GNSS Remote Sensing:Overview and selected recent developments - Jens Wickert C. Arras, M. Asgarimehr, E. Cardellach, G. Dick, S. Healy
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
GNSS Remote Sensing:Overview
and selected recent developments
Jens Wickert
C. Arras, M. Asgarimehr, E. Cardellach, G. Dick, S. Healy,
A. Kepkar, K. Lonitz, B. Männel, D. Masters,
T. Schmidt, M. Unwin, F. Zus
J. Wickert, IROWG8
1 April 7, 2021
From Errors to Signals Derivation of
GNSS Remote Sensing • Temperature and water vapor
• Water, ice and land surface properties
• Water vapor
• Electron density
Unique properties (all-weather, long-term stable, high
spatiotemporal resolution, cost effective)
J. Wickert, IROWG8
2 April 7, 2021
GNSS Observation Infrastructure
(Observation on different scales in space and time feasible)
GLONASS
GPS QZSS BeiDou
Galileo
FY3-C/D TerraSAR-X Metop A/B/C
COSMIC-1 (6) TanDEM-X
COSMIC-2 (6)
Mini satellites &
constellations GRACE-FO
LEMUR (~100)
Airships,
Aircrafts
(HALO)
Global and
GEROS-ISS regional GNSS
ground networks
CYGNSS (8)
Ships (e.g. Mozaic)
J. Wickert, IROWG8
3 April 7, 2021
Ground-based
GNSS Atmosphere Sounding
J. Wickert, IROWG8
4 April 7, 2021
Zenith/Slant Total Delay (ZTD, STD)
Integrated Water Vapor (IWV)
Total Electron Content (VTEC/STEC)
IWV
ZTD
VTEC
e-
O
H H
STD
STEC
J. Wickert, IROWG8
5 April 7, 2021
Operational ZTD/IWV/STD Monitoring at GFZ
• ~600 stations globally
ZTD
• ~300 in Germany IWV
• Operational delay
Next Generation Data Products
• DFG Project (started 01/2020): “Advanced MUlti-GNSS Array for Monitoring
Severe Weather Events (AMUSE)”
GNSS Weather model
Water vapour
gradients are
indicators for Cells of strong
weather front precipitation
• DFG Project (start in 2021): “Exploitation of GNSS Tropospheric Gradients for
Severe Weather Monitoring And Prediction (EGMAP)”
Wickert 2019/2020, DFG proposals
J. Wickert, IROWG8
7 April 7, 2021
Reference Upper Air Network
• Lead centre: DWD,
Germany
• GFZ is central GNSS
processing centre and
hardware provider since
2014
GNSS is priority one instrument
e.g., Ny Ålesund
Currently 30 stations (12/3 with GNSS)
www.gruan.org
J. Wickert, IROWG8
8 April 7, 2021
Ionospheric Perturbation above Germany
MediumScaleTravellingIonosphericDisturbance event
September 27, 2009 (~300 stations)
East to West, l~ 302 km, period ∼7 min, v~700 m/s
Deng et al., 2013
J. Wickert, IROWG8
9 April 7, 2021
IGS Product: Global Ionospheric Maps from GNSS
• Data from ~250 stations
• Multi-GNSS supported (GPS, GLONASS, Galileo, BeiDou, QZSS)
• Pre-operational maps (08:00 UTC)
• Day with moderate ionospheric activity (left)
• During the St. Patrick’s day geomagnetic storm (right)
Wickert et al., 2020
J. Wickert, IROWG8
10 April 7, 2021Satellite-based
GNSS Atmosphere Sounding:
Radio Occultation
J. Wickert, IROWG8
11 April 7, 2021Operational GNSS-RO Data from GFZ
S
l
i
d
e
to Improve Global Weather Forecasts
1
2
TerraSAR-X
TanDEM-X
Precondition: Development and operation of complex Infrastructure
inclusive of dedicated scientific analysis software
J. Wickert, IROWG8
12 April 7, 2021Operational GNSS-RO from GFZ (best effort)
TerraSAR-X TanDEM-X GRACE-FO
(since 2007) (since 2010) (since 2021)
NRT monitoring by ROM SAF @ MetOffice, Sat. April 4, 2021
TerraSAR-X: Average delay: 1h59
J. Wickert, IROWG8
13 April 7, 2021GRACE – Follow On
