National Geophysical Data Center Boulder, Colorado USA

Welcome to the
NOAA/NASA Pathfinder Climate Data CD-ROM

Revised: 1/1998

This CD-ROM contains seven data sets from the NOAA/NASA Pathfinder Program. The majority of the data are monthly one- by one-degree gridded files with many parameters, most of which are climate-related and can be used for analysis and research. The data are for the Pathfinder Benchmark period: April, 1987, through December, 1988.

The data sets included on this CD are:

Advanced Very High Resolution Radiometers (AVHRR) Land, and
Advanced Very High Resolution Radiometers (AVHRR) Ocean,
TIROS Operational Vertical Sounder (TOVS) Path - A,
TIROS Operational Vertical Sounder (TOVS) Path - C1, and
TIROS Operational Vertical Sounder (TOVS) Path - C2,
Special Sensor Microwave/Imager (SSM/I) Precipitation, and
Special Sensor Microwave/Imager (SSM/I) Atmospheric Moisture.
Parameters include normalized difference vegetation index, sea surface temperatures, course layer mean temperature, total cloud fraction, outgoing longwave radiation, cloud top pressure, total precipitable water values, lower stratosphere temperatures, lower tropospheric temperature, ocean precipitation, MSU adjacent FOV deep layer temperature, scan line deep layer temperature, and limb-corrected brightness temperatures.

Important information on the CD-ROM directory structure, instructions on visualization and browse software, an overview of the data and list of some NOAA/NASA Pathfinder web sites are all available in this document.


Directory Structure

The highest level of the directory structure has directories for each of the data sets and for software. The software directory includes tools developed at NOAA's National Geophysical Data Center (NGDC) for viewing the data as well as the files required to install the runtime version of Microsoft Video for Windows for viewing the movies included on the disc.

Many levels of the structure include directories named doc, data, movies, or process. The doc directories contain the documentation from the data provider for that data set. The data directories contain simple binary files of gridded data (.img) described in the ASCII documentation files (.doc), and external Hierarchical Data Format header files (.hdf). Some data directories include a directory named imdi_lbl. These directories contain external header files (.lbl) for the NASA Planetary Data System (PDS) DOS display program IMDISP for viewing integer data grids. The movie directories contain animation's of each parameter (.AVI). These animation's can be viewed using the Windows Media Player if Video for Windows has been installed. The process directories include data set dependent software tools that we have developed and used to process the data sets.

File Name Extensions
Extension Description of Extension
.doc ASCII documentation files
.img Simple binary files of gridded data
.lst GeoVu histogram information (variable summary) file
.hdf Hierarchical Data Format (HDF) files
.fmt Format descriptions define the formats of input and output data and headers.
.avi Movie files for each parameter
.men GeoVu uses custom menu files for each data collection that enables the end use to easily navigate the data.
.lbl External header files for the NASA Planetary Data System (PDS) DOS display program IMDISP for viewing integer data grids.

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Viewing the Data

The goal of this project is to make data easy to view with a wide variety of tools. The .img files on this disk are simple binary images (rows and columns:(90,180), (180,360) and (360,720), pc byte order). These can be viewed with many image visualization tools.

GEOVU - GeoVu is included to provide all users with basic access to the data. It is not intended to replace more sophisticated tools. This CD includes GeoVu for the PC, Mac, Sun and SGI (Silicon Graphics Workstations running UNIX). At NGDC, we have an online GeoVu FAQ which attempts to answer commonly asked questions about GeoVu. Please note that the PC GeoVu (Release 6.X) supports the movie browser however the Mac, SGI and UNIX version of GeoVu do not have a movie browser. To view the movies on the Mac or a UNIX machine see the movies section below.

To install GeoVu follow the instructions in the following files:
PC /software/geovu/pc/read_pc.htm (Disk space needed to install GeoVu on the PC is ~4.6 mb)
Mac /software/geovu/mac/read_mac.htm (Disk space needed to install GeoVu on the Mac is ~5.1 mb)
Sun /software/geovu/unix_sun/read_sun.htm (Disk space needed to install GeoVu on the Sun is ~7.6 mb)
SGI /software/geovu/unix_sgi/read_sgi.htm (Disk space needed to install GeoVu on the SGI is ~5.3 mb)

HDF -There are 2 types of Hierarchical Data Format (HDF) files on this CD-ROM. The original HDF files provided to NGDC by the data contributors and the external HDF header files created by NGDC. NGDC created the external HDF header files to expand access to the image (.img) data. The original HDF files are written in big endian byte order. They are platform independent and can be viewed using any HDF tool. Due to space limitations on this CD-ROM, the original HDF files are provided for only some of the datasets. The original HDF files are located in the org_hdf directory under the appropriate data directory. For example, the AVHRR Land original HDF files are in the directory /avhrr_ld/data/org_hdf. The Tovs Path - C2 original HDF files are in the directory /tovs_c2/apr87/org_hdf. The following datasets have the original HDF files:

