N: 38.15 S: -38.15 E: 180 W: -180
Description
The CYGNSS Level 1 Calibrated Raw IF Version 1.0 dataset is produced by the CYGNSS Science Team of the University of Michigan, and it contains the first release, Version 1.0, of the CYGNSS Calibrated Raw Intermediate Frequency (IF) based L1 Product. CYGNSS was launched on 15 December 2016, it is a NASA Earth System Science Pathfinder Mission that was launched with the purpose of collecting the first frequent space‐based measurements of surface wind speeds in the inner core of tropical cyclones. Originally made up of a constellation of eight micro-satellites, the observatories provide nearly gap-free Earth coverage using an orbital inclination of approximately 35°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 product includes several established signal coherence detectors, including the power-ratio P<sub>ratio</sub>, complex zero-Doppler delay waveform and full entropy E<sub>full</sub>, and a novel fast entropy detector E<sub>fast</sub>. Both entropy detectors are provided with two temporal resolutions: 2 ms and 50 ms. Several scattered signal strength products are included: Signal-to-Noise Ratio SNR, reflected power P<sub>g</sub>, reflectivity Γ, and Normalized Bistatic Radar Cross-Section NBRCS. Each of these products is derived using a coherent integration time of T<sub>c </sub>= 1 ms and incoherent integration times of N<sub>inc</sub> = 1000, 500, 250, 100, 50, and 2 ms. Signal strength time series at the shorter (2 and 50 ms) times provides excellent detection of land-water transitions in heterogeneous scenes. Delay Doppler Maps (DDMs) are also generated with high delay (∆τ = 1/16 chip) and Doppler (∆f= 50 Hz) resolution. This suite of coherence detection methods can be used to detect the presence of small inland water bodies.
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Variables
The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.
For questions on a specific variable, please use the Earthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor | Offset |
|---|---|---|---|---|---|---|---|
| gps_ant_gain_db_i | SV antenna gain in the direction of the specular point. Referenced from the heritage version of gps_eirp (v2.1 and earlier). | dBi | float | -9999 | N/A | 1 | N/A |
| gps_eirp | The estimated effective isotropic RF power (EIRP) of the L1 C/A code signal within ± 1 MHz of the L1 carrier radiated by space vehicle, sv_num, in the direction of the specular point, in Watts, at ddm_timestamp_utc. Variations in GPS transmit power are tracked by the direct signal power measured by the navigation receiver. One second samples are smoothed by a ± 10 second running average. | watt | float | -9999 | N/A | 1 | N/A |
| gps_off_boresight_angle_deg | SV antenna off boresight angle in the direction of the specular point | degree | float | -9999 | N/A | 1 | N/A |
| gps_tx_power_db_w | Power input to SV Tx antenna. Referenced from the heritage version of gps_eirp (v2.1 and earlier). | dBW | float | -9999 | N/A | 1 | N/A |
| inst_gain | The black body noise counts divided by the sum of the black body power and the instrument noise power, in count/W, at ddm_timestamp_utc. | 1 | float | -9999 | N/A | 1 | N/A |
| iq_imag | Quadrature component of the 1 ms coherently integrated complex delay waveforms. 1001 vector of waveform bin raw counts. | 1 | float | -9999 | N/A | 1 | N/A |
| iq_real | In-phase component of the 1 ms coherently integrated complex delay waveforms. 1001 vector of waveform bin raw counts. | 1 | float | -9999 | N/A | 1 | N/A |
| i_max | In-phase component at the peak of the 1 ms coherently integrated complex DDMs. | 1 | float | -9999 | N/A | 1 | N/A |
| land_reflectivity | 69 x 111 array of DDM bin reflectivity.. | linear | float | -9999 | N/A | 1 | N/A |
| land_reflectivity_peak | Single maximum value of bin in relectivity DDM. | linear | float | -9999 | N/A | 1 | N/A |
| les_scatter_area | The scattering area of the 3 x 5 region of the ddm used to calculate ddm_les. | meter2 | float | -9999 | N/A | 1 | N/A |
