title: ENSO's far reaching connection to Indian cold waves.
abstract: During boreal winters, cold waves over India are primarily due to transport of cold air from higher latitudes. However, the processes associated with these cold waves are not yet clearly understood. Here by diagnosing a suite of datasets, we explore the mechanisms leading to the development and maintenance of these cold waves. Two types of cold waves are identified based on observed minimum surface temperature and statistical analysis. The first type (TYPE1), also the dominant one, depicts colder than normal temperatures covering most parts of the country while the second type (TYPE2) is more regional, with significant cold temperatures only noticeable over northwest India. Quite interestingly the first (second) type is associated with La Niña (El Niño) like conditions, suggesting that both phases of ENSO provide a favorable background for the occurrence of cold waves over India. During TYPE1 cold wave events, a low-level cyclonic anomaly generated over the Indian region as an atmospheric response to the equatorial convective anomalies is seen advecting cold temperatures into India and maintaining the cold waves. In TYPE2 cold waves, a cyclonic anomaly generated over west India anomalously brings cold winds to northwest India causing cold waves only in those parts.
authors.affiliation: Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama Japan.
authors.forename: J V
authors.initials: JV
authors.lastname: Ratnam
authors.affiliation: Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama Japan.
authors.forename: Swadhin K
authors.initials: SK
authors.lastname: Behera
authors.affiliation: International Pacific Research Center and Department of Oceanography, University of Hawaii, USA.
authors.forename: H
authors.initials: H
authors.lastname: Annamalai
authors.affiliation: Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama Japan.
authors.forename: Satyaban B
authors.initials: SB
authors.lastname: Ratna
authors.affiliation: Ministry of Earth Sciences, New Delhi, India.
authors.forename: M
authors.initials: M
authors.lastname: Rajeevan
authors.affiliation: Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Yamagata