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GES DISC DAAC Data Guide: CZCS Level 1A GAC

Coastal Zone Color Scanner (CZCS)
1km Level 1 Calibrated Radiance and Temperature Tape (CRTT)
Dataset Guide Document

Level 1

Raw Radiance Counts in Six Bands

Cape Cod

Gibraltar

Abstract:

CZCS was a multi-spectral line scanner devoted principally to measurements of ocean color which operated from November 2, 1978 to June 22, 1986. It had six spectral bands (channels), four of which were devoted to ocean color, each having a 20 nanometer bandwidth and centered at 443, 520, 550, and 670 nanometers. These are referred to as channels 1 through 4, respectively. Channel 5 sensed reflected solar radiance and had a 100 nanometer bandwidth centered at 750 nanometers and a dynamic range which was more suited to land. Channel 6 operated in the 10.5 to 12.5 micrometer region and sensed emitted thermal radiance for derivation of equivalent black body temperature.

This document describes the 1 km resolution Calibrated Radiance and Temperature Tape (CRTT) format Coastal Zone Color Scanner Level 1 data products archived at the Goddard Space Flight Center (GSFC) Distributed Active Archive Center (DAAC). Other CZCS data products archived at Goddard include 4 km resolution CZCS Level 1A & 2 products and 18 km resolution Level 3 composite products. The characteristics of the CZCS Sensor are described in the Coastal Zone Color Scanner Sensor Guide and the Nimbus 7 platform is described in the Nimbus 7 Platform Guide.

 

Table of Contents

 

  1. Document Information
  2. Investigator(s)
  3. Dataset Information
  4. Theory of Measurements
  5. Equipment
  6. Procedure
  7. Observations
  8. Data Granularity
  9. Data Description
  10. Data Manipulations
  11. Errors
  12. Notes
  13. Application of the Dataset
  14. Dataset Plans
  15. References
  16. Related Software
  17. Data Access
  18. Output Products and Availability
  19. Glossary of Terms
  20. List of Acronyms

2. Investigators:

Dr. Gene Feldman
Goddard Space Flight Center, Code 610.2.3
Greenbelt, MD20771
(301)286-9428
email: gene@seawifs.gsfc.nasa.gov

 

Dr. Chuck McClain
McClain - Goddard Space Flight Center, Code 971
Greenbelt, MD20771
(301)286-8134
email: mcclain@calval.gsfc.nasa.gov

 

Dr. Wayne Esaias
Goddard Space Flight Center, Code 971
Greenbelt, MD20771
(301)286-5465
email: wayne@pelican.gsfc.nasa.gov

Title of Investigation:

Coastal Zone Color Scanner

Contacts (for Data Production Information):

CZCS Data -
Dr. Gene Feldman
Goddard Space Flight Center, Code 610.2.3
Greenbelt, MD20771
(301)286-9428
email: gene@seawifs.gsfc.nasa.gov

 

Software -
Dr. Bob Evans
University of Miami, RSMAS/MPO
4600 Rickenbacker Causeway
Miami, FL33149
(305)361-4799
email: bob@rrsl.rsmas.miami.edu

3. Dataset Information


Introduction:

For most regions of the world, the color of the ocean is determined primarily by the abundance of phytoplankton and their associated photosynthetic pigments. As the concentration of phytoplankton pigments increases, ocean color shifts from blue to green. The Coastal Zone Color Scanner (CZCS), was a multi-spectral line scanner developed by NASA to measure ocean color as a means of determining chlorophyll concentrations and the distributions of particulate matter and dissolved substances.

Objectives/Purpose:

The purpose of the CZCS on Nimbus-7 was to obtain a better understanding of the temporal and spatial distribution of phytoplankton biomass and primary production, and a better understanding of the processes regulating the growth of phytoplankton and of the processes influencing the ultimate fate of this organically fixed carbon. Satellite observations of ocean color were necessary to provide reliable estimates of marine phytoplankton biomass on synoptic scales which are useful in studies of phytoplankton processes. The mission objectives for the CZCS were to obtain observations of ocean color and temperature, particularly in the coastal zones, which would provide data with sufficient spatial and spectral resolution for the following applications:

 

  • Measure concentrations of chlorophyll-a and phaeophytin.
  • Map biologically productive areas.
  • Map suspended sediment distribution and determine the type of materials suspended in the water.
  • Map Gelbstoff (yellow substances) as an indicator of salinity.
  • Detect pollutants in the upper level of the oceans.
  • Map temperature of coastal waters and the open ocean.
  • Study the interactions between coastal effluents and open waters.