| lna_noise_figure | The low noise amplifier (LNA) noise figure, in dB, at ddm_timestamp_utc. Estimated from pre-launch characterization of LNA performance as a function of LNA temperature. | dB | float | -9999 | N/A | 1 | N/A |
| lna_temp_nadir_port | The temperature of the port antenna low noise amplifier at ddm_timestamp_utc, in degrees C. | degree_Celsius | float | -9999 | N/A | 1 | N/A |
| lna_temp_nadir_starboard | The temperature of the starboard antenna low noise amplifier at ddm_timestamp_utc, in degrees C. | degree_Celsius | float | -9999 | N/A | 1 | N/A |
| lna_temp_zenith | The temperature of the zenith antenna low noise amplifier at ddm_timestamp_utc, in degrees C. | degree_Celsius | float | -9999 | N/A | 1 | N/A |
| modis_land_cover | The MODIS Land Cover Classification type at the specular point latitude and longitude referenced from the MODIS Landcover 2012 Revision 1. | N/A | byte | -99 | N/A | 1 | N/A |
| nbrcs_scatter_area | The scattering area of the peak bin used to calculate peak_nbrcs. | meter2 | float | -9999 | N/A | 1 | N/A |
| noise_correction | The correction factor applied with ddm_noise_floor = (ddm_noise_floor_uncorrected*noise_correction). | 1 | float | -9999 | N/A | 1 | N/A |
| nst_att_status | Nano Star Tracker attitude status as reported by the ADCS subsystem. Enumeration, with 0 indicating OK, and non-zero indicating an erroneous condition. Values: 0 = ok 1 = not_used2 2 = bad 3 = too_few_stars 4 = quest_failed 5 = residuals_too_high 6 = too_close_to_edge 7 = pix_amp_too_low 8 = pix_amp_too_high 9 = backgnd_too_high 10 = track_failure 11 = pix_sum_too_low 12 = unused 13 = too_dim_for_starid 14 = too_many_groups 15 = too_few_groups 16 = channel_disabled 17 = track_blk_overlap 18 = ok_for_starid 19 = too_close_to_other 20 = too_many_pixels 21 = too_many_columns 22 = too_many_rows | N/A | byte | -99 | N/A | 1 | N/A |
| peak_brcs | Value of the BRCS at the peak point. | meter2 | float | -9999 | N/A | 1 | N/A |
| peak_nbrcs | Normalized BRCS at the peak point bin. | 1 | float | -9999 | N/A | 1 | N/A |
| pekel_sp_water_flag | If pekel_sp_water_percentage > 0, pekel_sp_water_flag = 1, else 0. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | N/A | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_flag_2km | If pekel_sp_water_percentage_2km > 0, pekel_sp_water_flag_2km = 1, else 0. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | N/A | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_flag_5km | If pekel_sp_water_percentage_5km > 0, pekel_sp_water_flag_5km = 1, else 0. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | N/A | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_flag_10km | If pekel_sp_water_percentage_10km > 0, pekel_sp_water_flag_10km = 1, else 0. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | N/A | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_local_map_5km | Local area map of Pekel (2018 Global Surface Water Explorer) percentage of surface water. Each cell of the local area map is 1km x 1km. The reported sp_lat, sp_lon, and sp_land_alt is the center cell of the local area map. | N/A | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_percentage | The interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | percent | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_percentage_2km | The percentage of water within a 2km circular region centered at the SP. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | percent | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_percentage_5km | The percentage of water within a 5km circular region centered at the SP. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | percent | byte | -99 | N/A | 1 | N/A |
| pekel_sp_water_percentage_10km | The percentage of water within a 10km circular region centered at the SP. Interpolated lookup of the percentage of water on the 1km x 1km Pekel water mask (2018 Global Surface Water Explorer). | percent | byte | -99 | N/A | 1 | N/A |
| phase_der | Phase derivative of the 1 ms coherently integrated complex DDMs. | degree | float | -9999 | N/A | 1 | N/A |
| port_gain_setting | The Nadir-Port Gain Setting (dB, 0=Automatic) | dB | int | -9999 | N/A | 1 | N/A |
