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January 2011 Issue

CLIVAR Continues Building Capacity To Observe, Model Climate

By Bob Molinari
Antonio Caltabiano
Staff Scientist
International CLIVAR Project Office
National Oceanography Centre
Southampton, England

The Climate Variability and Predictability Programme (CLIVAR), a core project of the World Climate Research Programme (WCRP), focused on ocean observations, modeling and synthesis in 2010.

CLIVAR's four ocean-basin panels, in the Atlantic, Pacific, Indian and Southern oceans, are responsible for activities that include the coordination of process studies in their respective ocean basins and the review and provision of scientific requirements for sustained observations. A particular success has been in the Indian Ocean where, working with the Intergovernmental Oceanographic Commission, an extensive ocean-observing capability is being deployed.

Another current CLIVAR activity, expected to be complete by the end of 2010, is the selection of a set of imperatives that will drive CLIVAR science and its implementation over the coming five years, with a continuing focus on the ocean's role in climate. The imperatives include anthropogenic climate change; decadal variability, predictability and prediction; intraseasonal predictability and prediction; improved atmosphere and ocean components of Earth system models; data synthesis, analysis, reanalysis and uncertainty; ocean-observing systems; and capacity building.

Indian Ocean Activities
The Indian Ocean observing system (IndOOS) is a multiplatform sustained observing system consisting of Argo floats; tide gauges; surface drifting buoys; expendable bathythermograph (XBT)/expendable conductivity, temperature, depth probe lines; and satellite measurements. A critical component of IndOOS, the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction, will eventually consist of 46 moorings, more than half of which have already been deployed. Because of the rapid progress in the implementation of IndOOS, new data obtained have already helped to improve our understanding of various phenomena of climate importance, such as the Indian Ocean dipole.

Pacific-Region Activities
One of CLIVAR's main activities in the Pacific Ocean has been the coordination of several observational efforts on the western boundary of the basin. The latest CLIVAR-endorsed project is the Northwestern Pacific Ocean Circulation and Climate Experiment (NPOCE), which is led by Chinese researchers and includes the participation of several other countries. NPOCE will carry out a large field experiment that will include in-situ measurements by moorings, Argo floats and gliders, in conjunction with hydrographic surveys and other existing observational networks. NPOCE observations will leave a sustainable monitoring network for the Northwestern Pacific circulation system, and it will also connect with other programs further south, such as SPICE, the Southwest Pacific Ocean Circulation and Climate Experiment.

Atlantic-Region Activities
In the Atlantic region, much of the observational focus has been directed toward the Tropical Atlantic Climate Experiment (TACE). TACE observations come from the Prediction and Research Moored Array in the Atlantic, Argo floats, XBTs, sea-level stations and hydrographic instruments, all of which are directed at characterizing and increasing the understanding of this complicated area and its role in both regional and global climate.

Another major CLIVAR effort, which encompasses the entire basin, involves observations of the Atlantic meridional overturning circulation (AMOC). Observations of this system come from Argo floats, hydrographic and XBT sections, and moored buoys. The success of AMOC, as with the majority of CLIVAR projects, is dependent on coordinated international programs.

Southern Ocean Observations
In the Southern Ocean, CLIVAR is working with other groups to define and promote the sustained Southern Ocean Observing System (SOOS), which is based on repeat hydrography, enhancement of the Argo array, sea-ice observations, remote sensing and—unique to this area—animal-borne sensors. The CLIVAR-cosponsored Argo network has dramatically increased hydrographic coverage in the upper 2,000 meters of the water column over the region and has helped to provide evidence for significant warming and freshening in the Southern Ocean. Beneath 2,000 meters, observations of bottom-water variations also point to large-scale warming. Despite these recent insights from observations, there remains the continued need for a more systematic and sustained approach to ocean measurements that will be provided by the SOOS.

Climate Modeling
Beyond its observational programs, CLIVAR also includes a significant numerical modeling component. CLIVAR's Working Group on Coupled Modelling has been particularly active in coordinating the Coupled Climate Model Intercomparison Project, Phase 5 (CMIP5).

CMIP5 model runs will be used as input for the Intergovernmental Panel on Climate Change reports. More than 20 global modeling groups are participating in climate change projections on decadal and centennial timescales. The increase in complexity and resolution provided by the models will allow for increased quantification and understanding of the sources of uncertainty in climate projections; the study of the carbon cycle and cloud feedbacks; the study of interactions between climate, atmospheric chemistry and air quality; the assessment of regional climate variability and change; and the response to mitigation measures.

Seasonal to Decadal Prediction
CLIVAR's Working Group on Seasonal to Interannual Prediction (WGSIP) coordinates projects among the leading seasonal to interannual forecasting groups around the world and maintains linkages to the applications community. The principal activity of WGSIP is the coordination of the Climate System Historical Forecast Project (CHFP).

The CHFP has been successful in expanding the seasonal forecast problem out of the traditional ocean-atmosphere domain to include other potential sources of seasonal to interannual predictability, including land, cryosphere and stratosphere processes. Several centers are now providing open access to CHFP data archives for use by the international climate community.

In September, CLIVAR's Working Group on Ocean Model Development met in a workshop dedicated to understanding the role of the ocean in decadal variability, predictability and prediction. A key outcome of the workshop will be the interaction that it will facilitate among various groups (e.g., modelers and observationalists) that are working on the decadal variability and prediction problem. The workshop also provided guidance on how to evaluate ocean models and the robustness of decadal variability in ocean and coupled climate models.

Future Developments
One recent development is that WCRP is proposing a new structure for their programs and activities. CLIVAR, as one of WCRP's projects, has been contributing to this activity. The definition of this new structure will result from WCRP's Open Science Conference scheduled for October 24 to 28 in Boulder, Colorado.

CLIVAR scientists will continue to work on the physical aspects of the climate system through modeling, observations and synthesis. The scientists will also begin to address the future of CLIVAR, which will also include biogeochemical processes (e.g., carbon issues), regional projects and climate services. These CLIVAR activities will be incorporated into the 'new' WCRP that will continue to serve society's global climate requirements.

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