 

Summary of Level 1 Parameters:

Level 1 data contain at-spacecraft raw radiance counts with calibration and earth location information appended, but not applied. These data contain radiances from the six spectral bands (channels):

	Channel		Wavelength				Purpose
	1		433-453 nm (blue)			chlorophyll absorption
	2		510-530 nm (green)			chlorophyll concentration
	3		540-560 nm (yellow)			Gelbstoff concentration
	4		660-680 nm (red)			aerosol absorption
	5		700-800 nm (far red)			land and cloud detection
	6		10.5-12.5 microns (infra-red)		surface temperature

 

4. Theory of Measurements:

Organic and inorganic particulate matter or dissolved substances suspended in water affect its color. Ocean water containing very little particulate matter scatters as a Rayleigh scatterer with the well known deep purple or bluish color of the open sea. As particulate matter is added to the water, its light scattering characteristics change and different water colors are observed. Phytoplankton, for instance, have specific absorption characteristics and normally change the water to a more greenish hue although some phytoplankton, such as various red tide organisms, can change the water to colors such as red, yellow, blue-green or mahogany. Inorganic particulate matter in water, such as the terrigenous outflow from rivers, has a different color from organic material typically brownish in color but sometimes varying with red. Differentiating between suspended organic an inorganic matter remains a challenge to ocean color scientists today. By sensing the color with very high signal-to-noise ratios in several narrow bands, CZCS provided a mechanism for correlating water color with its contents for the first time.

 


5. Equipment:

Instrument Description:

CZCS had a scan width of 1556 km centered on nadir and the ground resolution was 0.825 km at nadir.Channels 1-4 were devoted to ocean color, each having 20 nanometer bandwidth and centered at 443, 520, 550, and 670 nanometers respectively. Channel 5 sensed reflected solar radiance, but had a 100 nanometer bandwidth centered at 750 nanometers and a dynamic range which was more suited to land. Channel 6 operated in the 10.5 to 12.5 micrometer region and sensed emitted thermal radiance for derivation of equivalent black body temperature.

 

Collection Environment:

CZCS was launched aboard Nimbus-7 in October 1978. Due to the power demands of the various on-board experiments the CZCS operated on an intermittent schedule. The infra-red/temperature sensor (channel 6 10.5-12.5 microns) failed within the first year. Sometime in 1981 it was determined that the sensitivity of the other CZCS sensors was degrading with time, in particular channel 4. Sensitivity degradation was persistent and increased during the rest of the mission.

In mid-1984 NIMBUS-7 Mission personnel experienced turn-on problems with the CZCS system which were related to power supply problems and the annual lower power summer season of NIMBUS-7. Also spontaneous shut down of the CZCS system began occurring. These also persisted for the rest of the mission. From March 9, 1986 to June, 1986 CZCS system was given highest priority for the collection of a contemporaneous data set of ocean color. It was turned off in June at the start of the low power season with the intention of turning it back on in December when power conditions would be more favorable. Attempts to reactivate CZCS in December 1986 failed. The CZCS sensor was officially declared non-operational on 18 December 1986.

Platform Mission Objectives:

NIMBUS-7 was launched in October 1978 and was a research-and-development satellite serving as a stabilized, earth-observing platform for the testing of advanced systems for sensing and collecting data in the pollution, oceanographic and meteorological disciplines. It provided an opportunity to assess each instrument's operation in the space environment and to collect a sizable body of data with the global and seasonal coverage needed for support of each experiment. The mission also extended and refined the sounding and atmospheric structure measurement capabilities demonstrated by experiments on previous Nimbus observatories.

Nimbus-7 sensors included experiments were a limb infrared monitoring of the stratosphere (LIMS), stratospheric and mesopheric sounder (SAMS), coastal-zone color scanner (CZCS), stratospheric aerosol measurement (SAM II), earth radiation budget (ERB), scanning multichannel microwave radiometer (SMMR), solar backscatter UV and total ozone mapping spectrometer (SBUV/TOMS), and temperature-humidity infrared radiometer (THIR). These sensors were capable of observing several parameters at and below the mesospheric levels. After 11 years in orbit, three experiments, SAM II, SBUV/TOMS, and ERB, were still functioning successfully. Nimbus 7 was finally retired in 1995.