| power_analog | 69 x 111 array of DDM bin analog power, Watts. analog_power is the true power that would have been measured by an ideal (analog) power sensor. power_digital is the power measured by the actual 2-bit sensor, which includes quantization effects. power_analog has been corrected for quantization effects. | watt | float | -9999 | N/A | 1 | N/A |
| prn_code | The PRN code of the GPS signal associated with the DDM. Ranges from 0 to 32. 0 = reflectometry channel idle. 1 through 32 = GPS PRN codes. | 1 | byte | -99 | 0 to 32 | 1 | N/A |
| prn_fig_of_merit | The RCG Figure of Merit (FOM) for the DDM. Ranges from 0 through 15.The DDMI selects the four strongest specular points (SP) for DDM production. It ranks the strength of SPs using an antenna RCG map. The map converts the position of the SP in antenna azimuth and declination angles to an RCG FOM. 0 represents the least FOM value. 15 represents the greatest FOM value. | 1 | byte | -99 | N/A | 1 | N/A |
| pvt_timestamp_gps_sec | The GPS second of week of pvt_timestamp_utc, with nanosecond resolution. | second | double | N/A | N/A | 1 | N/A |
| pvt_timestamp_gps_week | The GPS week number of pvt_timestamp_utc | week | int | N/A | N/A | 1 | N/A |
| pvt_timestamp_utc | The spacecraft position and velocity epoch. The number of seconds since time_coverage_start with nanosecond resolution. This is the timestamp of the position and velocity reported by the DDMI. This is also the timestamp of the most recent GPS pulse per second. | seconds since 2024-01-03 19:09:46.699996840 | double | N/A | N/A | 1 | N/A |
| quality_flags | First group of the Per-DDM quality flags. 1 indicates presence of condition. More quality flags can be found in quality_flags_2. Flag bit masks: 1/0x00000001 = ocean_poor_overall_quality Set if this sample is determined to be of overall poor quality for ocean applications. The logical OR of the following flags. If any one of the following flags are set then ocean_poor_overall_quality will be set: large_sc_attitude_err black_body_ddm ddmi_reconfigured spacewire_crc_invalid ddm_is_test_pattern channel_idle low_confidence_ddm_noise_floor sp_over_land sp_very_near_land large_step_noise_floor large_step_lna_temp direct_signal_in_ddm low_confidence_gps_eirp_estimate rfi_detected brcs_ddm_sp_bin_delay_error brcs_ddm_sp_bin_dopp_error gps_pvt_sp3_error sp_non_existent_error brcs_lut_range_error ant_data_lut_range_error bb_framing_error fsw_comp_shift_error low_quality_gps_ant_knowledge sc_altitude_out_of_nominal_range anomalous_sampling_period invalid_roll_state incorrect_ddmi_antenna_selection(quality_flags_2) sp_in_sidelobe(quality_flags_2) fatal_nst_outage(quality_flags_2) low_zenith_ant_gain(quality_flags_2) poor_bb_quality(quality_flags_2) 2/0x00000002 = s_band_powered_up Set if S-band transmitter is powered up. 4/0x00000004 = small_sc_attitude_err Set if the absolute value of the spacecraft roll is between 1 and 30 degrees, the pitch is between 1 and 10 degrees, or the yaw is between 1 and 5 degrees. 8/0x00000008 = large_sc_attitude_err Set if the absolute value of the spacecraft roll is greater than or equal to 30 degrees, the pitch is greater than or equal to 10 degrees, or the yaw is greater than or equal to 5 degrees. 16/0x00000010 = black_body_ddm Set if the black body load was selected during the DDM sampling period. 32/0x00000020 = ddmi_reconfigured Set if the DDMI was reconfigured during the DDM sampling period. 64/0x00000040 = spacewire_crc_invalid Set if the DDM CRC transmitted from the DDMI to the spacecraft computer was not valid. 128/0x00000080 = ddm_is_test_pattern Set if the DDM is a test pattern generated by the DDMI. 256/0x00000100 = channel_idle Set if this reflectometry channel was not tracking a PRN. 512/0x00000200 = low_confidence_ddm_noise_floor Set if the difference between this DDM noise floor and the previous DDM noise floor is greater than 10 percent. 1024/0x00000400 = sp_over_land Set if the specular point is over land. Referenced using a map with 0.1 degree lat/lon bins. Coastline features or islands smaller than bin size may not be properly captured. 