AVHRR Land
TOVS Path - C1
TOVS Path - C2
SSM/I Precipitation
SSM/I Atmospheric Moisture

EXTERNAL HDF FILES - The external HDF header files, created at NGDC, describe simple binary gridded data files (.img files). The external HDF header contains a data description that enables an HDF viewer, able to read external headers, to display the selected .img data file. The external HDF header files (.hdf) are in the data directories with all the ".img", and ".doc" files.

At the present there is only one viewer that can handle the external HDF files, Noesys from Fortner Research Version 1.02. JHV Version 1.20 beta from the National Center for Supercomputing Applications (NCSA) has a problem reading the external HDF files due to the files being in pc byte order (little_endian). JHV doesn't presently support swapping bytes when external file elements are involved. This situation is being addressed by NCSA and should be rectified in there next release of JHV due out at the end of February, 1998.

LISTS (*.lst): In the lists directory (under the data directory) are ASCII x-y files that give the distribution of each parameter for that month and checkvar.out which lists the minimum and maximum for each parameter/month.

EXTERNAL .LBL FILES - The SSM/I Precipitation and Atmospheric Moisture and TOVS Path A and C1 data areas contain sub-directories named imdi_lbl. These directories contain external header files (.lbl) for the NASA PDS DOS display program, IMDISP, for viewing integer data grids. IMDISP only supports the following data types: byte, integer and long integer. For the Pathfinder data sets, if the data type is byte or short, then the image file has an external label file (.lbl). If the data type is float, then there is no external label file.

There seems to be a problem with IMDISP handling the signed short data types. If the keyword "UNSIGNED_INTEGER" is used in the label file to describe data that is actually signed integers, the image is displayed properly. However, there seems to be a glitch in the in the x-axis plotting for histograms. The histograms are labeled 0 to -32768 rather than -10 to 10000. In the PDS documentation it states that for signed integers use the following keywords: PC_INTEGER or LSB_INTEGER. If either of these 2 keywords are used for the data type descriptor, then the images come out very dark. The keyword "PC_INTEGER" was used for the Pathfinder data, even though this causes dark displays. The data sets affected by this are:

  1. Tovs A - 273 files - all Count image files (21 x 13 = 273)
  2. SSM/I Precipitation - 14 files - Counts only (14 x 1 = 14)
  3. SSM/I Atmospheric Moisture - 28 files - Counts only (14 x 2 =28).

MOVIES - The movies, written as Video for Windows files (".avi"), can be viewed using the Windows Media Player from your PC's Accessories Group. The PC version of GeoVu is the only platform with a built in movie browser. All the Video for Windows movie files have an ".avi" extension. All the ".mov" files in the movies directory are the header files for the GeoVu PC built in movie browser. (They are not in the Quicktime .mov format).

For the MAC user, you can download and use the free utility avi_to_qt.kit located at http://www.esperance.com/hacks to convert the .avi files to the Quicktime movie format.

For the UNIX user, you can download and use the free utility Xanim located at http://xanim.va.pubnix.com to view or convert the .avi files.

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Pathfinder Data Set Overview