Launch of a Falcon 9 rocket
GPS-RO antenna
The U.S./German Mission GRACE-FO
was launched May 19, 2018
German Co-PI: F. Flechtner (GFZ)
J. Wickert, IROWG8
14 April 7, 2021GRACE-FO Initial Results
July 1, 2020, 286 occultations
• Multiple carrier frequencies: L1, L2C, L5
• Occultations in polar regions
• Operational test data provision already started
J. Wickert, IROWG8
15 April 7, 2021GRACE-FO: Comparison with COSMIC-2
Co-located COSMIC-2 NRT data
(Dd≤300 km, DT≤3 hrs), 1 Jan – 28 Feb 2021
Fractional refractivity (GRFO-COSMIC2)/COSMIC2
Details: T. Schmidt, Monday, April 12, 09:35
J. Wickert, IROWG8
16 April 7, 2021Ionosphere: Vertical Electron Density Profiles
and Detection of Disturbances
Year – 2014
Day of Year - 24
UT – 08:53 hrs
Plasma
Bubbles
(F-Layer)
Sporadic
(E-Layer)
• Relevant for navigation and communication
• Studies of atmospheric coupling processes
J. Wickert, IROWG8
17 April 7, 2021Global Distribution of Sporadic E-Layers
2007-2019, 5⁰x5⁰ resolution, COSMIC-1 data
Important phenomenon:
~50% occurrence frequency
JJA DJF
• Several DFG research projects
• Provision of extensive data set to NASA (Prof. Bilitza) in 2020
for inclusion to the International Reference Ionosphere
J. Wickert, IROWG8
18 April 7, 2021Equatorial Plasma Bubbles
Global distribution 2009 Global distribution 2014
Occurrence % [20o lon x 5o lat]
8
7
6
Latitude [o]
5
4
3
2
Longitude [o] Longitude [o]
Altitude distribution 2009 Altitude distribution 2014
600 600 15
Occurrence % [5o lat x 15 km alt]
450 450 10
Altitude [km]
300 300 5
150 150 0
-50 -25 0 25 50 -50 -25 0 25 50
Latitude [o] Latitude [o] Kepkar et al., 2020
J. Wickert, IROWG8
19 April 7, 2021GNSS Reflectometry:
Complementary Observations
to GNSS RO
J. Wickert, IROWG8
20 April 7, 2021GNSS Reflectometry
GNSS • Multistatic radar
• Transmitters ~120,
GNSS signals „free of
charge“
GNSS
Receiver
• High rain
transmissivity
GNSS
• Reflections over
oceans, land, ice,
glistening zone snow
specular point
J. Wickert, IROWG8
21 April 7, 2021GNSS Reflectometry: Versatile Earth Observation
Ionosphere
Weather and
Wind, humidity, Space Weather
precipitation, … Electron density
Climate
Sea level, sea
ice, salinity, …
Disasters
Tsunamis,
flooding,
Land surfaces hurricanes, ...
Soil moisture,
biomass, snow, ... Infrastructure
Ship monitoring
Wickert et al., EU report GfG², 2012
J. Wickert, IROWG8
22 April 7, 2021Soil Moisture Snow Height Sea Level
Sutherland, South Africa Wettzell, Germany Kachemark Bay, Alaska
Precipitation events GNSS vs. ultra sonic sensor Nine meters
and evapotranspiration RMSE 1.7 cm tide amplitude
well visible Photo: K.Larson
Vey et al., 2016 Vey et al., 2016 Thanks K. Larson
J. Wickert, IROWG8
23 April 7, 2021Selected current GNSS-R missions
CYGNSS (8, since 2016) TDS-1 (since 2014)
LEMUR (100+ in Orbit) FY-3E (launch 2021) PRETTY (launch 2022)
Photo: K.Larson
J. Wickert, IROWG8
24 April 7, 2021CYGNSS: Global wind speed with AI
October 2018 – February 2019
Conventional method
CyGNSSnet CyGNSS Level 2
Average
Wind Speed
Bias
RMSE
The best quality of global wind products so far:
RMSE of 1.4 m/s using deep learning over a test dataset
Asgarimehr et al., 2021
J. Wickert, IROWG8
25 April 7, 2021GNSS-R can detect precipitation over oceans
GN
SS
Si
gn
als
Average bistatic radar cross section
versus wind speed at different rain
rates (RR).
