Northeast monsoon over India: variability and prediction

Meteorological applications

article

M. Rajeevan¹  C. K. Unnikrishnan¹  Jyoti Bhate¹  K. Niranjan Kumar¹  P. P. Sreekala⁴ 

[1] National Atmospheric Research Laboratory;Presently at the Ministry of Earth Sciences;Ministry of Earth Sciences, Prithvi Bhavan IMD Campus;Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science

关键词: northeast monsoon;    interannual variability;    seasonal forecasts;    diurnal variation;    intraseasonal variation;   

DOI  :  10.1002/met.1322

学科分类：社会科学、人文和艺术（综合）

来源: Wiley

【 摘 要 】

South peninsular India experiences a large portion of the annual rainfall during the northeast monsoon season (October to December). In this study, the facets of diurnal, intra-seasonal and inter-annual variability of the northeast monsoon rainfall (the NEMR) over India have been examined. The analysis of satellite derived hourly rainfall reveals that there are distinct features of diurnal variation over the land and oceans during the season. Over the land, rainfall peaks during the late afternoon/evening, while over the oceans an early morning peak is observed. The harmonic analysis of hourly data reveals that the amplitude and variance are the largest over south peninsular India. The NEMR also exhibits significant intra-seasonal variability on a 20–40 day time scale. Analysis also shows significant northward propagation of the maximum cloud zone from south of equator to the south peninsula during the season. The NEMR exhibits large inter-annual variability with the co-efficient of variation (CV) of 25%. The positive phases of ENSO and the Indian Ocean Dipole (IOD) are conducive for normal to above normal rainfall activity during the northeast monsoon. There are multi-decadal variations in the statistical relationship between ENSO and the NEMR. During the period 2001–2010 the statistical relationship between ENSO and the NEMR has significantly weakened. The analysis of seasonal rainfall hindcasts for the period 1960–2005 produced by the state-of-the-art coupled climate models, ENSEMBLES, reveals that the coupled models have very poor skill in predicting the inter-annual variability of the NEMR. This is mainly due to the inability of the ENSEMBLES models to simulate the positive relationship between ENSO and the NEMR correctly.

【 授权许可】

CC BY|CC BY-NC|CC BY-NC-ND