Data Set Data Type Grid Size (degrees) Time Period Data Sample
Rate
Images Image Size # Rows # Cols Movies Movie
Palette
IMDISP(.lbl)
AVHRR Land             
NDVI Float 1x1 Jan. 1, 1987 - Dec.31, 1988 10 days 72 259200 180 380 2 GVI_256.PAL NONE - All ARE FLOATS.
AVHRR Ocean             
SSTFloat.5x.5Jan. 1, 1987 - Dec.31, 1987 Monthly121036800 3607201256_SST.PAL NONE-ALL ARE FLOATS.
TOVS A            
MEANFloat1x1Apr. 1, 1987 - Dec. 31, 1988Monthly 213259200 18036039RGB_256.PALCOUNTS ONLY
COUNTShort   213 129600     HAVE .LBL FILES.
STD DEVFloat   213 259200      
Total Images Files     819      
TOVS C1            
COUNTByte1x1Mar. 1, 1987 - Nov. 31, 1988Monthly 4264800 1803607RGB_256.PALCOUNTS ONLY
MEANFloat   42 259200     HAVE .LBL FILES.
STD DEVFloat   42 259200      
OCN_PRECPFloat   21 259200      
Total Images Files     147       
TOVS C2            
COUNTFloat2x2Apr. 1, 1987 - Dec. 31, 1988Monthly 23164800 9018033RGB_256.PALNONE-All ARE
MEANFloat   231 64800     FLOATS.
STD DEVFloat   231 64800      
Total Images Files     693       
SSMI-PRECIP            
PRGFloat1x1Aug. 1, 1987 - Nov. 31, 1988Monthly 142592001803602RGB_256.PALCOUNTS ONLY
SSQFloat (Missing Dec., 1987 and Jan., 1988)  0259200    HAVE .LBL FILES.
NUMBERShort   14 129600    SSQ NOT
Total Images Files     28     PROCESSED.
SSMI-MOIST            
WVGFloat1x1Aug. 1, 1987 - Nov. 31, 1988Monthly 142592001803606RGB_256.PALWVN and LWN
WVSFloat (Missing Dec., 1987 and Jan., 1988)  14259200   RGB_256.PAL HAVE .LBL
WVNShort   14 129600   RGB_256.PALFILES.
LWGFloat   14 259200   RAINBOW.PAL 
LWSFloat   14 259200   RAINBOW.PAL 
LWNShort   14 129600   RGB_256.PAL 
Total Images Files     84      

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AVHRR - Land

This CD-ROM contains data produced by the AVHRR Land group and provided to NGDC by Mary James of NASA Goddard Space Flight Center (Replaced by Peter Smith 301-763-8071 of NASA Goddard Space Flight Center).

Goddard Space Flight Center
Code 902.2
Greenbelt, Maryland 20771
Telephone: (301) 286-5033
Fax: (301) 286-1775
email: gsfc@eos.nasa.gov

This data set is part of the Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Land Products. It consists of normalized difference vegetation index in 1 degree latitude - longitude equal angle bins. It is derived from the mean Channel 1 and mean Channel 2 reflectance for 1 degree areas for the Pathfinder Land 10-day Composite Data set. The periods are the 1st through the 10th, 11th through the 20th and 21st through the end of the month.

The only parameter for this data set is:

Descaling of the NDVI values

The data has been descaled for the physical NDVI values which range from -1.0 to 1.0. The equation to do the computation is:

NDVI = (pixel - 128) * 0.008
Missing Data Values

The original HDF data files denoted missing data and ocean data with values of 0 and 1 respectively. We remapped the 0 and 1 flags to 2 and 3 respectively to move the missing data flags out the the valid data range. The descaled data now have a valid data renge fo -0.5 to 0.77 with flag values of 2.0 for missing data and 3.0 for ocean data.

For this dataset, the overall minimum is -0.5 and the maximum is 3.0. If we use these minimum and maximum, GeoVu displays the images as black due to compressing the data into a small part of the pallette. To create a meaningful display in GeoVu, the minimum and maximum values for the entire data set have been set to -0.5 and 0.77. This results in a meaningful display with the missing data flags being consistently displayed with the same color.

AVHRR Land Table

Name Filename Description Type Min Max Units Comments
NDVI YYMMDD Normalized
Difference
Vegetation
Index
Mean -.50 .77 NDVI YY = year, MM = month, DD = day
The data files are in 10 day periods.
The 1st to the 10th, the 11th to the 20th
and the 21st to the end of the month.
Flag values = 2.0 and 3.0.

For the data providers documentation on this dataset.

AVHRR Land web site.

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AVHRR - Ocean

This CD-ROM contains data produced by the AVHRR Ocean group and provided to NGDC by Dr. Jorge Vazquez (818-354-6980) from the Jet Propulsion Laboratory .

Jet Propulsion Laboratory
4800 Oak Grove Drive
Mail Stop 300-320
Pasadena, California 91109
Telephone: (818) 354-9890
Fax: (818) 393-2718
email: jpl@eos.nasa.gov

The NOAA/NASA Pathfinder AVHRR Oceans data sets are global, multichannel, Sea Surface Temperature data derived from the Advanced Very High Resolution Radiometers (AVHRR) on the NOAA/TIROS operational meteorological satellites (NOAA-7, -9, and -11). These satellites provide a continuous daily and composite data set. This data collection includes monthly global browse images of the Sea Surface Temperature in half degree latitude-longitude equal angle bins. The product choosen for this cdrom is the Best Sea Surface Temperature Equal Area Browse HDF files (720x360). These images were created by binning the AVHRR level-1B data. The data provided is January to December for 1987.

