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Availability of Nimbus-7 coastal zone color (CZCS) data
I)cep-Sea Research, Vol. 29, No. 2A. pp. 281 to 283, 1982. Pergamon Press Ltd. Printed in Great Britain.
ANNOUNCEMENTS
Availability of Nimbus-7 Coastal Zone Color (CZCS) Data (Received 9 November 1981)
The Nimbus-7 spacecraft was launched in October 1978 and has been producing data for 3 years. The Coastal Zone Color Scanner (CZCS), flying on Nimbus-7, is a multi-spectral line scanner devoted principally to measurements of ocean color. It has six spectral bands; four chiefly for ocean color, each of 20-nm spectral bandwidth and centered at 443,520, 550, and 670 nm. These are referred to as channels 1 to 4, respectively. Channel 5 senses reflected solar radiance but has a 700 to 800-nm spectral bandwidth and a dynamic range more suited for land; it corresponds to the same spectral band flying on the Landsat MultiSpectral Scanner (MSS). Channel 6 operates in the 10.5 to 12.5-1am region and senses thermal radiance for derivation of equivalent blackbody temperature. Channel 6 operated from October 1978 until November 1979 and from April to October 1980 but has been out of operation since then. The sensor scans a swath of approximately 1600 km with a spatial resolution at the nadir of 800 m in all six channels. Channels 1 to 4 have variable gains, which are changed to accommodate varying solar elevation angles. The gains for these channels are set specifically for ocean conditions. Channels 2 to 4 will normally be saturated over land or clouds. The sensor also has a mechanism to avoid glint so that the angle of scan can be tilted in 2 '~ increments up to 20 '~ either ahead of or behind the spacecraft line of flight. The angle of tilt is determined by solar elevation angle. More detail is available in papers by Hovls et al. (1980) and GORDON, CLARK, Mb-ELLER and Hovls (1980). Data are taken in intervals varying from 2 up to 10 min. The data are processed, however, in 2-min intervals producing scenes of approximately 800 x 1600 kin. The data have been placed in a public archive and are available in two levels of processing. Level I data, the lowest level of processing, are available on both photograhic and magnetic computer compatible tape (CCT) format. The photographic product, as originally produced, is a 20 × 20 cm sheet showing one 800 x 1600-km scene in all six bands of the CZCS. Channels 1 to 4 are enhanced by subtraction of a dc level simulating Rayleigh correction to improve the contrast. The images are annotated with latitude and longitude and other information such as time of day and the solar elevation angle. Imagery is available in either negative or positive transparencies or paper prints at the size previously mentioned. Enlargements or 35-mm slides of individual channels from one scene can also be provided. A 16-level gray scale is provided, annotated in either radiance or equivalent blackbody temperature on the basic photographic product. The CCT for level I contains 6 rain of data. The user can request any three scenes to be stacked on one tape. All data are digital in 256 levels with calibration coefficients provided in the header documentation. No correction is applied to channels 1 to 5, and channel 6 has been converted to equivalent blackbody temperature, with coefficients provided to convert digital counts to temperature. A tape format document describing the tape is provided. 281
282
Announcements
Level II CZCS data are data on which calculations to derive certain products have been made. As part of the level II processing, the aerosol path radiance in channel 4 at 670 nm is derived, the subsurface upwelled radiance is derived for channels 1 to 3, and pigment concentration and diffuse attenuation coefficient are calculated from the subsurface radiance levels. Data are available in 20 x 20-cm photographic products; however, rather than six scenes on one sheet, there are two scenes on two sheets with each scene being twice the linear dimension of that of the level I images One photographic product contains the derived pigment and diffuse attenuation coefficient with a 16-level gray scale and appropriate annotation. The other level II photographic product contains an image of the calculated aerosol path radiance at 670 nm and the calculated upwelled subsurface radiance at 443 nm. It too, contains a gray scale with apropriate annotations. All level II products contain latitude and longitude marks and other ancillary information. The same type photographic products are available for level II data as for level I. The tape product for the level II data contains one 2-min