Observations for WCRP Kevin Trenberth JSC Feb 2010

1. Observations for WCRPKevin TrenberthJSC Feb 2010

2. Climate Observations • Process studies: atmosphere, ocean, land, cryosphere and their interactions • Sustained observations: the climate record • Enhanced monitoring • Analysis, assimilation and data products • Data stewardship, data access, QC

3. Whitepaper on: “Capabilities of Existing and Future Observing Systems” 3rd World Climate Conference (WCC-3) Geneva, Switzerland -- 1-September-2009 Thomas R. Karl,

4. Reanalysis • Integrated datasets, free of time-dependent biases, from various observing systems are required to meet the needs for model development and verification. • Atmospheric analyses provide a synthesis of the available observations in the context of a physical model. • More continuity and infrastructure required. • Atmospheric reanalyses are among the most valuable and widely used datasets in the history of climate science. • Essential for climate services and predictions Status • Significant advances in reanalysis (or synthesis) of ocean data; sea ice, Arctic, and land surface reanalysis; coupled atmosphere-ocean data assimilation. • International cooperation is vital

5. Reprocessing • Much more work is needed to take advantage of observations already made • To improve knowledge of what has happened and why • To make climate predictions. • The broad scientific community should be engaged in assessing derived data products and refining the algorithms for the generation of these products. • Parallel efforts on the collection, management and homogenisation of in-situ data records must be robust. • Reanalysis of comprehensive, multivariate sets of observations is becoming increasingly valuable for climate monitoring, research, and applications. Status • Some reprocessing efforts underway; emphasis on the construction of climate data records. • More algorithm development and increased computing power required. • Some variables from space platforms are lacking in this effort.

6. Reference Observations • Increasing emphasis has been placed on reference-quality networks for detecting climate trends. • They provide anchor points for existing networks, for calibrating satellite data, and for validating data products. • Reference quality in-situ networks are critical to fill in the inevitable gaps in the climate record caused by lack of overlapping satellite missions • Must be able to answer the question 50 years from now on how global climate has changed and for this reference observations are key Status • GCOS Reference Upper Air Network (GRUAN) is making some progress in spinning up but resources still inadequate for full implementation • Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a climate-focused mission that will become a key element of the climate observing system, but the launch is not scheduled until 2017.

7. Conclusions and Recommendations • Long-term, high-quality, calibrated, and un-interrupted in-situ and satellite observations of atmosphere, land and ocean are vital for all countries, especially as their economies and societies become increasingly affected by climate variability and change • Since the 1990s, some of the decline in observing networks has been halted and new observing systems have been established, but a number of past concerns remain, and new requirements have emerged • Established in-situ networks and space-based components must be sustained and operated with ongoing attention to data quality and application of the GCOS Climate Monitoring Principles (often these are not be followed) • Enhancements must be made to observing systems, filling gaps in coverage, improving measurement accuracy where needed, and establishing key networks of reference observations using absolute calibration and high standard operations. • Failure to fully observe climate ECVs seriously compromises the capabilities of governments to assess and adjust their policies for mitigating and adapting to climate variability and change.

8. Role of WCRP • Advocate improved observations and analysis suitable for climate (satisfying the GCOS Climate Monitoring Principles to ensure continuity of record). This especially includes those from space. • Data set development: evaluating observations and promoting global reprocessing and reanalysis. Develop new products and datasets, analytical and diagnostic techniques, high level derived products: for use in understanding and analyzing climate variability and change, and for evaluating models. • Mechanisms and modes of variability in climate anomalies; operational attribution, numerical experimentation in near real time to allow reliable statements to be made not only about what the state of the climate is, but also why it is the way it is and the mechanisms involved.

9. Role of WCRP • Data assimilation and analysis: initializing of coupled models for prediction. • Provide advice on best datasets for various purposes (climatologies and time series) and their merits and limitations. (Error bars are greatly needed.) • High priority needs are to have assessments of datasets for use in evaluating climate models, and specifically those used in the AR5 IPCC report that will participate in the CMIP5 activity

10. Role of WCRP • Help improve and promote sound data stewardship, including data archiving, management, and access. This includes making sure that climate-related data variables are reaching data archives, and that standards are set for archiving new types of data. • Help make data accessible and available e.g., through the internet. Promote shared efforts for data quality control.

11. Imperative:A climate information system • Observations: forcings,atmosphere, ocean, land • Analysis: comprehensive, integrated, products • Assimilation: model based, initialization • Attribution: understanding, causes • Assessment: global, regions, impacts, planning • Predictions: multiple time scales • Decision Making: impacts, adaptation An Integrated Earth System Information System