U.S. Committee for

Welcome to the second edition of the U.S. IIOE-2 Newsletter! Much has been accomplished since Newsletter #1 was published. The purpose of this newsletter is to keep the U.S. community of experts involved in Indian Ocean research informed about scientific activities of their U.S. colleagues and to provide the latest news about international IIOE-2 activities. Please contact Raleigh Hood at the University of Maryland (rhood@umces.edu) if you have questions or comments, or wish to communicate about your recent, current, or upcoming research activities in the Indian Ocean via this newsletter. Articles in future issues should be a maximum of 500 words and include one figure.

News from U.S. Committee for IIOE-2A committee of ocean scientists with an interest in Indian Ocean research was formed in 2015 under the leadership of Raleigh Hood of the Univ. of Maryland. The membership includes individuals from several institutions around the United States who have been active in Indian Ocean research (see final page of Newsletter). The overarching goal of this committee is to promote U.S. involvement in the 2nd International Indian Ocean Expedition. For more information, see the U.S. IIOE-2 Web site (www.us-iioe2.org).

The committee has been meeting quarterly by teleconference since early Fall 2015. The activities of the committee have been focused on working with scientists within the United States to promote Indian Ocean science among U.S. agencies, and to work with scientists from other countries to network U.S. and foreign science efforts. A major effort since the previous newsletter was to create a Science Plan for U.S. activities in the Indian Ocean.

U.S. Science Plan—Thanks to funding from the U.S. Ocean Carbon and Biogeochemistry (OCB) pro-gram, NOAA, the NASA Physical Oceanography Program, the Scripps Institution of Oceanography, and the Indo-U.S. Science and Technology Forum, a planning meeting was held at the Scripps Institution of Oceanography on 11-13 September 2017 (Figure 1). Discussions at the meeting led to the develop-ment of a U.S. IIOE-2 Science Plan, which was published in final form in late 2018 (see https://darchive.mblwhoilibrary.org/handle/1912/10510). The purpose of this document is to motivate and coordinate U.S. participation in IIOE-2 by outlining a core set of research priorities that will accelerate our under-standing of geologic, oceanic, and atmospheric processes and their interactions in the Indian Ocean.

U.S. IIOE-2 Newsletter #2 March 2019

Figure 1: US IIOE-2 science planning workshop participants.

Meetings—The U.S. Committee has planned and/or participated in several important meetings since the previous newsletter:

• KUDOS (Korea-US inDian Ocean Scientific research program) meetings were convened at Seoul National University on 29 November–1 December 2017 and at Scripps Institution of Oceanography on 6-8 November 2018 (Figure 2). The first meeting led to the development of a Science Plan for bilateral Korea–U.S. research in the Indian Ocean (see https://kiost-noaa-lab.wixsite.com/kudos2018) and the second meeting led to the development of specific plans for proposal development and submission to federal funding agencies in both Korea and the United States.

Figure 2: KUDOS 2 proposal development workshop participants.

• Town Hall Meeting at 2018 Fall AGU in Washington, D.C.—This was the 4th in a continuing series of Town Hall Meetings at AGU meetings to keep the U.S. community aware of developments in IIOE-2. The session included presentations by Raleigh Hood, Jerry Wiggert, Viviene Menezes and Lynne Talley about U.S. and International IIOE-2 activities and plans. • IIOE-2 Steering Committee Meeting – This meeting was convened in Jakarta, Indonesia on 18-21 March 2018. • IIOE-2 Science Working Group Meeting in Kiel, Germany—The IIOE-2 Science and Research Working Group (WG-1) is comprised of the leaders of the 6 science themes of IIOE-2. WG 1 met in Kiel, Germany on 28-30 November 2018 to brainstorm about creating scientific products at the project mid-point. One of the co-chairs of the Data Management Working Group (WG 2: Cyndy Chandler), and IIOE-2 and SCOR staff also participated in the meeting. Meeting participants decided to write a series of review papers along the lines of the International Science Plan science themes. Detailed outlines were due by the end of January 2019, anticipating submission of papers by the end of August 2019.• SCOR-InterRidge Symposium—One of the sponsors of IIOE-2, the Scientific Committee on Oceanic Research (SCOR) partnered with the InterRidge project to convene a workshop in Goa, India on 14-16 November 2018 (see http://interridge.org/files/interridge/ABSTRACT_SCOR-InterRidge_2018-1.pdf). The workshop focused on the geological, geophysical, geochemical and physical aspects of the mid-ocean ridges and the other geological features in the Indian Ocean and provided a forum for exchange of ideas and results.• IODP Workshop— International Ocean Discovery Program (IODP) Proposal Nurturing Workshop on Indian Ocean; Goa, India, 17–18 September 2018 (see https://eos.org/meeting-reports/investigating-the-northern-indian-oceans-puzzling-geodynamics). The focus of the workshop was to develop new ideas for research questions in the northern Indian Ocean that would best be answered through using of the scientific drilling assets available through IODP.

