Some Experiences and Recent Advances in Surface Radiation

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

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

Barrow, Alaska 71 deg. N American Samoa 14 deg. S. • 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 CMDL Baseline Observatories • ~1985 to present – upwelling irradiances Trinidad Head, CA 40 N • 1995 to present – WCRP BSRN participation Mauna Loa, Hawaii 19 deg. N South Pole – 90 S

Surface Radiation Budget Components, time averaging LW SW Erie Tower NOAA/BSRN GMD

Features • Site scientists • 18+ countries • Stand. Specs. • Long-term IOC • Central archive • Ref. Std. Devlp. • GRP review WMO • GCOS Goal: To acquire the highest possible quality, climatically-diverse, surface-based radiation measurements for climate & remote sen. applications Measurements Archiving Provisional • Direct & diffuse solar* • Downward infrared * • Upwelling irrad. • PAR & UV Regions • Aerosol optical depth Oceanic Tropics Desert • Surface meteorology* Polar Coastal Rain forest • Upper air met. • Sky imagery, cloud height Agricultural Prairie * all sites 1992 – 2006+ E. G. Dutton, 14 APR 06 Data Applications • GCM comparisons • Satellite prod. validation • Regional climatologies • Radiation budget apps. • Radiation model testing

NOAA / BSRN Instrument close-ups

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

BSRN (and the world) needs more in situ, representative, oceanic surface radiation measurements WARNING: • 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.

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

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.

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

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

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

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

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

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

BSRN Comparison to a new satellite product Y. Zhang, W. B. Rossow, A. A. Lacis, V. Oinas, M M. Mishchenko, accepted JGR, 2004 • SW, monthly avg BSRN • LW, monthly avg ISCCP model Figure 13. Scatter plots for all the available monthly mean surface fluxes from BSRN and corresponding values from ISCCP-FD: (a) S 9 s and (b) L 9 s in Wm!2. Statistics from the plot are given in Table 7 a.

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

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, groundbased 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…

The End

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

BSRN Operational Measurement Quality Compiled by Paul Stackhouse NASA/SRB