Recent Progress Towards an Indian Ocean Observing System for Climate Michael J. McPhaden NOAA/PMEL Prepared for NOAA Climate Observations Workshop 13-15 May 2003 Washington, DC

Summary There is an increasingly organized international effort to develop an Indian Ocean component to the Global Ocean Observing system in support of climate studies: Compelling unanswered scientific questions; Potential societal benefits (improved prediction of the monsoon rainfalls and teleconnections); Growing investments from Indian Ocean rim countries and others; One of the most poorly sampled regions of the world ocean in terms of in situ observations; Opportunities for the US to participate. Emphasize ISOs initially

Indian Ocean GOOS Conference Grand Baie, Mauritius, 1-9 November 2002 Oceans and Climate Workshop Goal: “…to identify actions required to develop an Implementation Plan for the Indian Ocean Global Ocean Observing System (IOGOOS), building on the SOCIO Workshop, meetings of the Climate Variability (CLIVAR) Asian/Australian Monsoon Panel, and the Global Ocean Data Acquisition Experiment (GODAE) Science Team…” Three workshops: one on coastal and one on satellites as well. Conferences on Climate, Coastal Zone, Satellite, Data Management 158 participants from 22 countries Co-sponsored by IOC/GOOS, CLIVAR, NOAA, ONR, NSF….

Indian Ocean Regional Science Drivers Seasonal monsoon variability Intraseasonal oscillations Indian Ocean dipole mode Decadal warming trends Interbasin connections (Indonesian throughflow & Algulas rings) Deep meridional overturning Subtropical/tropical overturning cells Emphasize ISOs initially

Indian Ocean Dipole Mode Three workshops: one on coastal and one on satellites as well. December 1997 SST Anomalies

Indian Ocean Regional Science Drivers Seasonal monsoon variability Intraseasonal oscillations Indian Ocean dipole mode Decadal warming trends Interbasin connections (Indonesian throughflow & Algulas rings) Deep meridional overturning Subtropical/tropical overturning cells Emphasize ISOs initially

Meridional overturning-- The shallow cell Schott et al. (2001)

Atmospheric Teleconnections Monsoon <=> ENSO interactions MJO influences on ENSO West coast US rainfall Tropical storms and hurricanes Indian Ocean SST influence on NAO?

Episodic westerly wind forcing May 2001-May 2003 Episodic westerly wind forcing MENTION: Newsletter reprint Some features of the evolution of the 2002-03 El Nino: Episodic wind forcing important. Much of this episodic wind forcing related to MJO generated over the Indian Ocean. Onset in May-June 2002 when persistent basin scale warming first appears in response to a westerly event of large zonal fetch in May. Several features which can qualitatively inferred from TAO/TRITON and other data are pointed out in the animations of this slide. These features require quantification through more rigorous diagnsotic and modeling study, but they can be considered working hypotheses.

The Madden-Julian Oscillation Cloudiness & Rainfall The Madden-Julian Oscillation June 2001 Convective flare-ups occur every 30-60 days over the Indian Ocean. These flare-ups are characterized by towering cumulus clouds, rainfall, and westerly surface winds that propagate into the Pacific sector. Dec 2002 cloudy/wet clear/dry Indian | Pacific | Atlantic MJO Convection

Atmospheric Teleconnections West Coast Rainfall Tropical Storms

Atmospheric Teleconnections Monsoon <=> ENSO interactions MJO influences on ENSO West coast US rainfall Tropical storms and hurricanes Indian Ocean SST influence on NAO?

Monsoon Dynamics and Linkages The present commitments in are time-limited.

Indian Ocean Observing System Status Satellite observations of sea level, SST, wind and ocean color are key elements of the Indian Ocean Observing System. Substantial progress in implementation of pilot in situ observations during the past two years (Argo, moorings, drifters, XBTs, etc). The present commitments in are time-limited.

Indian Ocean The present commitments in are time-limited. XBTs/Moorings Dec ‘02 Drifters, Jan ‘03 The present commitments in are time-limited. Efforts are underway to increase in situ measurements in the Indian Ocean Argo Floats, Feb ‘03

Indian Ocean Masumoto et al, 2002 Not shown: US interests in equatorial and BoB moorings Plans for 40 deep ocean moorings north of 5°N (NIOT) Madagascar Channel moorings (Dutch) See bullets for discussion. Masumoto et al, 2002

JAMSTEC ADCP mooring 0°, 90°E Indian Ocean JAMSTEC ADCP mooring 0°, 90°E See bullets for discussion. Masumoto et al, 2002