Publications—DSR-II special issues – Two special issues on IIOE-2 are under development. Thirty-eight manuscripts have been submitted to date, of which 13 papers are in production and 16 manuscripts are currently in review. If you are interested in submitting a manuscript for publication in one of these special issues, please contact Raleigh Hood (rhood@umces.edu).

U.S. IIOE-2 Web site—A Web site has been developed to keep U.S. investigators informed about the status of U.S. involvement in the IIOE-2. As mentioned above, the Web site can be found at the same URL as the previous Website: www.us-iioe2.org. Responsibility for the Web site has recently been taken up by the Ocean Carbon and Biogeochemistry (OCB) program. OCB has been very helpful in promoting the work of the U.S. IIOE-2 Committee. We welcome suggestions for making the site more useful to the U.S. community. The Website includes links to the international IIOE-2 Science Plan and Implementation Strategy, as well as the list of known cruises and other activities.

U.S. Science Activities in the Indian OceanNOAA Ship Ronald H. Brown Completes GO-SHIP IO7N Repeat Line in the Indian OceanBy Raleigh R. Hood University of Maryland Center for Environmental Science, Cambridge, MD

Figure 3: NOAA R/V Ronald H. Brown in port in Durban, South Africa before departure to sample GO-SHIP line IO7N (left panel) and the cruise track superimposed on surface Chlorophyll-a (right panel).

The NOAA Research Vessel Ronald H. Brown (Figure 3) completed sampling of the GO-SHIP IO7N repeat hydrography line, departing from Durban, South Africa on 23 April 2018 and arriving in Goa, India, on 6 June 2018. The cruise sampled a transect in the western Indian Ocean from 30oS to 20oN along 55oE (Figure 3). This was the first scientific occupation of line IO7N since 1995. The overall science goal of the cruise was to learn how the western Indian Ocean has changed over the last 23 years. Specifically, has the deep ocean warmed? Have the regional concentrations of dissolved oxygen, carbon dioxide, and/or nutrients changed? Has the Western Indian Ocean become more acidic? One of the key objectives of the cruise was to measure the amount of heat that is stored in this part of the ocean. Existing observations from different platforms show that the upper-ocean heat content for the global ocean has been steadily increasing since the 1970s. The Indian Ocean is the warmest ocean on the planet and the heat content of its upper 2,000 m has been increasing. But, has the excess heat penetrated deeper than 2,000 meters in the Western Indian Ocean? The data collected on this cruise will help to answer this question. In addition to the core CTD and chemical observations, state-of-the-art bio-optical measurements were collected along the transect to characterize biological processes and link them to satellite ocean color measurements. These observations, which were made possible by a NASA RAPID grant, included phytoplankton pigments, phytoplankton and zooplankton species composition, primary production, and fluorescence/light response. These data will be analyzed in a paper describing the phytoplankton community structure across biogeographic regimes delineated using the core CTD and chemical observations. These data will also be used to help improve satellite remote sensing estimates of chlorophyll concentration, primary production, and phytoplankton community size and structure. The cruise was a resounding success. The IO7N line was completed on schedule and all major scientific objectives were met.

