Special Sensor Microwave/Imager (SSM/I) Monthly Data Products from NCDC
Entry ID: RALPH_SSMI

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Summary
Abstract: The National Climatic Data Center (NCDC) home page is
"http://www.ncdc.noaa.gov/".

The Special Sensor Microwave/Imager (SSM/I) Dataset home page on the
WWW is "http://www.ncdc.noaa.gov/ol/satellite/ssmi/ssmiproducts.html".

For annonymous ftp, ftp.ncdc.noaa.gov, cd /pub/data/ssmi/1deg (1
degree), cd /pub/data/ssmi/25deg (2.5 degree).

The Defense Satellite Meteorological Program (DMSP) Special Sensor
Microwave/Imager(SSM/I) became operational in July 1987 on the F-8
satellite. Subsequent SSM/I's have been flown on the F-10 (November
1990), F-11 (December 1991), F-12 (August 1994), and most recently,
F-13 (March 1995) satellites. The SSM/I is a seven channel passive
microwave radiometer operating at four frequencies (19,35, 22,235,
37.0, and 85.5 GHz) and dual-polarization (except at 22.235 GHz which
is V-polarization only).

Researchers in the Microwave Sensing Group (MSG) of the Land Sciences
Branch (LSB) are actively involved in SSM/I algorithm development and
validation, and the application of such algorithms for weather
forecasting and analysis, and CLIMATE EVALUATION. Additionally, the
SSM/I is being used to develop algorithms for use on the NOAA-K,L,M
Advanced Microwave Sounding Unit (AMSU), which will contain some
frequencies similar to those on the SSM/I (e.g., 23.8, 31.4, and 89.0
GHz), but will not have polarization information.

These SSM/I products are useful for evaluating the mean climate state,
it's interannual and seasonal variations, and the detection of
anomalies associated with ENSO and regional climatic variations.

The MSG has assembled a time series of the entire SSM/I archive, which
includes data from July 1987 to the present. Monthly average products
are produced for precipitation, cloud liquid water, total precipitable
water, snow cover, sea-ice cover, and ocean surface wind speed.

A) 1-Degree Products

The files have the following naming convention:

ppp.yy

where ppp=product type and yy=year (e.g., 87 for 1987).

Each field is stored as a 1440 byte record of 4-byte real variables
which have been generated on a personal computer. Each record contains
360 values corresponding to each degree of longitude, with the first
element corresponding to longitude 0.5 degrees East, the second 1.5 E,
etc. and the last 0.5 degrees West. The first record contains data
centered at latitude 89.5 degrees South, the second record contains
data centered at 88.5 S, etc. and the last 89.5 N. Missing data are
indicated by a value of -999.0.

The first 180 records in the data set correspond to January of that
year, the next 180 is February, etc. The total length of each annual
data set is 180*1440*12=3,110,400 bytes.

The following describes the content of the 1 degree gridded files:

1. cfr.yy - Monthly mean cloud fraction (0 - 1.0)
2. ice.yy - Monthly mean sea-ice cover (0 - 100 percent)
3. lwp.yy - Monthly mean liquid water path (1000 * mm)
4. pfr.yy - Monthly mean rain fraction (0 - 1.0)
5. pre.yy - Monthly rainfall (mm)
6. snw.yy - Monthly mean snow cover fraction (0 - 1.0 percent)
7. ssa.yy - Monthly mean sampling fraction (0 - 1.0)
8. win.yy - Monthly mean surface wind speed (m/sec)
9. wvp.yy - Monthly mean total precipitable water (mm)


B) 2.5-Degree Products

The files have the following naming convention:

ppp.mon

where ppp=product type.

Each field is stored as a 576 byte record of 4-byte real variables
which have been generated on a personal computer. Each record contains
144 values corresponding to each 2.5 degree of longitude, with the
first element corresponding to longitude 1.25 degrees East, the second
2.5 E, etc. and the last 1.25 degrees West. The first record contains
data centered at latitude 88.75 degrees South, the second record
contains data centered at 86.25 S, etc. and the last 88.75 N. Missing
data are indicated by a value of -999.0.

The first 72 records in the data set correspond to January 1987, 72 is
February 1987, etc. and the last 72 records correspond to December
1995. The total length of each data set is 72*576*9=4,478,976 bytes.

The following describes the content of the 2.5 degree gridded files:

1. cfr.yy - Monthly mean cloud fraction (0 - 1.0)
2. lwp.yy - Monthly mean liquid water path (1000*mm)
3. pf1.yy - Monthly mean rain fraction (0 - 1.0) using 85 GHz
scattering algorithm over land, scattering/emission over ocean (ALG#1)
4. pr1.yy - Monthly rainfall (mm) using ALG#1
5. pf2.yy - Monthly mean rain fraction (0 - 1.0) using 37 GHz
scattering algorithm over land, emission over ocean (ALG#2)
6. pr2.yy - Monthly rainfall (mm) using ALG#2
7. ssa.yy - Monthly mean sampling fraction (0 - 1.0)


NOTES

a. If the data is used in other computer environments, the data may
have to be byte-swapped (e.g., byte 1 becomes byte 4, byte 2 becomes
byte 3, etc.).

b. The products are generated from a single satellite and contain the
following:

F8 satellite: July 1987 - June 1991
F11 satellite: January 1992 - May 1995
F13 satellite: June 1995 - present

There are some missing data periods as noted above.