2048/0x00000800 = sp_very_near_land Set if the specular point is within 25 km of land. Referenced using a map with 0.1 degree lat/lon bins. 4096/0x00001000 = sp_near_land Set if the specular point is within 50 km of land. Referenced using a map with 0.1 degree lat/lon bins. 8192/0x00002000 = large_step_noise_floor Set if the difference between this DDM noise floor and the previous DDM noise floor is greater than 0.24 dB. 16384/0x00004000 = large_step_lna_temp Set if the LNA temperature rate of change is greater than 1 degree C per minute. 32768/0x00008000 = direct_signal_in_ddm Set if the absolute value of the difference between direct signal code phase and the DDM signal code phase is less than or equal to four. 65536/0x00010000 = low_confidence_gps_eirp_estimate Set when there is low confidence in the GPS effective isotropic radiated power estimate. 131072/0x00020000 = rfi_detected Set when the kurtosis of the DDM noise floor deviates from pure Gaussian by more than 1.0. 262144/0x00040000 = brcs_ddm_sp_bin_delay_error Set if the calculated specular point bin delay row is outside of the valid range. This range is different for specular points over land and ocean. The zero-based valid range is greater than 4 (ocean) / 1 (land)and less than 8 (ocean) / 15 (land). 524288/0x00080000 = brcs_ddm_sp_bin_dopp_error Set if the calculated specular point bin Doppler column is outside of the valid range. This range is different for specular points over land and ocean. The zero-based valid range is greater than 4 (ocean) / 2 (land) and less than 6 (ocean) / 8 (land). 1048576/0x00100000 = neg_brcs_value_used_for_nbrcs Set if the BRCS bin used to calculate peak_nbrcs has a negative value. 2097152/0x00200000 = gps_pvt_sp3_error Cannot calculate GPS SV position/velocity/time from SP3 file. 4194304/0x00400000 = sp_non_existent_error Specular point does not exist. 8388608/0x00800000 = brcs_lut_range_error Unable to index into BRCS uncertainty lookup table. 16777216/0x01000000 = ant_data_lut_range_error Unable to index into antenna data lookup table. 33554432/0x02000000 = bb_framing_error Insufficient black body data for calibration. 67108864/0x04000000 = fsw_comp_shift_error Flight software telemetry encoding error of the fsw_comp_delay_shift and fsw_comp_dopp_shift variables. Corrected in FSW version 4.5. 134217728/0x08000000 = low_quality_gps_ant_knowledge Not enough data is available to properly calibrate the NBRCS for this sample's GPS satellite. 268435456/0x10000000 = sc_altitude_out_of_nominal_range The spacecraft's altitude is out of nominal altitude range. Nominal altitude is defined as between 490 km to 550 km. 536870912/0x20000000 = anomalous_sampling_period Set when an anomaly was observed on the CYGNSS or GPS satellite while this sample was taken. These samples have produced data that do not align with typical CYGNSS results. See up to date list at: https://docs.google.com/spreadsheets/d/1AFAZanVGDApLSnJQAAdPfOKoJQs0jnB8ZvIuD1Z5mAc/edit?usp=sharing 1073741824/0x40000000 = invalid_roll_state The spacecraft’s reported roll angle is more than 1 degree from the commanded roll. | N/A | int | -9999 | N/A | 1 | N/A |
| quality_flags_2 | Second group of the Per-DDM quality flags. 1 indicates presence of condition. The first group of quality flags can be found in quality_flags. Flag bit masks: 1/0x00000001 = incorrect_ddmi_antenna_selection The wrong (port or starboard) antenna was selected. 2/0x00000002 = high_signal_noise The signal is in the highest noise group, but there are still some OK noise rows. Samples are suspect, but may contain quality data. Flag only used for land applications. 4/0x00000004 = noise_floor_cal_error The signal is off or is very near the top rows of the full DDM. A proper noise floor cannot be computed. Flag only used for land applications. 8/0x00000008 = sp_in_sidelobe The specular point is in the sidelobe causing low confidence in the antenna gain. 16/0x00000010 = negligible_nst_outage Minor star track outage with negligible impact on attitude knowledge 32/0x00000020 = minor_nst_outage Minor star track outage with small but acceptable impact on attitude knowledge 64/0x00000040 = fatal_nst_outage Star track outage with unacceptable impact on attitude knowledge 128/0x00000080 = low_zenith_ant_gain Zenith antenna gain is less than -6 dB 256/0x00000100 = poor_bb_quality The distance between the surrounding BB samples > 1350 seconds OR the absolute value of the time to the nearest BB > 350 seconds. 