Ongoing Analysis of the Climate System (OACS)

1. Ongoing Analysis of the Climate System (OACS) • Relationship of OACS to: • CCSP Strategic Plan • CCSP Key Synthesis and Assessment Product • The fundamental need for updated and ongoing comprehensive analyses of the climate system is well recognized by the CCSP. This need is not new. It has been repeatedly emphasized by the scientific community and science advisory panels, including those advising NOAA at this meeting, e.g., • “Given the continuing improvement in our understanding of climate observations and the need for long time series, reprocessing is and will always be the hallmark of every climate observing system.” • (NOAA Climate and Global Change Advisory Panel, 2002).

2. Relationship to the CCSP Strategic Plan Specific CCSP SP goals, questions, objectives, research foci, and products directly connected or dependent on ongoing climate analyses are listed in: Ch 2. Integrating Climate and Global Change Research Ch 4. Climate Variability and Change (in three of five questions). Ch 10. Modeling Strategy. Ch 11. Decision Support Resources Development. Ch 12. Observing and Monitoring the Climate System. Ch 13 Data Management and Information. Ongoing climate analyses, and periodic reanalyses, are vital to the success of the CCSP. Such analyses directly support strategies across several major program elements. They directly link observations with modeling, and strongly contribute to advancing understanding and predictions of climate and to the development of decision support resources.

3. CCSP Key Synthesis and Assessment Product The fidelity and interpretation of climate analyses, including uncertainties, is a key issue for informing policy analysis and decision-making. Hence, the CCSP principals identified climate reanalyses - together with implications for attribution of causes of observed change - as one of 21 high-priority synthesis and assessment products to be delivered within the next 2-4 years. CCSP Product: Reanalysis of historical climate data for key atmospheric features. Implications for attribution of causes ofobserved change. Agencies: NOAA, NASA co- lead, DOE supporting. Primary end use: To inform policy decisions. Significance: Understanding the magnitude of past climate variations is key to increasing confidence in the understanding of how and why climate has changed and how it may change in the future.

4. Update on Progress and Plans The CCSP strategic plan provided only general guidance on the expectations and format of the synthesis and assessment products. Guidance is yet to be finalized on the process for developing and producing the synthesis and assessment products (in public review through May 3). Based on initial guidance, an interagency science working group (SWG) was convened late in 2003 to begin plans for developing this CCSP product(s).

5. Jeff Anderson (NCAR) Michael Bosilovich (GSFC/NASA) Gilbert Compo (CDC/NOAA) Tom Delworth (GFDL/NOAA) Huug van den Dool (CPC/NOAA) Wesley Ebisuzaki (EMC/NOAA) Mike Fiorino (LLL/DOE) Martin Hoerling (CDC/NOAA) Roy Jenne (NCAR) Eugnia Kalnay (Univ MD) Robert Kistler (EMC/NOAA) Arun Kumar (CPC/NOAA) John Lanzante (GFDL/NOAA) Steven Pawson (GSFC/NASA) David Rind (GISS/NASA) Suranjana Saha (EMC/NOAA) Ben Santer (LLL/DOE) Max Suarez (GSFC/NASA) Kevin Trenberth (NCAR) Jeffrey Whitaker (CDC/NOAA) Jack Woolen (EMC/NOAA) SWG Members Co-chairs: Siegfried Schubert (GSFC/NASA), Glenn White (EMC/NOAA). Reviewers: John Roads, Masao Kanamitsu (SIO), Jim Kinter (COLA)

6. SWG progress report The SWG conducted several meetings/teleconferences during December-March to identify key issues and possible products. There has been vigorous and useful debate in these meetings on directions and priorities in response to the CCSP language. To address major unresolved questions of the SWG, a meeting was held February 27 with Richard Moss, CCSPO Director. Attendees included Schubert and White (IWSG co-chairs), Koblinsky,Laver, Lord and Dole (NOAA), Cahalan and Lee (NASA), Arkin (U. MD). Moss indicated that the general directions and questions being considered by the the SWG were appropriate, and that both reanalysis and attribution should be included in the synthesis/assessment product(s). The SWG completed a first draft prospectus on March 24.