The overpass times of each of these satellites is approximately
6am/6pm local time.

Related URL
Link: GET DATA
Description: Access the Special Sensor Microwave/Imager (SSM/I) Monthly Data Products from
NCDC.




Special Sensor Microwave/Imager (SSM/I) Monthly Data Products from NCDC


Geographic Coverage
 N: 90.0 S: -90.0  E: 180.0  W: -180.0

Data Set Citation
Dataset Originator/Creator: Ralph Ferraro, E/RA2
Dataset Title: Special Sensor Microwave/Imager (SSM/I) Monthly Data Products from NCDC
Dataset Publisher: NOAA/NESDIS/Office of Research and Applications
Online Resource: http://www.ncdc.noaa.gov/oa/satellite/ssmi/ssmiproducts.html


Temporal Coverage
Start Date: 1987-07-01


Location Keywords
GEOGRAPHIC REGION > GLOBAL
VERTICAL LOCATION > BOUNDARY LAYER
VERTICAL LOCATION > SEA SURFACE
VERTICAL LOCATION > TROPOSPHERE


Data Resolution
Temporal Resolution: Monthly


Science Keywords
ATMOSPHERE >ATMOSPHERIC WATER VAPOR >PRECIPITABLE WATER    [Definition]
ATMOSPHERE >ATMOSPHERIC WINDS >SURFACE WINDS    [Definition]
ATMOSPHERE >CLOUDS >CLOUD PROPERTIES >CLOUD FREQUENCY    [Definition]
ATMOSPHERE >CLOUDS >CLOUD MICROPHYSICS >CLOUD LIQUID WATER/ICE    [Definition]
ATMOSPHERE >CLOUDS >CLOUD MICROPHYSICS >CLOUD PRECIPITABLE WATER    [Definition]
ATMOSPHERE >PRECIPITATION >LIQUID WATER EQUIVALENT    [Definition]
ATMOSPHERE >PRECIPITATION >PRECIPITATION AMOUNT    [Definition]
ATMOSPHERE >PRECIPITATION >PRECIPITATION RATE    [Definition]
ATMOSPHERE >PRECIPITATION >RAIN    [Definition]
CRYOSPHERE >SEA ICE >SEA ICE CONCENTRATION >ICE COMPACTNESS    [Definition]
CRYOSPHERE >SNOW/ICE >SNOW COVER    [Definition]
TERRESTRIAL HYDROSPHERE >SNOW/ICE >SNOW COVER    [Definition]
OCEANS >OCEAN WINDS >SURFACE WINDS    [Definition]
OCEANS >SEA ICE >SEA ICE CONCENTRATION    [Definition]


ISO Topic Category
CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
GEOSCIENTIFIC INFORMATION
INLAND WATERS
OCEANS


Platform
DMSP 5D-2/F10 >Defense Meteorological Satellite Program-F10    [Information]
DMSP 5D-2/F11 >Defense Meteorological Satellite Program-F11    [Information]
DMSP 5D-2/F12 >Defense Meteorological Satellite Program-F12    [Information]
DMSP 5D-2/F13 >Defense Meteorological Satellite Program-F13    [Information]
DMSP 5D-2/F8 >Defense Meteorological Satellite Program-F8    [Information]


Instrument
SSMI >Special Sensor Microwave/Imager    [Information]


Project
ESIP >Earth Science Information Partners Program    [Information]


Quality
Problem Areas

a. The 2.5 degree pr2 and pf2 products have artifacts along coastlines and the
sea-ice boundary. These are due to the larger footprint sizes of the lower
frequency channels (e.g., 19 GHz) used in the retrievals.

b. The 1 degree rainfall product does not make a distinction between "zero"
rain and "indeterminate" rain (due to snow and ice cover), which is indicated
as zero rain. It is done within the 2.5 degree products.


Keywords
CLIMATE EVALUATION
CLOUD LIQUID WATER
GRID DATA
MONTHLY DATA
OCEAN SURFACE WIND SPEED
SEA-ICE COVER
SNOW COVER
TOTAL PRECIPITABLE WATER
WEATHER FORECASTING
TEMS
GTOS
G3OS/


Originating Center
NOAA/NESDIS/NCDC


Data Center
National Climatic Data Center, NESDIS, NOAA, U.S. Department of Commerce    [Information]
Data Center URL: http://www.ncdc.noaa.gov/

Data Center Personnel
Name: NCDC CUSTOMER SERVICE
Phone: 828-271-4800
Fax: 828-271-4876
Email: ncdc.orders at noaa.gov
Contact Address:
151 Patton Avenue, Room 120
City: Asheville
Province or State: NC
Postal Code: 28801-5001
Country: USA



Distribution
Distribution_Media: Online


Personnel
RALPH FERRARO
Role: INVESTIGATOR
Email: Ralph.Ferraro at noaa.gov
Contact Address:
ESSIC/CICS
2207 Computer and Space Sciences Building
University of Maryland
City: College Park
Province or State: MD
Country: USA


SCOTT A. RITZ
Role: DIF AUTHOR
Phone: 301-614-5126
Fax: 301-614-5268
Email: Scott.A.Ritz at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City: Greenbelt
Province or State: Maryland
Postal Code: 20771
Country: USA



Creation and Review Dates
Last DIF Revision Date: 2011-07-21

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