Science Investigations: The Legacy of Explorer VII

byProfessor Tom Vonder Haar

CIRA and Dept. of Atmospheric ScienceColorado State University

Program on 50 Years of Meteorological Satellite ObservationsUniversity of Wisconsin, Madison

November 2nd, 2009

Scope of this paper – The Legacy of Explorer VII for:

• Global Satellite Observing Systems

• Global Synoptic Weather Analyses and Forecasting

• New Scientific Information and the Opening of New Lines Inquiry

(from Vaeth, J.G., 1965, Weather Eyes in the Sky, Ronald Press, NY. 124 pages)

The thermal radiation experiment on board Explorer 7 was proposed by Dr. Verner Suomi of the University of Wisconsin and Dr. Harry Wexler of the US Weather Bureau. The experiment was designed to measure solar, reflected and terrestrial radiation to gain a better understandingof Earth’s Energy Budget.

 The primary instrumentation for the thermal radiation experiment consisted of bolometers in the form of hollow silver Hemispheres. Instruments included two black hemispheres that responded

to solar and terrestrial radiation, one white hemisphere that was more sensitive to terrestrial radiation and one gold hemisphere designed to absorb short-wave radiation. Explorer made 4000 radiation observations daily and 400 to 1000 readings were collected for analysis. Observations

were made every 30 seconds and recorded at a low rate to a tape recorder. The data was transmitted at a high rate to 1 of 21 ground stations.

Explorer 7 loopftp://ftp.ssec.wisc.edu/rickk/explorer-7-loop.avi

(Conway, 2008)

Today’s Global Satellite Observing Systems Provide

Much Greater Coverage

New Satellite Systems Include Trains and Constellations

Global Synoptic Weather Analysis and Forecasting

• Weinstein and Suomi conclude their paper with a note that daily nephanalyses and improved synoptic charts might be possible with combination of the (nighttime) IR and the newly available (daytime) TIROS VIDICON images.

• Indeed, at the USAF Global Weather Central in Omaha, these operational analyses were done throughout the 1960’s. They were used for ship routing, air traffic control including flight refueling over the Pacific, and synoptic scale weather forecasting including South East Asia.

In the early 1960’s Suomi-type radiometers were onboard USAF sun-synchronous satellites providing global Earth Radiation Budget measurements

FINAL SCIENTIFIC REPORT

Contract AF 04 (695) - 822

The University of Wisconsin Department of Meteorology

November, 1967

PRINCIPAL INVESTIGATORS: V. E. Suomi R. J. Parent

SCIENTIFIC ADVISOR: E. W. Wahl

PROJECT SUPERVISOR: T. H. Vonder Haar

CONTRIBUTIONS BY J. Bohlson D. Nelson R. Hankins R. Smith

T. Vonder Haar

Distribution List for

FINAL SCIENTIFIC REPORT

Contract AF (04(695)-822)

Copies

Contracting Agency 10V. Suomi, U.W. 2R. Parent, U.W. 2E. Wahl, U.W. 1T. Vonder Haar, U.W. 2E. Smith, U.W. 1D. Nelson, Aerospace 1D. Nelson 1R. Hankins 1R. Smith 1J. Bohlson 1SSEC Library 1D. Johnson (NESC) 1W. Nordberg (GSFC) 1W. Bandeen (GSFC) 1N. Bradshaw 1F. House 1Meteorology File 1

30

Summary of satellite radiation data through 1965 (Vonder Haar, 1968)

Mean annual values of longwave radiation from the earth-atmosphere system (HL). Units 10-2 cal. cm-2. min -1 and regions of HL>0.35 are shaded. 1 cal. cm. -2 min. -1 = 698 watts.m-2

Vonder Haar, 1968)

“We found that Earth was a Warmer and Darker Planet than previously believed - - especially in the Tropical Regions. We found that 40% More Energy must be transported poleward by the Atmosphere and Ocean Circulations!”(Vonder Haar and Suomi, 1969, 1971)

Much more energy gain in the tropics

Could these early results be true?

• If so, there were far-reaching implications to better understand and model Atmospheric and Ocean Circulations; Air-Sea Interactions; and both the Earth’s Energy and Water Cycles!

• The Scientific Method requires reproducibility of results.

