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ICRP Field Experiments G. S. Bhat Centre for Atmospheric & Oceanic Sciences Indian Institute of Science Bangalore. Celebrating the Monsoon 24-28 July, 2007 Indian Institute of Science, Bangalore. Outline. Past Monsoon Experiments ICRP – I ndian C limate R esearch P rogramme

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ICRP Field Experiments G. S. Bhat Centre for Atmospheric & Oceanic Sciences

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ICRP Field Experiments

G. S. Bhat

Centre for Atmospheric & Oceanic Sciences

Indian Institute of Science Bangalore

Celebrating the Monsoon

24-28 July, 2007

Indian Institute of Science, Bangalore


Outline

  • Past Monsoon Experiments

  • ICRP – Indian Climate Research Programme

  • ICRP Field Experiments

    • Completed: BOBMEX, ARMEX

    • Planned - CTCZ


Monsoon Experiments

  • IIOE – International Indian Ocean Expedition

  • 1960 – 1965

  • multinational,20 countries

  • 40 ships, aircraft (drop-sonde), etc.

  • 2. ISMEX - Indian Summer Monsoon Experiment

  • 1973

  • Indo-Soviet

  • 6 research ships (4 – USSR, 2 Indian)

  • Arabian Sea, the equatorial region

  • and southern Indian Ocean

  • 3. MONSOON-77

  • 1977

  • Indo-Soviet

  • Monsoon Onset, depression, etc.

  • 4. MONEX-79, Monsoon Experiment (FGGE)

  • 1979 (summer MONEX)

  • Multinational

  • ~20 ships, research air craft


Leadership – External

Indians – Participated

Many benefits to India

a. New institutes (e.g., NIO IIOE)

b. Infrastructure development

c. Man power training

d. Data over the Indian region (ocean & land)

e. India’s own measurements started (MONEX-79)

Impetus to developing national field programmes


5. MONTBLEX- Monsoon Trough

BL Experiment

1990

Indian

Northern India, BoB

6. LASPEX – Land Surface Proc. Ex.

1997-98

Indian

North-Western India

land surface processes in a semi-arid

area

7. BOBMEX - Bay of Bengal Monsoon Experiment

1999

Indian

Bay of Bengal

8. ARMEX - Arabian Sea Monsoon Experiment

2002-2005

Indian

Arabian Sea & West Coast of India

9.JASMINE – Joint Air-Sea Monsoon Interaction Expt.

1999 (pre to onset, end)

International

Equatorial IO & Central BoB


Post 1980 Expts. - Indian, except for JASMINE

(Conceived, planned & executed by Indian Sci.)

BOBMEX, ARMEX  ICRP

Next

CTCZ- Continental Trough Convergence Zone

(2008 – 2010)


ICRP - Genesis

Early 1990s :- Indian Scientists

(a) What we know about Indian Monsoon?

(b) What needs to be understood?

Action plan to address outstanding

problems utilizing limited national resources

Science Plan

Indian Climate Research Programme

(DST 1996)

ICRP Implementation Plan, DST1998


ICRP

Main Focus: Understanding monsoon variability on timescales ranging from sub-seasonal to inter annual and decadal, and its impact on critical national resources

  • Observational

  • Modeling

  • Data Analysis

  • Inter-Agency & Multi-Institutional

  • Department of Science & Technology (Lead)

  • Department of Ocean Development

  • Department of Space

  • India Meteorology Department(MoES)

  • Ministry of Defence

  • Research Institutes

  • Universities


maximum impact from the limited resources available in the country, a road map formonsoon research in the country for the coming decade with well focused programmes

  • Observational

  • Modeling

  • Data Analysis

  • Field Experiments : 2 Executed + 1 planned

  • Focus: Indian Region

  • Strategy in Field Expts.

  • Science objectives

  • Test the hypothesis or

  • Find answers to a burning question

  • Implementation Plan - Used all available national resources


ICRPExperiments

Bay of Bengal Monsoon Experiment (BOBMEX):

1998-1999

Arabian Sea Monsoon Experiment (ARMEX):

Jun-Aug 2002, Mar - June 2003 , April-May 2005

1998

July 26, 2005

Mumbai ~940 mm

BOBMEX – 1998-99

Air-sea Coupling

Rapid SST Recovery

Northward Propagation

North-South gradients

(Bhat et al, BAMS, 2001)

  • ARMEX – 2002-2003, 2005

  • Intense Rainfall Events on WC

  • Warm pool build up & Collapse

  • Monsoon Onset over Kerala

  • Mausam Jan. 2005 (Special Issue)


ORV Sagar Kanya

Indian Oceanographic Research Vessel

~110 m long

31 Scientists + 65 Crew


North Bay SST- maintenance

OLR, Rainfall (GPCP)

(shaded) (cont.)

