CYGNSS Level 1 Science Data Record Version 3.2
(CYGNSS_L1_V3.2)| Version | 3.2 |
| Processing Level | 1 |
| Start/Stop Date | 2018-Aug-01 to Present |
| Short Name | CYGNSS_L1_V3.2 |
| Description | This CYGNSS Level 1 (L1) science data record dataset contains the version 3.2 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. This version supersedes Version 3.1: https://doi.org/10.5067/CYGNS-L1X31. 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 6 days (or better) from the last recorded measurement time. The correction for coarse quantization effects that was implemented in v3.1 for the signal portion of the DDM has been updated to include a correction to the noise floor portion of the DDM. This update is found to improve the sensitivity to soil moisture over land and to have a minimal effect on the sensitivity to wind speed over ocean. An update is made to the correction for the temperature dependence of the receiver electronics. This update reduces slow variations in calibration bias associated with a ~60 day oscillation in the mean temperature of the satellites. L1 variables over land and ocean are now combined in common netcdf data files, with additional details added regarding the specular point calculation over land. Nadir (science) antenna pattern and NBRCS rescaling has been updated to improve the inter-satellite consistency of the L1 calibration. The CYGNSS is a NASA Earth System Science Pathfinder Mission that is intended to collect the first frequent space‐based measurements of surface wind speeds in the inner core of tropical cyclones. Made up of a constellation of eight micro-satellites, the observatories provide nearly gap-free Earth coverage using an orbital inclination of approximately 35° from the equator, with a mean (i.e., average) revisit time of seven hours and a median revisit time of three hours. This inclination allows CYGNSS to measure ocean surface winds between approximately 38° N and 38° S latitude. This range includes the critical latitude band for tropical cyclone formation and movement. |
| DOI | 10.5067/CYGNS-L1X32 |
| Measurement | SPECTRAL/ENGINEERING > RADAR > RADAR CROSS-SECTION SPECTRAL/ENGINEERING > RADAR > RADAR REFLECTIVITY |
| Swath Width | 25 km |
| Platform/Sensor | CYGNSS / Platform Name: Cyclone Global Navigation Satellite System (CYGNSS) Inclination Angle: 35.0 degrees Orbit Period: 94.0 minutes DDMI SENSOR Name: Delay Doppler Mapping Instrument (DDMI) Swath Width: 25.0 kilometers Description: Spacecraft angular distance from orbital plane relative to the Equator. |
| Project | Cyclone Global Navigation Satellite System (CYGNSS) |
| Data Provider | Publisher: PO.DAAC Creator: CYGNSS Release Place: PO.DAAC Release Date: 2024-Mar-05 Resource: https://cygnss.engin.umich.edu/ |
| Format | netCDF-4 |
| 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, version 3.2, v3.2 |
Questions related to this dataset? Contact podaac@podaac.jpl.nasa.gov
Resolution Spatial Resolution: 25000 Meters x 25000 Meters Temporal Resolution: Hourly - < Daily Coverage 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 PresentSwath Width: 25 km Projection Projection Type: Satellite native along-track Projection Detail: Geolocation information included for each pixel Ellipsoid: WGS 84 |
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| us-west-2 | |
| podaac-ops-cumulus-protected/CYGNSS_L1_V3.2 | |
| podaac-ops-cumulus-public/CYGNSS_L1_V3.2 | |
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| Name | Long Name | Unit |
|---|---|---|
| add_range_to_sp | Additional range to specular point at DDM sample time | 1 |
