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
Dave Doelling
Dave Rutan
Y.C. Zhang
Laura Hinkelman
Chuck Long
Bill Rossow
Beate Liepert
Norm Loeb
Steve Cox x2
Atsumu Ohmura
…
Bruce Wielicki
Rachel Pinker
Tom Charlock
Dave Kratz
BSRN site scientists
John Augustine
Joe Michalsky
Rolf Philipona
Taiping Zhang
Andreas Roesch
Claus Fröhlich
E.G. Dutton
SORCE S.T. Mtg
20 Sept 2006
San Juan Islands, Wash
Surface Radiation’s Role in Climate
Global Annual Mean Budget
OCEAN STORAGE?
Components of Surface Radiation (SRB) Budget are Dependent on:
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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
Surface Radiation
Climate Driver(s)
Climate Driven
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
E.G. Dutton
predominately meteorological community.
SORCE S.T. Mtg
20 Sept 2006
San Juan Islands, Wash
Surface Radiation Budget:
A Cooperative Approach
GOES CERES SRB
ISCCP NPOESS GERB
SORCE, Glory,……
Va
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Climate-quality surface
observations
BSRN
BSRN
(NASA NOAA DOE/ARM
WMO WCRP GEWEX GCOS)
Models
Validation
Assimilation
Direct Observations
Multiple R.T. +
weather and
climate
simulations
E.G. Dutton
SORCE S.T. Mtg
20 Sept 2006
San Juan Islands, Wash
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)
30 & 31 Aug 2006
Surface SW Down (Annual avg.)
50 years of solar transmission
Mauna Loa
Monthly
Apparent Trans.
NASA GEWEX/SRB
NOAA/GMD
ICSU
IOC
Goal:
To acquire the
highest possible
quality, climatically-diverse,
surface-based
radiation
measurements for
climate research
3600 station-months of 1-minute data
(1992- 2006) archived as of Jun 2006
WMO
Measurements
• Direct & diffuse solar*
• Downward infrared *
• Upwelling rad.
• PAR & UV
• Aerosol optical depth
• Surface meteorology*
• Upper air met.
* all sites
Archiving
Provisional
Regions
Oceanic Tropics Desert
Polar Coastal Rain forest
Agricultural Prairie
E.G. Dutton, 14Jan04
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
Improving SRB Calibration Standards
Improvements in Pyrgeometer (Downward IR) Accuracy
35
30
Sources of Uncertainty
watts meter-2
25
Routine Field Operations
Ideal Operations
Calibration Reference
20
15
10
Philipona and Marty
5
0
1988
1993
1995
Year
1998
2001
Target
E.G. Dutton, 2002
Clear-sky surface solar closure, diffuse and direct
Solar Diffuse comparisons
Wm-2
~20 days
Michalsky et al 2003
Michalsky et al 2006
~17 cases
Over last 6 years climate models approach BSRN downwelling LW results
BSRN (344 W m-2)
(1992-2000)
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
Relative Temporal Variations
E.G. Dutton
SORCE S.T. Mtg
20 Sept 2006
San Juan Islands, Wash
LONGWAVE DOWNWARD RADIATION
MEASUREMENTS SHOW PROMISE FOR
GREENHOUSE DETECTION STUDIES
GCM simulation – ECHAM5 T106
Signal to noise (Delta/S.D)
=> LWD emerges earlier from background noise than temperature
Surface Longwave down
2 meter air
temperature
Complements of M. Wild
Annual mean global radiation for Japan & her 13 regions
200
y = 0.0407x
2
- 161.66x + 160510
190
Solar (“Global”) Dimming –
180
170
G. Stanhill et al, Gilgen et al, Liepert circa 2004
W/m2
160
150
140
130
What happened after ~1990?
120
110
100
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
“Brightening”
(Wild et al. & Pinker et al. Science 2005)
What’s Happened Since 2001?
NOAA/GMD (formerly CMDL) Solar Radiation Project
■
Boulder
Research-driven climate-related solar irrad. observations
Continuous for 1975 – 2006
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
San Juan Islands, Wash
Annual Average SWdwn Anomalies from GMD 5-site average
run mean
Dutton et al., JGR 2006
Lyman et al., GRL (this week)
1.3 Wm-2
0.8 Wm-2
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
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
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SORCE S.T. Mtg
20 Sept 2006
San Juan Islands, Wash
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
South Pole Annual Avg. SWdwn
Core calibration
uncertainty
r = .80
Sunspot number
= 11.1 years
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
Hale Sunspot Cycle = 22.2 years
r = - 0.75
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