NOAA Ship Ronald H. Brown Establishes New Mooring Sites in the Arabian SeaBy Mike McPhadenNOAA/PMEL, Seattle, Washington

Following GO-SHIP IO7N Repeat Line, the R/V Ron Brown departed Goa on June 14 to establish three new sites of the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) in the Arabian Sea along 65°E and 67°E. The cruise also maintained five existing RAMA moorings along 67°E before finishing on 19 July in Darwin, Australia. The new moorings bring RAMA to 91% completion. Data from these moorings support international research efforts and help NOAA and other weather forecast centers around the world continue to improve monsoon predictions.

U.S. GO-SHIP will revisit the I6S line along 30°E in the southern Indian OceanBy Alejandro Orsi Department of Oceanography, Texas A&M University

Sustaining a coordinated global network of hydrographic transects is an essential component of the Global Ocean/Climate Observing System. Repeat high-quality shipboard measurements of climate-relevant physical-chemical properties are fundamental to characterize complex oceanic responses to climate change. Since its inception in 2007, GO-SHIP transoceanic surveys provide full water column hydrographic observations with temporal and spatial resolutions adequate to resolve decadal variability in oceanic storage of heat, freshwater, carbon, oxygen, nutrients and transient tracers. In April-May 2019, U.S. GO-SHIP will revisit the intercontinental I6S line along 30°E in the southern Indian Ocean. The first U.S. occupation of I6S was in 2008, itself a repeat of the original 1996 WOCE transect by France. Repeat hydrographic measurements along I6S during 1996-2019 will enable scientists to better tackle important unresolved aspects of Southern Ocean adjustment to atmospheric global warming. The heat content of bottom waters in the Weddell-Enderby Basin shows a large long-term (1990s -mid 2000s) increase rate, while their parent waters over the Antarctic continental shelves have not revealed any significant warming over the years. The 2008 and 2019 measurements of dissolved inorganic carbon will allow quantifying the anthropogenic component in the total inventory changes of surface and deep waters. Similarly, decadal dissolved organic carbon measurements on I6S will elucidate if concentrations in the Circumpolar Deep Water are mainly determined by local or distant processes. Combined carbon and current measurements from the repeat I6S line will be investigated to determine rates of regional carbon accumulation and exchange with adjacent circulations.

Topographic Effects on Tropical Cyclone Formation over the Indian OceanBy Richard H. Johnson Department of Atmospheric Science, Colorado State University

Tropical cyclones (TCs) are commonly occurring severe weather phenomena over the Indian Ocean (IO). TC activity over the northern IO is bimodal, peaking in November and May, whereas activity over the southern IO has a broad single peak in austral summer. While IO TCs have been studied for decades, their formation mechanisms are still not well understood. However, a recent study has shown that Sumatra and surrounding landmasses have a significant impact on the development of TCs over the IO (Fine et al. 2016). When the low-level flow is easterly across Sumatra, the flow is deflected around the ends of the island under typical environmental conditions and lee vortices are produced downstream over the IO. Since Sumatra straddles the equator (extending in a northwest–southeast direction from approximately 6°N to 6°S) these vortices, while counter-rotating, are cyclonic in both hemispheres. There is no other place on earth where a similar geographic setup exists that leads to cyclonic vortex production in both hemispheres. Some lee vortices are subsequently shed and move farther westward from the northern and southern tips of Sumatra where they can serve as initial disturbances that eventually intensify into TCs over the IO. Data from two tropical field campaigns, the 2008–2010 Year of Tropical Convection (YOTC) and the 2011 Dynamics of the Madden–Julian Oscillation (DYNAMO), are used to study these phenomena. These datasets reveal the frequent occurrence of shed and non-shed terrain-induced cyclonic circulations over the IO, the majority of which occur during boreal fall and winter. During the 2.5 years of the two campaigns, 13 wake vortices (13% of the shed circulations identified) were tracked and observed to subsequently develop into TCs over the northern and southern IO. These terrain-induced vortices accounted for a remarkable 25% of the total TCs forming over the IO during that period. The environmental conditions conducive to terrain-induced TC formation over the IO involve easterly flow over Sumatra, which is commonplace during the boreal winter monsoon and also occurs when the Madden-Julian Oscillation (MJO) is developing over the central IO.

Shed vortices that occur during a developing MJO have greater chance of intensifying into a TC due to the very moist conditions that exist over the central IO at that time. Recognition of this set of conditions can be an aid to forecast centers that have the responsibility for TC warnings in the IO basin.