| add_range_to_sp_pvt | Additional range to specular point at PVT time | 1 |
| att_timestamp_gps_sec | Attitude timestamp - GPS Seconds | second |
| att_timestamp_gps_week | Attitude timestamp - GPS Week | week |
| att_timestamp_utc | Attitude timestamp - UTC | seconds since 2018-08-15 00:00:00.999261540 |
| bb_nearest | Time to most recent black body reading | second |
| bb_power_temperature_density | Black Body Power Temperature Density | Counts/Kelvin |
| bit_null_offset_port | Port bit count null offset | 1 |
| bit_null_offset_starboard | Starboard bit count null offset | 1 |
| bit_null_offset_zenith | Zenith bit count null offset | 1 |
| bit_ratio_lo_hi_port | Port low/high bit counter ratio | 1 |
| bit_ratio_lo_hi_starboard | Starboard low/high bit counter ratio | 1 |
| bit_ratio_lo_hi_zenith | Zenith low/high bit counter ratio | 1 |
| brcs | DDM bin bistatic radar cross section | meter2 |
| brcs_ddm_peak_bin_delay_row | BRCS DDM peak bin delay row | 1 |
| brcs_ddm_peak_bin_dopp_col | BRCS DDM peak bin Doppler column | 1 |
| brcs_ddm_sp_bin_delay_row | BRCS DDM specular point bin delay row | 1 |
| brcs_ddm_sp_bin_dopp_col | BRCS DDM specular point bin Doppler column | 1 |
| coherency_ratio | Coherency Ratio | 1 |
| coherency_state | Coherency State | 1 |
| commanded_sc_roll | Commanded spacecraft attitude roll angle | radian |
| comp_ddm_sp_delay_row | Compressed DDM specular point bin delay row | 1 |
| comp_ddm_sp_doppler_col | Compressed DDM specular point bin Doppler column | 1 |
| ddm | DDM reflectometry channel | 1 |
| ddm_ant | DDM Antenna | |
| ddm_brcs_uncert | DDM BRCS uncertainty | 1 |
| ddm_end_time_offset | DDM end time offset | 1e-9 s |
| ddm_kurtosis | DDM kurtosis | 1 |
| ddm_les | Leading edge slope | 1 |
| ddm_nadir_bb_correction_next | Nadir BB Correction Factor Next | 1 |
| ddm_nadir_bb_correction_prev | Nadir BB Correction Factor Previous | 1 |
| ddm_nadir_signal_correction | Nadir Signal Correction Factor | 1 |
| ddm_nbrcs | Normalized BRCS | 1 |
| ddm_nbrcs_center | DDM NBRCS calculated around the central bin | 1 |
| ddm_nbrcs_peak | DDM NBRCS calculated at the peak bin | 1 |
| ddm_nbrcs_scale_factor | Normalized BRCS Scale Factor | 1 |
| ddm_noise_floor | DDM noise floor | 1 |
| ddm_snr | DDM signal to noise ratio | dB |
| ddm_source | Level 0 data source | |
| ddm_time_type_selector | DDM sample time type selector | |
| ddm_timestamp_gps_sec | DDM sample timestamp - GPS Seconds | second |
| ddm_timestamp_gps_week | DDM sample timestamp - GPS Week | week |
| ddm_timestamp_utc | DDM sample timestamp - UTC | seconds since 2018-08-15 00:00:00.999261540 |
| ddmi_tracker_delay_center | DDMI Tracker Delay Center | |
| delay_resolution | DDM delay bin resolution | 1 |
| dopp_resolution | DDM Doppler bin resolution | s-1 |
| eff_scatter | DDM bin effective scattering area | meter2 |
| fresnel_coeff | Fresnel power reflection coefficient at specular point | 1 |
| fsw_comp_delay_shift | Flight software DDM compression delay shift | 1 |
| fsw_comp_dopp_shift | Flight software DDM compression Doppler shift | s-1 |
| gps_ant_gain_db_i | GPS SV transmit antenna gain | dBi |
| gps_eirp | GPS effective isotropic radiated power | watt |
| gps_off_boresight_angle_deg | GPS off boresight angle | degree |
| gps_tx_power_db_w | GPS SV transmit power | dBW |
| inst_gain | Instrument gain | 1 |
| les_scatter_area | LES scattering area | meter2 |
| lna_noise_figure | LNA noise figure | dB |
| lna_temp_nadir_port | Port Antenna LNA temperature | degree_Celsius |