Key Variables:

Nominal orbit parameters for the Nimbus-7 spacecraft were:

	Launch date			10/24/78
	Orbit				Sun-synchronous, near polar
	Nominal Altitude (km)		955
	Inclination (deg)		104.9
	Nodal Period (min.)		104
	Equator Crossing Time		1200 noon (ascending)
	Nodal Increment (deg)		26.1

Instrument Measurement Geometry:

CZCS was a cross-track scanning system. The Instrument Field of View (IFOV) of each detector was .865 mrad, yielding a resolution of 825 m at the satellite subpoint. The swath covered 1566 km in width from a maximum scan angle of approximately 40 degrees. 1970 samples per scan were collected for channels 1-6. This yielded 94,560 samples per second with an 8 bit (256 level) quantizing resolution. Data were then transmitted to a receiving station at a rate of 800 kbps.

 

Manufacturer of Instrument:

Ball Aerospace and Technologies Corporation , (http://www.ball.com/corporate/hspacebu.html).

 

Calibration:

Prelaunch calibration of the CZCS used a 76 centimeter diameter integrating sphere as a source of diffuse radiance for channels 1 through 5 and a blackbody source for calibration of channel 6. The integrating sphere was especially constructed for calibration of the CZCS and was calibrated from a standard lamp from the National Bureau of Standards utilizing a spectrometer and another integrating sphere to transfer calibration from the lamp to the sphere.

In addition to the sphere and the blackbody, a collimator was used to calibrate the CZCS in vacuum testing. In-flight calibration of the CZCS is accomplished for the first five bands by using a built-in incandescent light source. This in-flight calibration source was calibrated using the instrument itself as a transfer against the referenced sphere output.

Channel 6 was calibrated by viewing the blackened housing of the instrument whose temperature is monitored. Deep space is another calibration viewed during the 360 degrees rotation of the scan mirror.

For further details on the CZCS sensor and the Nimbus 7 satellite, please consult  The Coastal Zone Color Scanner Instrument Guide, (http://disc.sci.gsfc.nasa.gov/guides/GSFC/guide/CZCS_Sensor.gd.html) and the Nimbus 7 Platform Guide , (http://podaac-www.jpl.nasa.gov:2031/SOURCE_DOCS/nimbus7.html).


6. Procedure:

 

Data Acquisition Methods:

The raw data from the six channels of the CZCS were either directly transmitted to the ground station in real-time or recorded on the satellite tape recorder for later playback and transmission to the ground station. Data were stored on magnetic tape and sent to the Image Processing Division (IPD) at Goddard Space Flight Center (GSFC). In addition to radiance measurements, these data also include the calibration lamp data and Image Location Data (ILT).

7. Observations:

Data Notes:

(This information is not available for CZCS.)

Field Notes:

(This information is not available for CZCS.)

8.Data Granularity:

Each Level 1 granule is a partial orbital swath with a maximum of 2 minutes of data. One two-minute CZCS scene covers approximately 1.3 million square kilometers of the Earth's surface.

9.Data Description:

Spatial Characteristics:

Spatial Coverage:

Spatial Coverage is global with an emphasis on coastal regions.Spatial coverage varied widely and was very irregular.The first plot below shows a composite of the spatial coverage for the entire CZCS mission while the following 9 plots show the geographic distribution of CZCS data for each of the nine years from 1978-1986. Each dot on these plots represents the center point of one CZCS Level 1 scene. These images show the irregular spatial distribution of the CZCS data set graphically.

78-86

Spatial Resolution:

Level 1 CZCS scenes had a spatial resolution at nadir of 800 meters in each of the 6 co-registered channels.

 

Projection:

Level 1 scenes have satellite swath projection.

Temporal Characteristics:

Temporal Coverage:

The archive of CZCS data products began on November 2, 1978 and continued until June 22, l986. However, there are several periods of intermittent coverage. When operating full time, approximately 400 images were collected each month. The following figure shows a graphical display of the temporal distribution of the CZCS Level 1 data set.

Temporal Resolution:

Each CZCS scan viewed the Earth for approximately 27.5 microseconds. During this period, each channel of the analog data output was digitized to obtain a total of about 2000 samples. Successive scans occured at the rate of 8 per second. Subsequent coverage of the same geographic area varied greatly from place to place and over the lifetime of the instrument.

