© 2017 The Aerospace Corporation

COSMIC-2 Space Weather Cal/Val Plans

Lynette GelinasPaul Straus

The Aerospace Corporation

September 25, 2017

2

• Overview of CalVal Objectives• Description of instruments and Space Weather data products• CalVal schedule• CalVal efforts for each instrument• Ground truth and higher-order products

Space Weather CalVal plansOutline

3

Cal/Val Objectives

• General focus: Establish the COSMIC-2 sensor products are ready for operational use by both USAF & NOAA– NOAA is lead for TGRS terrestrial weather productsØ SMC/RSFW is lead for COSMIC-2 Space Weather products

• Calibration: Determine constants needed for accurate sensor data analysis• Validation: Assess Environmental Data Records (EDRs) to establish accuracy (e.g.,

via ground truth comparisons & sanity checks)• Two space weather mission areas are addressed by COSMIC-2

– Ionospheric specification (e.g., TEC, ne via GAIM)– Ionospheric scintillation specification & prediction (e.g., via SNFT)– IVM provides key data that is helpful to both mission areas

• Perform analyses needed to “blaze the trail” for full operationalization of COSMIC-2 data– Some COSMIC-2 products are already in use via the COSMIC-1 or DMSP programs and will

easily be transitioned to operations (e.g., RO limb TEC, IVM ne)– Others require some additional work prior to ingest into operational models (e.g., IVM drifts,

RO scintillation)

4

• Measurements will be made at both the L1 & L2 frequencies (but, for GPS satellites, L2 measurements are independent of L1 only if the GPS satellite transmits the L2C code)

• S4 (accurately) computed on-board for all GNSS satellite tracks from 50 Hz SNR data (10 second cadence)

• For occultation profiles having S4 greater than a programmable threshold, the underlying 50 Hz SNR & carrier phase observations will be downlinked

• TEC– Measurement Range: 0 to 2000 TECu– Measurement Uncertainty 0.3 TECu (relative)/3

TECu (absolute)• Scintillation

– S4 Measurement Range: 0 to 1.5– S4 Measurement Uncertainty: 0.1– σφ Measurement Range: 0 to 20 radians– σφ Measurement Uncertainty: 0.1 radians

TGRSInstrument description and EDRs

RO Antennas

POD Antennas

Electronics

TGRS pictures courtesy JPL

5

• Tones transmitted at 3 frequencies: 400 MHz, 965 MHz, 2200 MHz

• Spread spectrum “channel probe” also transmitted at 395 MHz (presently not a focus of Cal/Val)

• Receivers • TEC

– Measurement Range: 0 to 200 TECu– Measurement Uncertainty (relative) 0.01

TECu• Scintillation (similar to TGRS)

– S4 Measurement Range: 0 to 1.5– S4 Measurement Uncertainty: 0.1– σφ Measurement Range: 0 to 20 radians– σφ Measurement Uncertainty: 0.1 radians– S4/σφ reporting cadence of 10 seconds

RF BeaconInstrument description and EDRs

Beacon Electronics Unit

Antenna Unit

RF Beacon drawing/picture courtesy SRI

RF Beacon Ground Sites*

*RFBRs to be fielded at 6-10 ISTO sites

6

• RPA and DM measure cross-track and in-track plasma drifts– RPA/DM require O+ dominant ion accuracy– Works best at final altitude

• EDRs:– Plasma drifts

• In-track accuracy/precision: ±10 m/s & ±5 m/s• Cross-track accuracy/precision: ±5 m/s & ±1

m/s– In-situ plasma density

• Range: 103 – 5x106 /cc• Accuracy/precision: 5%,1%

– In-situ ion composition:• O+, H+, He+

• Accuracy/precision: 5%, 5%• In-situ ion temperature:

– Range: 500-10,000K– Accuracy/precision: 10%, 5%

IVMInstrument description and EDRs

IVM image courtesy UTD

Differential precession for separation of COSMIC-2 orbit planes takes ~18 months

7

Sensor & S/C CheckoutS/C #1 at 550 kmS/C #2 at 550 kmS/C #3 at 550 kmS/C #4 at 550 kmS/C #5 at 550 kmS/C #6 at 550 km

TGRSBias determinationMultipath mappingTEC sanity checksScintillation assessmentUpward TEC assessment

IVMInitial CalibrationFinal CalibrationModel/radar comparisonsE-field/bubble model

RF BeaconRFBR fieldingAntenna mappingRadar comparisonsGround truth for TGRS

“Ground” Truth CollectionALTAIRJicamarca

L+2m L+10m L+22mL+6m L+14m

Draft COSMIC-2 Space Weather Cal/Val ScheduleLaunch L+18m

Limb TEC

7

Zenith TEC#1 #2-6

#1 #2 #3 #4 #5 #6

E-fields & “Bubble Map”

Density

TEC/Scintillation

Scintillation

?* ?*

*Dependent on time between launch & “scintillation season”

HR Alg. Eval.

