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 Originally made up of a constellation of eight micro-satellites, the observatories provide nearly gap-free Earth coverage using an orbital inclination of approximately 35°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.
Product Summary
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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 |
|---|---|---|---|---|---|---|---|
| srtm_dem_alt | Altitude interploated from a 1 km (0.0083 x 0.0083 degree) resolution SRTM DEM. | meter | float | -9999 | N/A | 1 | N/A |
| srtm_slope | Slope interploated from a 1 km (0.0083 x 0.0083 degree) resolution SRTM DEM slope. | degree | float | -9999 | N/A | 1 | N/A |
| starboard_gain_setting | The Nadir-Starboard Gain Setting (dB, 0=Automatic) | dB | int | -9999 | N/A | 1 | N/A |
| static_gps_eirp | Heritage version of gps_eirp (v2.1 and earlier) that assumed a static value for the power level of the L1 signal transmitted by the GPS satellite, prior to implementation of dynamic gps_eirp monitoring in August 2018. | watt | float | -9999 | N/A | 1 | N/A |
| status_flags_one_hz | One Hz status flags. These flags apply to all four DDMs. 1 indicates presence of condition. Flag masks: 1 = Milky way in zenith antenna field of view 2 = Sun in zenith antenna field of view 4 = Sub-satellite point over open ocean 8 = Sub-satellite point latitude ascending, i.e. sc_lat has increased since the previous DDM sample | N/A | int | -9999 | N/A | 1 | N/A |
| surface_water_percentage | Percentage of surface water referenced from the nearest 1km by 1km Pekel (2018 Global Surface Water Explorer) grid cell. | percent | byte | -99 | N/A | 1 | N/A |
| sv_num | The GPS unique space vehicle number that transmitted prn_code. | 1 | int | -9999 | N/A | 1 | N/A |
| track_id | A track is a temporally contiguous series of DDMs that have the same prn_code. Each track in the file is assigned a unique track_id starting with one. track_id ranges from 1 to N, where N is the total number of tracks in the file. | 1 | int | -9999 | N/A | 1 | N/A |
| tx_clk_bias | The GPS spacecraft (sv_num) clock time minus GPS constellation time (in seconds) times the speed of light, in meters. | meter | float | -9999 | N/A | 1 | N/A |
| tx_pos_x | The X component of the GPS spacecraft WGS84 reference frame ECEF position, in meters, at ddm_timestamp_utc | meter | int | -99999999 | N/A | 1 | N/A |
| tx_pos_y | The Y component of the GPS spacecraft WGS84 reference frame ECEF position, in meters, at ddm_timestamp_utc | meter | int | -99999999 | N/A | 1 | N/A |
| tx_pos_z | The Z component of the GPS spacecraft WGS84 reference frame ECEF position, in meters, at ddm_timestamp_utc | meter | int | -99999999 | N/A | 1 | N/A |
| tx_to_sp_range | The distance between the GPS satellite and the specular point, in meters, at ddm_timestamp_utc. | meter | int | -9999 | N/A | 1 | N/A |
| tx_vel_x | The X component of the GPS spacecraft WGS84 reference frame ECEF velocity in meters, at ddm_timestamp_utc | meter s-1 | int | -9999 | N/A | 1 | N/A |
| tx_vel_y | The Y component of the GPS spacecraft WGS84 reference frame ECEF velocity in meters, at ddm_timestamp_utc | meter s-1 | int | -9999 | N/A | 1 | N/A |
| tx_vel_z | The Z component of the GPS spacecraft WGS84 reference frame ECEF velocity in meters, at ddm_timestamp_utc | meter s-1 | int | -9999 | N/A | 1 | N/A |
| zenith_code_phase | The DDMI-measured code phase of the direct GPS signal for prn_code interpolated to ddm_timestamp_utc. 0 <= zenith_code_phase < 1023.0. | 1 | float | -9999 | N/A | 1 | N/A |
| zenith_sig_i2q2 | Raw counts of detected power in direct GPS L1 C/A signal received by zenith navigation antenna and detected by navigation receiver. | 1 | float | -9999 | N/A | 1 | N/A |
| zenith_sig_i2q2_add_correction | The additive correction factor applied with zenith_sig_i2q2_corrected = 10*log10(zenith_sig_i2q2*zenith_sig_i2q2_mult_correction)-zenith_sig_i2q2_add_correction. | 1 | float | -9999 | N/A | 1 | N/A |
| zenith_sig_i2q2_corrected | The zenith_sig_i2q2 after a correction factor, based on the zenith antenna bin ratio, has been applied. | 1 | float | -9999 | N/A | 1 | N/A |
| zenith_sig_i2q2_mult_correction | The multiplicative correction factor applied with zenith_sig_i2q2_corrected = 10*log10(zenith_sig_i2q2*zenith_sig_i2q2_mult_correction)-zenith_sig_i2q2_add_correction. | 1 | float | -9999 | N/A | 1 | N/A |