Parameter/Variable Description/Definition:

Level 1 data contain at-spacecraft raw radiance counts with calibration and Earth location information appended, but not applied. Visible and infrared radiances were measured in six spectral channels. The spectral region and band widths of the six channels and primary use of each are indicated in the following table:

 

Channel	 	Spectral Band	        Primary purpose	
		     (micrometers)

1		0.433 - 0.453		Chlorophyll absorption
2		0.510 - 0.530		Chlorophyll correlation
3		0.540 - 0.560		Yellow substance (Gelbstoff)
4		0.660 - 0.680		Aerosol correction
5		0.700 - 0.800		Land/cloud flag
6		10.5 - 12.5		 Surface temperature; failed shortly after launch

Unit of Measurement:

Level 1 Calibrated radiances were measured in units of mW/(cm2.sr.micron) with 1 km x 1km resolution

Data Source:

CZCS was flown aboard the Nimbus-7 satellite.

Data Format:

The original Level 1 CZCS data were produced and stored on 9-track magnetic tape in Calibrated Radiance and Temperature Tape (CRTT) format. In this original format, two files were created per scene: an EBCDIC header describing the data, and a data file containing the instrument scans. When these data were transferred onto digital optical disks, the files in CRTT Tape format were modified slightly to create files in CRTT Archive format. A major change was the combining of the separate files into one file and adding a format header block. The Level 1 files archived and distributed by the Goddard DAAC are in this CRTT Archive format.

The CRTT Tape format has been retained for the most part. See the Nimbus-7 Coastal Zone Color Scanner Level 1 Data Product User's Guide (NASA TM 86203) for a complete description of the original CRTT Tape format.

The added format header block is the first 512 byte block in the file. This block was written on a VAX prior to being written on the platters. The files were then archived into the GSFC DAAC directly off of the optical platters. The header block contains 16-bit (2 byte) integers which only the first 16 are useful. Because the VAX writes to memory in Little Endian order, if you are on a machine which uses Big Endian order, you will have to swap the order of the bytes of the integers. Little Endian byte order puts the byte at the least significant positions in the word (the little end). Big Endian byte order puts the byte at the most significant position in the word (the big end). The DEC PDP-11/VAX and Intel 80x86 follow the Little Endian model, while the IBM 360/370 and Motorola 680x0, and others follow the Big Endian model. The byte swapping only applies to these first 16 integers of the header block. These bytes contain information on the format of the file. In the following description, each HEADER refers to a two byte integer:

 

HEADER( 1)      'magic' to signal archive header record
HEADER( 2)      'magic' to signal archive header record
HEADER( 3)      Length of data record (bytes)
HEADER( 4)      Number of documentation records (2 normally)
HEADER( 5)      First data record offset (blocks)
HEADER( 6)      Type code (101=CZCS)
HEADER( 7)      Number of data records (1-970)
HEADER( 8)      Orbit number
HEADER( 9)      Year of pass
HEADER(10)      Header record offset (blocks)
HEADER(11)      Header record length (bytes)
HEADER(12)      Documentation record length (bytes)
HEADER(13)      --
HEADER(14)      --
HEADER(15)      --
HEADER(16)      Scanner tilt (*100)

An example of the first 512 byte block from a CZCS level 1 file is 
(this was done on an SGI IRIX with the Unix octal dump command: 
od -x 79005164931.ni7 .):

0000000 aaaa aaaa ec31 0200 1000 6500 d802 f703
0000016 bb07 0200 7602 d014 0000 0000 0000 5802
0000032 0000 0000 0000 0000 0000 0000 0000 0000
*
0001000

The variables translate to:

                   swapped
              hex   bytes  decimal  comments
              ---   -----  -------  --------
HEADER( 1) = aaaa   aaaa    43690   magic number 
HEADER( 2) = aaaa   aaaa    43690   magic number
HEADER( 3) = ec31   31ec    12780   Length of record (bytes)
HEADER( 4) = 0200   0002        2   Number of documentation records
HEADER( 5) = 1000   0010       16   First data record offset (blocks)
HEADER( 6) = 6500   0065      101   type code (101=czcs)
HEADER( 7) = d802   02d8      728   number of records
HEADER( 8) = f703   03f7     1015   orbit number
HEADER( 9) = bb07   07bb     1979   year
HEADER(10) = 0200   0002        2   header record offset (blocks)
HEADER(11) = 7602   0276      630   header record length (bytes)
HEADER(12) = d014   14d0     5328   documentation record length (bytes)
HEADER(13) = 0000   0000        0   ---
HEADER(14) = 0000   0000        0   ---
HEADER(15) = 0000   0000        0   ---
HEADER(16) = 5802   0258      600   scanner tilt (*100)

From this example the layout of the file is:

bytes        comment
-----        -------
0-31         File description.
1024-1654    Header information. Start at HEADER(10) and is HEADER(11) length.
             This information is EBCDIC.
2048-7376    Documentation record. Start at next block and is HEADER(12) 
             length.
8192-20972   First record. Start at HEADER(5) and is HEADER(3) length.
20992-33772  Next record. Start at next 512 byte block and HEADER(3) length.
...          Continue for a total of HEADER(7) records.
9326592-9332224  The trailing documentation record. The last 304 bytes are
             null characters. This file is padded out to be an even 
             multiple of 512 to keep integrity of the 512 byte blocks.