Considerable splash effect at winds lower than 6 m/s
Asgarimehr et al., 2018
J. Wickert, IROWG8
April 7, 2021Rain – dual polarization observations
Onsala Space Observatory
Rain signatures in polarimetric measurent at low winds –
proof of concept for future space missions
Asgarimehr et al., 2021
J. Wickert, IROWG8
27 April 7, 2021HydroGNSS:
A new ESA mission
for GNSS reflectometry
(provided by M. Unwin/E. Cardellach)
J. Wickert, IROWG8
28 April 7, 2021HydroGNSS
• Presence of water over land impacts weather, climate,
ecosystems, human welfare and agriculture
– Water systems currently inadequately
measured
– Global Climate Observing System
requiring better measurements
– Special needs at higher latitudes incl.
permafrost, biomass
NASA SMAP
– Vital SMOS and SMAP L-Band missions L-Band Passive
have no immediate successors
• HydroGNSS to sense 4 ECVs NASA SMAP
L-Band Active
– Soil Moisture
– Inundation / wetlands
– Freeze / Thaw state
– Biomass NASA CYGNSS
L-Band GNSS-R
• ESA Scout opportunity
– Science driven mini-Explorer Satellite observations of streams and tributaries
– HydroGNSS selected to proceed across the Amazon basin (Chew et al. 2018)
J. Wickert, IROWG8
29 April 7, 2021HydroGNSS Instrument & Mission
Innovative GNSS-R measurements
• New GNSS-R Instrument (based on TDS-1/CYGNSS)
• Multi-GNSS reception, including Galileo and GPS
• Left and Right Polarisation DDMs
– Mitigation of vegetation and soil roughness
• Higher rate coherent complex channel
– Separation of diffuse / coherent terms
– Fine scale mapping over wetlands, rivers,
• Dual frequency L1/E1 and L5/E5
Platform Constellation
• 1 or 2 satellites
• SSTL-21, 40 kg, 5 year life target • Global coverage every 15 days
• More frequent at high latitudes
• Up to 160 Mbps X-band downlink via Svalbard • Suitable for upscaling to larger
(12+) constellation to achieve
• Payload Data Ground Segment built upon daily coverage
www.merrbys.org
J. Wickert, IROWG8
30 April 7, 2021Slide 31
Selected future
Developments
J. Wickert, IROWG8
31 April 7, 2021More than 18,000 GNSS Stations Globally
(as of 12.01.2021)
• Station positions, velocities, IWV
• TEC feasible (not yet provided)
Thanks J. Blewitt, geodesy.unr.edu
J. Wickert, IROWG8
32 April 7, 2021COSMIC-2 Launch June 25, 2019 Falcon Heavy
• Tracking GPS, GLONASS, and Galileo
• 6 satellites in low inclination orbit (24o at 520 km)
• > 8,000 RO soundings per day
Thanks B. Schreiner (UCAR)
J. Wickert, IROWG8
33 April 7, 2021Commercial RO becomes reality
• Spire operates the third largest
constellation of satellites (100+)
• Established company with 250
people (growing) across six offices
• Spire first commercial company
collecting RO data, 20+ launch
campaigns, 30+ ground stations
• Two talks (D. Masters, V. Nguyen)
• Two posters (V. Irisov, V. Nguyen)
J. Wickert, IROWG8
34 April 7, 2021Spire Earth Observation with GNSS
• Atmosphere sounding (NWP, Climate)
• Ionosphere sounding for Space Weather
• Thermosphere density, gravity through POD
• Scatterometry (soil moisture, ocean winds, sea ice)
• Grazing angle altimetry with RO satellites
J. Wickert, IROWG8
35 April 7, 2021Integrated measure of 24 hour forecast
