INDIAN SUMMER MONSOON EXPERIMENTS SAFETY IS A MISSION

INDIAN SUMMER MONSOON EXPERIMENTS

“SAFETY IS A MISSION NOT AN INTERMISSION”

IIOE Cruise tracks as in 1961. More than 40 oceanographic research vessels belonging to 13 countries surveyed the Indian Ocean from 1960 to 1965.

INDIAN SUMMER MONSOON EXPERIMENTS • The International Indian Ocean Expedition (IIOE, 1960 -1965) • Monsoon Experiment of 1979 (MONEX)) • Monsoon Trough Boundary Layer Experiment (MONTBLEX 1990)) • LASPEX (1995 -97) • Bay of Bengal Monsoon Experiment (BOBMEX-1999) • Arabian Sea Monsoon Experiment ( ARMEX-2002 -03) • Continental TCZ (CTCZ 2009 -2012)

• • It was hoped that IIOE would help in finding answers to the following issues/problems in physical oceanography and meteorology, many of which are relevant even 5 decades later. a. How can the large scale atmospheric circulation of Indian Ocean be described? b. How can evaporation and vertical heat flux be determined over large areas? c. What is the areal distribution of vertical flux of water vapour, heat and momentum? d. What are the local interface fluxes at the air sea boundary? e. What is the average energy transfer or heat budget for the atmosphere and the ocean? f. How do we interpret satellite cloud photographs and infra-red measurements in terms of such meteorological observations?

MONSOON EXPERIMENT OF 1979 (MONEX) • Planetary scale aspects: Investigation of heat sources (determination of the components of heat sources and sinks at the earth's surface, within the atmosphere, and at the top of the atmosphere, to evaluate their role in the annual cycle of the planetary-scale monsoonal circulations), monsoon onset and breaks in monsoon. ) • Synoptic scale regional aspects: Arabian Sea Component – low level jet and boundary layer inversion, MTC and monsoon onset mechanism. Bay of Bengal component - development and structure of monsoon depressions, structure and energetic of monsoon troughs and prediction of monsoon depressions. • Interactions with atmospheric circulation • Numerical simulation and prediction

MONTBLEX • Main objectives of MONTBLEX were: (a) the description of the structure of the ABL across the entire extent of the trough (b) the study of eddy fluxes and energetics (c) the formulation of better parameterization schemes for the boundary layer for use in atmospheric general circulation models (d) To understand the interactions between the moist, ascending • eastern end of the monsoon trough with the dry subsidence regime at its western end. A pilot experiment was conducted at Kharagpur in July 1989, and was followed by the full field experiment in 1990. The main phase of MONTBLEX included observations from four 30 m surface layer masts at Jodhpur, Delhi, Varanasi and Kharagpur. Ocean cruises by ORV Sagarkanya. Observations over IMD network, sodar and tethersonde measurements. Extensive aircraft flights carried out by the Indian Air Force. A comprehensive account of the results from the various investigations carried out was published in 1997 (Narasimha et al 1997).

LASPEX • LASPEX was a sequel to MONTBLEX whose planning began in 1992 and specifically carried out to understand land surface process with Indian Institute of Tropical Meteorology (IITM) as a nodal agency. The area chosen for the study was the Sabarmati river basin in Gujarat. Main obecjectives were: • To collect a complete surface and sub-surface atmospheric hydrological data base against which parameterized models for land surface processes. • To provide in-situ measurements as ground truths for the data to be obtained through ERS-I, for evaluating soil moisture over the region. The Pilot phase was carried out during April-July 1995, and the main phase during January 1997 to March 1998. Five 10 m high micrometeorological towers with Anand as center were installed (Aanad also had a 30 m tower). Data on soils, crops and weather, energy fluxes, upper air data were collected. Focus of LASPEX was on processes near the surface (i. e. , the boundary layer).

BOMBEX • The emphasis in BOBMEX was on collecting high quality data over the bay and the surrounding coastal areas during different phases of monsoon. • The low saline water makes the top layer of the ocean very stable for vertical mixing. Thus, we expected the nature of the response of the ocean to atmospheric forcing to be different in the northern and southern parts of the bay. • Indian research vessels INS Sagardhwani and ORV Sagar Kanya were deployed at TS 1 (13°N, 87°E) and TS 2 (17. 5°N, 89°E) • BOBMEX was carried out during July-August 1999 with a Pilot during October-November 1998.

ARMEX • ARMEX was carried out during 2002 -2003 with some measurements completed in 2005. • One of the objectives of ARMEX was to understand the mini-warm pool dynamics and test the hypotheses. The monsoon onset processes over Kerala and dramatic collapse of SST during the monsoon onset was another important issue.

CTCZ • Having the characteristics of tropical convergence zone (TCZ) observed over the oceans, the low pressure belt over the plains of north India is called the continental TCZ (CTCZ). • The main objective of the CTCZ programme is to understand the mechanisms leading to the space-time variation of rainfall and the embedded monsoon disturbances during the summer monsoon over the core region. • A pilot phase of CTCZ was carried out during 01 July to 31 August 2009 utilizing most of the existing observational monitoring networks including Radars, aerosols, agro meteorological stations, met-ocean data buoys, Argo floats and 517 drifters, two ships (ORV Sagar Kanya and ORV Sagar Nidhi), two aircrafts with state-of-the art instrumentation, additional radiosonde systems at Kharagpur and over northern bay, three micrometeorological towers (Kharagpur, Ranchi, and Anand), stand-alone atmospheric observing systems (e. g. micropulse lidars ) at few locations north of 18°N, up to foothills of Himalayas.

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