Rescaling of the SST values

NGDC received the original source files as bytes. The data was descaled into floats by NGDC to regain the original data value in degree celsius. The equation to calculate the original SST is:

  SST = 0.15*DN + (-3.0)
	where:
        SST = sea surface temperature (degrees Celsius)
	DN = digital number
        (DN = 0) Indicates a missing value or the presence of ice, land or cloud coverage.
The data range is between -3.0 and 35 degree Celsius.

This data set only has one parameter:

Missing Data Values

The flag value for the Sea Surface Temperature is -3 which indicates a missing value or the presence of ice, land or cloud coverage.

AVHRR Ocean Table

Name Filename Description Type Min Max Units Comments
SST YYMMam Sea Surface Temperature Mean -3.00 33.75 C YY = year, MM= month
Flag value = -3

For the data providers data description on this dataset.

For the data providers user guide on this dataset.

AVHRR Ocean web site.

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TOVS PATH - A

This CD-ROM contains data produced by the TOVS Path A group and provided to NGDC by Geoge Serafino (301-286-3021) of NASA Goddard Space Flight Center.

Goddard Space Flight Center
Code 902.2
Greenbelt, Maryland 20771
Telephone: (301) 286-5033
Fax: (301) 286-1775
email: gsfc@eos.nasa.gov

Due to the experimental nature of this CD-ROM and the space limitations only the AM data were processed. This dataset contains the TIROS Operational Vertical Sounder (TOVS) level 3 geophysical parameters. For each parameter, each cell in a 1 by 1 degree grid is characterized by a mean value, a standard deviation, and the number of observations. There are grids for each month. This data collection includes the following parameters:

Missing Data Values

For all mean and standard deviation arrays, a fill of -999.99 is used to indicate that data for that gridbox is either missing, invalid or suspect. For the count arrays, a corresponding fill value of 0 is used under these circumstances.

Tovs Path A Table

Name Filename Description Type Min Max Units Comments
CLTEMP CLT1
CLT1CN
CLT1SD
CLT3
CLT3CN
CLT3SD
CLT5
CLT5CN
CLT5SD
CLTS
CLTSCN
CLTSSD
100-30 mb layer
100-30 mb layer
100-30 mb layer
300-100 mb layer
300-100 mb layer
300-100 mb layer
500-300 mb layer
500-300 mb layer
500-300 mb layer
For the Surface
For the Surface
For the Surface
Mean
Count
Std dev
Mean
Count
Std dev
Mean
Count
Std dev
Mean
Count
Std dev
182.15
0.00
0.00
186.08
0.00
0.00
210.97
0.00
0.00
217.99
0.00
0.00
247.30
72.00
17.13
240.39
72.00
12.02
263.89
72.00
9.73
291.04
72.00
10.91
K
Number
K
K
Number
K
K
Number
K
K
Number
K
Coarse layer mean temperature for the surface-500, 500-300, 300-100, and 100-30 mb layers
FCLD FCLD
FCLDCN
FCLDSD
Total cloud fraction
Total cloud fraction
Total cloud fraction
Mean
Count
Std dev
0.00
0.00
0.00
1.00
77.00
0.50
0-1
Number
0-1
Total cloud fraction
OLR OLR
OLRCN
OLRSD
Outgoing longwave radiation
Outgoing longwave radiation
Outgoing longwave radiation
Mean
Count
Std dev
83.06
0.00
0.00
340.57
77.00
83.96
W/m^2
Number
W/m^2
Outgoing longwave radiation
PCLD PCLD
PCLDCN
PCLDSD
Cloud top pressure
Cloud top pressure
Cloud top pressure
Mean
Count
Std dev
93.68
0.00
0.00
975.00
70.00
473.00
mb
Number
mb
Cloud top pressure
PRWAT PRW300
PRW300CN
PRW300SD
PRW500
PRW500CN
PRW500SD
PRW700
PRW700CN
PRW700SD
PRW850
PRW850CN
PRW850SD
PRWSUR
PRWSURCN
PRWSURSD
300 mb layer
300 mb layer
300 mb layer
500 mb layer
500 mb layer
500 mb layer
700 mb layer
700 mb layer
700 mb layer
850 mb layer
850 mb layer
850 mb layer
Surface layer
Surface layer
Surface layer
Mean
Count
Std dev
Mean
Count
Std dev
Mean
Count
Std dev
Mean
Count
Std dev
Mean
Count
Std dev
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.08
72.00
0.08
0.84
72.00
0.33
2.57
72.00
0.87
5.22
72.00
1.62
7.85
72.00
2.26
cm
Number
cm
cm
Number
cm
cm
Number
cm
cm
Number
cm
cm
Number
cm
Total precipitable water value above surface, 850, 700, 500, and 300 mb
TSURF TSURF
TSURFCN
TSURFSD
Surface Skin Temperature
Surface Skin Temperature
Surface Skin Temperature
Mean
Count
Std dev
200.14
0.00
0.0
314.02
72.00
18.95
K
Number
K
Surface Skin Temperature

For the data providers documentation on this dataset.