512/0x00000200 = poor_quality_bin_ratio Bin ratio on the nadir or zenith antenna is associated with degraded performance. 1024/0x00000400 = low_coherency_ratio The coherency ratio is below 0.1 on a land sample. 2048/0x00000800 = land_poor_overall_quality Set if this sample is determined to be of overall poor quality for land applications. The logical OR of the following flags. If any one of the following flags are set then land_poor_overall_quality will be set: large_sc_attitude_err black_body_ddm ddmi_reconfigured spacewire_crc_invalid ddm_is_test_pattern channel_idle low_confidence_ddm_noise_floor large_step_noise_floor large_step_lna_temp direct_signal_in_ddm low_confidence_gps_eirp_estimate rfi_detected brcs_ddm_sp_bin_delay_error brcs_ddm_sp_bin_dopp_error gps_pvt_sp3_error sp_non_existent_error brcs_lut_range_error ant_data_lut_range_error bb_framing_error fsw_comp_shift_error low_quality_gps_ant_knowledge sc_altitude_out_of_nominal_range anomalous_sampling_period invalid_roll_state incorrect_ddmi_antenna_selection(quality_flags_2) high_signal_noise(quality_flags_2) noise_floor_cal_error(quality_flags_2) sp_in_sidelobe(quality_flags_2) fatal_nst_outage(quality_flags_2) low_zenith_ant_gain(quality_flags_2) poor_bb_quality(quality_flags_2) low_coherency_ratio(quality_flags_2) sp_over_ocean(quality_flags_2) sp_extremely_near_ocean(quality_flags_2) sp_very_near_ocean(quality_flags_2) 4096/0x00001000 = sp_over_ocean Set if the specular point is over ocean. Referenced using a map with 0.1 degree lat/lon bins. Coastline features or islands smaller than bin size may not be properly captured. 8192/0x00002000 = sp_extremely_near_ocean Set if the specular point is within 10 km of ocean. Referenced using a map with 0.1 degree lat/lon bins. When this flag is set the reflectivity_peak and ddm_nbrcs are both considered to be of poor quality. 16384/0x00004000 = sp_very_near_ocean Set if the specular point is within 25 km of ocean. Referenced using a map with 0.1 degree lat/lon bins. When this flag is set the ddm_nbrcs is considered to be poor quailty, but thereflectivity_peak may still contain good quality data. | N/A | int | -9999 | N/A | 1 | N/A |
| q_max | Quadrature component at the peak of the 1 ms coherently integrated complex DDMs. | 1 | float | -9999 | N/A | 1 | N/A |
| raw_counts | 69 x 111 array of DDM bin raw counts These are the uncalibrated power values produced by the DDMI. | 1 | int | -9999 | N/A | 1 | N/A |
| rx_clk_bias | The receiver clock bias (in seconds) multiplied by the speed of light as reported by the DDMI, interpolated to ddm_timestamp_utc, in meters. | meter | float | -9999 | N/A | 1 | N/A |
| rx_clk_bias_pvt | The receiver clock bias (in seconds) multiplied by the speed of light as reported by the DDMI at pvt_timestamp_utc, in meters. | meter | float | -9999 | N/A | 1 | N/A |
| rx_clk_bias_rate | The receiver clock bias rate (in seconds/second) multiplied by the speed of light as reported by the DDMI, interpolated to ddm_timestamp_utc, in m/s. | meter s-1 | float | -9999 | N/A | 1 | N/A |
| rx_clk_bias_rate_pvt | The receiver clock bias rate (in seconds/second) multiplied by the speed of light as reported by the DDMI, at pvt_timestamp_utc, in m/s. | meter s-1 | float | -9999 | N/A | 1 | N/A |
| rx_clk_doppler | TBD | N/A | float | -9999 | N/A | 1 | N/A |
| rx_to_sp_range | The distance between the CYGNSS spacecraft and the specular point, in meters, at ddm_timestamp_utc. | meter | int | -9999 | N/A | 1 | N/A |
| sample | The netCDF coordinate variable associated with the sample dimension, which enumerates the zero-justified index range of the DDM time instants contained in the file. | 1 | int | N/A | N/A | 1 | N/A |
| sc_alt | Spacecraft altitude above WGS-84 ellipsoid, in meters, at ddm_timestamp_utc | meter | int | -9999 | N/A | 1 | N/A |