• The Nimbus 2 & 3 MRIR experiments, the Nimbus 6 & 7 ERB and the ERBE Program were designed to check, verify, and expand the results from the 1960’s.

So, Nimbus – 3 supports earlier satellite results!

S

Warmer

Darker

Annual zonal averages of albedo (percent) and outgoing long wave radiation obtained from Nimbus 3 (dashed line) and from earlier satellites (solid line; Vonder Haar and Suomi, 1971) and from calculations with climatological data (open circles London, 1957)

A 3rd Mission, ERBE, to decrease uncertainty began with the launch of the Earth Radiation Budget Satellite from the Shuttle Challenger on Oct. 4, 1984.

ERBE fits Nimbus and thus the early ERB results from the 1960’s have been confirmed and greatly expanded during the 1970’s and 1980’s

• Therefore, by 1985, the early Earth Radiation Budget Results from the Suomi Experiments were replicated twice by Nimbus and ERBE

• This knowledge of the fundamental global Earth Radiation Budget provides an important point of closure for understanding Earth’s Climate System

Opening Lines of New Science Inquiry

• Observed variations of Earth Radiation Budget are due to changing Earth temperature, clouds, water vapor, carbon dioxide, etc.

• Therefore many new science observations were stimulated as part of the legacy from Explorer 7.

2008 annual cloud cover anomaly (%) for the period 1982-2008, PATMOS-x dataset.

2008 annual total column water vapor anomaly (mm) for the period 1997-2008, SSM/I/GPS dataset.

NVAP Daily Total Precipitable Water

The newest Global Science Challenge; CO2 Sources, Sinks and Transport (modeling simulation by Parazoo and Denning, 2008)

Summary• With concepts and science objectives developed for the

International Geophysical Year in the late 1950's, Vern Suomi's Explorer-VII experiment launched the era of Earth Observing Systems.  With his students and colleagues in the new space programs of NASA, the US Weather Bureau, the US Air Force and aerospace industries, new lines of science inquiry and global observations were embarked.

• The early Earth Radiation Budget measurements from the first three decades following Explorer-VII had great scientific impact.  The science legacy of Explorer-VII continues in successive, larger space observing programs related to Earth's Energy, Water and Carbon Cycles.

• Today, it is the knowledge of intersections among these three cycles and budgets which provides us so much promise for new scientific understanding.

Verner E. Suomi

BACK UP SLIDES

 The radius of coverage for each observed data point covered about 23 o of equatorial latitude (~2500 km) at perigee and 31.5 degrees (~3500 km)

at apogee. Half the radiation was received from an area below the satellite with a radius of 5.3 degrees (545 km) at perigee and 9 degrees

(~1015 km) at apogee.

Col. Ralph Steele

Inverse Modeling of COInverse Modeling of CO22

Air Parcel Air Parcel

Air Parcel

Sources Sinks

transport transport

t

(C) (CrV ) SC

(model) (solve for)

concentration transport sources and sinks(observe)

Sample Sample

Studies of Earth’s Radiation Budget

• Dines (1915)• Simpson, G.C. (1929), Mem. Roy. Soc.• Baur and Philips (1935), Gerlands Beitr. Geophys.• Lettan, H. (1954), Arkiv. Meteor., Geophys. und

Bioklima• London, J. et al., Report, NYU--------------------------------------------------------Age of Artificial Earth Satellites 1957

-Vonder Haar, T. and V. Suomi (1969), Science-Vonder Haar, T. and V. Suomi (1971), J. Atmos. Sci.

More

Launched by a Juno rocket fired from Cape Canaveral Air Force station on October 13, 1959, Explorer 7 achieved an orbit with initial apogee of 1090 km, a perigee of 555 km, inclination of 50 degrees and a period of 101 min. The satellite is still in orbit today.

Wielicki et al., Science, 2005

Comparison of Nimbus-7 and the new ERBE results in 1985(after Kyle et al, 1990)

(Courtesy: Gary Rottman, CU)

Recent MeasurementsTotal Solar Irradiance at Earth

0.5%

Suomi, V.E., K.J. Hanson and T. H. Vonder Haar, 1967:  The Theoretical Basis for Low-Resolution Radiometer Measurements from a Satellite, Annual Report on Weather Bureau Grant ( WBG-27 ), Department of Meteorology, The University of Wisconsin, Madison, p 79-100.