For the data providers readme on this dataset.

Tovs Path A web site.

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TOVS PATH - C1

This CD-ROM contains data produced by the TOVS Pathfinder group and provided to NGDC by Janice Tillman (205-922-5875) and Michael Goodman (205-922-5890) both from the NASA Marshall Space Flight Center.

Marshall Space Flight Center
Building 4492
Huntsville, Alabama 35812
Telephone: (205) 544-6329
Fax: (205) 544-5147
Email: msfc@eos.nasa.gov

Due to the experimental nature of this CD-ROM and the space limitations only the AM data was processed. This data collection includes global 1 X 1 images for 3 parameters:

The temperature images were created by binning the Level 2 TOVS data. Three images exist for each parameter:

  1. the mean for each pixel
  2. the standard deviation
  3. the count.

The ocean precipitation images were created differently. Note that the ocean precipitation data sets are identical for the AM and PM satellites. Only the ocean precipitation AM directories were processed.

Missing Data Values

Oceanic precipitation estimates are only calculated between the latitudes 60S and 60N. All grids outside this latitude band are set to -999.00. All variables for TOVS C1 have a missing data flag value of -999.00.


Variable                           Missing flag value

Lower Tropospheric Temperature        -999.00
Lower Stratospheric Temperature       -999.00
Standard Deviation Troposphere        -999.00
Standard Deviation Stratosphere       -999.00
Counts Troposphere                    -999.00
Counts Stratosphere                   -999.00
Ocean Precipitation                   -999.00

Potential Data Errors

The Ocean Precipitation data presents many interesting challenges. The missing data flag of -999 creates problems for display programs which insist on calculating the minimum and the maximum from all of the data. Also, while most data values are between 0 and 20, there are a number of data values which are above 100. These seem to occur in the Hudson Bay and Sea of Japan. The spatial concentration of these data suggest that these may be bad data values. This data range problem causes a very dark image for the individual data and movie files for the ocean precipitation variable.

Tovs Path C1 Table

Name
Filename
Type
Min
Max
Units
Comments
Lower Tropospheric Temperature
Lower Stratospheric Temperature
Standard Deviation Troposphere
Standard Deviation Stratosphere
Counts Troposphere
Counts Stratosphere
Ocean Precipitation
lstrtemp
ltrotemp
ltrostd
lstrstd
ltrocnt
lstrcnt
ocnprecp
Mean
Mean
Std Dev
Std Dev
Count
Count
Mean
184.00
195.00
0.00
0.00
0.00
0.00
0.00
238.00
287.00
7.50
2.30
155.00
157.00
121.50
K
K
K
K
Number
Number
mm/day
Flag value = -999.00






For the data providers documentation on this dataset.

Tovs Path C1 web site.

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TOVS PATH - C2

This CD-ROM contains data produced by the NOAA TOVS Pathfinder group and provided to NGDC by Mitch Goldberg (301-763-8136). The data are available at the Satellite Active Archive.

Satellite Active Archive
5627 Allentown Road
Suite 100 PES
Suitland, Maryland 20746
Telephone: (301) 763-8400
Fax: (301) 763-8443
email: saainfo@nesdis.noaa.gov

This data collection includes global 2 X 2 images for 11 parameters:

These images were created by binning the Level 2 TOVS data. Three images exist for each parameter:

  1. the mean for each pixel
  2. the standard deviation
  3. the count.

The NOAA TOVS Pathfinder Group converted floating point values into integers by applying a scaling or unit conversion to allow for a smaller transfer file size. The data providers multiplied standard deviation data values by 256 and multiplied the mean data values by 64. At NGDC, we applied the reverse conversion to recover the original units. Standard deviation data were divided by 256 and the mean data were divided by 64. We provide this data set in both converted (image) and original units (scatter plot).

The original transfer files contained 11 parameters (e.g., scan line deep layer temperature at the 100 millibar level) and each parameter contains three statistics (i.e., count, mean, and standard deviation). We divided each parameter and statistic into separate files and applied unit conversions to recover the original floating point values. The transfer (original units) files are displayed in GeoVu as point displays (scatter plots) and the converted files as image displays.

Original data file: (Point data on the CD-ROM)

Processed Data file: (Image data on the CD-ROM)

Missing Data Values

The missing data flag value for this data set is 0. The counts have a value of 0 for the first few rows at the top and bottom of each data file.

