Some Experiences and Recent Advances in Surface Radiation Measurements

1. Some Experiences and Recent Advances in Surface Radiation Measurements Ellsworth G. Dutton NOAA ESRL Global Monitoring Division Boulder, Colo. 80305 ells.dutton@noaa.gov

2. GATE -1974, USCG Dallas Kirby Hanson’s Met & Radiation Boom

3. American Samoa 14 deg. S. Barrow, Alaska 71 deg. N • 1956 to present - solar transmission (Mauna Loa only) • 1975 to present - total downwelling solar irrad • 1976 to present – wideband direct solar – AOD • ~1985 to present – downwelling thermal IR • ~1985 to present – upwelling irradiances • 1995 to present – WCRP BSRN participation CMDL Baseline Observatories Trinidad Head, CA 40 N Mauna Loa, Hawaii 19 deg. N South Pole – 90 S

4. Surface Radiation Budget Components, time averaging LW  LW SW  SW  Erie Tower NOAA/BSRN GMD

5. Measurements • Direct & diffuse solar* • Downward infrared * • Upwelling irrad. • PAR & UV • Aerosol optical depth • Surface meteorology* • Upper air met. • Sky imagery, cloud height • * all sites • Data Applications • GCM comparisons • Satellite prod. validation • Regional climatologies • Radiation budget apps. • Radiation model testing Regions Oceanic Tropics Desert Polar Coastal Rain forest Agricultural Prairie E.G. Dutton, 14APR06 Baseline Surface Radiation Network • Features • Site scientists • 18+ countries • Stand. Specs. • Long-term • Central archive • Ref. Std. Devlp. • GRP review • GCOS Goal: To acquire the highest possible quality, climati-cally-diverse, surface-based radiation measurements for climate & remote sen. applications IOC WMO Archiving Provisional 1992 – 2006+

6. NOAA / BSRN Instrument close-ups

7. Surface-based broadband radiation measurement issues addressed by BSRN • Spatial representativeness of data • Extent of climatic regimes sampled • Calibration references, SW diffuse & LW • Component sum vs. global SW • Thermal errors in thermopile sensors • Effects and benefits of artificial ventilation • UV, PAR, albedo, aerosol O.D. • Specifications and Operations Manual

8. BSRN (and the world) needs more in situ, representative, oceanic surface radiation measurements • BSRN is an international cooperative project of the World Climate Research Program and GEWEX and as such has NO central funding, only volunteers generally working as their country’s radiation experts and representatives to WMO/WCRP are involved – these folks are called BSRN Site Scientists with their own national or whatever funding. • BSRN requires adherence to its specifications. WARNING:

9. BSRN has a new (2004) Oceanic Working Group • Issues – platforms, measurement accuracy (available and required), moving sites, instrument orientation, obstructions, sea spray+, lack of upper air soundings… • Assess the required accuracy needed in interesting very data-poor regions to contribute to satellite and climate model projects • Revisit BSRN specifications and consider drafting an oceanic version • Inventory candidate platforms • Recruit potential participants – encourage improvements • Evaluate of impact on stated requirement for long-time series and other complications • Ken Rutledge NASA/Langley chair (Chesapeake Light House SS) Contact me if interested -- ells.dutton@noaa.gov

10. The BSRN approach Step 1.Assess current accuracy and that required to contribute to atmospheric research. 188 pp Step 2. Figure out how to get there.

11. Step 3. Get there. Improving Ground-based Radiation Meas. Calibration Standards Philipona and Marty Wm-2 Michalsky et al 2004, 2006

12. IPASRC-I Oklahoma ARM/SGP PYRGEOMETERS Candidate Reference, ASR

13. IR Radiometer Intercomparisons Difference Relative to Proposed Ref. Meas. (Wm-2) 1999 Mid-West US, 270-300 W m-2 2001 Arctic – Barrow, 120-145 W m-2 ObservationsModels BSRN-ARM/CMDL Philipona et al., 2001/Marty et al., 2003

14. Clear-sky surface radiative closure, diffuse and direct Average of 30 cases on 13 days S. KatoC. Gueymard Michalsky et al., 2005

15. BSRN (344 W m-2) Model Avg. (329) Circa 1999 GCM models (global means) BSRN (344) Avg. (337) Circa 2005 GCM models global means Over last 6 years climate models approach BSRN downwelling IR results M. Wild 2001& 2005

16. Satellite Results: Long-term Annual Averages Downward Surface SW Flux (Wm-2) Downward Surface LW Flux (Wm-2) GEWEX SRB Paul Stackhouse, NASA/Langley

17. BSRN Comparison to a new satellite product • Y. Zhang, W. B. Rossow, A. A. Lacis, V. Oinas, M M. Mishchenko, accepted JGR, 2004 • LW, monthly avg • SW, monthly avg BSRN ISCCP model • Figure 13. Scatter plots for all the available monthly mean surface fluxes from BSRN and corresponding values from ISCCP-FD: (a) S9s and (b) L9s in Wm!2. Statistics from the plot are given in Table 7a.

18. SRB Validation: Reanalysis, CERES Surface-only fluxes (time averaged) BSRN sites: Bermuda, Billings, Florinapolis, Goodwin Creek, Kwajalein, Manus, Tateno

19. Summary • Surface-based surface solar and infrared radiation measurements are of considerable value today. • BSRN has pursued improving the accuracy and confidence of surface irradiance obs. • Work is ongoing to establish recognized and lasting radiation reference standards. • An IPCC Radiative Flux Assessment is being prepared. • While BSRN was original intended for fixed-site, ground-based observations, a substantial need for open-ocean obs has emerged and BSRN is attempting to address that need. • Potential BSRN-like shipboard radiation measurements include: downwelling solar and longwave irradiances, direct and diffuse solar, Aerosol optical depth, cloud imagery, meteorology, PRT SST…

20. The End

21. NOAA Station data x-correlated with NASA / ISCCP annual averages, total surface solar 1984 - 2000 ▲ SMO ▲ BLD ▲ ▲ ▲ Units are X-Corr. Coef. / S. E. E. Dutton et al., 2006

22. BSRN Operational Measurement Quality Compiled by Paul Stackhouse NASA/SRB