Related Datasets:

Other ocean color data sets include SeaWiFS, MOS-PRIRODA, OCTS and some airborne data collected by NASA and NOAA. Many investigations benefit from correlating CZCS data with available in situ and sea surface temperature data.

More information is on our Satellite Based Ocean Color Instruments page.

10. Data Manipulations:

Derivation Techniques and Algorithms:

The greatest problems encountered in analyzing the CZCS data are in the correction for atmospheric interference and differentiating between chlorophlyy concentrations and suspended inorganic substances. In the visible portion of the spectrum, the largest contribution to the signal received by CZCS was from the atmosphere. Rayleigh and aerosol scattering in the atmosphere must be compensated for before a high degree of accuracy in the determination of pigment concentration and diffuse attenuation coefficient can be obtained.

The calibration procedure is quite complex and will not be discussed in detail here. In essence the Rayleigh component is assumed constant and can be subtracted from the signal. Aerosol scattering is variable and is measured by assuming that the red region of the spectrum is completely absorbed by the ocean surface and is therefore returning no signal to the instrument. From this assumption, aerosol scattering can be calculated for the rest of the visible spectrum. References 11.2.b and 11.2.c describe these principles in detail. The final data are in the form of calibrated radiances.

Chlorophyll concentration algorithms were used to reduce the data produced from the Level 1 radiance data to Level 2 pigment concentration imagery. These algorithms use radiance data ratios to determine concentrations. Channels 1 and 3 were used for concentrations less than 1.5 mg/m**3 and channels 2 and 3 for concentrations above that level. These algorithms also account for the atmospheric scattering present, both Rayleigh and aerosol, by empirical coefficients in the equations for concentration. The Rayleigh component was assumed constant and can be subtracted from the signal. Aerosol scattering is variable and was measured by assuming that the red region of the spectrum is completely absorbed by the ocean surface and is therefore returning no signal to the instrument.

Data Processing Sequence:

Processing Steps (and Datasets):

At Goddard Space Flight Center the data were converted from voltages to radiances for bands 1 through 5, and to equivalent blackbody temperatures for band 6. The Level 1 radiance data were used to produce black and white images. Algorithms developed by the CZCS Nimbus Experiment Team were then applied to produce Level 1A and 2 data of suspended and dissolved materials on the water. These algorithms have continued to evolve since the beginning of data collection, especially for retrieval of water properties in sediment-laden coastal regions.

Processing Changes:

The entire CZCS digital archive was later converted from the original 1600-bpi magnetic tape to Sony digital optical disk at Goddard Space Flight Center. 38,000 nine track magnetic tapes were read 24 hours per day, 7 days per week for 18 months in order to transfer the data to approximately 185, 12 inch optical discs. The newly archived data format was nearly identical to the Calibrated Radiance and Temperature Tape (CRTT) product. These optical platters are now stored at the Goddard DAAC and remain a primary archive for the CZCS data set.

11. Errors:

Quality Assessment:

Some Level 1 scenes were flagged as containing unreliable data and were not included in the Level 3 composites but are still available from the Goddard DAAC. During ingest into the Goddard DAAC, metadata contained in the Level 1 files were accessed and used to produce a comprehensive and consistent database for all CZCS holdings. Many duplicate files and errors were eliminated in this first effort. In 1996 the metadata themselves were reviewed uncovering several types of navigational errors. Based on that analysis the database was updated and corrected again. The corrected data base entries now provide the framework for operational Browse and request processing.

Data Validation by Source:

In situ data useful for CZCS applications are available from SeaBASS (http://shark.gsfc.nasa.gov/~schieb/seabass/html/seabass.html). SeaBASS is a product of the Calibration/Validation element of the NASA Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. SeaBASS provides an interface to the Project's holdings of bio-optical and laboratory instrument calibration data. The interface allows access to over 1000 individual data files provided by numerous investigators.

