The Solar Backscatter Ultraviolet (SBUV/2) sensor monitors density and distribution of ozone in the Earth’s atmosphere from 6 to 30 miles. An operational remote sensor, the SBUV/2 flies in identical units on the National Oceanic and Atmospheric Administration (NOAA) weather satellites. Ball Aerospace & Technologies Corp. has produced a family of eight SBUV/2s under contract to NASA/Goddard Space Flight Center and NOAA since 1980. Successive generations of the sensor have flown on Nimbus-7 (November, 1978 through June 21, 1999 ) NOAA 9 (December 1984 through August, 1993), NOAA 11 (September, 1988 through March, 1995), and NOAA 14 (December, 1994 through September 21, 2000 ). NOAA 14 is replaced by NOAA 16 (September 21, 2000 through present). NOAA 17 launched June 2002 and NOAA 18 launched May, 2005.
The calibration unit -the Shuttle Solar Backscatter Ultraviolet Radiometer 2 (SSBUV/2)- flew eight missions in nine years as a Getaway Special aboard the space shuttle before it was retired from service.

Atmospheric ozone measurements produced by the Solar Backscatter Ultraviolet Radiometer 2 (SBUV/2) are now being integrated into an ultraviolet index compiled by the National Weather Service (NWS) and the Environmental Protection Agency (EPA).

Objectives

The purpose of the SBUV instrument is to measure the Solar irradiance and Earth radiance in the near ultraviolet spectrum. From these data, the following atmospheric properties can be deduced :

• The global and vertical distribution of stratospheric ozone
• The structure and dynamics of stratospheric ozone
• Photochemical processes and the influence of "trace" constituents on the ozone layer
• Long-term solar activity in the Ultraviolet spectrum

Instrument

The SBUV/2 is a nadir-pointing nonspatial spectrally scanning ultraviolet radiometer carried in two modules.The two modules are the Sensor Module with the optical elements/detectors and the Electronics Module. The overall radiometric resolution is approximately 1 nanometer (nm). Two optical radiometers form the heart of the instrument: a monochrometer and a “Cloud Cover Radiometer” (CCR). The monochrometer measures the Earth radiance directly and selectively the Sun when a diffuser is deployed. The CCR measures the 379-nm wavelength and is coaligned to the monochrometer. The output of the CCR represents the amount of cloud cover in a scene and is used to remove cloud effects in the monochrometer data.

The SBUV/2 measures solar irradiance and Earth radiance (backscattered solar energy) in the near ultraviolet spectrum (160 to 400 nm). The following atmospheric properties are measured from this data.

• The global ozone concentration in the stratosphere to an absolute accuracy of 1 percent.
• The vertical distribution of atmospheric ozone to an absolute accuracy of 5 percent.
• The long-term solar spectral irradiance from 160 to 400 nm Photochemical processes and the influence of “trace” constituents on the ozone layer.

Data Access

SBUV/2 data can be accessed under following site:

• National Oceanic and Atmospheric Administration Global Climate Monitoring
• TOMS/SBUV merged total and profile ozone data sets
• Nimbus 7 SBUV data

The Nimbus 7 and NOAA Platforms

Nimbus 7 was placed in a 955 km sun-synchronous polar orbit on 25 October 1978. Its repeat cycle allowed for global coverage every six days, or every 83 orbits. Because of power limitations aboard the spacecraft, sensors were not run simultaneously, but were scheduled on a priority basis.

The Nimbus-7 platform allowed a number of experiments related to pollution control, oceanography, and meteorology to be conducted. Mission objectives were:

• To observe gases and particulates in the atmosphere for the purpose of determining the feasibility to map sources, sinks, and dispersion mechanisms of atmospheric pollutants (SBUV/TOMS - SAM II - SAMS-LIMS)
• To observe ocean color, temperature, and ice conditions, particularly in coastal zones, with sufficient spatial and spectral resolution to determine the feasibility of applications such as:
  - detecting pollutants in the upper level of the oceans
  - determining the nature of materials suspended in the water
• To continue to make baseline measurements of variations of long wave radiation fluxes outside the atmosphere and of atmospheric constituents for the purpose of determining the effect of these variations on the earth's climate (ERB-SBuv/TOMS -- LIMS).

The NOAA-POES series are regarded as the backbone of the US meteorological program. The current POES series satellites are named simply NOAA-9 through NOAA-17 in order of launch. The program has evolved over several years starting in 1960 with TIROS. The philosophy of NOAA is to maintain at least two operational satellites in complementary orbit. The POES satellites will operate till 2010.

All NOAA-POES satellites have a circular, sun-synchronous polar orbit with a nominal flight height of 833 km. The even numbered satellites cross the equator at local solar times of approximately 7:30 and 19:30, while the odd-numbered satellites cross the equator at local solar times of approximately 2:30 and 14:30.

The calibration unit—the Shuttle Solar Backscatter Ultraviolet Radiometer 2 (SSBUV/2)—flew eight missions in nine years as a Getaway Special aboard the space shuttle before it was retired from service. The most recent instrument in the series was delivered to NASA/NOAA in late 1996.

For further details concerning the NOAA satellites look at the NOAA internet sites ( NOAA - documentation ).

Links

Contact

If you would like to have more information about the SBUV/2 data, please contact wdc@dlr.de.