Bay of Bengal intraseasonal oscillations and the 2018 monsoon onset

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 similar to 20-day research cruise was characterized by warm sea surface temperature (SST > 30 degrees 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 similar to 20 to 50 m), cooling SST (by similar to 1 degrees 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 degrees 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.

To Access Resource:

Questions? Email Resource Support Contact:

  • opensky@ucar.edu
    UCAR/NCAR - Library

Resource Type publication
Temporal Range Begin N/A
Temporal Range End N/A
Temporal Resolution N/A
Bounding Box North Lat N/A
Bounding Box South Lat N/A
Bounding Box West Long N/A
Bounding Box East Long N/A
Spatial Representation N/A
Spatial Resolution N/A
Related Links N/A
Additional Information N/A
Resource Format PDF
Standardized Resource Format PDF
Asset Size N/A
Legal Constraints

Copyright 2021 American Meteorological Society (AMS).
Access Constraints None
Software Implementation Language N/A

Resource Support Name N/A
Resource Support Email opensky@ucar.edu
Resource Support Organization UCAR/NCAR - Library
Distributor N/A
Metadata Contact Name N/A
Metadata Contact Email opensky@ucar.edu
Metadata Contact Organization UCAR/NCAR - Library

Author Shroyer, Emily
Tandon, Amit
Sengupta, Debasis
Fernando, Harindra J. S.
Lucas, Andrew J.
Farrar, J. Thomas
Chattopadhyay, Rajib
de Szoeke, Simon
Flatau, Maria
Rydbeck, Adam
Wijesekera, Hemantha
McPhaden, Michael
Seo, Hyodae
Subramanian, Aneesh
Venkatesan, R
Joseph, Jossia
Ramsundaram, S.
Gordon, Arnold L.
Bohman, Shannon M.
Pérez, Jaynise
Simoes-Sousa, Iury T.
Jayne, Steven R.
Todd, Robert E.
Bhat, G. S.
Lankhorst, Matthias
Schlosser, Tamara
Adams, Katherine
Jinadasa, S. U. P
Mathur, Manikandan
Mohapatra, M.
Rama Rao, E. Pattabhi
Sahai, A. K.
Sharma, Rashmi
Lee, Craig
Rainville, Luc
Cherian, Deepak
Cullen, Kerstin
Centurioni, Luca R.
Hormann, Verena
MacKinnon, Jennifer
Send, Uwe
Anutaliya, Arachaporn
Waterhouse, Amy
Black, Garrett S.
Dehart, Jeremy A.
Woods, Kaitlyn M.
Creegan, Edward
Levy, Gad
Kantha, Lakshmi H.
Subrahmanyam, Bulusu
Publisher UCAR/NCAR - Library
Publication Date 2021-10-01T00:00:00
Digital Object Identifier (DOI) Not Assigned
Alternate Identifier N/A
Resource Version N/A
Topic Category geoscientificInformation
Progress N/A
Metadata Date 2023-08-18T18:34:50.971077
Metadata Record Identifier edu.ucar.opensky::articles:24902
Metadata Language eng; USA
Suggested Citation Shroyer, Emily, Tandon, Amit, Sengupta, Debasis, Fernando, Harindra J. S., Lucas, Andrew J., Farrar, J. Thomas, Chattopadhyay, Rajib, de Szoeke, Simon, Flatau, Maria, Rydbeck, Adam, Wijesekera, Hemantha, McPhaden, Michael, Seo, Hyodae, Subramanian, Aneesh, Venkatesan, R, Joseph, Jossia, Ramsundaram, S., Gordon, Arnold L., Bohman, Shannon M., Pérez, Jaynise, Simoes-Sousa, Iury T., Jayne, Steven R., Todd, Robert E., Bhat, G. S., Lankhorst, Matthias, Schlosser, Tamara, Adams, Katherine, Jinadasa, S. U. P, Mathur, Manikandan, Mohapatra, M., Rama Rao, E. Pattabhi, Sahai, A. K., Sharma, Rashmi, Lee, Craig, Rainville, Luc, Cherian, Deepak, Cullen, Kerstin, Centurioni, Luca R., Hormann, Verena, MacKinnon, Jennifer, Send, Uwe, Anutaliya, Arachaporn, Waterhouse, Amy, Black, Garrett S., Dehart, Jeremy A., Woods, Kaitlyn M., Creegan, Edward, Levy, Gad, Kantha, Lakshmi H., Subrahmanyam, Bulusu. (2021). Bay of Bengal intraseasonal oscillations and the 2018 monsoon onset. UCAR/NCAR - Library. http://n2t.net/ark:/85065/d7pg1w7f. Accessed 26 June 2025.

Harvest Source