Currently, the SeaBASS bio-optical holdings include radiometric data and in situ pigments collected as part of these experiments:

       Nimbus Experiment Team (NET) 
       U.S. Joint Global Ocean Flux Study (JGOFS) 
       CHORS_JGOFS 
       Bermuda Bio-Optical Program (BBOP) 
       CHORS/British Ocean Flux Study (BOFS) 
       Bermuda Area Time Series (BATS) 
       Hawaii Ocean Time Series (HOTS) 
       Tokyo Bay 
       MOCE1 
       MOCE2 
       MOCE3 
       CALCOFI Cruises 
       LTER 
       NORTH SEA Experiments 
       Chesapeake Bay 

SeaBASS also includes instrument calibration data collected as part of SIRREX-1, SIRREX-2, and eventually SIRREX-3/4/5. New data sets are received and archived on a regular basis. SeaBASS is described in much greater detail in Volume 20 of the SeaWiFS Technical Report Series (NASA Tech. Memorandum 104566). You may request a copy of Vol. 20 via the SeaWiFS TM Series order form from the Goddard DAAC Helpdesk via email or phone:gsfc-help-disc@lists.nasa.gov, (301) 614-5224.

Confidence Level/Accuracy Judgement:

CZCS performed better than its design requirements for signal-to-noise ratio in all channels. The table below shows the minimum signal-to-noise ratio specified for the instrument at its most sensitive gain setting. In the worst case, the chlorophyll concentration can be determined within a factor of 2 of the actual concentration.
     Channel/ Signal/Noise
     Band    Ratio (mW/cm**2-ster)   Radiance        NETD    Temp

     1       150                     5.41
     2       140                     3.50
     3       125                     2.86
     4       100                     1.34
     5       100                     10.8
     6       N/A                     N/A             0.220K  270K

Measurement Error for Parameters and Variables:

No additional measurement error assessments are available.

 

Additional Quality Assessments:

No additional quality assessments are available.

Data Verification by Data Center:

The Goddard DAAC has not performed data verification on the CZCS dataset. Only metadata verification has been performed.

 

12. Notes:

Known Problems with the Data:

The internal metadata in the header and trailer documentation records for Level 1 files is known to be erroneous in several instances. The Goddard DAAC's data base has been corrected, but the individual header and trailer records have not been corrected.

Any other Relevant Information about the Study:

Assumptions in the atmospheric correction of the data during processing resulted in an accuracy of 35% in ocean color measurements in Case I waters (chlorophyll and associated pigments determine the reflectance) and within a factor of 2 generally.

Due to the limited duty cycle (10%) and the non-uniform coverage, sampling was highly skewed. Temporal sampling frequency also varied, resulting in potential errors. An in depth overview of the entire history of the CZCS Project is included in Reference 4, below.

13. Application of the Dataset:

(Please refer to Section 4.)

 

14. Future Dataset Plans:

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) is scheduled to launch in 1997 as a follow-on to CZCS.SeaWiFS data will be distributed to authorized users by the Goddard DAAC. Numerous documents describing SeaWiFs data and the SeaWiFS Project activities may be obtained from the The Ocean Color Data and Resources website at

http://disc.sci.gsfc.nasa.gov/oceans/

Users should refer to the SeaWiFS Project homepage for the latest information on SeaWiFS:

http://seawifs.gsfc.nasa.gov.

15. References

  1. "CZCS Sensor Guide Document", prepared by the Distributed Active Archive Center, NASA Goddard Space Flight Center, Greenbelt, Maryland, 1995.
  2. "The Living Ocean: Observing Ocean Color From Space", NASA Publication PAM-554, Goddard Space Flight Center, Greenbelt, Maryland, 1993.
  3. "Coastal zone color scanner 'system calibration': A retrospective examination." R.H. Evans & H.R. Gordon, Journal of Geophysical Research, Vol.99. No. C4, pages 7293-7307, April 15, 1994.
  4. "Coastal Zone Color Scanner", European Space Research Institute, Frascati, Italy.
  5. Nimbus 7 Coastal Zone Color Scanner (CZCS) Level 1 Data Product Users' Guide NASA TM 86203, S.P. Williams, E.F. Szajna and W.A. Hovis. Goddard Space Flight Center, Greenbelt, MD 20771. July, 1986, 53 pages.

Journal Articles and Study Reports:

The April 15, 1994 issue of the Journal of Geophysical Research (Volume 99, Number C4) contains a Special Section entitled "Ocean Color From Space: A Coastal Zone Color Scanner Retrospective."

