Bill Schreiner and UCAR/COSMIC Team UCAR COSMIC Program Observation and Analysis Opportunities Collaborating with the ICON and GOLD Missions Sept 27, 216 GPS RO Overview Outline COSMIC Overview COSMIC-2 Overview Summary 2 1
9/29/16 GPS Radio Occultation GPS RO is a new method (first demonstrated in 1995 by UCAR) for performing atmospheric measurements on Earth. As a satellite in low-earth orbit carrying a radio receiver passes behind Earth, the radio waves for two L-band frequencies (L1 and L2) from a GPS satellite pass through the atmosphere and are slowed and bent along the way. α The amount of bending, depends on the temperature and water vapor in the lower atmosphere and the electron density in the ionosphere. 3 GNSS Remote Sensing of the Ionosphere Ground-based Remote Sensing of Ionosphere Space-based Remote Sensing of Ionosphere Ionosphere TEC2 TEC1 TEC = Total Electron Content (Total Number Of Electrons in column between transmitter and receiver) TEC3 Determine: Number of electrons above receiver 4 2
9/29/16 COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) US/Taiwan Collaboration 6 Satellites launched in April 26 Three instruments: GPS receiver, TIP, Tri-band beacon Weather + Space Weather data Global observations of: Bending angle, Refractivity Pressure, Temperature, Humidity Ionospheric Total Electron Content (TEC) and Electron Density Ionospheric Scintillation Demonstrate quasi-operational GPS sounding with global coverage in near-real time BAMS, March 28 5 > 4.3 Million COSMIC Ionospheric Profiles 4/21/6 9/26/216 COSMIC: Two of six still operating ten years after launch (design life: 2-3 yr) COSMIC continues to provide up to 1, GPS Ionospheric RO soundings per day 6 3
Scientific Uses of Radio Occultation Data Weather Improve global weather analyses, particularly over data void regions such as the oceans, tropics, and polar regions Improve skill of numerical weather forecasts, including hurricanes Improve understanding of tropical, mid-latitude and polar weather systems and their interactions Ionosphere and Space Weather Observe global electronic density distribution Improve the analysis and prediction of space weather Improve monitoring/prediction of scintillation (e.g. equatorial plasma bubbles, sporadic E clouds) Climate Monitor climate change and variability with unprecedented accuracy - world s most accurate, precise, and stable thermometer from space! Evaluate global climate models and analyses Calibrate infrared and microwave sensors and retrieval algorithms 7 TEC Precision from Collocated Tracks COSMIC (26.23-245) COSMIC trans-ionospheric radio links for a 1-min period, June 29, 27 8 4
Ionosphere Reanalysis at UCAR/COSMIC - UCAR has developed an ionosphere reanalysis product - Uses a Kalman filter to assimilate ground and space based GNSS TEC. IRI is used as the background model [Yue et al., 212] - Grid dimensions are 1 h UT, 1-2 km altitude, 5 latitude, and 15 longitude - Result is a 4-dimensional monthly mean electron density reanalysis - Analysis results shown bottom left. - Comparison with independent ionosonde observations (NmF2) shown bottom right. - Monthly mean gridded electron densities will be available to the community via CDAAC (http://cdaacwww.cosmic.ucar.edu/cdaac/) within the next couple months. 