Data Products
A Cross-Calibrated Multi-Platform Ocean Surface Wind Velocity Product for Meteorological and Oceanographic Applications
Two product streams are produced by this project : First-look (FLK) and Late-look (LLK). Each data stream contains three standard products designated as level 3.0, 3.5 and 2.5. The primary data set, denoted Level 3.0, contains 6-hourly gridded VAM analyses. These analyses are time averaged over 5-day and monthly periods to derive the Level 3.5 products. Only those grid points with one or more analyzed observations are used in the average. Finally, directions from the VAM analyses are assigned to the wind speed observations for each microwave sensor to derive the Level 2.5 products.
Level 3.0 and 3.5 data sets are stored in the Network Common Data Format (NeTCDF) in compressed form to minimize storage requirements. NeTCDF is an industry standard for managing scientific data and is freely available. Applications using the Hierarchical Data Format (HDF) can also be used to read these files.
Level 2.5 products are stored in binary "bytemap" files to parallel the original satellite data files from RSS. These are easy to use files that employ maximum compression techniques to reduce storage requirements for large volumes of satellite data. Daily observations are mapped to a 25km grid and packed into 1-byte integers. AM and PM passes are stored separately to minimize overlap. The grid auto-navigates the data thus reducing the need to store latitudes and longitudes. In addition, bytemap files are highly compressable using GNU zip (gzip). gzip is an industry standard, fully supported compression utility available to all users.
Each data set is archived using the following naming convention:
| NAME_YYYYMMDD_vVVlLLPPP.TTT.gz | |
| where | |
| NAME | unique identifier describing the data |
| YYYYMMDD | date/time expressed as year, month, day |
| VV | product version number (in tenths) |
| LL | product level designation (in tenths) |
| PPP | product stream (flk or llk) |
| TTT | file type designating the data format |
For example, "analysis_20040101_v10l30flk.nc.gz" designates a level 3.0 (l30) data set containing VAM analyses for January 1, 2004 from version 1.0 (v10) of the first-look (flk) product stream in NetCDF (.nc) format. The ".gz" node indicates that the file must first be de-compressed using the GNU zip (gzip) compression utility.
Below is a detailed description of available data sets and their contents:
| NAME | analysis | VAM analyses centered at 0,6,12 and 18z. See grid-1 |
| pentad | 5-day means starting on the first day of each year. In leap years, the pentad starting on 2/26 will include 6-days such that the starting date for each pentad remains the same across all years. See grid-1 | |
| monthly | Monthly means starting on the first day of each month. See grid-1 | |
| f08,f10,f11,f13,f14,f15 | DMSP SSM/I satellite wind speeds with assigned directions (stored 2x daily as AM and PM orbits). See grid-2 | |
| amsre | AMSRE satellite wind speeds with assigned directions (stored 2x daily as AM and PM orbits). See grid-2 | |
| tmi | TRMM TMI satellite wind speeds with assigned directions (stored 2x daily as AM and PM orbits). See grid-3 | |
| YYYY | 1987-2007 | 4-digit year |
| MM | 01-12 | 2-digit month |
| DD | 01-31 | 2-digit day |
| VV | 11 | Version 1.1 |
| PPP | flk | First-look data stream |
| llk | Late-look data stream | |
| LL | 30 | Level 3.0 instantaneous analyses containing: time,uwnd,vwnd,nobs |
| 35 | Level 3.5 time averaged analyses containing: time,uwnd,vwnd,upstr,vpstr,wspd,nobs | |
| 25 | Level 2.5 satellite wind speed observations with assigned directions: time,uwnd,vwnd | |
| TTT | nc | NetCDF (network Common Data Form) |
| bmap | Bytemap: flat binary data format containing 1-byte lat/lon grids |
Data Products
- NASA Official: Michael S. Seablom
- Project Manager: Joseph V. Ardizzone
- Website Manager: Lara Clemence