This data set contains Arctic TOVS-derived Level-3 atmospheric parameters obtained using the physical-statistical retrieval method of Chedin et al. (1985, Improved Iteration Inversion Algorithm, 3I). The method has been improved for use in sea ice-covered areas (Francis 1994) and the data set has been designed to address the particular needs of the Polar research community. The data set represents the so called Path-P as designated by the TOVS Science Working Group. This research is part of the EOS Interdisciplinary Science (IDS) effort POLar Exchange at the Sea surface (POLES)  Funding for this project has been provided by the NOAA/NASA Pathfinder Program.


LATITUDE_GRID Latitude for each gridpoint
LONGITUDE_GRID Longitude for each gridpoint
ELEVATION elevation for each gridpoint
TEMP Temperatures at pressure levels: 
50,70, 100, 300, 400, 500, 600, 700, 850, 900 mb [K]
WVAPOR Preciptable water of layers bounded by pressure levels [mb]: 
300-400, 400-500, 500-700, 700-850, 850-surface [mm]
SKTEMP Surface Skin Temperature [K]
HIRS_CLDY Percentage of cloudy pixels per III retrieval box. [%]
FCLD Total effective cloud fraction [%]
CLPRESS Cloud-top pressure [mb] 
CLTEMP Cloud-top temperature [K]
EMISS Emissivity  (MSU Channel 1 50 GHz)
ISICE Surface Type Flag  0=open water, 1=sea ice, 3=land, 10= Mixed surface, last orbit open water
11=Mixed surface, last orbit ice, 13=Mixed surface, last orbit land
SOLZEN Average solar zenith angle arccos(cos)  [Deg]
PRESS NCEP sea level pressure [ mb ]
PBLSTRAT Boundary layer bulk stratification [K]
Cg Geostrophic drag coefficient over sea ice
ALPHA Turning angle between geostrophic wind and the surface wind over sea ice. 

Temporal Coverage

Currently July 1979-Dec 1996 are available from NSIDC. Data for 1997-1998 will become available in the near future. 

Spatial Coverage

North Polar Region: North of 60 Deg. Areas over 1000 m are currently not included so that the Greenland ice sheet is not included. South Polar Region:  We will begin processing TOVS Path-P data for the Southern Ocean south of 50 Deg early next year. We expect to have  data for the full period processed  by mid 2000.

Data Format

The data are daily grids formatted in the Hierarchical Data Format. Detailed documentation on how to read the data is provided with the data set.

Data Access



The data set has been thoroughly validated using  data from the Soviet North Pole (NP) drifting stations and from SHEBA. For  specific validation results follow the links below:


TOVS Path-P data are currently being used by the following sample of  research projects. If you are using Path-P data and would like to provide a link for this section send us  e-mail

Quick Looks

Release Notes

Information regarding known issues: 

Related Projects


NSIDC supports this data set. For more information contact: NSIDC user services

For comments regarding this WEB site contact: www@psc.apl.washington.edu

The TOVS Path-P Team


Funding for this project was provided by the NOAA/NASA Pathfinder Program and  the NASA EOS-IDS Polar Exchange at the Sea Surface. Thanks are due to the folks at LMD: Noelle Scott, Raymond Armante, Claudia Stubenrauch, Chantal Claud, Alan Chedin. We also thank the NOAA  Satellite Active Archive (SAA) for providing data. Special thanks go to Peter Topoly and Alex Kidd and to the people working the tape machines.  We also thank  Rachel Hauser, Julienne Stroeve, and Mary-Jo Brodzik at NSIDC are thanked for providing tools, documentation, and additional QC.