TOVS Pathfinder Path A Atmospheric and Surface ParametersEntry ID: GSFC_DAAC_TOVS_PATH_PATHA
Abstract: This dataset contains the TIROS Operational Vertical Sounder (TOVS)
level 3 geophysical parameters derived using the physical retrieval
method of Susskind et al. (1984) and processed by the Satellite Data
Utilization Office of the Goddard Laboratory for Atmospheres at
NASA/GSFC. This method, which is hydrodynamic model- and a priori
... data-dependent, is designated as the so-called Path A scheme by the
TOVS Pathfinder Science Working Group. The 20 channel High resolution
Infrared Radiation Sounder 2 (HIRS2) and the 4 channel Microwave
Sounding Unit (MSU) aboard the NOAA-xx series of Polar Orbiting
Satellites are used to produce global fields of the 3-dimensional
temperature-moisture structure of the atmosphere. In addition to
profiles of temperature and moisture, the HIRS2/MSU data are used to
derive important quantities such as land and sea surface temperature,
outgoing longwave radiation, cloud fraction, cloudtop height, total
ozone overburden and precipitation estimates.
The Path A system steps through an interactive
forecast-retrieval-analysis cycle. In each 6 hour synoptic period, a
2nd order General Circulation Model (Takacs et al., 1994) is used to
generate the 6 hour forecast fields of temperature and humidity. These
global fields are used as the first guess for all soundings occuring
within a 6 hour time window centered upon the forecast time. These
retrievals are then assimilated with all available insitu measurements
(such as radiosonde and ship reports) in the 6 hour interval using an
Optimal Interpolation (OI) analysis scheme developed by the Data
Assimilation Office of the Goddard Laboratory for Atmospheres. This
analysis is then used to specify the initial conditions for the next 6
hour forecast, thus completing the cycle.
The retrieval algorithm itself is a physical method based on the
iterative relaxation technique originally proposed by Chahine
(1968). The basic approach consists of modifying the temperature
profile from the previous iteration by an amount proportional to the
difference between the observed brightness temperatures and the
brightness temperatures computed from the trial parameters using the
full radiative transfer equation applied at the observed satellite
zenith angle. For the case of the temperature profile, the updated
layer mean temperatures are given as a linear combination of
multichannel brightness temperature differences with the coefficients
given by the channel weighting functions. Constraints are imposed upon
the solution in order to ensure stability and convergence of the
iterative process. For more details see Susskind et al (1984).
There are 6 level 3 data product files, each of which is in the HDF
format and each representative of a different averaging time
period. All files contain the same number of geophysical parameter
arrays stored as HDF Scientific Data Sets (SDSs). The time periods
include daily, 5 day (pentad) and monthly, with the AM and PM portions
of the orbits treated separately. All data are mapped to a 1 degree
longitude by 1 degree latitude global grid.
Data Set Citation
Dataset Title: TOVS Pathfinder Path A Atmospheric and Surface ParametersOnline Resource: http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?t...
Start Date: 1987-04-01Stop Date: 1988-11-30
ATMOSPHERE > ATMOSPHERIC PRESSURE > ATMOSPHERIC PRESSURE MEASUREMENTS
ATMOSPHERE > ATMOSPHERIC TEMPERATURE > AIR TEMPERATURE
ATMOSPHERE > ATMOSPHERIC WATER VAPOR > HUMIDITY
ATMOSPHERE > ATMOSPHERIC WATER VAPOR > WATER VAPOR > HUMIDITY
ATMOSPHERE > CLOUDS > CLOUD PROPERTIES > CLOUD FREQUENCY
ATMOSPHERE > CLOUDS > CLOUD PROPERTIES > CLOUD HEIGHT
ATMOSPHERE > PRECIPITATION > PRECIPITATION AMOUNT
ATMOSPHERE > ATMOSPHERIC RADIATION > OUTGOING LONGWAVE RADIATION
LAND SURFACE > LAND TEMPERATURE > LAND SURFACE TEMPERATURE
OCEANS > OCEAN PRESSURE > SEA LEVEL PRESSURE
OCEANS > OCEAN TEMPERATURE > SEA SURFACE TEMPERATURE
OCEANS > SEA SURFACE TOPOGRAPHY > SEA SURFACE HEIGHT
SPECTRAL/ENGINEERING > INFRARED WAVELENGTHS > INFRARED IMAGERY
SPECTRAL/ENGINEERING > MICROWAVE > BRIGHTNESS TEMPERATURE
SPECTRAL/ENGINEERING > MICROWAVE > MICROWAVE IMAGERY
ATMOSPHERE > ATMOSPHERIC CHEMISTRY > OXYGEN COMPOUNDS > OZONE
ISO Topic Category
Role: TECHNICAL CONTACT
Email: joel.susskind-1 at nasa.gov
Goddard Space Flight Center Mailstop 613.0
Province or State: MD
Postal Code: 20771
Chahine, M. T., 1968, "Determination of the Temperature Profile in an
Atmosphere from its Outgoing Radiances", J. Opt. Soc. Am., 58, 1634-1637.
Reuter, D., J. Susskind, and A. Pursch, 1988, "First Guess Dependence of
a Physically Based Set of Temperature Humidity Retrievals from HIRS2/MSU
Data", J. Atm. Ocean. Tech., 5, 70-83.
Susskind, J., J. Rosenfield, D. Reuter, and M. T. Chahine, 1984, "Remote
Sensing of Weather and Climate Parameters from HIRS2/MSU on TIROS-N",
J. Geophys. Res., 89D, 4677-4697.
Susskind J. and D. Reuter, 1985, "Retrieval of Sea-Surface Temperatures
from HIRS2/MSU", J. Geophys. Res., 90C, 11602-11608.
Susskind, J., D. Reuter, and M. T. Chahine, 1987, "Cloud Fields Derived
from Analysis of HIRS2/MSU Sounding Data", J. Geophys. Res., 92D, 4035-4050.
Takacs, L., A. Molod, and T. Wang, 1994, "Documentation of the Goddard Earth
Observing System (GEOS) General Circulation Model Version 1", NASA Technical
Memorandum 104606, April 1994.
Wu, M. L. C. and J. Susskind, 1990, "Outgoing Longwave Radiation Computed
from HIRS2/MSU Soundings", J. Geophys. Res. 95D, 7579-7602.
Creation and Review Dates
Last DIF Revision Date: 2009-09-14