| lna_temp_nadir_starboard | Starboard antenna LNA temperature | degree_Celsius |
| lna_temp_zenith | Zenith Antenna LNA temperature | degree_Celsius |
| modis_land_cover | MODIS Land Cover classification | |
| nbrcs_scatter_area | NBRCS scattering area | meter2 |
| nst_att_status | NST attitude status | |
| pekel_sp_water_flag | Possible surface water at SP | |
| pekel_sp_water_flag_10km | Water found within 10km of SP? | |
| pekel_sp_water_flag_2km | Water found within 2km of SP? | |
| pekel_sp_water_flag_5km | Water found within 5km of SP? | |
| pekel_sp_water_local_map_5km | Local area map of the water mask | |
| pekel_sp_water_percentage | Percentage of water at SP | percent |
| pekel_sp_water_percentage_10km | Percentage of water within 10km of SP | percent |
| pekel_sp_water_percentage_2km | Percentage of water within 2km of SP | percent |
| pekel_sp_water_percentage_5km | Percentage of water within 5km of SP | percent |
| port_gain_setting | The Nadir-Port Gain Setting | dB |
| power_analog | DDM bin analog power | watt |
| prn_code | GPS PRN code | 1 |
| prn_fig_of_merit | PRN selection figure of Merit | 1 |
| pvt_timestamp_gps_sec | PVT timestamp - GPS Seconds | second |
| pvt_timestamp_gps_week | PVT timestamp - GPS Week | week |
| pvt_timestamp_utc | PVT timestamp - UTC | seconds since 2018-08-15 00:00:00.999261540 |
| quality_flags | Per-DDM quality flags 1 | |
| quality_flags_2 | Per-DDM quality flags 2 | |
| raw_counts | DDM bin raw counts | 1 |
| reflectivity_peak | Peak linear reflectivity | linear |
| rx_clk_bias | GPS receiver clock bias | meter |
| rx_clk_bias_pvt | GPS receiver clock bias at PVT time | meter |
| rx_clk_bias_rate | GPS receiver clock bias rate | meter s-1 |
| rx_clk_bias_rate_pvt | GPS receiver clock bias rate at PVT time | meter s-1 |
| rx_clk_doppler | Rx Clock Doppler | |
| rx_to_sp_range | Rx to specular point range | meter |
| sample | Sample index | 1 |
| sc_alt | Spacecraft altitude | meter |
| sc_lat | Sub-satellite point latitude | degrees_north |
| sc_lon | Sub-satellite point longitude | degrees_east |
| sc_pitch | Spacecraft attitude pitch angle at DDM sample time | radian |
| sc_pitch_att | Spacecraft attitude pitch angle at attitude time | radian |
| sc_pos_x | Spacecraft position X at DDM sample time | meter |
| sc_pos_x_pvt | Spacecraft position X at PVT time | meter |
| sc_pos_y | Spacecraft position Y at DDM sample time | meter |
| sc_pos_y_pvt | Spacecraft position Y at PVT time | meter |
| sc_pos_z | Spacecraft position Z at DDM sample time | meter |
| sc_pos_z_pvt | Spacecraft position Z at PVT time | meter |
| sc_roll | Spacecraft attitude roll angle at DDM sample time | radian |
| sc_roll_att | Spacecraft attitude roll angle at attitude time | radian |
| sc_vel_x | Spacecraft velocity X at DDM sample time | meter s-1 |
| sc_vel_x_pvt | Spacecraft velocity X at PVT time | meter s-1 |
| sc_vel_y | Spacecraft velocity Y at DDM sample time | meter s-1 |
| sc_vel_y_pvt | Spacecraft velocity Y at PVT time | meter s-1 |
| sc_vel_z | Spacecraft velocity Z at DDM sample time | meter s-1 |
| sc_vel_z_pvt | Spacecraft velocity Z at PVT time | meter s-1 |
| sc_yaw | Spacecraft attitude yaw angle at DDM sample time | radian |
| sc_yaw_att | Spacecraft attitude yaw angle at attitude time | radian |
| sp_alt | Specular point altitude | meter |
| sp_az_body | Specular point body frame azimuth angle | degree |
| sp_az_orbit | Specular point orbit frame azimuth angle | degree |
| sp_calc_method | Specular point calculation method | |
| sp_ddmi_delay_correction | Correction to DDMI specular point delay | 1 |
