TOMS
STATUS
1978-1993, 1991-94, 1996-1997
AVAILABILITY
The TOMS program was managed by NASA's Goddard Space Flight Center, Greenbelt, Md., for the Office of Mission to Planet Earth, Washington, D.C. TOMS data are available online from the website: http://macuv.gsfc.nasa.gov
REQUEST PROCEDURE
The TOMS program is managed by NASA's Goddard Space Flight Center, Greenbelt, Md., for the Office of Mission to Planet Earth, Washington, D.C. http://toms.gsfc.nasa.gov/ftpdata_v8.html
Satellite Instruments
TOMS was part of NASA's Mission to Planet Earth a long term, coordinated research effort to study the Earth as a global environmental system. Using the unique perspective available from space, NASA observes, monitors and assesses large-scale environmental processes, focusing on climate change. MTPE satellite data, complemented by aircraft and ground data, allows humans to better understand natural environmental changes and to distinguish natural changes from human induced changes. MTPE data, which NASA distributes to researchers worldwide, is essential to humans making informed decisions about their environment. The TOMS instrument is a second generation backscatter ultraviolet ozone sounder. TOMS measures "total-column-ozone" the total amount of ozone in a "column" of air from the Earth's surface to the top of the atmosphere under all daytime observing and geophysical conditions. TOMS observations are based on measurements in the near ultraviolet region of the electromagnetic spectrum, where sunlight is absorbed only partially by ozone. TOMS measures total ozone by observing both incoming solar energy and backscattered ultraviolet (UV) radiation at six wavelengths. "Backscattered" radiation is solar radiation that has penetrated to the Earth's lower atmosphere and is scattered by air molecules and clouds back through the stratosphere to the satellite sensors. The ratio of a wavelength strongly absorbed by ozone to a wavelength weakly absorbed by ozone is used to very accurately estimate the total amount of ozone in the optical path . TOMS makes 35 measurements every 8 seconds, scanning from left to right of the spacecraft. Each measurement covers from 30 to 125 miles (50 to 200 kilometers) spots on the ground, depending on the view direction. Almost 200,000 daily measurements cover every single spot on the Earth except for areas near one of the poles, where the Sun remains close to or below the horizon during the entire 24 hour period. The extremely high quality of TOMS ozone data has also helped scientists in detecting a small but steady long-term damage to the ozone layer over several parts of the globe, including most of the heavily populated areas in the northern mid-latitudes. This discovery helped lead to the curtailment of the production of ozone-depleting chemicals through an international treaty signed in Montreal in the 1980s. TOMS measurements were made by the instrument on Nimbus 7 from November 1978 until the instrument failed in May of 1993. A TOMS flown on the Russian Meteor-3 spacecraft provided coverage from August 1991 through December 1994. After a short data gap in 1995, a new TOMS was launched in July 1996 that provided ozone coverage until the spacecraft transmitter failed in December 2006. The time series of TOMS ozone measurements is now being continued with data from the Dutch built OMI instrument flying on the Aura spacecraft. Data from October 2004 through the present (December 2009) are available.
CONTACT
Dr. Richard McPeters
NASA
Principal Investigator for Earth Probe TOMS NASA GSFC Code 613.3
mcpeters@wrabbit.gsfc.nasa.gov
http://toms.gsfc.nasa.gov/ftpimage_v8.html
SPECIFICATIONS
Measurment TypeVisible/IR-imager
Platform TypeTOMS
OrbitSun synchronous
Spectral CoverageUV 317.5 , 331.2 and 360 nm
Active/PassivePassive
Scan PatternPush broom
VariablesTotal column ozone image Volcanic Ash
Altitude
Inclination
Repeat Time
Wavelength to nm
Number of Bands
Temporal Coverage
Swath Width
REFERENCES
http://toms.gsfc.nasa.gov/ http://toms.gsfc.nasa.gov/news/news.html http://toms.gsfc.nasa.gov/fltmodel/spacecr.html
REMARKS
On December 2, 2006, contact with the Earth Probe spacecraft was lost. Tests confirmed that the transmitter had failed but that the receiver still worked. Presumably TOMS still works, but with no way to bring the data down, there is no point in continuing to operate the spacecraft. The decision has been made to power down the spacecraft late this spring. Since there is no more on-board fuel, it is not possible to do a controlled re-entry. But at its altitude of 730 km., it will be decades before Earth Probe re-enters the atmosphere
UPDATED ON
5 Jan 2010 11:04