Air-Sea Interaction in the Austral-Asian Monsoon:
The Joint Air-Sea Monsoon Investigation (JASMINE-99) Pilot Study
Program Description
The Joint Air-Sea Monsoon Investigation (JASMINE) is based on the hypothesis that
intraseasonal variability of the Asian-Australasian monsoon system is the result of coupled ocean-atmosphere interaction in a region of very large cross-equatorial surface pressure gradient.
JASMINE is presently planned in two phases: a pilot study in 1999 and a main experiment in
2000. The overall aim of these process studies in the North Indian Ocean is to determine the
dynamic and thermodynamic structure of the active and break periods of the monsoon (i.e., the
intraseasonal variability) and link them to variations in sea surface temperature and coupled
ocean-atmospheric interactions. The maximum amplitude of the variation in monsoon
precipitation occurs at approximately 90-E and 13-N. This process study is in direct support of
the major scientific objectives of the Global-Ocean-Atmosphere-Land
System (GOALS) Program.
GOALS seeks to increase the prediction of elements of the monsoon circulation. Thus, the
processes that produce the intraseasonal variations of the Asian-Australasian monsoon are central
scientific issues for GOALS. Details are provided in the document "Intraseasonal Variability of
the South Asian Monsoon System: The Concept of JASMINE" by P. J. Webster and Collaborators
(contact P. Webster at mailto:pjw@willywilly.colorado.edu for a copy).
Measurement Strategy
The particular purposes of the 1999 cruise are to determine the ocean-atmosphere interactions during
these intraseasonal variations, document the changes that occur in the upper ocean and lower
troposphere during the transitions, and provide background information for the more
comprehensive study to follow. Thus, besides measuring the elements of the surface heat budget,
the upper ocean and lower troposphere will also be profiled with a variety of remote and in situ
sensors. On the atmospheric side, meteorological radars will monitor cloud, precipitation, and
disturbance structures during the time on station. A strong emphasis will be placed on
measurements of atmospheric boundary-layer dynamical properties and structures across the
monsoon system. These are key problems in numerical modeling of coupled air-sea processes.
The suite of instruments required will be closely equivalent to those planned for the joint
DOE/NOAA ARM experiment being planned for
the vicinity of Nauru. On the ocean side, a
strategy involving TOGA-
COARE style box or butterfly patterns centered at 90-E and 10 N with a
combination of TAO/IMET buoys is being developed to examine heat and salt budgets. E-W
transects near the equator will be obtained in the going to and from the experimental area. There
has never been a high-quality study in this region in this season; T and S structures are thought to
be very shallow and should have a strong effect on air-sea fluxes.
It is planned that the cruise will take part in an intensive observation period of a year-long
monitoring program along a line from the Bay of Bengal to south of the equator. Atlas TAO
moorings and a WHOI IMET buoy will be deployed along this line. It is also planned to deploy a
research aircraft along the mooring line during the intensive observation phase thus providing a
context and connection for the buoys and ship. The Australian R/V Franklin will participate in the
October/November time frame to recover/service buoys and take meteorological and
oceanographic data.
Relevance to NOAA's Mission and Relationship to Strategic Plan Elements
The emphasis of this program is directly relevant to the Seasonal to Interannual Forecast element.
There are also implications for the both Decadal to Centennial Change and Short Term Forecast
elements.
Key Co-Investigators
Dr. P. J. Webster, University of Colorado
Drs. Robert Houze and Sandra Yuter, University Of Washington
Drs. Peter Hacker and Roger Lukas, University of Hawaii
Dr. Stuart Godfrey, CSIRO Marine Research (Australia)
Dr. Frank Bradley, CSIRO Land and Water (Australia)
Drs. Bates and Quinn, PMEL