Potential Data Errors

In processing the TOVS Path C2 data we discovered several pixels that appear to be inconsistent. These are:
October 1987 MSU Channel 2 Standard deviation image has a value of 5988 at point 176,0.
October 1987 MSU Channel 3 Standard deviation image has a value of 2381 at point 176,0.

Tovs Path C2 Table

Name
Filename
Point Data
Histogram Filename
Description
Type
Min
Max
Units
SDLCT






SDLMT






LCBT











SDLST





CNT_100
CNT_150
CNT_225
CNT_350
CNT_500
CNT_650
CNT_800
MEAN_100
MEAN_150
MEAN_225
MEAN_350
MEAN_500
MEAN_650
MEAN_800
MSU1_CT
MSU1_MN
MSU1_SD
MSU2_CT
MSU2_MN
MSU2_SD
MSU3_CT
MSU3_MN
MSU3_SD
MSU4_CT
MSU4_MN
MSU4_SD
STD_100
STD_150
STD_225
STD_350
STD_500
STD_650
STD_800
dlt1_count
dlt2_count
dlt3_count
dlt4_count
dlt5_count
FOV_count
dlt6_count
dlt1_mean (x64*)
dlt2_mean (x64*)
dlt3_mean (x64*)
dlt4_mean (x64*)
dlt5_mean (x64*)
FOV_mean (x64*)
dlt6_mean (x64*)
lcbt1_count
lcbt1_mean (x64*)
lcbt1_std (x256**)
lcbt2_count
lcbt2_mean (x64*)
lcbt2_std (x256**)
lcbt3_count
lcbt3_mean (x64*)
lcbt3_std (x256**)
lcbt4_count
lcbt4_mean (x64*)
lcbt4_std (x256**)
dlt1_sd (x256**)
dlt2_sd (x256**)
dlt3_sd (x256**)
dlt4_sd (x256**)
dlt5_sd (x256**)
FOV_std (x256**)
dlt6_sd (x256**)
Scan Line Deep Layer Temperature(100 mb)
Scan Line Deep Layer Temperature(150 mb)
Scan Line Deep Layer Temperature(225 mb)
Scan Line Deep Layer Temperature(350 mb)
Scan Line Deep Layer Temperature(500 mb)
MSU Adjacent FOV Deep Layer Temp (650 mb)
Scan Line Deep Layer Temperature(800 mb)
Scan Line Deep Layer Temperature(100 mb)
Scan Line Deep Layer Temperature(150 mb)
Scan Line Deep Layer Temperature(225 mb)
Scan Line Deep Layer Temperature(350 mb)
Scan Line Deep Layer Temperature(500 mb)
MSU Adjacent FOV Deep Layer Temp (650 mb)
Scan Line Deep Layer (800 mb)
Limb Corrected Brightness temp (Surface)
Limb Corrected Brightness temp (Surface)
Limb Corrected Brightness temp (Surface)
Limb Corrected Brightness temp (600 mb)
Limb Corrected Brightness temp (600 mb)
Limb Corrected Brightness temp (600 mb)
Limb Corrected Brightness temp (300 mb)
Limb Corrected Brightness temp (300 mb)
Limb Corrected Brightness temp (300 mb)
Limb Corrected Brightness temp (90 mb)
Limb Corrected Brightness temp (90 mb)
Limb Corrected Brightness temp (90 mb)
Scan Line Deep Layer Temperature(100 mb)
Scan Line Deep Layer Temperature(150 mb)
Scan Line Deep Layer Temperature(225 mb)
Scan Line Deep Layer Temperature(350 mb)
Scan Line Deep Layer Temperature(500 mb)
MSU Adjacent FOV Deep Layer Temp (650 mb)
Scan Line Deep Layer Temperature(800 mb)
Count
Count
Count
Count
Count
Count
Count
Mean
Mean
Mean
Mean
Mean
Mean
Mean
Count
Mean
Std Dev
Count
Mean
Std Dev
Count
Mean
Std Dev
Count
Mean
Std Dev
Std Dev
Std Dev
Std Dev
Std Dev
Std Dev
Std Dev
Std Dev
0
0
0
0
0
0
0
179.813
192.906
203.781
203.406
211.000
199.641
170.219
0
158.094
0.0039
0
200.328
0.0039
0
197.422
0.0039
0
182.234
0.0039
0.0156
0.0039
0.01170
0.01950
0.03120
0.0039
0.0078
87
87
87
87
87
130
87
239.813
231.000
240.797
258.781
267.453
278.828
294.844
120
291.922
27.6719
120
265.609
11.2305
120
235.875
11.2539
120
242.734
21.8867
16.4531
13.0625
8.97266
8.37891
8.78125
19.6641
30.0742
Number
Number
Number
Number
Number
Number
Number
K
K
K
K
K
K
K
Number
K
K
Number
K
K
Number
K
K
Number
K
K
K
K
K
K
K
K
K

*multiply data values by 64
**multiply data values by 256

For the data providers documentation on this dataset.

