Ellsworth Dutton & Paul Stackhouse NOAA, Earth System Research Lab & NASA, Langley Radiation Sciences

Transcription

1 Surface Radiation Budget Observations: From Instantaneous Point Measurements to Longterm Global Means, Progress and Challenges (with emphasis on broadband downwelling components) Ellsworth Dutton & Paul Stackhouse NOAA, Earth System Research Lab & NASA, Langley Radiation Sciences With contributions from: Martin Wild Bruce Wielicki Dave Doelling Rachel Pinker Dave Rutan Tom Charlock Y.C. Zhang Dave Kratz Laura Hinkelman BSRN site scientists Chuck Long John Augustine Bill Rossow Joe Michalsky Beate Liepert Rolf Philipona Norm Loeb Taiping Zhang Steve Cox x2 Andreas Roesch Atsumu Ohmura Claus Fröhlich E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

2 Surface Radiation s Role in Climate Global Annual Mean Budget OCEAN STORAGE?

3 Components of Surface Radiation (SRB) Budget are Dependent on: Extraterrestrial Solar, total and geometry Air and surface skin temperature Surface types land, ocean, snow, ice, soil, veg Surface orientation Soil moisture Ocean penetration, overturning, (SST) and waves Vegetation - transpiration, type, age, density, Wind speed and direction Clouds - multiple 4-D properties Aerosols - multiple 4-D properties Spectral surface reflection Trace gases H2O, CO2, O3 Complex interactions of above Complex spatiotemporal variations of above For Climate Applications: SRB components and their variations have been shown to be sufficiently too complicated to be accurately and extensively computed, hence, systematic confirmation with substantiated observations is highly desirable. Corollary 1: To independently substantiate SRB observations from different perspectives, appropriate spatial and temporal sampling and averaging is required. Corollary 2: Interpretation of SRB observations frequently requires complex models, which provides the opportunity for mutual but not definitive verification. Conundrum: There is little popular interest in current or forecast observable SRB quantities, which leads to difficulties in sustaining the observations in a predominately meteorological community. Surface Radiation Climate Driver(s) Climate Driven E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

4 Surface Radiation Budget: A Cooperative Approach Validation GOES CERES SRB ISCCP NPOESS GERB SORCE, Glory, Retrieval Assimilation Validation Climate-quality surface observations BSRN BSRN (NASA NOAA DOE/ARM WMO WCRP GEWEX GCOS) Validation Assimilation Models Multiple R.T. + weather and climate simulations Direct Observations E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

5 Main strenghts of two observation approaches Satellite-based (indirect at surface) Surface LW Down June 12, 2006 Ground-based (direct point meas.) Continuous 1-min avg. 1-hz samples Boulder (Terra + Aqua CERES/TISA) Surface SW Down (Annual avg.) 30 & 31 Aug years of solar transmission Mauna Loa Monthly Apparent Trans. NASA GEWEX/SRB NOAA/GMD

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7 Goal: To acquire the highest possible quality, climatically-diverse, surface-based radiation measurements for climate research Measurements Direct & diffuse solar* Downward infrared * Upwelling rad. PAR & UV Aerosol optical depth Surface meteorology* Upper air met. * all sites ICSU 3600 station-months of 1-minute data ( ) archived as of Jun 2006 Archiving Regions Provisional Oceanic Tropics Desert Polar Coastal Rain forest Agricultural Prairie E.G. Dutton, 14Jan04 IOC WMO Features Site scientists 18+ countries Stand. Specs. Long-term Central archive Ref. Std. Devlp. GRP review GCOS Data Applications GCM comparisons Satellite validation Regional climatologies Global radiation budget Radiation model testing

8 Improving SRB Calibration Standards 35 Improvements in Pyrgeometer (Downward IR) Accuracy watts meter Sources of Uncertainty Routine Field Operations Ideal Operations Calibration Reference Philipona and Marty Target Year E.G. Dutton, 2002 Solar Diffuse comparisons Clear-sky surface solar closure, diffuse and direct ~20 days Wm -2 Michalsky et al 2003 Michalsky et al 2006 ~17 cases

9 Over last 6 years climate models approach BSRN downwelling LW results BSRN (344 W m -2 ) ( ) Model Avg. (329) Circa 1999 GCM models (global means) M. Wild 2001& 2005 BSRN (344) Avg. (337) Circa 2005 GCM models global means E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

10 Relative Temporal Variations E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

11 LONGWAVE DOWNWARD RADIATION MEASUREMENTS SHOW PROMISE FOR GREENHOUSE DETECTION STUDIES GCM simulation ECHAM5 T106 => LWD emerges earlier from background noise than temperature Signal to noise (Delta/S.D) Surface Longwave down 2 meter air temperature Complements of M. Wild

12 Annual mean global radiation for Japan & her 13 regions W/m y = x x Solar ( Global ) Dimming G. Stanhill et al, Gilgen et al, Liepert circa 2004 What happened after ~1990? Brightening (Wild et al. & Pinker et al. Science 2005)

13 What s Happened Since 2001? NOAA/GMD (formerly CMDL) Solar Radiation Project Boulder Research-driven climate-related solar irrad. observations Continuous for Centrally operated and calibrated (WRR) 1-minute averages of 1-hz pyranometer data Pacific baseline transect 72N to 90S E.G. Dutton SORCE S.T. Mtg 20 Sept 2006

14 Annual Average SWdwn Anomalies from GMD 5-site average run mean Dutton et al., JGR 2006

15 Lyman et al., GRL (this week) 0.8 Wm Wm -2

16 Conclusions Dimming issue: Some of the same measurement series that indicated solar dimming and then brightening now show dimming again, not inconsistent with 3 ISCCP SRB products but with long-term stability to within ±1%, within most observational uncertainly limits General: Continuous, adequately accurate and precise observations of surface radiation budget components are necessary to help confirm expected and reveal unexpected and un-understood features of the earth s climate. E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

17 Summary Progress: Reference ground-based observations to within <5 Wm -2, SW & LW Useful ground-based and satellite obs for validation of models and other obs. are available Mean agreement between satellite and ground-based irradiances to within 5-10 W m -2, LWdwn <5 W m -2 CERES and ground-based downwelling obs closely track (<2 W m -2 ) each other, given enough appropriate comparisons Convergence of GCM modeled mean LWdwn with BSRN and satellite obs Challenges: Perpetuate long time series to establish actual climate variations Utilize proper spatial and temporal averaging when validating obs Obtain further agreement between GCMs and obs Validation of satellite and model upwelling irradiances (A. Roesch) Select/establish a sub-set of ground-based sites that might be globally representative on longer time scales Continued improved obs of atmospheric state for model and retrieval inputs E.G. Dutton SORCE S.T. Mtg 20 Sept 2006 San Juan Islands, Wash

18 Following is presented only as a curiosity between two data sets. No analysis or claims of relationship or cause and effect are made by the presenter

19 South Pole Annual Avg. SWdwn Core calibration uncertainty

20 r =.80

21 = 11.1 years Sunspot number This is presented only as a curiosity between two data sets. No analysis or claims of relationship or cause and effect are made by the presenter

22 Hale Sunspot Cycle = 22.2 years r = This is presented only as a curiosity between two data sets. No analysis or claims of relationship or cause and effect are made by the presenter