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ASAR Data Formats Products
Geolocation Grid ADSRs
Doppler Centroid parameters
Chirp parameters
Antenna Elevation pattern
ASAR external characterization data
ASAR external calibration data
Level 0 SPH
Level 0 MDSR
SPH for auxiliary data with N=1 DSDs
Wave Mode Geolocation ADS
ASAR Wave Mode Products Base SPH
Slant Range to Ground Range conversion parameters
Measurement Data Set containing spectra. 1 MDSR per spectra.
Ocean Wave Spectra
Map Projection parameters
ASAR Image Products SPH
Measurement Data Set 1
Auxilliary Products
ASA_XCH_AX: ASAR External characterization data
ASA_XCA_AX: ASAR External calibration data
ASA_INS_AX: ASAR Instrument characterization
ASA_CON_AX: ASAR Processor Configuration
Browse Products
ASA_WS__BP: ASAR Wide Swath Browse Image
ASA_IM__BP: ASAR Image Mode Browse Image
ASA_GM__BP: ASAR Global Monitoring Mode Browse Image
ASA_AP__BP: ASAR Alternating Polarization Browse Image
Level 0 Products
ASA_WV__0P: ASAR Wave Mode Level 0
ASA_WS__0P: ASAR Wide Swath Mode Level 0
ASA_MS__0P: ASAR Level 0 Module Stepping Mode
ASA_IM__0P: ASAR Image Mode Level 0
ASA_GM__0P: ASAR Global Monitoring Mode Level 0
ASA_EC__0P: ASAR Level 0 External Characterization
ASA_APV_0P: ASAR Alternating Polarization Level 0 (Cross polar V)
ASA_APH_0P: ASAR Alternating Polarization Level 0 (Cross polar H)
ASA_APC_0P: ASAR Alternating Polarization Level 0 (Copolar)
Level 1 Products
ASA_IMS_1P: ASAR Image Mode Single Look Complex
ASA_IMP_1P: ASAR Image Mode Precision Image
ASA_IMM_1P: ASAR Image Mode Medium Resolution Image
ASA_IMG_1P: ASAR Image Mode Ellipsoid Geocoded Image
ASA_GM1_1P: ASAR Global Monitoring Mode Image
ASA_APS_1P: ASAR Alternating Polarization Mode Single Look Complex
ASA_APP_1P: ASAR Alternating Polarization Mode Precision Image
ASA_APM_1P: ASAR Alternating Polarization Medium Resolution Image product
ASA_WSS_1P: Wide Swath Mode SLC Image
ASA_WVS_1P: ASAR Wave Mode Imagette Cross Spectra
ASA_WSM_1P: ASAR Wide Swath Medium Resolution Image
ASA_APG_1P: ASAR Alternating Polarization Ellipsoid Geocoded Image
Level 2 Products
ASA_WVW_2P: ASAR Wave Mode Wave Spectra
ASAR Glossary Terms
Sea Ice Glossary
Land Glossary
Oceans Glossary
Geometry Glossary
ASAR Instrument Glossary
Acronyms and Abbreviations
ASAR Frequently Asked Questions
The ASAR Instrument
Instrument Characteristics and Performance
Inflight Performance Verification
Preflight Characteristics and Expected Performance
Instrument Description
Internal Data Flow
ASAR Instrument Functionality
Payload Description and Position on the Platform
ASAR Products and Algorithms
Auxiliary Products
Common Auxiliary Data Sets
Auxiliary Data Sets for Level 1B Processing
Summary of Auxiliary Data Sets
Instrument-specific Topics
Level 2 Product and Algorithms
Level 2 Product
ASAR Level 2 Algorithms
Level 1B Products
ASAR Level 0 Products
Level 0 Instrument Source Packet Description
Product Evolution History
Definitions and Conventions
Organisation of Products
ASAR Data Handling Cookbook
Hints and Algorithms for Higher Level Processing
Hints and Algorithms for Data Use
ASAR Characterisation and Calibration
The Derivation of Backscattering Coefficients and RCSs in ASAR Products
External Characterisation
Internal Calibration
Pre-flight Characterisation Measurements
ASAR Latency Throughput and Data Volume
Data Volume
Products and Algorithms Introduction
Child Products
The ASAR User Guide
Image Gallery
Further Reading
How to Use ASAR Data
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How to Choose ASAR Data
Special Features of ASAR
Geophysical Coverage
Principles of Measurement
Scientific Background
Geophysical Measurements
ASAR Product Handbook
ASAR instrument characterization data
Wave Mode processing parameters
ASAR processor configuration data
Main Processing parameters
ASA_WVI_1P: ASAR Wave Mode SLC Imagette and Imagette Cross Spectra
Product Terms
RADAR and SAR Glossary
Level 1B Products
Summary of Applications vs Products
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6.6.14 Ocean Wave Spectra

This MDS contains the ocean wave spectrum of the imagette . There is one MDSR per wave cell. The format of the wave-spectrum MDS closely matches that of the cross spectrum MDS where some fields in the cross-spectrum MDS are substituted
by new values pertaining to the ocean wave spectrum product. Each ocean wave spectrum MDSR is described below:

Table 6.51 Ocean Wave Spectra

Ocean Wave Spectra

# Description Units Count Type Size
Data Record
0 zero_doppler_time
First Zero Doppler Azimuth time of the wave cell. Time of first range line in the SLC Imagette MDS described by this data set
MJD 1 mjd 12 byte(s)
1 quality_flag
Quality Indicator.

