CYGNSS Level 1 Climate Data Record Version 1.2

Processing Level1
Start/Stop Date2018-Aug-01 to Present
Short NameCYGNSS_L1_CDR_V1.2
DescriptionThis Level 1 (L1) dataset contains the Version 1.2 Climate Data Record (CDR) of the geo-located Delay Doppler Maps (DDMs) calibrated into Power Received (Watts) and Bistatic Radar Cross Section (BRCS) expressed in units of m2 from the Delay Doppler Mapping Instrument aboard the CYGNSS satellite constellation. Other useful scientific and engineering measurement parameters include the DDM of Normalized Bistatic Radar Cross Section (NBRCS), the Delay Doppler Map Average (DDMA) of the NBRCS near the specular reflection point, and the Leading Edge Slope (LES) of the integrated delay waveform. The L1 dataset contains a number of other engineering and science measurement parameters, including sets of quality flags/indicators, error estimates, and bias estimates as well as a variety of orbital, spacecraft/sensor health, timekeeping, and geolocation parameters. At most, 8 netCDF data files (each file corresponding to a unique spacecraft in the CYGNSS constellation) are provided each day; under nominal conditions, there are typically 6-8 spacecraft retrieving data each day, but this can be maximized to 8 spacecraft under special circumstances in which higher than normal retrieval frequency is needed (i.e., during tropical storms and or hurricanes). Latency is approximately 1 week. The Version 1.2 CDR is a collection of reanalysis products derived from the SDR v3.1 Level 1 data ( ). Calibration accuracy and long term stability are improved relative to SDR v3.0 using the same trackwise correction algorithm as was used by CDR v1.1 ( ), which was derived from SDR v2.1 Level 1 data ( ). Details of the algorithm are provided in the Trackwise Corrected CDR Algorithm Theoretical Basis Document. Trackwise correction is applied to the two primary CYGNSS L1 science data products, the normalized bistatic radar cross section (NBRCS) and the LES. The correction compensates for small errors in the Level 1 calibration, due e.g. to uncertainties in the GPS transmitting antenna gain patterns and the CYGNSS receiving antenna gain patterns. It should be noted that the trackwise correction algorithm cannot be successfully applied to all v3.1 SDR L1 data, so there is also some loss of samples that were present in v3.1.
Swath Width25 km
Name: Cyclone Global Navigation Satellite System (CYGNSS)
Orbit Period: 94.0 minutes
Inclination Angle: 35.0 degrees
Name: Delay Doppler Mapping Instrument (DDMI)
Swath Width: 25.0 kilometers
Description: Spacecraft angular distance from orbital plane relative to the Equator.

ProjectCyclone Global Navigation Satellite System (CYGNSS)
Data ProviderPublisher: PO.DAAC
Creator: CYGNSS
Release Place: PO.DAAC
Release Date: 2022-Oct-18