scene. The tape contains, in 256 digital levels, the calculated upweUed subsurface radiance for channels 1 to 3; the calculated aerosol path radiance for channel 4; the equivalent blackbody temperature; the calculated pigment concentration; the calculated diffuse attenuation coefficient; and a land-cloud flag used to reduce areas detected as being land or clouds to 0 digital counts so they will normally appear black in level II imagery. A tape format document is provided to those who order level II tapes. All of the data produced for the CZCS program are archived at the Environmental Data and Information Service (EDIS) of NOAA at the World Weather Building, Room 100. Washington, DC. 20233. EDIS has available catalogs and costs for interested users. One catalog lists all of the archived products, including the date, the orbit number, the time at which the data were taken, and the coordinates of flae four corners of the image. Anol her catalog shows the orbital passes for each day of CZCS operation in monthly increments and shows areas along the orbital tracks for which satisfactory data have been acquired and will eventually be processed (if not already processed). Because of funding limitations. only a small fraction of the level I data will be reduced to level II archival data. Plans now are to produce 500 level II scenes in 1982 of data from years 1 to 3. Some level II products have already been entered into the archive and are available as samples for investigators wishing to gain experience in their use, Selection of those scenes from level I to be processed into level II is being made through the Nimbus Experiment Team (NET) for the CZCS. starting with 115 scenes identified as validation scenes that were acquired over ships of the NET during the early life of the instrumet. Requests for other scenes to be processed into level II can be forwarded through any member of the NET or directly to the chairman. In addition to the chronological archive of photographic products held by EDIS, there are other places at which photographic data can be viewed. In the United States, there is a partial archive at the Visibility Laboratory Scripps Institution of Oceanography, La Jolla, California, and a full, geographic, aUy cataloged archive at the Satellite Experiment Laboratory of NOAA in Suitland, Maryland. Members of the NET have limited archives at their facilities. European data are archived by the Joint Research Centre of the Commission of European Communities in Ispra, Italy, and South African data are archived at the National Research Institute for Oceanology in Stellenbosch. South Africa. Questions concerning use of these archives, location of the NET members, or location of centers that have computer facilities to analyze CZCS data should be forwarded to the writer.
Announcements
Satellite Experiment Laboratory National Oceanic and Atmospheric Administrators National Earth Satellite Service Washington, DC 20233, U.S.A.
283
WARREN A. Hovls, Chairman Nimbus Experiment Team
REFERENCES GORDt)NH. R., D. K. CLARK,J. L. MUI-LLERand W. A. Hovls (1980) Phytoplankton pigments from the Nimbus7 Coastal Zone Color Scanner: Comparisons with surface measurements. Science. 210, 63. Hovls W. A., D. K. CLARK,F. ANDERSON,R. W. AUSTIN,W. H. WILSON,E. T. BAKER,D. BALL,H. R. GORDON, J. L. MUELLER, S. Z. EL-SAVED,B. STORM,R. C. WRI~:iLEYand C. S. YENTSCH(1980) Nimbus-7 Coastal Zone Color Scanner: System description and initial imagery. Science, 210, 60.
N A T O Advanced Study Institute on THE AIR-SEA EXCHANGE
O F GASES AND P A R T I C L E S
19-30 July 1982 New England Conference Center, University of New Hampshire, Durham, N H , U.S.A.
Lecturers (tentative) include D. H. P. F.
C. BLANCHARD,S U N Y C. BROECKER, University of H a m b u r g BUAT-MENARD,C N R S , Gif sur Yvette DOBSON, Bedford Institute
*P. S. LIss, University of E. Anglia C. A. PAULSON,OSU L. K. PETERS, University of Kentucky *W. G. N. SLINN, Battelle P N L
The goal of the Institute will be to conduct an advanced examination of the physical, chemical, and biological principles governing the exchange of gases and particles across the air-sea interface. The course will consist of lecture/discussion sessions, demonstrations of equipment, examination of case studies, as well as presentations by 'student' participants. A limited amount of financial assistance will be available to selected participants. If you are interested in receiving further information about the Institute, please direct inquiries to : Dr. P. S. Lms School of Environmental Sciences University of East Anglia Norwich N R 4 7TJ, U.K. Tel: (0)60356161 Ext. 2563
* Course directors.