Fine, C. M., R. H. Johnson, P. E. Ciesielski, and R. K. Taft, 2016: The role of topographically induced vortices in tropical cyclone formation over the Indian Ocean. Mon. Wea. Rev., 144, 4827-4847, doi: 10.1175/MWR-D-16-0102.1.

Promotion of U.S. research on marine geology and geophysics in the Indian Ocean—The U.S. IIOE-2 Committee will enter discussions to follow up on the recent SCOR-InterRidge and IODP meetings focused on the Indian Ocean region to develop mechanisms for greater U.S. involvement in these activities.

BGC Sensors on RAMA moorings—Plans are underway for adding new biogeochemical sensors on RAMA moorings by University of Miami scientists.

IIOE-2 special session at the IMBER Open Science Conference in June 2019 in Brest, France— The Second International Indian Ocean Expedition (IIOE-2): Motivating New Exploration in a Poorly Understood Basin. Conveners: Jerry Wiggert, Raleigh Hood, Jerome Vialard, Benjamin Kürten, and Francis Marsac. The abstract submission deadline was January 15, 2019.

Potential IUSSTF-funded proposal for bilateral U.S.-Indian planning for joint research in the Indian Ocean—The U.S. IIOE-2 Steering Committee plans to submit a proposal to the Indo-U.S. Science and Technology Forum (IUSSTF) to convene a bilateral India–U.S. IIOE-2 proposal development workshop in fall 2019. This meeting will be open to all interested U.S. investigators. New Members of U.S. IIOE-2 Committee—The U.S. IIOE-2 Committee will be looking for new members and has been discussing a variety of names.

Port Elizabeth Meetings—Joint meetings of the IIOE-2 Steering Committee, CLIVAR’s Indian Ocean Regional Panel (IORP), the Sustained Indian Ocean Biogeochemical and Ecosystem Research (SIBER) Program, the Indian Ocean GOOS (IOGOOS) program, the IndOOS Resources Forum (IRF) and the IOC Regional Committee for the Central Indian Ocean (IOCINDIO) will be convened at Nelson Mandela University in Port Elizabeth, South Africa on 11-15 March 2019. This meeting is open to all interested participants. Contact Raleigh Hood (rhood@umces.edu) for more information.

Indian Ocean Bubble-2—The Indian Ocean Bubble-2 is a newsletter devoted to informing the international IIOE-2 community about ongoing work, scientific questions, meetings, cruises, research results, and other important information. Articles are accepted from any scientist working in or interested in Indian Ocean science. Raghu Murtugudde from the University of Maryland has contributed several thought-provoking articles to the Indian Ocean Bubble-2: • Can Chlorophyll Help Improve Subseasonal-to-Seasonal (S2S) Predictions over the Indian Ocean?• Model SST and Precipitation Biases over the Indian Ocean• What IIOE-2 Observations are needed to Address Monsoon Forecast Biases?• A Shout-out for Better Estimates of Ocean Mixed Layer Depths from Observations – available soon online as part of Issue No. 10

This is an excellent forum for short articles by other U.S. scientists.

International IIOE-2

Upcoming Plans and Activities

U.S. Committee for IIOE-2

Raleigh Hood (Chair,University of Maryland,biological oceanography)

Dwi Susanto (University of Maryland, physicaloceanography)

Lisa Beal (University of Miami, RSMAS, physical oceanography)

Mike McPhaden (NOAA, PMEL, physical oceanography and climate)

Lynne Talley (Scripps Institution of Oceanography, physical oceanography)

Greg Cutter (Old Dominion University, chemical oceanography)

Mike Landry (Scripps Institution of Oceanography, biological oceanography)

Chidon Zhang (NOAA, PMEL, atmospheric science)

Subrahmanyam Bulusu (University of South Carolina, physical oceanography and satellite oceanography)

Joaquim Goes (Columbia University, LDEO, biological oceanography and satellite oceanography)

Karen Lloyd (University of Tennessee Knoxville, deep-sea microbiology)

Jerry Wiggert (University of Southern Mississippi, interdisciplinary modeling)

Henry Dick (Woods Hole Oceanographic Institution, marine geology and geophysics)