Keyword(s)cygnss, ddm, ddmi, ddma, doppler, delay doppler, delay, specular point, waveform, les, leading edge slope, bistatic, bi-static, radar, brcs, sigma0, sigma-0, sigma naught, sigma-naught, nbrcs, wind, winds, wind speed, cdr, version 1.2, v1.2
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Spatial Resolution: 25000 Meters x 25000 Meters
Temporal Resolution: Hourly - < Daily
Region: GLOBAL
North Bounding Coordinate: 40 degrees
South Bounding Coordinate: -40 degrees
West Bounding Coordinate: -180 degrees
East Bounding Coordinate: 180 degrees
Time Span: 2018-Aug-01 to Present
Granule Time Span: 2018-Aug-01 to 2024-May-19
Swath Width: 25 km
Projection Type: Satellite native along-track
Projection Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
NameLong NameUnit
add_range_to_spAdditional range to specular point at DDM sample time1
add_range_to_sp_pvtAdditional range to specular point at PVT time1
att_timestamp_gps_secAttitude timestamp - GPS Secondssecond
att_timestamp_gps_weekAttitude timestamp - GPS Weekweek
att_timestamp_utcAttitude timestamp - UTCseconds since 2018-08-01 00:00:00.999261489
bb_nearestTime to most recent black body readingsecond
bb_power_temperature_densityBlack Body Power Temperature DensityCounts/Kelvin
bit_null_offset_portPort bit count null offset1
bit_null_offset_starboardStarboard bit count null offset1
bit_null_offset_zenithZenith bit count null offset1
bit_ratio_lo_hi_portPort low/high bit counter ratio1
bit_ratio_lo_hi_starboardStarboard low/high bit counter ratio1
bit_ratio_lo_hi_zenithZenith low/high bit counter ratio1
brcsDDM bin bistatic radar cross sectionmeter2
brcs_ddm_peak_bin_delay_rowBRCS DDM peak bin delay row1
brcs_ddm_peak_bin_dopp_colBRCS DDM peak bin Doppler column1
brcs_ddm_sp_bin_delay_rowBRCS DDM specular point bin delay row1
brcs_ddm_sp_bin_dopp_colBRCS DDM specular point bin Doppler column1
commanded_sc_rollCommanded spacecraft attitude roll angleradian
ddmDDM reflectometry channel1
ddm_antDDM Antenna
ddm_brcs_uncertDDM BRCS uncertainty1
ddm_end_time_offsetDDM end time offset1e-9 s
ddm_kurtosisDDM kurtosis1
ddm_lesLeading edge slope1
ddm_les_origThe original observable, before track-wise correction1
ddm_nbrcsNormalized BRCS1
ddm_nbrcs_origThe original observable, before track-wise correction1
ddm_noise_floorDDM noise floor1
ddm_noise_floor_correctedDDM noise floor corrected1
ddm_snrDDM signal to noise ratiodB
ddm_sourceLevel 0 data source
ddm_time_type_selectorDDM sample time type selector
ddm_timestamp_gps_secDDM sample timestamp - GPS Secondssecond
ddm_timestamp_gps_weekDDM sample timestamp - GPS Weekweek
ddm_timestamp_utcDDM sample timestamp - UTCseconds since 2018-08-01 00:00:00.999261489
delay_resolutionDDM delay bin resolution1
dopp_resolutionDDM Doppler bin resolutions-1
eff_scatterDDM bin effective scattering areameter2
era5_wind_speed10m ERA5 reference wind speedm s-1
fresnel_coeffFresnel power reflection coefficient at specular point1
fsw_comp_delay_shiftFlight software DDM compression delay shift1
fsw_comp_dopp_shiftFlight software DDM compression Doppler shifts-1
gps_ant_gain_db_iGPS SV transmit antenna gaindBi
gps_eirpGPS effective isotropic radiated powerwatt
gps_off_boresight_angle_degGPS off boresight angledegree
gps_tx_power_db_wGPS SV transmit powerdBW
inst_gainInstrument gain1
les_modThe model observable1
les_scatter_areaLES scattering areameter2
les_tw_outlierTrack-wise corrected observable is an outlier1
les_tw_r2The R^2 correlation coefficient of the track-wise linear regression1
les_tw_slopeThe slope of the track-wise correction1
les_tw_yintThe y-intercept of the track-wise correction1
lna_noise_figureLNA noise figuredB
lna_temp_nadir_portPort Antenna LNA temperaturedegree_Celsius
lna_temp_nadir_starboardStarboard antenna LNA temperaturedegree_Celsius
lna_temp_zenithZenith Antenna LNA temperaturedegree_Celsius
nbrcs_modThe model observable1
nbrcs_scatter_areaNBRCS scattering areameter2
nbrcs_tw_outlierTrack-wise corrected observable is an outlier1
nbrcs_tw_r2The R^2 correlation coefficient of the track-wise linear regression1
nbrcs_tw_slopeThe slope of the track-wise correction1
nbrcs_tw_yintThe y-intercept of the track-wise correction1
noise_correctionDDM noise floor correction factor1
nst_att_statusNST attitude status
port_gain_settingThe Nadir-Port Gain SettingdB
power_analogDDM bin analog powerwatt
prn_codeGPS PRN code1
prn_fig_of_meritPRN selection figure of Merit1
pvt_timestamp_gps_secPVT timestamp - GPS Secondssecond
pvt_timestamp_gps_weekPVT timestamp - GPS Weekweek
pvt_timestamp_utcPVT timestamp - UTCseconds since 2018-08-01 00:00:00.999261489
quality_flagsPer-DDM quality flags 1
quality_flags_2Per-DDM quality flags 2
raw_countsDDM bin raw counts1
rx_clk_biasGPS receiver clock biasmeter
rx_clk_bias_pvtGPS receiver clock bias at PVT timemeter
rx_clk_bias_rateGPS receiver clock bias ratemeter s-1