8

Space Weather Cal/Val Participants (Preliminary)Organization Roles & ResponsibilitiesThe Aerospace Corporation • Technical Lead for USAF

• EDR analysis & multi-s/c algorithmsUCAR • TGRS/IVM data processing

• TGRS multipath analysis• TGRS TEC performance analysis

JPL • TGRS sensor support

UTD • IVM sensor support• IVM calibration, EDR analysis & multi-s/c algorithms

SRI • RF Beacon sensor support

NSPO/SSTL • COSMIC-2 spacecraft support

Air Force Research Lab (AFRL) • Scintillation (TGRS/Beacon) & IVM EDR analysis

Space Dynamics Lab (SDL) • RF Beacon Receiver performance evaluation

Boston College • Scintillation & TEC (TGRS/Beacon) modeling & EDR analysis

NOAA Space Weather Prediction Center (SPWC)

• Model utility studies (TGRS/IVM)

TBD • Ground truth data liaison

9

TGRSCalVal Tasks Sample Single Orbit Coverage (C/NOFS)

C/NOFS Orbit

Scintillation RegionsDay NightIonosphericOccultations

• Absolute/relative TEC– L1/L2 differential bias determination– Multipath corrections to reduce

leveling errors– Comparisons to models & ground

GPS/ionosondes– Altair radar comparisons?– Upward looking TEC ingest into

GAIM• Scintillation

– ISTO/Altair radar/other comparisons – Use of limb measurements in SNFT– Localization of scintillation regions (w/

IVM)– RF Beacon provides ground truth

0

400A

ltitu

de (k

m)

Electron Density

800

Scintillation

S4

Graphic courtesy AFRL

10

• Temporary RFBR fielding (delays in fielding of operational sensors at ISTO sites)– Seasonal considerations

• Performance vs. elevation angle (antenna pattern mapping)

• ISTO sensor & ISR comparisons• Corrections for LEO satellite Doppler• Ingest into SNFT model• Improved operational support for “non-

traditional” end users (i.e., going beyond S4)

RF BeaconCalVal Tasks

Beacon Data

Graphic courtesy AFRL

11

IVM Cal/Val Tasks/IssuesCalVal Tasks

SatCom/GPSSatellite

Receiver

Irregularitiesin Ionosphere

Plasma Density Fluctuations• IVM calibration

• Assess proper grid biases for operations • Performed at parking & final s/c altitudes• Long term trending for correction to

aging of electronics• COSMIC-2 s/c attitude knowledge

• Key factor in accuracy of drifts • Sanity checks to look for biases (orbit-

averaged vertical drift ~0 m/s) • Inter-s/c comparisons Calibration of IVM

electronics• Cannot complete analysis until satellites

are at final altitude• Comparisons to models/ISRs• Development of bubble/equatorial

electric field model for use in GAIM/SNFT

Scintillation,comm dropouts,GPS loss of lock

Graphics courtesy AFRL

12

Ground Truth

• Incoherent scatter radars (ISRs) will provide the primary ground truth for Cal/Val– Accurate scintillation/TEC data on “COSMIC-2 to ground” & occultation signal paths– Also measures plasma density & Electric Fields for IVM validation

• Augment ISRs w/ RF Beacon receivers (once validated) & other scintillation sensors

• Modeling will also be used to sanity check products

Graphic shows sample RO/ISR comparison from C/NOFS mission

Occultation TP Track

CORISSSNR

21 Apr 2009 10:09 UT

Lines of sight

C/NOFS Orbital Track

ALTAIR data sample courtesy AFRL/Boston College

13

Generation of Important Higher Level Products

• First principle ionospheric models need key physical drivers that may be comprehensively measured for the first time by COSMIC-2 – Map of instability regions to enable

assessment of where small scale physics becomes important (“bubble map”)

– Equatorial electric fields provide a critical driving force/model self-consistency check

• IVM measurements provide insight into both– Bubble mapping limited to regions where

bubbles rise up to COSMIC-2 altitude (a function of apex altitude or magnetic latitude)

– Will likely need to augment with TGRS observations of scintillation to achieve good equatorial refresh at solar minimum

– Plasma drift data from 6 COSMIC-2 s/c will allow deconvolution of large scale temporal & spatial effects• As with bubbles, E-fields can be extrapolated

along magnetic field lines

Cal/Val effort will initiate development of multi-s/c algorithms needed for science/operational models

In-situ Measurements Within ±20° Magnetic Latitude

Bubble Map Refresh Time

15-30 minute scintillation evolution time scale

14

• COSMIC-2 Space Weather CalVal planning draws from COSMIC, DMSP experience– TEC: data products validated for ingestion in operational models (GAIM)– Scintillation: end-use applications assessment in addition to validation of EDRs

• Consider usage of COSMIC-2 data in higher-level SpWx models:– Map of instability regions to enable assessment of where small scale physics

becomes important (“bubble map”)– Equatorial electric fields provide a critical driving force/model self-consistency check

• Next steps – detailed plan development:– Ionospheric density and TEC

• TGRS & IVM products– Scintillation:

• Establish draft plans for RF Beacon (scintillation & TEC) & TGRS (scintillation) product validation

• Discuss paths forward to operational use of COSMIC-2 data for scintillation support

Summary