January 2012 Issue
CLIVAR’s Ocean Observational Activities and Data
By Bob Molinari
International CLIVAR Project Office
National Oceanography Centre Southampton
Historically, the World Climate Research Programme’s Climate Variability and Predictability (CLIVAR) project has worked toward the coordination of regional and global scientific projects directed at increased understanding and prediction of the physical processes that control the ocean’s role in atmospheric climate. These studies include timescales from subseasonal to centennial. The three major foci of CLIVAR are observations, modeling and process studies; this article will discuss the observational aspects of CLIVAR.
A review of the primary modeling component of CLIVAR is in the Special Issue of the CLIVAR newsletter, Exchanges, No. 56, Vol 16, No. 2, May 2011 (http://bit.ly/sUBTwZ). Hard copies can be obtained from CLIVAR at firstname.lastname@example.org.
Global Ocean Observation
Under its observations mandate, CLIVAR promotes the scientific needs for ocean observations and, together with intergovernmental bodies, advocates sustained observations. This work is led by CLIVAR’s Global Synthesis and Observations Panel (GSOP), which communicates the societal benefits of a sustained ocean observation system, in order to highlight the need for timely, freely accessible and quality-controlled data.
One of GSOP’s main contributions is the evaluation of the present generation of ocean synthesis/reanalysis products and the use of these products to study climate-related aspects of global ocean circulation. The evaluation has led to several improvements in the products, including the first specification of uncertainties in ocean syntheses. KlimaCampus, a network of climate research experts in Hamburg, Germany, has been providing since July 2010 information on several ocean syntheses products and distributing data in a common format to all interested researchers. This builds on the GSOP-developed Ocean Synthesis Directory for the modeling community as a means to obtain easy-to-use products for model initialization (http://bit.ly/tEc3IW).
GSOP’s activities foster cooperation among the observation, synthesis and climate model communities. For example, the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP), cosponsored by the International Ocean Carbon Coordination Project and CLIVAR, is collaborating with several other programs to ensure that the high-quality CTD data collected by GO-SHIP are available for the calibration and quality control of Argo profiles.
Other GO-SHIP activities include providing opportunities for float deployment in remote regions of the global ocean and enabling calibration of expendable bathythermographs via simultaneous drops of the devices at hydrographic stations. GSOP has also fostered the examination of the expendable bathythermograph program to ensure community consensus on methods to remove fall-rate and temperature biases in these data and to standardize metadata reporting.
CLIVAR Ocean Basin Activities
CLIVAR’s ocean basin projects aim to enhance our understanding of regional oceanic and atmospheric phenomena. Sustained observations and modeling activities in the ocean basins are complemented by process studies aimed at understanding western boundary currents, meridional heat flux, and the role of the ocean in monsoon regions, for example.
Southern Ocean. Because of the obvious logistical challenges, the Southern Ocean is the least observed ocean basin. This body of water provides the principal connection among the Earth’s major ocean basins and, as a result, strongly influences global climate patterns through interactions with the atmospheric Southern Annular Mode, for example. Long time series are needed to detect, interpret and respond to changes in this region.
The Southern Ocean Observing System (SOOS) plan, completed last year, presents a scheme for an integrated multidisciplinary observing system for the Southern Ocean, including: repeat hydrography; multidisciplinary observations (i.e., expanding from a primarily physics view to include biological and chemical perspectives) of the surface ocean and meteorology from volunteer observing ships; enhanced Argo float deployments; observations from instrumented marine animals; moored time series in key deepwater outflows, boundary currents and fronts; and sea ice observations.
The plan builds on some components already in place in the region, and the total implementation of the plan will take a few years. In order to support the implementation of SOOS, a project office has been set up in Australia. CLIVAR has been instrumental in developing this plan and providing ongoing advocacy for observations in this poorly observed region.
Indian Ocean. The need to understand the effects of the Indian Ocean on climate variability is essential, as the region is bounded by countries that collectively are inhabited by one-third of the world’s population. CLIVAR has been involved in increasing the ocean-observing capability in the tropical Indian Ocean and the use of model-generated data to study ocean and coupled air-sea processes in the basin.
The Indian Ocean Observing System’s critical component, RAMA, consists of 46 planned moorings, of which 65 percent have been deployed as of November. Because of the rapid progress in the implementation of the Indian Ocean Observing System, new data have already helped improve our understanding of various climate-related phenomena, such as: the ocean dynamics associated with the Indian Ocean Dipole; dynamics of the equatorial currents at intraseasonal, semiannual and annual time scales; and the upper ocean response (sea surface temperature and mixed layer depth) to the Madden-Julian Oscillation, cyclone forcing and its potential feedbacks.
Unfortunately, piracy in the northwest Indian Ocean is impeding the completion of this array, adversely impacting Indian Ocean climate research, observations and modeling.
Pacific Ocean. CLIVAR continues to coordinate several observational and modeling efforts in the western boundary currents region of the Pacific Ocean. In January 2011, the Northwestern Pacific Ocean Circulation and Climate Experiment (NPOCE), led by Chinese researchers with participation from several other countries, successfully deployed several moorings in the study area and performed a 52-day survey of the northwestern Pacific. This cruise was the first of a series planned as part of the project. In addition, NPOCE will carry out in-situ measurements using Argo floats and gliders this year.
Further south, the Southwest Pacific Ocean Circulation and Climate Experiment (SPICE) has monitored currents in the Coral Sea region and found they can be very deep, with a large temporal variability and potential implications for the equatorial Pacific. CLIVAR is also supporting the coordination of efforts in the Indonesia throughflow region, which is an important component of the global meridional overturning circulation.
Atlantic Ocean. CLIVAR is coordinating studies of the meridional overturning circulation from the South Atlantic to North Atlantic. The South Atlantic Meridional Overturning Circulation (SAMOC) project has already begun collecting data in the subtropical gyre of this basin. Further north, the Tropical Atlantic Circulation Experiment (TACE) completed its observation period in 2011, and efforts to synthesize the resulting data are being planned. In the subtropical North Atlantic, observations of the meridional overturning circulation by the RAPIDWATCH, EU-THOR and US-AMOC projects continue.
When these observing systems are in place, and as analyses of previously collected data continues, monitoring of the meridional overturning circulation will include most of the Atlantic Ocean. CLIVAR is active in coordinating these projects and identifying both observations and modeling issues that could be jointly addressed by project researchers.
Monsoon Regions. In the southeastern Pacific, the VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS) aims to develop and promote scientific activities that will improve understanding of the southeastern Pacific coupled ocean-atmosphere-land system on diurnal to interannual timescales. The study has a large field program, with oceanic and atmospheric properties measured by vessels, planes and moorings.
In the Indian Ocean, the CINDY2011 and DYNAMO experiments have brought together researchers from 13 countries/territories, collecting in-situ atmospheric and oceanic observations to advance knowledge of the Madden-Julian Oscillation and improve simulations and predictions.
These monsoon region projects have been endorsed by CLIVAR, which maintains a regular assessment of progress, identifying any potential gaps that need to be addressed.
Future CLIVAR Activities
In 2012 and beyond, CLIVAR’s activities will expand into new areas driven by societal needs for diversified climate data. Multidisciplinary activities in the Southern Ocean, which are also taking place in the other three ocean basins, have been mentioned.
CLIVAR will also venture into climate services. The objective of these activities, now in planning stages, will be to ensure that society is obtaining the information from CLIVAR studies needed to make informed decisions on mitigation and adaptation responses to climate change.