 

16.Related Software:

The Goddard DAAC provides a mirror site for the distribution of SEAPAK CZCS data processing software. We have also written a read program to help you get started withyour analysis of Level 1 CZCS data. Below are the software descriptions and ftp links to the software.

 

CZCS Level 1 Read Program

The level 1 CZCS data product is stored as raw binary data. The program we have written will dump selected data fields from selected data records found in a CZCS Level 1 data file. It will also dump selected data fields from the documentation records which precede and follow the data records.

ball CZCS_L1_SW

PC-SEAPAK

SEAPAK is a user-interactive satellite data analysis package that was developed at the NASA/Goddard Space Flight Center. The primary application of SEAPAK is for the processing and interpretation of Level 1 Coastal Zone Color Scanner (CZCS) and Advanced Very High Resolution Radiometer (AVHRR) data. In addition, CZCS Level 1A and 2 DSP images can be converted to the SEAPAK format using the SEAPAK package. (DSP is image processing software developed at the Rosenstiel School of Marine and Atmospheric Sciences of the University of Miami.)

Two versions of the SEAPAK CZCS processing software are available online and on tape from the Goddard DAAC. PC-SEAPAK runs on PC-AT, 386, or 486 class machines. UNIX-SEAPAK operates only on SGI's Unix Workstation. Besides including most major programs in PC-SEAPAK to process CZCS and AVHRR satellite data, Unix-SEAPAK also includes programs to handle ancillary data.

Note: The DAAC is a mirror site to shark.gsfc.nasa.gov. We do not support the maintenance and development of SEAPAK. We will provide timely updates and information to directly contact the authors.

Software System Requirements:

PC-SEAPAK runs on PC-AT, 386, or 486 class machines. UNIX-SEAPAK operates on SGI Unix Workstations only.

To be able to use all of PC-SEAPAK's graphics functions, you will need to have a Matrox graphics board installed on your PC. Even if you do not have this board, the whole PC-SEAPAK package should be installed. It will work on a PC without the board but the you won't be able to run the display related programs. To request a non-graphical version of PC-SEAPAK on diskettes, contact the Goddard DAAC Helpdesk: daacuso@daac.gsfc.nasa.gov.

Software Documentation:

Copies of the 350 page PC-SEAPAK User's Guide are available online and in hardcopy from the Goddard DAAC Helpdesk. This documentation is intended to be used by both UNIX and PC customers and it is the only SEAPAK documentation available from the Goddard DAAC.

PC-SEAPAK User Guide

Software Access and Installation:


PC-SEAPAK

The PC version of SEAPAK is available through FTP.

FTPPC-SEAPAK directory

In this directory, you will find four compressed files and one program to decompress those files as well as three update files:

 

seapak.zip
The compressed file that contains all the PC-SEAPAK version 4.0 programs data base file (in 5-minute resolution)
ciadb.zip
The compressed file that contains the eight CIA world data base files.
pctoms.zip
The compressed file that contains nine PCTOMS data base files.
halo88.zip
The compressed file that contains HALO88 font files and the driver program for the MVP-AT image board
pkunzip.exe
The decompressing program to be used on PC to decompress those compressed zip files.

These update files have to be restored (in any temporary directory using 'pkunzip') and installed (copied) IN ORDER into the SEAPAK directory after you have installed the original PC-SEAPAK 4.0.

  • update.zip
  • update1.zip
  • update2.zip

Download all of these files to the PC first. Then run PKUNZIP to decompress all the ZIP files. Type PKUNZIP at the DOS prompt and you will get a detailed description about how to use this command.

For example, to decompress all files in 'SEAPAK.ZIP' to the directory 'D:\SEAPAK', just type 'PKUNZIP SEAPAK.ZIP D:\SEAPAK'. All other compressed files should be decompressed the same way. It is recommended that you decompress different zip files into different directories. After all compressed files are restored, you need set up the SEAPAK environmental variable, modify SEAPAK.FIG file if necessary, run the programs SPKSETUP and INIT.

For further information, read SYSTEM ENVIRONMENT: SOFTWARE section in the PC-SEAPAK User's Guide.


UNIX-SEAPAK

The UNIX version of SEAPAK is available through FTP.

FTP UNIX-SEAPAK directory

The files 'ANNOUNCEMENT', 'README.SEAPAK.PLEASE!' in the UNIX SEAPAK directory contain information about how to install UNIX-SEAPAK. Because there is no UNIX-SEAPAK User's Guide available, UNIX SEAPAK users should request a copy of the PC-SEAPAK User's Guide from the Goddard DAAC Helpdesk: gsfc-help-disc@lists.nasa.gov.