(-1 for blank MDSR, 0 otherwise)

flag 1 BooleanFlag 1 byte(s)
2 range_spectral_res
Range spectral bin size of the cartesian cross spectrum
- 1 fl 4 byte(s)
3 az_spectral_res
Azimuth spectral bin size of the cartesian cross spectrum
- 1 fl 4 byte(s)
4 spare_1
- 1 SpareField 4 byte(s)
5 spec_tot_energy
Spectrum Total Energy
- 1 fl 4 byte(s)
6 spec_max_energy
Spectrum Max Energy
- 1 fl 4 byte(s)
7 spec_max_dir
Direction of Spectrum Max (deg)

Direction is given clockwise from north in the direction the wave propogates

deg 1 fl 4 byte(s)
8 spec_max_wl
Wavelength of Spectrum Max (m)

On higher resolution grid.

m 1 fl 4 byte(s)
9 az_image_shift_var
Variance of the azimuth image shift caused by the orbital velocity
m^2 1 fl 4 byte(s)
10 az_cutoff
Azimuthal Clutter Cut-off wavelength (m)
m 1 fl 4 byte(s)
11 nonlinear_spectral_width
Spectral width of the non-linear part of the cross spectra
m 1 fl 4 byte(s)
12 image_intensity
Image Intensity
- 1 fl 4 byte(s)
13 image_variance
Normalised image variance
- 1 fl 4 byte(s)
14 spare_2
- 1 SpareField 56 byte(s)
15 min_spectrum
Min value of ocean wave spectrum
m^4 1 fl 4 byte(s)
16 max_spectrum
Max value of ocean wave spectrum
m^4 1 fl 4 byte(s)
17 spare_3
- 1 SpareField 8 byte(s)
18 wind_speed
Wind speed used in the wave spectra retrieval (m/s)
m/s 1 fl 4 byte(s)
19 wind_direction
Wind direction used in the wave spectra retrieval.

(clockwise from north from where the wind from if confidence is 0, relative to range otherwise) (deg)

deg 1 fl 4 byte(s)
20 norm_inv_wave_age
Normalised inverse wave age
- 1 fl 4 byte(s)
21 SAR_wave_height
SAR swell wave height
m 1 fl 4 byte(s)
22 SAR_az_shift_var
Variance of the azimuth shift computed from the SAR swell wave spectra
m^2 1 fl 4 byte(s)
23 backscatter
Radar backscatter cross section
dB 1 fl 4 byte(s)
24 confidence_swell
Confidence measure of the swell inversion. 0 = inversion successful (a unique spectrum in terms of propagation direction); 1 = inversion not successful (symmetric spectrum)
- 1 us 2 byte(s)
25 signal_to_noise
Average signal-to-noise ratio
- 1 fl 4 byte(s)
26 radar_vel_corr
Radar velocity off-set correction
m/s 1 fl 4 byte(s)
27 cmod_cal_const
Geophysical Calibration constant - CMOD
- 1 fl 4 byte(s)
28 confidence_wind
Confidence measure of the wind retrieval. 0 = external wind direction used during inversion; 1 = external wind direction not used during inversion.
- 1 us 2 byte(s)
29 spare_4
- 1 SpareField 24 byte(s)
30 ocean_spectra
Ocean Wave Swell spectra polar grid.

Number of bins in wavelength and direction defined in SPH (nominally 24 by 36). Arranged as 24 wavelength cells from longest to shortest wavelength, for zero degrees, then 10 degrees, up to 350 degrees (i.e clockwise direction).

- uc 1 byte(s)
Record Length : 196

DS_NAME : Ocean Wave Spectra

Format Version 114.0  

The ocean wave spectrum is given in the MDS as real samples distributed on a polar grid. The size of the ocean wave spectrum grid is given in the SPH . Typically this will be 24 by 36 bins in wavelength and direction respectively.

The ocean wave spectrum values shall be stored in an unsigned integer format, each part linearly scaled to the maximum and minimum values of the representation (e.g., 0 to 255). The original maximum and minimum values are reported.

The detected spectrum statistics are derived from a high-resolution polar spectrum, prior to encoding for output to the product, or at other intermediate stages of the processing.

If the processor is unable to produce the ocean wave spectra for a given wave cell, the MDSR is time stamped with the time that the ocean wave spectra would have corresponded to, the Quality Flag is set to -1, and the MDSR data fields are all set
to zero.