| sp_ddmi_dopp | DDMI Doppler at specular point | s-1 |
| sp_ddmi_dopp_correction | Correction to DDMI specular point Doppler | s-1 |
| sp_delay_error | Flight software specular point delay error | 1 |
| sp_dopp_error | Flight software specular point Doppler error | s-1 |
| sp_fsw_delay | Flight software specular point delay | 1 |
| sp_inc_angle | Specular point incidence angle | degree |
| sp_land_confidence | Confidence in land specular point | |
| sp_land_valid | Is land SP valid? | |
| sp_lat | Specular point latitude | degrees_north |
| sp_lon | Specular point longitude | degrees_east |
| sp_pos_x | Specular point position X | meter |
| sp_pos_y | Specular point position Y | meter |
| sp_pos_z | Specular point position Z | meter |
| sp_rx_gain | Specular point Rx antenna gain | dBi |
| sp_theta_body | Specular point body frame theta angle | degree |
| sp_theta_orbit | Specular point orbit frame theta angle | degree |
| sp_vel_x | Specular point velocity X | meter s-1 |
| sp_vel_y | Specular point velocity Y | meter s-1 |
| sp_vel_z | Specular point velocity Z | meter s-1 |
| spacecraft_id | CCSDS spacecraft identifier | 1 |
| spacecraft_num | CYGNSS spacecraft number | 1 |
| srtm_dem_alt | SRTM DEM altitude | meter |
| srtm_slope | SRTM DEM slope | degree |
| starboard_gain_setting | The Nadir-Starboard Gain Setting | dB |
| static_gps_eirp | Static GPS effective isotropic radiated power | watt |
| status_flags_one_hz | 1 Hz Status Flags | |
| sv_num | GPS Space Vehicle Number | 1 |
| track_id | DDM Track ID | 1 |
| tx_clk_bias | GPS transmitter clock bias | meter |
| tx_pos_x | GPS Tx position X | meter |
| tx_pos_y | GPS Tx position Y | meter |
| tx_pos_z | GPS Tx position Z | meter |
| tx_to_sp_range | Tx to specular point range | meter |
| tx_vel_x | GPS Tx velocity X | meter s-1 |
| tx_vel_y | GPS Tx velocity Y | meter s-1 |
| tx_vel_z | GPS Tx velocity Z | meter s-1 |
| zenith_code_phase | Zenith signal code phase | 1 |
| zenith_sig_i2q2 | Zenith Signal I2Q2 | 1 |
| zenith_sig_i2q2_add_correction | Zenith Signal I2 Q2 additive correction factor | 1 |
| zenith_sig_i2q2_corrected | Zenith Signal I2Q2 Corrected | 1 |
| zenith_sig_i2q2_mult_correction | Zenith Signal I2Q2 Multiplicative Correction Factor | 1 |
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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. 2024. CYGNSS Level 1 Science Data Record Version 3.2. Ver. 3.2. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/CYGNS-L1X32
For more information see Data Citations and Acknowledgments.
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| Journal Reference | Ruf, C., S. Asharaf, R. Balasubramaniam, S. Gleason, T. Lang, D. McKague, D. Twigg, and D. Waliser. 2019. In-Orbit Performance of the Constellation of CYGNSS Hurricane Satellites., Bulletin of the American Meteorological Society, 100, 10. Gleason, S., M. M. Al-Khaldi, C. Ruf, D. S. McKague, T. Wang, A. Russel . 2021. Characterizing and Mitigating Digital Sampling Effects on the CYGNSS Level 1 Calibration, IEEE Trans. Geosci. Remote Sens. 10.1109/TGRS.2021.3120026 Pascual, D., M. P. Clarizia, C. S. Ruf . 2021. Improved CYGNSS Wind Speed Retrieval Using Significant Wave Height Correction, Remote Sensing. 10.3390/rs13214313 Wang, T., Ruf, C. S., Gleason, S., O'Brien, A. J., McKague, D. S., Block, B. P., Russel, A.. 2021. Dynamic Calibration of GPS Effective Isotropic Radiated Power for GNSS-Reflectometry Earth Remote Sensing, IEEE Trans. Geosci. Remote Sens.. https://doi.org//10.1109/TGRS.2021.3070238 |
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