Tovs Path C2 web site.

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SSM/I PRECIPITATION

This CD-ROM contains data produced by the SSM/I group and provided to NGDC by Ron Schudalla (205-922-5792) of Marshall Space Flight Center (MSFC).

Marshall Space Flight Center
Building 4492
Huntsville, Alabama 35812
Telephone: (205) 544-6329
Fax: (205) 544-5147
Email: msfc@eos.nasa.gov

This data collection includes global 1 X 1 grids characterized by a weighted average value, a sum of the squared precipitation rates and the number of pixels per bin. The 3 parameters are:

The Sum of the Squared Precipitation Rates (SSQ) was not processed due to an error in the processing prior to our receiving the data. The sums were calculated as floating point values and then converted to 4 byte integers. Sums which were larger than the maximum value of a 4 byte integer were truncated in this process. The effect of this truncation is that the maximum value for the SSQ variable is 2,147,483,647 which is incorrect. Many months of data include over 300 of these values. There is no way to correct this error without reprocessing the original data. The SSQ images are on the CD-ROM as floats, but are not accessible from the GeoVu menu files. Also, no movie has been made for the SSQ parameter.

The satellite was launched in July, 1987, so the SSM/I Benchmark period is from August 1987 to November 1988. As opposed to the usual starting period of April 1987. The December 1987 monthly file was not generated because the SSM/I instrument was turned off on December 3, 1987 due to overheating. The January 1988 monthly file was also not generated.

Missing Data Values


                  Flags For Precipitation Rates

                 -------------------------------
                 |           | FLAG 1 | FLAG 2 |
                 -------------------------------
                 |PRG, SSQ   | -10   |  -20    |
                 -------------------------------

where:
PRG = Monthly Precipitation Rate
SSQ = Monthly Precipitation Rate Squared
FLAG 1 = No precipitation rate data was accumulated in the bin.
FLAG 2 = For pentads, if more than 40% of the valid pixel precipitation values in a bin were associated with the cold surfaces and/or identified as ambiguous, the bin value is set to the -20. For monthly grids, a 20% threshold is used.

Rescaling of the Pentad (Monthly)Precipitation Rate Grid (PRG)

The original monthly precipitation rate grid values are a weighted average of valid precipitation rate values multiplied by 100 before storing to retain a precision of 0.01 mm/day. For example, 31.5 mm/day is stored as 3150. At NGDC, we descaled the PRG data by dividing each data value by 100 except the two flag value of -10 and -20.

Original data file:

Processed Data file: (Image data on the CD-ROM)

SSM/I Precipitation Table

Name
Filename
Description
Type
Min
Max
Units
COMMENTS
PRGMMMYYPRG Precipitation Rate Grid Weighted average-20 77.93mm/day MMM= month,YY = year
Flag values = -10, -20.
SSQNot processed (See above)       
NUMMMMYYNUM Number of Pixels per Bin Count-20 4442Number Flag values = -10, -20.

For the data providers documentation on this dataset.

SSM/I Data web site.

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SSM/I ATMOSPHERIC MOISTURE

This CD-ROM contains data produced by the SSM/I group and provided to NGDC by Ron Schudalla (205-922-5792) of Marshall Space Flight Center (MSFC).

Marshall Space Flight Center
Building 4492
Huntsville, Alabama 35812
Telephone: (205) 544-6329
Fax: (205) 544-5147
Email: msfc@eos.nasa.gov

This data collection includes global 1X1 grids characterized by a weighted average value, a sum of the squared precipitation rates and the number of pixels per bin. The 6 parameters are:

The Sum of the Squared Cloud/Rain Liquid Water values (LWS) contains the same error as described above for the SSM/I Precipitation data set. There is no way to correct this error without reprocessing the original data. Unlike the SSM/I data, NGDC processed the LWS data with the error because there were only 10 pixels with the maximum value of 2,147,483,647. The LWS data for March 1988 and April 1988 were changed from 2,147,483,647 to 2,147,483,520 to make processing possible. March 1988 data at the following 6 x, y locations were changed; x, y pairs: (32,325), (31,326), (32,326), (31,327), (32,327), and (31,328). April 1988 data at the following 4 x, y location were changed; x, y pairs: (31,325), (32,325), (33,325) and (32,326).