7. Proposed foci for rean/attribution Proposed Primary Activities and Deliverables A. State-of-science science reviews 1. Assessment of first generation reanalysis products 2. Assessment of current understanding of causes of 20th century climate variability and trends B. Develop high quality observational datasets for reanalyses. C. Initiate next generation reanalyses Three proposed activity streams 1. Satellite era (~1979 to present) 2. Period with substantial upper air network (~ post-1948) 3. Period with minimum set of surface obs (~1895 to present)

8. Proposed SARs CCSP Synthesis and Assessment Reports Proposed report topics 1) State-of-science assessment of strengths and weaknesses of first generation reanalyses, focusing on their suitability for studies of climate variability and trends. State-of-science assessment of present knowledge of understanding and uncertainties of causes of observed climate variations and trends during the 20th century. Possible additionalreport, or in 1): 3) Report on progress since first generation reanalysis to improve climate analyses and reanalyses, key issues, and necessary further steps to address outstanding science and policy-relevant questions.

9. Scientific and Technical Challenges • Data inhomogeneities and model biases. • How to optimize reanalyses for climate research? Use of data, minimization of spurious trends, bias, etc. • Representation of processes and forcing, e.g., precipitation, clouds, interactions with surface. • Horizontal and vertical resolution. • Improved estimates of uncertainties. • Extension of reanalyses back in time (pre-radiosonde era).

10. Analysis of pre-radiosonde era Third stream: Reanalysis before the radiosonde era • Can identification and descriptions of large-scale climate variations (e.g., teleconnections, storm tracks) prior to the radiosonde era be improved through reanalysis methods? • Current analyses consist of subjectively produced hand-drawn SLP maps that did not use all available observations. Can modern data assimilation systems improve on these analyses? • Before 1948, few upper-air observations are available, but many new surface observations have been recovered. Can surface pressure observations alone provide sufficient data to produce useful analyses of the lower troposphere? • This possibility has been tested, using data removal and ensemble • data assimilation techniques, with analyses using only • surface pressure observations at data densities representative • of earlier times (1895, 1915, 1935).

11. 500mb Height Analyses for 0Z 15 Dec 2001 5500 m contour is thickened Black dots show pressure observation locations Full CDAS (120,000+ obs) EnSRF 1895 (214 surface pressure obs) RMS = 39.8 m r (z’,NH)= 0.96 OI 1895 (214 surface pressure obs) RMS = 82.4 m

12. Results indicate that: • Reanalyses of the lower-tropospheric circulation prior to 1948 are feasible using just the availablesurface observations. • Using recent advances in ensemble data assimilation methods may improve results, even in the upper troposphere. • Providing additional observations, especially in data sparse regions, will produce further improvement. Present approaches and data coverage should enable lower tropospheric reanalyses that are as accurate as current 2-3 day forecasts.

13. Funding Status and Plans for Ongoing Analysis of the Climate System OGP funded first reanalysis. Present NOAA funding is through “base”. Budget changes (current plan) FY04 – 0 FY05 – 0 FY06-FY10: Proposed funding increase in NOAA plan. What are realistic funding requirements to build and sustain these efforts?

14. Some key issues • Leadership. Will NOAA take on this role? • Funding. Direct implications for time lines, scope of activities, deliverables. • Approval of initial deliverables. What else could or should be accomplished before FY08? • Roles and responsibilities. Coordination within NOAA and across agencies and with extramural community. • International coordination. Linkage to EOS/GEO.

15. Summary - Overall Strategy • A complete climate observing system requiresboth ongoing, near-real time climate analyses and periodic reanalyses that use improved data sets and data assimilation methods. Both must considered as essential components of a long-term climate observing strategy. • CCSP high-priority synthesis and assessment products are short-term deliverables (next 1-4 years). While they may take different forms, they are typically envisioned as “state-of-science” reports. • Without doubt, the CCSP synthesis reports place another “burden” on the science community. They are also an opportunity. • So far, reanalysis efforts have focused principally on the atmosphere. A longer-term strategy must be developed to analyze and eventually bring together the other, disparate components of the Earth system (oceans, land, cryosphere, hydrology, biosphere) through coupled model assimilation. This will enable a more comprehensive synthesis and understanding of the climate system.