If you have any problem or need assistance with installing or using SEAPAK, contact:

Gary Fu
301-286-7107
email: gfu@shark.gsfc.nasa.gov

For more information on scientific applications of the SEAPAK and DSP image processing systems contact:

SEAPAK:
Dr. Charles McClain
SeaWiFS Project Scientist
email: mcclain@calval.gsfc.nasa.gov

DSP:
Dr. Robert Evans,
University of Miami's Rosenstiel School of Marine Sciences
email: bob@ARWIN.rsmas.miami.edu

17. Data Access:

Contacts for Archive/Data Access Information:

Goddard DAAC Ocean Color Data and Resources Website

Goddard DAAC Helpdesk
Code 610.2
NASA Goddard Space Flight Center
Greenbelt MD 20771 USA
gsfc-help-disc@lists.nasa.gov
(301) 614-5224
(301) 614-5268 fax

Archive Identification:

NASA Goddard Space Flight Center DAAC

 

Procedures for Obtaining Data:

The Goddard DAAC is the central archive and distribution facility responsible for providing access to the entire CZCS data set. The entire collection of Coastal Zone Color Scanner (CZCS) ocean color data and images is available on-line via the World Wide Web in the Data Section of the NASA Goddard DAAC Ocean Color Data and Resources Web site at

http://disc.sci.gsfc.nasa.gov/oceans/

Users may view Level 2 browse images of 59,337 CZCS files and place FTP or tape orders with the Goddard DAAC for those CZCS data products they desire. Each Level 2 browse file maps to corresponding Level 1 and 1A files. All Level 1A and 2 files are also available via anonymous ftp. CZCS Level 1 files are orderable via the Browser but do not reside online due to the size of the Level 1 collection.

 

Data Archive Status/Plans:

Archive of the CZCS data set at the Goddard DAAC is complete. Ocean Color website documentation and access development is also nearing completion. Future activities will be dedicated to the support of SeaWiFs archive and distribution starting in calendar year 1997.

 

18. Output Products and Availability:

Tape Media:

8mm tape (8200 and 8500 bpi)
4mm tape (60m and 90m)

Other Products:

electronic transfer (ftp)

19.Glossary of Terms

Calibration: the adjustment or systematic standardization of the output of a quantitative measuring instrument or sensor.
Chlorophyll: any of a group of related green pigments found in photosynthetic organisims.
Contemporaneous: originating, existing or happening during the same period of time.
Dynamic Range: the range between the maximum and minimum amount of input radiant energy that an instrument can measure.
Gelbstoffe: particulate matter, usually outflow sediment from rivers, which, when suspended in water, gives it a yellowish color. (from German: "yellow stuff").
Infrared Light: electromagnetic radiation having wavelengths longer than red light (7700 angstroms) but less than radio waves (~.1 meter).
Nadir: the point on the Earth directly below an orbiting satellite.
Photosynthesis: the process by which chlorophyll-containing cells in green plants convert incident light to chemical energy and synthesize organic compounds from inorganic compounds, especially carbohydrates from carbon dioxide and water, with the simultaneous release of oxygen.
Phytoplankton: drifting, often microscopic oceanic plants which conduct the process of photosynthesis.
Primary productivity: the rate at which photosynthesis proceeds.
Radiometer: a device that detects and measures electromagnetic radiation.
Spatial Resolution: the size of the smallest object recognizable using the detector.
Spectral Band: a narrow range of the electromagnetic spectrum.
Spectral Response: the relative amplitude of the response of a detector vs. the frequency of incident electromagnetic radiation.
Visible Light: electromagnetic radiation with wavelength in the 3900 to 7700 angstrom range.

20. List of Acronyms:

AVHRR: Advanced Very High Resolution Radiometer
CZCS: Coastal Zone Color Scanner
DST: Data Support Team
EOSDIS: Earth Observing System Data and Information System
ESDIS: EOSDIS Data and Information System
ESRIN: European Space Research Institute
IFOV: Instrument Field of View
MODIS: Moderate Resolution Imaging Spectrometer
Nimbus: NASA Meteorological Satellites (1 through 7)
NOAA: National Oceanic and Atmospheric Administration.
SeaWiFS: Sea-viewing Wide Field-of-view Sensor

Change History

Version 2.0
Version baselined on addition to the GES Controlled Documents List, Feb 18, 2000.
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