The original March 1988 image is saved as mar88lws.old in the directory \ssmi_at\mar88\org_hdf\. The original April 1988 image is saved as apr88lws.old in the directory \ssmi_at\apr88\org_hdf\. The corrected image files, mar88lws.img and apr88lws.img are used in all of our subsequent processing.

The palette file rainbow.pal was used for the parameters Cloud/Rain Liquid Water (LWG) and Sum of Squared Cloud/Rain Liquid Water values (LWS). These two parameters have a nonlinear distribution of the data values. A majority of the data values are clustered around zero, but also have high maximums. Viewing the data with the standard Pathfinder palette file RGB_256.pal results in a black image. To get a meaningful display of the image, the 16 color palette rainbow.pal was used and the number of display colors was set to 256. By doing this, the colors of rainbow.pal correspond to the first 16 data bins, where 95% of the data values fall. All the other parameters for the SSM/I Atmospheric Moisture data used the RGB_256.pal for the palette file. One can still select the palette file RGB_256.pal in GeoVu by choosing "search" and "create" and then select RGB_256.pal. In the movie files for the parameters LWG and LWS the palette RGB_256.pal was used. This creates very dark movies due to the nonlinear distribution of the data values.

The satellite was launched in July 1987, so the SSM/I Benchmark period extends from August 1987 to November 1988 as opposed to the usual start of April 1987. The December 1987 monthly file was not generated because the SSM/I instrument was turned off on December 3, 1987 due to overheating. The January 1988 monthly file was also not generated.

Missing Data Values

                Flags For Atmospheric moistures

                 -------------------------

                 |            | FLAG 1   |
                 -------------------------
                 | LWG      |      -10   |

                 | WVG      |      -10   |

                 -------------------------

where:
LWG = Monthly Cloud/Rain Liquid Water in mg/cm2
WVG = Monthly Columnar Water Vapor in g/cm2
FLAG 1 = No atmospheric moisture data was accumulated in the bin.

Rescaling of the Cloud/rain liquid water (LWG) and Columnar Water Vapor Grid (WVG)

The original monthly Cloud/rain liquid water grid values were multiplied by 10 before storing to retain a precision of 0.1 mg/cm2. For example, 31.5 mm/day is stored as 315. At NGDC, we descaled the LWG data by dividing each data value by 10 except the flag value of -10. The minumum value is 0, and the maximum unscaled value is 1000.

The origianl monthly Columnar Water Vapor Grid (WVG) values were multiplied by 100 before storing to retain a precision of 0.01 g/cm2. For example, 3.15 g/cm2 is stored as 315.At NGDC, we descaled the WVG data by dividing each data value by 100 except the flag value of -10. The minumum value is 0, and the maximum unscaled value is 10.

Original data file:

Processed Data file: (Image data on the CD-ROM)

SSM/I Atmospheric Moisture Table

Name
Filename
Description
Type
Min
Max
Units
COMMENTS
LWGMMMYYlwg Cloud/Rain Liquid Water Weighted average-10 1000mg/cm2 MMM= month,YY = year
LWSMMMYYlws Sum of Squared Cloud/Rain Liquid Water values sum of the squares-10 2147383250mg2/cm4 2147383250 is the
corrected max value
for the lws parameter
LWNMMMYYlwn Number of Cloud/Rain Liquid Water Pixels per Bin Count-10 1110number  
WVGMMMYYwvg Columnar Water VaporWeighted average -1010 g/cm2 
WVSMMMYYwvs Sum of Squared Columnar Water Vapor Values sum of the squares-10 6273969g2/cm4 Flag values = -10 for all
parameters.
WVNMMMYYwvn Number of Columnar Water Vapor Pixels per Bin Count-10 1110number  

For the data providers documentation on this dataset.

SSM/I Data web site.

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NOAA / NASA WWW Pathfinder Sites:



NOAA-NASA Pathfinder Program
NGDC Pathfinder CD-ROM Home Page
Tovs Path A
Tovs Path C1
TOVS Path C2: Home or Interactive Visualization
AVHRR Land
AVHRR Ocean
SSM/I Data

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The NOAA/NASA Pathfinder CD-ROM was created at NGDC by Patrick J. Hayes under the supervision of Ted Habermann.



Solid Earth Geophysics Division
National Geophysical Data Center
325 Broadway Mail Stop E/GC1
Boulder, CO 80303
(303) 497-6472

If you have any problems, email the GeoVu team at: "geovu@ngdc.noaa.gov" or visit our on-line GeoVu Frequently Asked Questions at: http://www.ngdc.noaa.gov/seg/geovu/faq.html