ANNOUNCEMENTS
Availability of Nimbus-7 Coastal Zone Color (CZCS) Data (Received 9 November 1981)
The Nimbus-7 spacecraft was launched in October 1978 and has been producing data for 3 years. The Coastal Zone Color Scanner (CZCS), flying on Nimbus-7, is a multi-spectral line scanner devoted principally to measurements of ocean color. It has six spectral bands; four chiefly for ocean color, each of 20-nm spectral bandwidth and centered at 443,520, 550, and 670 nm. These are referred to as channels 1 to 4, respectively. Channel 5 senses reflected solar radiance but has a 700 to 800-nm spectral bandwidth and a dynamic range more suited for land; it corresponds to the same spectral band flying on the Landsat MultiSpectral Scanner (MSS). Channel 6 operates in the 10.5 to 12.5-1am region and senses thermal radiance for derivation of equivalent blackbody temperature. Channel 6 operated from October 1978 until November 1979 and from April to October 1980 but has been out of operation since then. The sensor scans a swath of approximately 1600 km with a spatial resolution at the nadir of 800 m in all six channels. Channels 1 to 4 have variable gains, which are changed to accommodate varying solar elevation angles. The gains for these channels are set specifically for ocean conditions. Channels 2 to 4 will normally be saturated over land or clouds. The sensor also has a mechanism to avoid glint so that the angle of scan can be tilted in 2 '~ increments up to 20 '~ either ahead of or behind the spacecraft line of flight. The angle of tilt is determined by solar elevation angle. More detail is available in papers by Hovls et al. (1980) and GORDON, CLARK, Mb-ELLER and Hovls (1980). Data are taken in intervals varying from 2 up to 10 min. The data are processed, however, in 2-min intervals producing scenes of approximately 800 x 1600 kin. The data have been placed in a public archive and are available in two levels of processing. Level I data, the lowest level of processing, are available on both photograhic and magnetic computer compatible tape (CCT) format. The photographic product, as originally produced, is a 20 × 20 cm sheet showing one 800 x 1600-km scene in all six bands of the CZCS. Channels 1 to 4 are enhanced by subtraction of a dc level simulating Rayleigh correction to improve the contrast. The images are annotated with latitude and longitude and other information such as time of day and the solar elevation angle. Imagery is available in either negative or positive transparencies or paper prints at the size previously mentioned. Enlargements or 35-mm slides of individual channels from one scene can also be provided. A 16-level gray scale is provided, annotated in either radiance or equivalent blackbody temperature on the basic photographic product. The CCT for level I contains 6 rain of data. The user can request any three scenes to be stacked on one tape. All data are digital in 256 levels with calibration coefficients provided in the header documentation. No correction is applied to channels 1 to 5, and channel 6 has been converted to equivalent blackbody temperature, with coefficients provided to convert digital counts to temperature. A tape format document describing the tape is provided. 281
282
Announcements
Level II CZCS data are data on which calculations to derive certain products have been made. As part of the level II processing, the aerosol path radiance in channel 4 at 670 nm is derived, the subsurface upwelled radiance is derived for channels 1 to 3, and pigment concentration and diffuse attenuation coefficient are calculated from the subsurface radiance levels. Data are available in 20 x 20-cm photographic products; however, rather than six scenes on one sheet, there are two scenes on two sheets with each scene being twice the linear dimension of that of the level I images One photographic product contains the derived pigment and diffuse attenuation coefficient with a 16-level gray scale and appropriate annotation. The other level II photographic product contains an image of the calculated aerosol path radiance at 670 nm and the calculated upwelled subsurface radiance at 443 nm. It too, contains a gray scale with apropriate annotations. All level II products contain latitude and longitude marks and other ancillary information. The same type photographic products are available for level II data as for level I. The tape product for the level II data contains one 2-min scene. The tape contains, in 256 digital levels, the calculated upweUed subsurface radiance for channels 