2.5 Jicamarca (75W, 12S) UT = Rean Obs IRI Obs 2 1.5 MHz 1.5 1 2 3 4 5 6 7 8 9 1 11 12 Month 9 Ionosphere Variability During Sudden Stratosphere Warmings Sudden Stratosphere Warming (SSW): warming of the high-latitude winter stratosphere; associated with dramatic changes in temperatures and winds in the middle atmosphere at highlatitudes. SSWs are known to influence the low-latitude ionosphere COSMIC observations reveal F-region peak height (hmf2) variability occurs at mid to high latitudes in the Southern Hemisphere during SSWs. Model simulations reveal that mid-latitude variability is due to neutral winds which raise and lower the F-region peak height at mid-latitudes. Since no other observations provide the necessary global coverage, especially in the Southern Hemisphere, COSMIC data are critical for studying these perturbations. Mag. Latitude b. 6 4 2 2 4 COSMIC ΔhmF2, 12 LT COSMIC hmf2 12 LT SSW Peak 6 5 1 1 15 2 25 3 35 4 45 5 55 6 d. TIME GCM Day hmf2 of without Year, 29 lunar tide 12 LT 5 1 15 2 25 3 35 4 45 5 55 d. TIME GCM TIME-GCM U with ΔU lunar, 12 tide 12 LT LT 6 4 2 2 4 5 1 15 2 25 3 35 4 45 5 55 Day of Year, 29 U U V Equatorward wind in Southern Hemisphere will increase hmf2 4 2 2 4 km 15 1 5 5 1 15 m/s (Pedatella and Maute, 215) U Neutral wind U - Field-aligned wind V - Field-aligned plasma velocity 5
GPS L-band Scintillation 8 No scintillation 8 Scintillation To GPS ~4, km F Region LEO CASNR (Volts/Volt) 7 6 5 4 3 CASNR (Volts/Volt) 7 6 5 4 3 2 2 1 1 2 4 6 time (sec) 2 4 6 time (sec) Ionospheric irregularities cause rapid fluctuations in the amplitude and phase of GPS signals (scintillation) Where is the source region of the scintillation? Localize irregularities: [see Sokolovskiy et al., 22] The COSMIC-2/FORMOSAT-7 Partnership Organization Taiwan NSPO NOAA USAF Responsibilities 12 Spacecraft (From SSTL) Command & control (1 ground site) Secondary sensors for polar SVs Lead US agency COSMIC-2 ground sites TGRS ground processing TGRS sensors for polar SVs All sensors for equatorial SVs Launch RF Beacon ground system RF Beacon/IVM ground processing NASA TGRS TriG Electronics Development at JPL COSMIC-2/FORMOSAT-7 is jointly sponsored by NOAA and NSPO, as designated representatives of AIT and TECRO. 12 6
The COSMIC-2 Spacecraft IVM TGRS POD Antenna RF Beacon Antenna TGRS RO Antenna The COSMIC-2 spacecraft are being developed by Surrey Satellite Technologies Limited (SSTL) Under Contract to Taiwan s National Space Organization Graphic courtesy SSTL 13 12 satellites 6 launched into Equatorial orbit Q1 217 6 launched into polar orbit (not yet fully funded) TGRS GNSS RO Payloads JPL heritage GPS and GLONASS tracking TEC, electron density, and scintillation Ion Velocity Meter (IVM) Retarding Potential Analyzer (RPA) measures density, temperature, composition & in-track drift Ion Drift Meter (IDM) measures crosstrack drifts RF Beacon payloads Tones at 4 MHz, 965 MHz & 22 MHz TEC and scintillation COSMIC-2 Summary 1 st Launch 217 1 st and 2 nd Launch 14 7
9/29/16 COSMIC-2 SW Product Requirements Product Description Requirement UCAR/CDAAC* filename TGRS TEC arcs # of soundings/overhead arcs/day 1/COSMIC-2 satellite Level1b/podTc2 Absolute TEC 3 TECU Relative TEC.3 TECU TGRS Scintillation S4/σφ measurement uncertainty.1/.1 radians Level1a/scn1c2, Level1b/scnLv2, Level2/scnSpc IVM In-situ ion density accuracy 5% Level2/ivmLv2 In-track drift measurment accuracy ±1 m/s Cross-track drift measurement accuracy ±5 m/s RF Beacon Scintillation S4/σφ measurement uncertainty.1/.1 radians RF Beacon TEC Relative TEC.1 TECU TGRS & IVM Latency Median data latency 3 min * COSMIC Data Analysis and Archive Center, http://cdaac-www.cosmic.ucar.edu/cdaac/products.html 15 OSSE Study for COSMIC-2 (Yue et al., DOI:1.119/TGRS.213.2275753) ) Hourly RO Mean Nowcast Error Launch #1 Launch #2 Launches #1 & #2 16 8
Summary Radio Occultation is a proven high-impact and low-cost global observing system COSMIC data are useful to specify ionospheric electron density and its irregularities for space weather applications COSMIC-2 will provide IVM products and > 1, GNSS soundings/day/sc with 3 min median latency With COSMIC-2, an even greater impact is expected on weather, space weather, and climate applications 17 9