The Working Group proposed three pilot projects: IOGOOS Meeting Working Group 1: Basin-scale Contributions to the Observing System The Working Group proposed three pilot projects: to develop the deployment of Argo floats, from the present level of about 67 to 170 in 2003, and to 450 in 2005; the implementation of a new Ship-of-Opportunity XBT Project, with emphasis on high-resolution, frequently repeated lines across the Indian Ocean. to develop Indian Ocean mooring arrays in the equatorial zone and in four zones of significant sea-surface temperature anomalies (northern Bay of Bengal, off the southern coasts of Sumatra and Java, western Arabian Sea, and the southern Indian Ocean); However, the other elements of the sustained integrated ocean-observing system for climate that have been identified as needed were not discussed, for lack of time. • Moreover, for lack of time, only the broadest of outlines were discussed for these pilot projects, most notably #3. • Naturally there will be challenges: funding, ship time, vandalism, data management, internatiional coordination.

IOGOOS, Mauritius, 4-8 November 2002 Indian Ocean IOGOOS, Mauritius, 4-8 November 2002 IOGOOS participants moved to establish an ad hoc working group* of the Tropical Moored Buoy Implmentation Panel (TIP) to develop and coordinate implementation of a moored buoy array to address CLIVAR scientific objectives and to support operational analyses and seasonal-to-interannual climate forecasting. * Initial interested parties: M. McPhaden (USA), M. Jury (So. Africa), Y. Masumoto (Japan), R. Molcard (France), M. Ravichandran (India), C. Perigaud (USA), G. Vecchi (USA), G. Meyers (Australia), VSN Murty (India), and P. Hacker (USA). See bullets for discussion.

CLIVAR Asian/Australian Monsoon Panel (AAMP) Atlanta, Georgia, 25-27 February 2003 Considering the rapid development of, and many nations’ involvement in, the Indian Ocean Observing System, AAMP strongly recommended that an Indian Ocean Panel be formed for coordination and for CLIVAR to help drive forward the implementation of ocean observations in the region. The AAMP suggested that the new panel be set up jointly with IOC in the framework of the recently established IOGOOS. See bullets for discussion. CLIVAR SSG endorsement SSG-12, Victoria, BC, 6-9 May 2003

Indian Ocean Science & Implementation Challenges Array design(s) Funding Deployment platforms (RVs, VOS, etc) Fishing vandalism (moorings) Measurement standards Data management International coordination and partnerships for sustaining observations Emphasize ISOs initially

Global Ocean Observing System Sea Surface Temperature, Sea Surface Height, and Surface Vector Wind from Space CLIVAR has Pac/At panels, IO not needed since until recently not much happening. IO lags Pac/At in terms of obs sys development, but there is some optimism that this part of the world ocean will be getting more attention in the near future. Tide Gauge Network 45 % complete 3˚x3˚ Argo Profiling Float Array 25% complete 5˚x5˚ Surface Drifting Buoy Array 35 % complete Moored Buoy Existing Planned Ocean Reference Station Existing Planned High Resolution XBT and Flux Line Existing Planned Frequently Repeated XBT Line Existing Planned Carbon Inventory & Deep Ocean Line Survey 1.5 lines/year, 50 % funded Figure 1

Summary There is an increasingly organized international effort to develop an Indian Ocean component to the Global Ocean Observing system in support of climate studies: Compelling unanswered scientific questions; Potential societal benefits (improved prediction of the monsoon rainfalls and teleconnections); Growing investments from Indian Ocean rim countries and others; One of the most poorly sampled regions of the world ocean in terms of in situ observations; Opportunities for the US to participate. Emphasize ISOs initially

Indian Ocean Research Issues Four unique characteristics of the Indian Ocean generate a “heat pool” with basin-scale variability over a broad range of time scales Closed in the north by Asia, creating monsoons and blocking export of oceanic heat to the north Open to the Pacific, creating Indonesian throughflow and import of warm equatorial, upper ocean waters Cross-equatorial transports of heat in the ocean and atmosphere, creating the shallow overturning cell Open to exchange with the Southern Ocean, creating the deep overturning cell. Emphasize ISOs initially

Comparison with previous El Niños Comparison of NINO3.4 index for El Niños of the past 20 years. Time series for each event start in July the year before the event onset (Yr-1) and continues through January after the El Niño has ended (Yr+2). Last point for the current event is February 2003. The 2003 El Niño would be considered moderate strength based on this index, and significantly weaker than either the 1982-83 event or the 1997-98 event. Adapted from International Research Institute NINO-3.4