Ocean Analysis and Reanalysis: 

Phil Arkin, ESSIC, University of Maryland

• Background• Concept and Implementation• Issues

We need more comprehensive climate observations and we must make more efficient use

of those that are and will be available.

THE NEED FOR A SYSTEMS

APPROACH TO CLIMATE

OBSERVATIONSBY KEVIN E. TRENBERTH, THOMAS R. KARL, AND THOMAS W. SPENCE

Because climate is changing, we need to determine how and why. How do we best track and provide useful information of sufficient quality on climate?

Bulletin of the American Meteorological Society:

November 2002, 83, 1593-1602

Observing Observing systemsystem means a comprehensive means a comprehensive approach, includingapproach, including

• Climate observationsClimate observations from both space-based and in situ from both space-based and in situ platforms taken in ways that address climate needs and adhere platforms taken in ways that address climate needs and adhere to the ten principles outlined by the NRC (1999).to the ten principles outlined by the NRC (1999).

• A global telecommunications network and satellite data A global telecommunications network and satellite data telemetry capacity to enable data and products to be telemetry capacity to enable data and products to be disseminated. disseminated.

• A climate observations analysis capability that produces global A climate observations analysis capability that produces global and regional analyses of products for the atmosphere, oceans, and regional analyses of products for the atmosphere, oceans, land surface and hydrology, and the cryosphere, based on four land surface and hydrology, and the cryosphere, based on four dimensional data assimilation capabilities that process the dimensional data assimilation capabilities that process the multivariate data in a physically consistent framework to multivariate data in a physically consistent framework to enable production of the analyses: for the atmosphere and enable production of the analyses: for the atmosphere and oceans, land surface and so on.oceans, land surface and so on.

• Global climate models that encompass all parts of the climate Global climate models that encompass all parts of the climate system and which are utilized in data assimilation and in system and which are utilized in data assimilation and in making ensemble predictions.making ensemble predictions.

Strategic Plan for the Integrated Earth Observation SystemInteragency Working Group on Earth Observations

THE GEOSS/IEOS TEMPLATE

What do we do What do we do nownow about the analysis issue? about the analysis issue?

The goal is an accurate description of the current The goal is an accurate description of the current and past state of the complete coupled climate and past state of the complete coupled climate system – ocean, land, atmosphere, …system – ocean, land, atmosphere, … Such a description is the product of an analysis systemSuch a description is the product of an analysis system

Ocean Climate Observing System(s) must be Ocean Climate Observing System(s) must be accompanied by appropriate Climate Analysis accompanied by appropriate Climate Analysis System(s)System(s) Utilize the analysis system to inform decisions on Utilize the analysis system to inform decisions on

observing system designobserving system design OCO set up a “Team of Experts” – scientists OCO set up a “Team of Experts” – scientists

doing research with ocean observations – to get doing research with ocean observations – to get started on this by using the observations to started on this by using the observations to perform new and interesting researchperform new and interesting research

Team of Experts: Team of Experts: Goals/ObjectivesGoals/Objectives Use products from the observing system and other sources, including operational Use products from the observing system and other sources, including operational

and experimental analyses, to document the ocean’s role in climate variability and and experimental analyses, to document the ocean’s role in climate variability and changechange

Regularly deliver a suite of ocean products that will describe sea level, ocean carbon Regularly deliver a suite of ocean products that will describe sea level, ocean carbon content and its air-sea exchange, SST, surface currents, sea surface pressure and content and its air-sea exchange, SST, surface currents, sea surface pressure and air-sea exchanges of heat, momentum, and fresh water, ocean heat and fresh water air-sea exchanges of heat, momentum, and fresh water, ocean heat and fresh water content and transports and sea ice thickness and concentrationscontent and transports and sea ice thickness and concentrations

Assist the OCO in the development and implementation of appropriate quantitative Assist the OCO in the development and implementation of appropriate quantitative performance metrics to evaluate the adequacy of the global ocean observing system performance metrics to evaluate the adequacy of the global ocean observing system in meeting the following climate goals:in meeting the following climate goals:

Document long term trends in sea level changeDocument long term trends in sea level change Document ocean carbon sources and sinksDocument ocean carbon sources and sinks Document the ocean’s storage and global transport of heat and fresh waterDocument the ocean’s storage and global transport of heat and fresh water Document the ocean-atmosphere exchange of heat and fresh waterDocument the ocean-atmosphere exchange of heat and fresh water

Team of Experts: DeliverablesTeam of Experts: Deliverables Products: analyze the present state of the global ocean; evaluate how the Products: analyze the present state of the global ocean; evaluate how the

present state compares with the past, including confidence/uncertainty updated present state compares with the past, including confidence/uncertainty updated at least annually. Publicly available and understandable by decision-makers and at least annually. Publicly available and understandable by decision-makers and non-scientists wherever possible.non-scientists wherever possible.

Evaluation: help test the composite observing system against ocean climate Evaluation: help test the composite observing system against ocean climate variables and make recommendations at least annually for the evolution of the variables and make recommendations at least annually for the evolution of the observing system.observing system.

Summary annual report: describe the state of the ocean with regard to the Summary annual report: describe the state of the ocean with regard to the parameter(s) being analyzed and how the present state compares with the past. parameter(s) being analyzed and how the present state compares with the past. Contributions to Contributions to State of the OceanState of the Ocean and other reports. and other reports.

Performance metrics: once developed, calculate and report to OCO quarterly Performance metrics: once developed, calculate and report to OCO quarterly and meet NOAA requirements. and meet NOAA requirements.

Reports: Each performance metric project must file with OCO, quarterly if Reports: Each performance metric project must file with OCO, quarterly if appropriate but at least annually, reports recommending evolution of the appropriate but at least annually, reports recommending evolution of the observing system and/or better use of satellite and in situ data to improve observing system and/or better use of satellite and in situ data to improve observing system performance.observing system performance.

Progress ReportProgress Report Team has been established and has met several times by Team has been established and has met several times by

conference call and yesterdayconference call and yesterday Added GODAS team (Behringer/Xue) as ex-officio Added GODAS team (Behringer/Xue) as ex-officio

membersmembers Contributed ocean summaries for State of the Climate Contributed ocean summaries for State of the Climate

2005 coordinated by NCDC for publication in BAMS2005 coordinated by NCDC for publication in BAMS Contributed Chapter 2 in State of the Ocean – edited by Contributed Chapter 2 in State of the Ocean – edited by

Joel Levy Joel Levy Individual reports to follow – in particular, relate to GODAS Individual reports to follow – in particular, relate to GODAS

wherever possiblewherever possible Issues/questions:Issues/questions:

What else should we be doing?What else should we be doing? Course corrections needed?Course corrections needed?