The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt
-
Upload
grssieee -
Category
Technology
-
view
479 -
download
1
Transcript of The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt
![Page 1: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/1.jpg)
July 27, 2011 1
The role of numerical weather models (NWM) in mitigation of tropospheric delay for SAR Interferometry
Shizhuo Liu1, Agnes Mika2, Wenyu Gong3, Franz Meyer3, Ramon Hanssen1, Don Morton3 and Peter Webley3
1 Delft institute of Earth Observation and Space Systems (DEOS), the Netherlands2 BMT AGROSS, the Netherlands3 University of Alaska Fairbanks, United States
Department of Earth Observation and Space Systems (DEOS), Aerospace engineering
InSAR WRF
![Page 2: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/2.jpg)
Delay observed by repeat-pass SAR Interferometry
07/27/11 2
€
Dp,qt1, t2 = Dp - Dq( )
t1- Dp - Dq( )
t2
• Temporal difference:
• Spatial difference:
€
DpDt = Dp
t1 - Dpt2
€
Dpq = Dp
t - Dqt
p q
t1 t2
observed delay: (spatio-temporal difference)
€
Dpt1
€
Dpt2
€
Dqt1
€
Dqt2
![Page 3: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/3.jpg)
Spatial characteristics of delay in InSAR
07/27/11 3
8 ERS1/2 tandem interferograms over Groningen, the Netherlands
a b c d
e f g h
trend: c, e, h
local anomaly: a, g
trend+anomaly: b, d, f Trend + Variation (water vapor)
mm
![Page 4: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/4.jpg)
Delay in mountainous regions
07/27/11 4
p
q
Atmospheric-only interferogram Hawaii topography
h
trend + variation+ vertical stratification
mmm
![Page 5: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/5.jpg)
Studies of regions with different climates
07/27/11 5
Netherlands
Hawaii
Mexico City
Lake Moore, WA
![Page 6: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/6.jpg)
Forecasting setup
• WRF (ver 3.1): includes non-hydrostatic dynamics;• Spatial domains: 27, 9, 3, 1 km ;• Spin-up time: 12-16 hours ;• Initial-boundary condition: FNL data (100 km, 6
hours);• Land topography data: SRTM (90 m);• Land-use data (MODIS 20-category);• Microphysics: Morrison 2-moment• Vertical levels: 28 (10 under 2km)
07/27/11 6
![Page 7: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/7.jpg)
InSAR - WRFInSAR (35-day)
Hawaii (case No.1)
07/27/11 7
InSAR WRF InSAR - WRF
€
σinsar =19.4mm
s wrf = 23.8mm
s diff =11.4mm
WRF
Foster JGRL, vol. 33, 2006
mm
![Page 8: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/8.jpg)
Hawaii (case No.2)
07/27/11 8
InSAR (35-day) WRF InSAR - WRF
InSAR WRF InSAR - WRF
€
σinsar =16.9mm
s wrf =14.2mm
s diff =10.5mm
![Page 9: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/9.jpg)
Topography of Mexico City
07/27/11 9
m
![Page 10: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/10.jpg)
Mexico City (case No.1)
07/27/11 10
InSAR (35-day) WRF InSAR-WRF
InSAR WRF InSAR-WRF
€
σinsar = 7.6mm
s wrf = 7.6mm
s diff = 4.6mm
mm
![Page 11: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/11.jpg)
Mexico City (case No.2)
07/27/11 11
InSAR (35-day) WRF InSAR - WRF
InSAR WRF InSAR - WRF
€
σinsar =11.7mm
s wrf = 9.5mm
s diff = 5.9mm
![Page 12: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/12.jpg)
Inconsistency (case No.3)
07/27/11 12
InSAR (35-day) WRF InSAR - WRF
€
σinsar = 8.0mm
s wrf = 7.4mm
s diff = 9.4mm
![Page 13: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/13.jpg)
Cross-validation with MERIS
07/27/11 13
WRFInSAR MERIS
mm
![Page 14: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/14.jpg)
Flat regions
07/27/11 14
![Page 15: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/15.jpg)
Netherlands (9 cases)
07/27/11 15
InSAR (35-day) WRF InSAR-WRF
€
σinsar = 6.9mm
s wrf = 4.0mm
s diff = 5.4mmNo.1
€
σinsar = 5.3mm
s wrf =1.7mm
s diff = 5.8mmNo.2
€
σinsar = 4.2mm
s wrf = 2.4mm
s diff = 5.5mmNo.3
mm
![Page 16: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/16.jpg)
Netherlands
07/27/11 16
€
σinsar = 4.4mm
s wrf = 2.1mm
s diff = 4.7mm
€
σinsar = 5.0mm
s wrf = 2.8mm
s diff = 3.8mm
€
σinsar = 3.7mm
s wrf =1.1mm
s diff = 3.7mm
InSAR (35-day) WRF InSAR-WRF
No.4
No.5
No.6
![Page 17: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/17.jpg)
Netherlands
07/27/11 17
€
σinsar = 3.4mm
s wrf = 0.9mm
s diff = 3.4mm
€
σinsar = 3.8mm
s wrf = 2.1mm
s diff = 3.4mm
€
σinsar = 4.0mm
s wrf = 2.0mm
s diff = 3.7mm
InSAR (35-day) WRF InSAR-WRF
No.7
No.8
No.9
![Page 18: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/18.jpg)
Southwest Australia (5 cases)
07/27/11 18
InSAR (35-day) WRF InSAR-WRF
€
σinsar =1.9mm
s wrf = 0.8mm
s diff =1.9mm
€
σinsar = 3.2mm
s wrf =1.9mm
s diff = 4.0mm
€
σinsar =1.8mm