rx_clk_bias_rate_pvtGPS receiver clock bias rate at PVT timemeter s-1
rx_to_sp_rangeRx to specular point rangemeter
sampleSample index1
sc_altSpacecraft altitudemeter
sc_latSub-satellite point latitudedegrees_north
sc_lonSub-satellite point longitudedegrees_east
sc_pitchSpacecraft attitude pitch angle at DDM sample timeradian
sc_pitch_attSpacecraft attitude pitch angle at attitude timeradian
sc_pos_xSpacecraft position X at DDM sample timemeter
sc_pos_x_pvtSpacecraft position X at PVT timemeter
sc_pos_ySpacecraft position Y at DDM sample timemeter
sc_pos_y_pvtSpacecraft position Y at PVT timemeter
sc_pos_zSpacecraft position Z at DDM sample timemeter
sc_pos_z_pvtSpacecraft position Z at PVT timemeter
sc_rollSpacecraft attitude roll angle at DDM sample timeradian
sc_roll_attSpacecraft attitude roll angle at attitude timeradian
sc_vel_xSpacecraft velocity X at DDM sample timemeter s-1
sc_vel_x_pvtSpacecraft velocity X at PVT timemeter s-1
sc_vel_ySpacecraft velocity Y at DDM sample timemeter s-1
sc_vel_y_pvtSpacecraft velocity Y at PVT timemeter s-1
sc_vel_zSpacecraft velocity Z at DDM sample timemeter s-1
sc_vel_z_pvtSpacecraft velocity Z at PVT timemeter s-1
sc_yawSpacecraft attitude yaw angle at DDM sample timeradian
sc_yaw_attSpacecraft attitude yaw angle at attitude timeradian
sp_altSpecular point altitudemeter
sp_az_bodySpecular point body frame azimuth angledegree
sp_az_orbitSpecular point orbit frame azimuth angledegree
sp_ddmi_delay_correctionCorrection to DDMI specular point delay1
sp_ddmi_doppDDMI Doppler at specular points-1
sp_ddmi_dopp_correctionCorrection to DDMI specular point Dopplers-1
sp_delay_errorFlight software specular point delay error1
sp_dopp_errorFlight software specular point Doppler errors-1
sp_fsw_delayFlight software specular point delay1
sp_inc_angleSpecular point incidence angledegree
sp_latSpecular point latitudedegrees_north
sp_lonSpecular point longitudedegrees_east
sp_pos_xSpecular point position Xmeter
sp_pos_ySpecular point position Ymeter
sp_pos_zSpecular point position Zmeter
sp_rx_gainSpecular point Rx antenna gaindBi
sp_theta_bodySpecular point body frame theta angledegree
sp_theta_orbitSpecular point orbit frame theta angledegree
sp_vel_xSpecular point velocity Xmeter s-1
sp_vel_ySpecular point velocity Ymeter s-1
sp_vel_zSpecular point velocity Zmeter s-1
spacecraft_idCCSDS spacecraft identifier1
spacecraft_numCYGNSS spacecraft number1
starboard_gain_settingThe Nadir-Starboard Gain SettingdB
static_gps_eirpStatic GPS effective isotropic radiated powerwatt
status_flags_one_hz1 Hz Status Flags
sv_numGPS Space Vehicle Number1
track_idDDM Track ID1
tw_numNumber of samples used in the track-wise linear regression1
tx_clk_biasGPS transmitter clock biasmeter
tx_pos_xGPS Tx position Xmeter
tx_pos_yGPS Tx position Ymeter
tx_pos_zGPS Tx position Zmeter
tx_to_sp_rangeTx to specular point rangemeter
tx_vel_xGPS Tx velocity Xmeter s-1
tx_vel_yGPS Tx velocity Ymeter s-1
tx_vel_zGPS Tx velocity Zmeter s-1
zenith_code_phaseZenith signal code phase1
zenith_sig_i2q2Zenith Signal I2Q21
zenith_sig_i2q2_add_correctionZenith Signal I2 Q2 additive correction factor1
zenith_sig_i2q2_correctedZenith Signal I2Q2 Corrected1
zenith_sig_i2q2_mult_correctionZenith Signal I2Q2 Multiplicative Correction Factor1
    Ruf, C., R. Atlas, P. Chang, M. Clarizia, J. Garrison, S. Gleason, S. Katzberg, Z. Jelenak, J. Johnson, S. Majumdar, A. O'Brien, D. Posselt, A. Ridley, R. Rose, V. Zavorotny (2015). New Ocean Winds Satellite Mission to Probe Hurricanes and Tropical Convection. Bull. Amer. Meteor. Soc., doi:10.1175/BAMS-D-14-00218.1.
    Gleason, S., C. Ruf, M. P. Clarizia, A. O'Brien, 'Calibration and Unwrapping of the Normalized Scattering Cross Section for the Cyclone Global Navigation Satellite System (CYGNSS)', IEEE Trans. Geosci. Remote Sens., doi:10.1109/TGRS.2015.2502245, 2016.
Citation is critically important for dataset documentation and discovery. Please cite the data as follows, and cite the reference papers when it is appropriate.
Citation CYGNSS. 2022. CYGNSS Level 1 Climate Data Record Version 1.2. Ver. 1.2. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

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For more information see Data Citations and Acknowledgments.

Journal Reference Gleason, S., C. S. Ruf, A. O'Brien, D. S. McKague. 2018. The CYGNSS Level 1 Calibration Algorithm and Error Analysis Based On On-Orbit Measurements, IEEE J. Sel. Topics Appl. Earth Obs. Remote Sens, 12, 1. 10.1109/JSTARS.2018.2832981

VersionDatasetVersion DateStatus
3.2CYGNSS Level 1 Climate Data Record Version 3.22024-04-10ACTIVE2024-04-10T19:40:00.000Z
1.2CYGNSS Level 1 Climate Data Record Version 1.22022-05-19ACTIVE2022-05-19T21:15:00.000Z
1.1CYGNSS Level 1 Climate Data Record Version 1.12022-04-11ACTIVE2022-04-11T16:51:00.000Z
1.0CYGNSS Level 1 Climate Data Record Version 1.02021-04-22COMPLETE2021-04-22T15:18:00.000Z