June-Sept.: 1978-95

  • Maximum Precipitation

  • Region of highest clouding in the entire region

  • Cloud systems - Cut off solar radiation

  • Wind speed generally increases

  • SST decreases

  • How SST is maintained above the

  • threshold level (28oC)

  • Top fresh water layer – shallow mixed layer

  • (solar penetration, Debasis, et al.

  • GRL, 2002)


ARMEX :

1. Intense Rainfall Events on West Coast

2. Warm pool dynamics

Year : 1998

(Source: NIOT Buoy data)


Temp

salinity

Density

(ARMEX & BOBMEX)

Differences in the Ocean Mixed Layer

North Bay and Arabian Sea (AS)


Rainfall & SST

CAPE


Differences in the surface energy balance over Bay & AS

(weak phase of convection/ break monsoon)

Net heat flux:- Bay: 140-180 W/m2; AS:- ~zero!

IO (JASMINE) ~ 80Wm-2.

WP(TOGA-COARE) ~80 Wm-2

Bay – Positive feedback between ocean & atmosphere

AS - Low precipitation, stronger winds, atmos.inversion


BAY

weak winds

High RH – lower LHF & NLW

AS

Winds stronger

Lower RH – High LHF


Wind speed dependence of latent heat flux

over different basins


ARMEX – 2002 : Temperature inversion at air-sea interface

Theory (M-O similarity profile)

measurement

Diurnal range : SST <0.2oC; Tair >1oC

Comparison of measured & Monin-Obukhov similarity profiles

(Bhat (2006), GRL)


SST

Ta

Buoy data

(WHOI,1995 )

1. SST<Tair, over a period of a month!

2. Heat lost to water ~ 10-20 W m-2


SST

Ta

(WHOI)

Absorption by Sea

salt particles

(Bhat, GRL, 2006)

Hydrodynamic instability


Hydrodynamic instability

Wind shear & stable stratification (Kelvin-Helmholtz)

Wave breaking takes place – strong low level jet

can account for

up to 30 W/m2 of heat flux under the

conditions prevailing over the Arabian Sea

Atmos.

Ocean


CTCZ

BriefBackground


Monsoon

Zone

Mean June–September rainfall over

the Indian region south of 30 N


Too many issues to address

All appear important!


  • Observations – Rainfall results from Propagation

  • of monsoon systems

  • Models - unable to simulate this propagation

  • in the monsoon zone

  • Monsoon rainfall simulation - Poor

  • CTCZ - ?

  • Can we understand the mechanism of

  • propagation in nature?

  • Better prediction of Monsoon rainfall


Dynamic surface conditions

May

Jul

Jun

Aug

Pre-onset & onset – Hot & dry

Peak monsoon (July-Aug) – Wet & moist

Cloud systems & their propagation


Land-surface processes – complex terrain & varying vegetation

Land-atmosphere coupling strength diagnostic for boreal summer (the difference,dimensionless, describing the impact of soil moisture on precipitation), averaged across the 12 models participating in GLACE (after Koster et al 2004,2006).


Aerosols & cloud microphysics

(High concentration of Aerosols)

Enormous Aerosol loading

East – west gradient

Marine – dry

Aerosol – cloud interactions


Clouds are important

Monsoon  Clouds & Rain

Cloud scales processes?

Cloud microphysics?


CTCZ

  • Coupled Land-Ocean-Biosphere-Atmosphere Experiment

  • Modulation of monsoon by land hydrological processes

  • Cloud scale processes

  • Aerosols & cloud microphysics

  • Multi-year programme

    Planning Stage

    Science plan being prepared

  • Pilot : 2008

  • Main : 2009-10


Super sites


Global Teleconnections


Some positive developments: Indian

1.IMD’s expansion plans – network of AWSs, DWRs, high resolution radiosondes, raingauge network, satellites,

2. IITM – Cloud Seeding Expt - Research aircraft

3. STORM Project – Infracture

4. Megha-Tropiques

5. Validation sites, ship, etc.


Weather knows no national boundaries

Collaboration with other Asian countries

AMY08, MAHASRI

YOTC


Thank you


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