Skip to main content

Description

This dataset contains the RapidScat Level 2B 12.5km Version 1.2 science-quality ocean surface wind vectors, which are intended as a replacement and continuation of the Version 1.1 data forward from orbital revolution number 5127, corresponding to 19 August 2015; the overlapping time period starting on 19 August 2015 corresponds to the first time period of the recorded low signal-to-noise ratio (SNR). The Level 2B wind vectors are binned on a 12.5 km Wind Vector Cell (WVC) grid and processed using the Level 2A Sigma-0 dataset. RapidScat is a Ku-band dual beam circular rotating scatterometer retaining much of the same hardware and functionality of QuikSCAT, with exception of the antenna sub-system and digital interface to the International Space Station (ISS) Columbus module, which is where RapidScat is mounted. The NASA mission is officially referred to as ISS-RapidScat. Unlike QuikSCAT, ISS-RapidScat is not in sun-synchronous orbit, and flies at roughly half the altitude with a low inclination angle that restricts data coverage to the tropics and mid-latitude regions; the extent of latitudinal coverage stretches from approximately 61 degrees North to 61 degrees South. Furthermore, there is no consistent local time of day retrieval. This dataset is provided in a netCDF-3 file format that follows the netCDF-4 classic model (i.e., generated by the netCDF-4 API) and made available via FTP and OPeNDAP. For data access, please click on the "Data Access" tab above. This Version 1.2 dataset differs from the previous Version 1.1 dataset as follows: 1) L1B sigma-0 has been re-calibrated during the periods of low signal-to-noise ratio (SNR) and 2) during low SNR periods the L1B sigma-0 calibration is determined using re-pointed L1B QuikSCAT data. It is advised for users to avoid using the "wind_obj" variable in this dataset since it is minimally applicable and meant primarily for quality assurance; for users who wish to access the objective function values for each ambiguity, it is suggested to use only the "ambiguity_obj" variable. The "wind_obj" variable contains DIRTH probabilities (which are derived form the "ambiguity_obj" objective function values) in the range of 0 to 1 indicating the conditional probability that the true direction is within + or - 2.5 degrees of the retrieved wind direction given the observed backscatter measurements in the cell. If you have any questions or concerns, please visit our Forum at https://podaac.jpl.nasa.gov/forum/.

Product Summary

Platforms
ISS
Instruments
RapidScat
Spatial Extent

N: 61 S: -61 E: 180 W: -180

Spatial Resolution
12.5 Kilometers x 12.5 Kilometers
Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2015-08-19 to 2016-08-19
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2526576305-POCLOUD
Data State
COMPLETE
Number of Files/Granules
4912
Processing Level
2
Published
Updated
Science Keywords
Surface Winds

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

SeaPAC. (2016). RapidScat Level 2B Ocean Wind Vectors in 12.5km Slice Composites Version 1.2 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/RSX12-L2B12 Date Accessed: 2025-12-14

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
ambiguity_direction wind direction ambiguity degrees float -9999 0 to 360 1
ambiguity_obj wind objective function values 1 float -9999 -199 0 1
ambiguity_speed wind speed ambiguity m s-1 float -9999 0 to 100 1
atmospheric_speed_bias atmospheric speed bias m s-1 float -9999 -100 to 100 1
cross_track_wind_speed_bias relative wind speed bias with respect to sweet spot m s-1 float -9999 -100 to 100 1
eflags extended wind vector cell quality flags bit short 32767 0 to 15 1
flags wind vector cell quality flags bit short 32767 0 to 32643 1
lat latitude degrees_north float N/A -90 to 90 1
lon longitude degrees_east float N/A 0 to 360 1
nudge_wind_direction model wind direction degrees float -9999 0 to 360 1
nudge_wind_speed model wind speed m s-1 float -9999 0 to 100 1
number_in_aft number of inner aft looks in wind vector cell 1 byte 0 1 to 127 1
number_in_fore number of inner forward looks in wind vector cell 1 byte 0 1 to 127 1
number_out_aft number of outer aft looks in wind vector cell 1 byte 0 1 to 127 1
number_out_fore number of outer forward looks in wind vector cell 1 byte 0 1 to 127 1
num_ambiguities number of ambiguous wind directions found in point-wise wind retrieval prior to spatial filtering 1 byte 0 1 to 4 1
rain_impact impact of rain upon wind vector retrieval 1 float -9999 0 to 100 1
retrieved_wind_direction equivalent neutral wind direction at 10 m degrees float -9999 0 to 360 1
retrieved_wind_speed equivalent neutral wind speed at 10 m m s-1 float -9999 0 to 100 1
retrieved_wind_speed_uncorrected wind speed without rain correction m s-1 float -9999 0 to 100 1
time date and time seconds since 1999-1-1 0:0:0 double N/A N/A 1
wind_obj retrieved wind objective function value 1 float -9999 -199 0 1
You're viewing 22 of 22