The CYGNSS Level 1 Calibration Algorithm and Error Analysis Based on On-Orbit Measurements

The calibration algorithm used by the Cyclone Global Navigation Satellite System (CYGNSS) mission to produce version 2.1 of its Level 1 (L1) science data products is described. Changes and improvements have been made to the algorithm, relative to earlier versions, based on the first year of on-orbit result. The L1 calibration consists of two parts: first, the Level 1a (L1a) calibration converts the raw Level 0 delay Doppler maps (DDMs) of processed counts into received power in units of watts. Second, the L1a DDMs are then converted to Level 1b DDMs of bistatic radar cross section values by unwrapping the forward scattering model, which are then normalized by the surface scattering area to arrive an observation of $ \sigma _0$. An update to the bottom up term-by-term error analysis is also presented, using on-orbit results to better quantify the accuracy of the rolled-up L1 calibration. The error analysis considers uncertainties in all known input calibration parameters. Finally, a method for calibrating the time delay of CYGNSS measurements is presented.

[1]  James L. Garrison,et al.  Mediterranean Balloon Experiment: ocean wind speed sensing from the stratosphere, using GPS reflections , 2003 .

[2]  Tianlin Wang,et al.  Design and Performance of a GPS Constellation Power Monitor System for Improved CYGNSS L1B Calibration , 2019, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

[3]  Christopher S. Ruf,et al.  Assessment of CYGNSS Wind Speed Retrieval Uncertainty , 2019, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

[4]  Shuanggen Jin,et al.  GNSS Remote Sensing: Theory, Methods and Applications , 2013 .

[5]  Kamal Sarabandi,et al.  Microwave Radar and Radiometric Remote Sensing , 2013 .

[6]  Christopher Ruf,et al.  Calibration and Unwrapping of the Normalized Scattering Cross Section for the Cyclone Global Navigation Satellite System , 2016, IEEE Transactions on Geoscience and Remote Sensing.

[7]  Scott Gleason,et al.  Fading statistics and sensing accuracy of ocean scattered GNSS and altimetry signals , 2010 .

[8]  F. Soulat,et al.  Sea surface remote sensing with gnss and sunligth reflections , 2004 .

[9]  M. Kayton,et al.  Global positioning system: signals, measurements, and performance [Book Review] , 2002, IEEE Aerospace and Electronic Systems Magazine.

[10]  Philip Jales,et al.  Spaceborne Receiver Design For Scatterometric GNSS Reflectometry. , 2012 .

[11]  Scott Gleason,et al.  Space-Based GNSS Scatterometry: Ocean Wind Sensing Using an Empirically Calibrated Model , 2013, IEEE Transactions on Geoscience and Remote Sensing.

[12]  Carmela Galdi,et al.  Analysis of GNSS‐R delay‐Doppler maps from the UK‐DMC satellite over the ocean , 2009 .

[13]  Stephen J. Katzberg,et al.  Comparison of reflected GPS wind speed retrievals with dropsondes in tropical cyclones , 2009 .

[14]  Yoaz E. Bar-Sever,et al.  A new model for GPS yaw attitude , 1996 .

[15]  Michael James Armatys.  Estimation of sea surface winds using reflected GPS signals , 2001 .

[16]  J. Garrison,et al.  Effect of sea roughness on bistatically scattered range coded signals from the Global Positioning System , 1998 .

[17]  S. Gleason,et al.  Remote sensing of ocean, ice and land surfaces using bistatically scattered GNSS signals from low Earth orbit , 2006 .

[18]  Martin Unwin,et al.  Detection and Processing of bistatically reflected GPS signals from low Earth orbit for the purpose of ocean remote sensing , 2005, IEEE Transactions on Geoscience and Remote Sensing.

[19]  James L. Garrison,et al.  GPS Signal Scattering from Sea Surface: Wind Speed Retrieval Using Experimental Data and Theoretical Model , 2000 .

[20]  R. Cordey,et al.  Multistatic Scatterometry , 1988, International Geoscience and Remote Sensing Symposium, 'Remote Sensing: Moving Toward the 21st Century'..

[21]  Randall Rose,et al.  New Ocean Winds Satellite Mission to Probe Hurricanes and Tropical Convection , 2016 .

[22]  Christopher Ruf,et al.  TOPEX/Poseidon Microwave Radiometer (TMR). II. Antenna pattern correction and brightness temperature algorithm , 1993, IEEE Trans. Geosci. Remote. Sens..

[23]  Valery U. Zavorotny,et al.  Scattering of GPS signals from the ocean with wind remote sensing application , 2000, IEEE Trans. Geosci. Remote. Sens..

[24]  Bertrand Chapron,et al.  The Eddy Experiment II: GNSS-R speculometry for directional sea-roughness retrieval from low aircraft , 2004 .

[25]  Philip Jales,et al.  Implementing GNSS-Reflectometry in Space on the TechDemoSat-1 Mission , 2014 .

[26]  Cinzia Zuffada,et al.  First spaceborne observation of an Earth‐reflected GPS signal , 2002 .

[27]  Adriano Camps,et al.  Tutorial on Remote Sensing Using GNSS Bistatic Radar of Opportunity , 2014, IEEE Geoscience and Remote Sensing Magazine.

[28]  M. Martín-Neira.  A pasive reflectometry and interferometry system (PARIS) application to ocean altimetry , 1993 .