Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: Rashmi Sharma x
  • Bulletin of the American Meteorological Society x
  • Refine by Access: All Content x
Clear All Modify Search
Hemantha W. Wijesekera
,
Emily Shroyer
,
Amit Tandon
,
M. Ravichandran
,
Debasis Sengupta
,
S. U. P. Jinadasa
,
Harindra J. S. Fernando
,
Neeraj Agrawal
,
K. Arulananthan
,
G. S. Bhat
,
Mark Baumgartner
,
Jared Buckley
,
Luca Centurioni
,
Patrick Conry
,
J. Thomas Farrar
,
Arnold L. Gordon
,
Verena Hormann
,
Ewa Jarosz
,
Tommy G. Jensen
,
Shaun Johnston
,
Matthias Lankhorst
,
Craig M. Lee
,
Laura S. Leo
,
Iossif Lozovatsky
,
Andrew J. Lucas
,
Jennifer Mackinnon
,
Amala Mahadevan
,
Jonathan Nash
,
Melissa M. Omand
,
Hieu Pham
,
Robert Pinkel
,
Luc Rainville
,
Sanjiv Ramachandran
,
Daniel L. Rudnick
,
Sutanu Sarkar
,
Uwe Send
,
Rashmi Sharma
,
Harper Simmons
,
Kathleen M. Stafford
,
Louis St. Laurent
,
Karan Venayagamoorthy
,
Ramasamy Venkatesan
,
William J. Teague
,
David W. Wang
,
Amy F. Waterhouse
,
Robert Weller
, and
Caitlin B. Whalen

Abstract

Air–Sea Interactions in the Northern Indian Ocean (ASIRI) is an international research effort (2013–17) aimed at understanding and quantifying coupled atmosphere–ocean dynamics of the Bay of Bengal (BoB) with relevance to Indian Ocean monsoons. Working collaboratively, more than 20 research institutions are acquiring field observations coupled with operational and high-resolution models to address scientific issues that have stymied the monsoon predictability. ASIRI combines new and mature observational technologies to resolve submesoscale to regional-scale currents and hydrophysical fields. These data reveal BoB’s sharp frontal features, submesoscale variability, low-salinity lenses and filaments, and shallow mixed layers, with relatively weak turbulent mixing. Observed physical features include energetic high-frequency internal waves in the southern BoB, energetic mesoscale and submesoscale features including an intrathermocline eddy in the central BoB, and a high-resolution view of the exchange along the periphery of Sri Lanka, which includes the 100-km-wide East India Coastal Current (EICC) carrying low-salinity water out of the BoB and an adjacent, broad northward flow (∼300 km wide) that carries high-salinity water into BoB during the northeast monsoon. Atmospheric boundary layer (ABL) observations during the decaying phase of the Madden–Julian oscillation (MJO) permit the study of multiscale atmospheric processes associated with non-MJO phenomena and their impacts on the marine boundary layer. Underway analyses that integrate observations and numerical simulations shed light on how air–sea interactions control the ABL and upper-ocean processes.

Full access
Emily Shroyer
,
Amit Tandon
,
Debasis Sengupta
,
Harindra J. S. Fernando
,
Andrew J. Lucas
,
J. Thomas Farrar
,
Rajib Chattopadhyay
,
Simon de Szoeke
,
Maria Flatau
,
Adam Rydbeck
,
Hemantha Wijesekera
,
Michael McPhaden
,
Hyodae Seo
,
Aneesh Subramanian
,
R Venkatesan
,
Jossia Joseph
,
S. Ramsundaram
,
Arnold L. Gordon
,
Shannon M. Bohman
,
Jaynise Pérez
,
Iury T. Simoes-Sousa
,
Steven R. Jayne
,
Robert E. Todd
,
G. S. Bhat
,
Matthias Lankhorst
,
Tamara Schlosser
,
Katherine Adams
,
S. U. P Jinadasa
,
Manikandan Mathur
,
M. Mohapatra
,
E. Pattabhi Rama Rao
,
A. K. Sahai
,
Rashmi Sharma
,
Craig Lee
,
Luc Rainville
,
Deepak Cherian
,
Kerstin Cullen
,
Luca R. Centurioni
,
Verena Hormann
,
Jennifer MacKinnon
,
Uwe Send
,
Arachaporn Anutaliya
,
Amy Waterhouse
,
Garrett S. Black
,
Jeremy A. Dehart
,
Kaitlyn M. Woods
,
Edward Creegan
,
Gad Levy
,
Lakshmi H. Kantha
, and
Bulusu Subrahmanyam

Abstract

In the Bay of Bengal, the warm, dry boreal spring concludes with the onset of the summer monsoon and accompanying southwesterly winds, heavy rains, and variable air–sea fluxes. Here, we summarize the 2018 monsoon onset using observations collected through the multinational Monsoon Intraseasonal Oscillations in the Bay of Bengal (MISO-BoB) program between the United States, India, and Sri Lanka. MISO-BoB aims to improve understanding of monsoon intraseasonal variability, and the 2018 field effort captured the coupled air–sea response during a transition from active-to-break conditions in the central BoB. The active phase of the ∼20-day research cruise was characterized by warm sea surface temperature (SST > 30°C), cold atmospheric outflows with intermittent heavy rainfall, and increasing winds (from 2 to 15 m s−1). Accumulated rainfall exceeded 200 mm with 90% of precipitation occurring during the first week. The following break period was both dry and clear, with persistent 10–12 m s−1 wind and evaporation of 0.2 mm h−1. The evolving environmental state included a deepening ocean mixed layer (from ∼20 to 50 m), cooling SST (by ∼1°C), and warming/drying of the lower to midtroposphere. Local atmospheric development was consistent with phasing of the large-scale intraseasonal oscillation. The upper ocean stores significant heat in the BoB, enough to maintain SST above 29°C despite cooling by surface fluxes and ocean mixing. Comparison with reanalysis indicates biases in air–sea fluxes, which may be related to overly cool prescribed SST. Resolution of such biases offers a path toward improved forecasting of transition periods in the monsoon.

Full access