impact: time series in 2020
• Spire provided RO data to
ECMWF, UK MetOffice,
U.S. Air Force during
Covid19 to compensate GPSRO
for lack of aircraft
measurements
• ECMWF saw significant
increase in relative
forecast sensitvity to
observation impact (FSOI)
when COSMIC-2 was
assimilated in 2020 and
again when Spire RO were
assimilated in May Spire May 13 (10%-14%)
COSMIC-2 March 25 (4%-10%)
J. Wickert, IROWG8 36
36 April 7, 2021Spire Batch-2 GNSS-R mission 2021
• Two satellites already launched in January 2021
• Going operational later this year
J. Wickert, IROWG8
37 April 7, 2021Ionosphere monitoring using GNSS-R
Initial idea already in 1996
(Katzberg/Garrison)
August 24, 2017, 00:00-24:00 UTC
S4 index from
CYGNSS with
corresponding
SWARM plasma
density
observations
(NNeFI)
much more data
from CYGNSS
Recent pioneering study for ionosphere monitoring over oceans
Plasma Bubbles on the signal path after reflection over calm sea
Molina/Camps, 2020
J. Wickert, IROWG8
38 April 7, 2021ESA Small Satellite PRETTY
Antenna Array:
• Cubesat 10/10/30cm³ (lead RUAG) 8 segments, L1, RHCP, 16 db
• GNSS Reflectometry
• Space Weather Payload
RadFET Dosimeter
• Launch planned for 2022
FloatingGate
• GNSS-R Science Team Dosimeter
Uni Trondheim, DLR, GFZ, IEEC
+ Particle Detection
J. Wickert, IROWG8
39 April 7, 2021ATMOSAT: New Mission with RO
• Improvement of regional climate and
mid term weather prediction
• KIT/FZJ leading, GFZ contributing
• Proposed 2016 within large research
structure investments in Germany
(>50 Mio€)
• Scientific evaluation with highest
possible result (2017), not yet funded
• Key payload: GLORIA (3D atmosphere
mapping); GFZ: TriG RO receiver
(Atmosphere/Ionosphere,
Reflectometry)
• Recent activities to prepare iterated TriG RO receiver
proposal
J. Wickert, IROWG8
40 April 7, 2021Galileo: Next Generations
• GNSS Science Advisory Board
(J. Wickert member since 2021)
• Scientific exploitation of GNSS
for Earth, navigational and
physical sciences Inter-satellite links
between MEO-LEO
and LEO-LEO
• GNSS policy in Europe
• Future missions and new projects (calls, ITT), workshops
• Selected aspects under investigation: intersatellite links,
inclusion of LEOs, ionosphere correction/sounding,
additional payloads (accelerometers),
Kepler concept (Günther et al.) with optical links
J. Wickert, IROWG8 41
April 7, 2021Conclusions and Outlook
• Overview on selected GNSS remote sensing activities with focus
on satellite based activities was given
• Ground based atmosphere sounding is operationally applied for
weather forecast and part of the Global Climate Observing
system, operational TEC observations provided
• Selected recent GNSS RO activities from GFZ reviewed, e.g.
GRACE-FO, ionospheric irregularities (sporadic E, EPB)
• GNSS reflectometry introduced as synertgetic complement to RO
and novel and versatile Earth Observation technique with
examples
• Selected new developments in GNSS Earth Observation/Remote
Sensing and missions ideas briefly introduced (e.g.
HydroGNSS, Spire small satellites)
J. Wickert, IROWG8
42 April 7, 2021Thank you !
Geodetic Institute, GFZ
J. Wickert, IROWG8
43 April 7, 2021You can also read