s wrf = 0.9mm
s diff =1.9mm
No.1
No.2
No.3
![Page 19: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/19.jpg)
Southwest Australia
07/27/11 19
InSAR (35-day) WRF InSAR-WRF
€
σinsar = 5.4mm
s wrf = 3.6mm
s diff = 6.2mm
€
σinsar = 5.7mm
s wrf = 4.4mm
s diff = 7.8mm
No.4
No.5
![Page 20: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/20.jpg)
Variograms of delay
07/27/11 20
Netherlands Australia
Distance [km]
InSAR
WRF
![Page 21: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/21.jpg)
Results review
• In mountainous regions, topography dependent delay is well predicted by WRF in most cases. In these cases, 40% to 50% delay reduction can be achieved. However, its reliability is not 100% (80%)
• In flat regions, delay prediction by WRF is unrealistic and hardly bring significant delay reduction
• Moreover, the spatio-temporal delay variation predicted by WRF is underestimated at all spatial scales
07/27/11 21
![Page 22: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/22.jpg)
Model tuning
• Initial boundary conditions: FNL -> ECMWF (50 km) ;
• Longer spin-up time: 12 hours -> 24 hours ;
• Vertical levels: 28 -> 40 (30 below ABL) ;
07/27/11 22
![Page 23: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/23.jpg)
ECMWF versus FNL
07/27/11 23
Mexico City (case No.3) same model settings
![Page 24: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/24.jpg)
Netherlands (case No.2)
07/27/11 24
InSAR ECMWF(WRF) InSAR-ECMWF
FNL(WRF) InSAR-FNL
![Page 25: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/25.jpg)
Netherlands (case No.9)
07/27/11 25
InSAR ECMWF(WRF) InSAR-ECMWF
FNL(WRF) InSAR-FNL
![Page 26: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/26.jpg)
Longer spin-up time and more vertical levels
07/27/11 26
Hawaii Mexico City
Netherlands Australia
InSAR
WRF tuned
WRF original
![Page 27: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/27.jpg)
07/27/11 27
• NWM (numerical weather models) work for topography-dependent delay when topography variation is significant (> 2000 km)
- max 50% RMS reduction with ; - a reliability of 80% (improvement for 4 out of 5) ;• NWM fail for lateral variation of water vapor at small scales (< 50 km) - always underestimation ; - max 30% reduction ; - a poor reliability (improvement for 2 out of 14)
The low reliability of NWM for flat regions excludes it from operational tools for delay mitigation in SAR Interferometry. For mountainous
regions, delay correction could go wrong as well, users should be careful and critical
Conclusions
![Page 28: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/28.jpg)
Thank you !
07/27/11 28
![Page 29: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/29.jpg)
Is the weather model generally bad for delay prediction ?
07/27/11 29
MERIS WRFAbsolute delay:
![Page 30: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/30.jpg)
Mean delay
07/27/11 30
![Page 31: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/31.jpg)
Recommendations
• To improve the reliability of NWM it is necessary to include more meteorological observations with high spatial density
• Hindcasting using observations after satellite acquisitions would be also useful to constrain NWM aiming to increase its reliability
07/27/11 31
![Page 32: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/32.jpg)
Tropospheric delay experienced by MW
07/27/11 32
hydrostatic (gas components) wet (water vapor) cloud droplets
€
Dpt1 = Nhydro
t1ò ds + Nwett1ò ds + Ndroplet
t1ò ds
absolute delay due to troposphere:
hydrostatic: long wavelength spatial gradient(pressure, temperature), i.e., trend
wet/cloud: significant spatial variation, i.e., local variation
![Page 33: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/33.jpg)
Numerical forecasting for delay mitigation
07/27/11 33
Earth’s surface
NWMprediction
dh
z(h)
(T, e, P)
P: total air pressuree: water vapour pressureT: air temperature
x
y
wetchydrostati NN
T
ek
T
ek
T
PkN
23'21 ++=
Constants (Davis et al., 1985)
Refractivity
€
Dp,qt1 ,t2 is obtained by taking temporal
and spatial difference in sequence
![Page 34: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/34.jpg)
Hawaii (case No.3)
07/27/11 34
InSAR (35-day) WRF InSAR - WRF
InSAR WRF InSAR - WRF
€
σinsar =11.5mm
s wrf =10.2mm
s diff =14.9mm
![Page 35: The role of weather models in mitigation of tropspheric delay for SAR Interferometry.ppt](https://reader034.fdocuments.us/reader034/viewer/2022042715/559cbf931a28ab81268b484e/html5/thumbnails/35.jpg)
Hawaii (case No.4)
07/27/11 35
InSAR (35-day) WRF InSAR-WRF
InSAR WRF InSAR-WRF
€
σinsar =12.0mm
s wrf = 6.8mm
s diff =13.3mm