by June itself. Forecasts from high-resolution coupled forecasting system (CFS) developed by the Indian Institute of Tropical Meteorology, Pune, under the Monsoon Mission also suggested a deficient monsoon in 2015. In this article we provide details of the operational forecasting models and verification of these forecasts. Brief description about the experimental CFS developed under the Monsoon Mission and CFS forecast for the 2015 southwest monsoon season is also presented.

Keywords

AISMR Data, Long-Range Forecasts, IMD, Monsoon Rainfall.

Full Text

   

Smitha Nair ¹, P. Chandrasekhara Rao ¹, D. S. Pai ¹

Affiliations
1 India Meteorological Department, Pune 411 005, IN

Abstract

Heat wave conditions from 17 May to 1 June 2015 caused deaths of over 2000 people, especially in the south Indian states of Andhra Pradesh and neighbouring Telangana. This study comprises the analysis of synoptic features associated with this deadly heat wave. It was found that the presence of large amplitude anticyclonic flow in the upper levels, above normal 500 hPa height values, above normal lower tropospheric temperatures, below normal precipitable water and higher outgoing longwave radiation (OLR) values are major factors associated with the occurrences of heat wave.

Keywords

Air Temperature, Heat Waves, Geopotential Height, Precipitable Water.

Full Text

   

Divya E. Surendran ¹, Latha Sridhar ¹, Aradhana Kumari ¹, O. P. Sreejith ¹, D. S. Pai ¹

Affiliations
1 Climate Research and Services, India Meteorological Department, Pune 411 005, IN

Abstract

Heavy rainfall (≥ 100 mm or HR) events and moderate rainfall (≥ 5 mm to 100 mm or MR) events over Kerala for June–September were analysed statistically to understand the influence of climate change in MR and HR events for the period 1901–2019 and its two different parts; 1901–1970 and 1971–2019. Most parts of coastal Kerala receive more than 50 HR events/season except the southernmost parts which receive 40–50 HR events/season. Significant negative trend was observed for MR (99%) and HR (95%) events for the entire period of 1901–2019. The total seasonal rainfall averaged over Kerala also showed significant negative trend during the entire period of 1901–2019. In dekad (10 days period) wise trend analysis for MR events during July and August, third dekad of July (21–31 July) showed significant negative trend for the entire period (99%), second dekad of August (11–20 August) showed significant negative trend (95%) for the second part of the data period. In case of HR events, first and third dekads of July (1–10 July; 21–31 July) showed significant negative trends (95% and 99.9% respectively) for the entire data period. The third dekad of July (21–31 July) showed significant negative trend (95%) for the first part of the data period (1901–1970) while the third dekad of July (21–31 July) showed significant negative trend (95%) for second part (1970–2019). First dekad of August (1–10 August) showed significant increasing trend (95%) for the second part of the data period exhibiting its peak in 2019 with 127 HR events. Both MR and HR events frequency during the entire data period was seen to be significantly decreasing (99% and 95%) over the entire Kerala. HR events frequency over few grids of eastern part of the state showed significant increase in the second part of the data period (1971–2019), where Kerala recently experienced exceptionally heavy rainfall spells of shorter durations and landslides.

Keywords

Climate Change, Disaster Potentials, Gridwise Trend Analysis, Heavy and Moderate Rainfall.

Full Text