1 to 3; the calculated aerosol path radiance for channel 4; the equivalent blackbody temperature; the calculated pigment concentration; the calculated diffuse attenuation coefficient; and a land-cloud flag used to reduce areas detected as being land or clouds to 0 digital counts so they will normally appear black in level II imagery. A tape format document is provided to those who order level II tapes. All of the data produced for the CZCS program are archived at the Environmental Data and Information Service (EDIS) of NOAA at the World Weather Building, Room 100. Washington, DC. 20233. EDIS has available catalogs and costs for interested users. One catalog lists all of the archived products, including the date, the orbit number, the time at which the data were taken, and the coordinates of flae four corners of the image. Anol her catalog shows the orbital passes for each day of CZCS operation in monthly increments and shows areas along the orbital tracks for which satisfactory data have been acquired and will eventually be processed (if not already processed). Because of funding limitations. only a small fraction of the level I data will be reduced to level II archival data. Plans now are to produce 500 level II scenes in 1982 of data from years 1 to 3. Some level II products have already been entered into the archive and are available as samples for investigators wishing to gain experience in their use, Selection of those scenes from level I to be processed into level II is being made through the Nimbus Experiment Team (NET) for the CZCS. starting with 115 scenes identified as validation scenes that were acquired over ships of the NET during the early life of the instrumet. Requests for other scenes to be processed into level II can be forwarded through any member of the NET or directly to the chairman. In addition to the chronological archive of photographic products held by EDIS, there are other places at which photographic data can be viewed. In the United States, there is a partial archive at the Visibility Laboratory Scripps Institution of Oceanography, La Jolla, California, and a full, geographic, aUy cataloged archive at the Satellite Experiment Laboratory of NOAA in Suitland, Maryland. Members of the NET have limited archives at their facilities. European data are archived by the Joint Research Centre of the Commission of European Communities in Ispra, Italy, and South African data are archived at the National Research Institute for Oceanology in Stellenbosch. South Africa. Questions concerning use of these archives, location of the NET members, or location of centers that have computer facilities to analyze CZCS data should be forwarded to the writer.
Announcements
Satellite Experiment Laboratory National Oceanic and Atmospheric Administrators National Earth Satellite Service Washington, DC 20233, U.S.A.
283
WARREN A. Hovls, Chairman Nimbus Experiment Team
REFERENCES GORDt)NH. R., D. K. CLARK,J. L. MUI-LLERand W. A. Hovls (1980) Phytoplankton pigments from the Nimbus7 Coastal Zone Color Scanner: Comparisons with surface measurements. Science. 210, 63. Hovls W. A., D. K. CLARK,F. ANDERSON,R. W. AUSTIN,W. H. WILSON,E. T. BAKER,D. BALL,H. R. GORDON, J. L. MUELLER, S. Z. EL-SAVED,B. STORM,R. C. WRI~:iLEYand C. S. YENTSCH(1980) Nimbus-7 Coastal Zone Color Scanner: System description and initial imagery. Science, 210, 60.
N A T O Advanced Study Institute on THE AIR-SEA EXCHANGE
O F GASES AND P A R T I C L E S
19-30 July 1982 New England Conference Center, University of New Hampshire, Durham, N H , U.S.A.
Lecturers (tentative) include D. H. P. F.
C. BLANCHARD,S U N Y C. BROECKER, University of H a m b u r g BUAT-MENARD,C N R S , Gif sur Yvette DOBSON, Bedford Institute
*P. S. LIss, University of E. Anglia C. A. PAULSON,OSU L. K. PETERS, University of Kentucky *W. G. N. SLINN, Battelle P N L
The goal of the Institute will be to conduct an advanced examination of the physical, chemical, and biological principles governing the exchange of gases and particles across the air-sea interface. The course will consist of lecture/discussion sessions, demonstrations of equipment, examination of case studies, as well as presentations by 'student' participants. A limited amount of financial assistance will be available to selected participants. If you are interested in receiving further information about the Institute, please direct inquiries to : Dr. P. S. Lms School of Environmental Sciences University of East Anglia Norwich N R 4 7TJ, U.K. Tel: (0)60356161 Ext. 2563
* Course directors.