Jan 28, 2008Symposium on Imaging Ground-based and Space- based Radar Precipitation Imaging...
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Transcript of Jan 28, 2008Symposium on Imaging Ground-based and Space- based Radar Precipitation Imaging...
Jan 28, 2008 Symposium on Imaging
Ground-based and Space-based Radar Precipitation
Imaging
V.Chandrasekar
Colorado state University
January 28, 2008
Jan 28, 2008 Symposium on Imaging
Introduction
• CSU-CHILL radar
- PPI (Plan Position Indicator) scan - RHI (Range Height Indicator) scan
• Tropical Rainfall Measurement Mission (TRMM) - Precipitation Radar (PR)
Jan 28, 2008 Symposium on Imaging
CSU-CHILL radar : New antenna installation
Jan 28, 2008 Symposium on Imaging
Example of PPI scan
Jan 28, 2008 Symposium on Imaging
Example of RHI scan
Jan 28, 2008 Symposium on Imaging
The received signal corresponds to resolution volume determined by the transmit pulse width
& beam width
Bcx rR : Resolution Range-Cross
Backscattered signal in weather radars is from distributed target
Cross range resolution is dependent on the antenna beam width and range
Jan 28, 2008 Symposium on Imaging
2
2ln8
2
2ln8
2ln24
BB
Be erferff
widthbeam antenna dB 3
cyclen integratio onein Azimuth
B
Jan 28, 2008 Symposium on Imaging
r0,0,0 r,, r2
Wn r 2 f 2 ,0
f 2 ,0 dsin drd
f 2 0, f 2 0, d d
If a r,, r2
Wn r 2 f 2 ,0
f 2 ,0 dsin drd
r0,0,0 a f 2 0, 0 f 2 0, d d
Jan 28, 2008 Symposium on Imaging
Intrinsic backscattering properties of hydrometeor is described by the backscattering covariance matrix
Intrinsic backscattering properties of hydrometeor in a linear polarization basis enables the measurements such as size, shape and spatial orientation
++
+
++
+
++ +
+--
----
- - -- 2max
cTr
Tv
4max
Waveform Coding at CSU-CHILL radar
Jan 28, 2008 Symposium on Imaging
vhS
hhS
hvS
vvS
Ev
Eh
Backscattered signal from horizontal polarization
Backscattered signal from vertical polarization
Backscattering covariance matrix is given by
2
2
2
2
222
2
vvhvvvhhvv
vvhvhvhhhv
vvhhhvhhhh
BSA
SSSSS
SSSSS
SSSSS
Waveform Coding at CSU-CHILL radar
Jan 28, 2008 Symposium on Imaging
The received signal in the two polarization channels can be written as
Tvvvhhvhh VVVVz
2
2
2
2
vvhvvvvhvvhhvv
vvhvhvvhhvhhhv
vvvhhvvhvhhhvh
vvhhhvhhvhhhhh
T
VVVVVVV
VVVVVVV
VVVVVVV
VVVVVVV
EE Kzz
The covariance matrix of the received signal is given by
Dual ChannelDigital
Waveform Generator
REF OSCILLATOR
H-Transmitter
V-Transmitter
V- Receiver
H- Receiver
DuplexerSTALO
H
V
Waveform Coding at CSU-CHILL radar
Jan 28, 2008 Symposium on Imaging
Reflectivity from (a) Alternate mode (20:34:00 UTC) (b) Walsh coded
simultaneous mode (20:28:51 UTC). Data collected by CSU-CHILL on May 29, 2007
LDR estimated from (a) Alternate mode (20:34:00 UTC) (b) Walsh coded simultaneous mode
(20:28:51 UTC). Data collected by CSU-CHILL on May 29, 2007
Waveform Coding at CSU-CHILL radar
Jan 28, 2008 Symposium on Imaging
Networked System Processing
KSAO
KRSPKLWE
KCYR
Jan 28, 2008 Symposium on Imaging
UNFILTERED FILTERED
Tornadic circulation feature; wind speeds greater than 40 m/s (90 mph)
Networked System Processing
Jan 28, 2008 Symposium on Imaging
Networked System Processing
Measurement at each radar node
Networked retrieval
Jan 28, 2008 Symposium on Imaging
Reflectivity retrieval in a networked radar environment: Demonstration
from IP-1 radar network
Jan 28, 2008 Symposium on Imaging
KTLX
Before After
May 7, 2007 CSE
Jan 28, 2008 Symposium on Imaging
May 8, 2007 CSE
KTLX
Before After
Jan 28, 2008 Symposium on Imaging (Adopted from TRMM data user handbook, 2001)
TRMM : Tropical Rainfall Measurement Mission - Joint mission between NASA and JAXA - Observing precipitation over tropical regions between 37oS and 37oN - Satellite was lunched in 1997
PR : Precipitation Radar (installed on TRMM) - 13.8 GHz Ku-band radar - Horizontal resolution at nadir : 4.3 km. ( 5 km. postboost) - Range resolution : 250 m. - Swath width : 215 km. ( 245 km postboost) - Altitude : 350 km. ( 402.5 km postboost) Note : TRMM was boosted in altitude in August 2001
215 km.
A hurricane in TRMM-PR track
TRMM-PR : orbital and observatory characteristics
Jan 28, 2008 Symposium on Imaging
Ground and Space-based radar volume matching
• Performance and system cross validation
Jan 28, 2008 Symposium on Imaging
Effective vertical resolution = xr + xb
= h*cosθ + r θB sin θ
Effective horizontal resolution = hr + hb
= h*sinθ + r θB cos θ
Geometry of pulse volume and resolution degradation effect of space-based radar measurement.
to surface
Jan 28, 2008 Symposium on Imaging
Geometric distortion in the space-base radar imagecaused by platform motion
Jan 28, 2008 Symposium on Imaging
Difference in resolution between space and ground-based radar images
NEXRAD : KAMX Miami, FL TRMM-PR
• A couple example from simultaneous observations between NEXRAD and TRMM
Jan 28, 2008 Symposium on Imaging
NEXRAD : KEVX , Red Bay/Eglin, FL TRMM-PR
Jan 28, 2008 Symposium on Imaging
3-D volume matching and shifting based on GR and SR resolution volumes
Jan 28, 2008 Symposium on Imaging
Matched and Aligned images between SR and GR
GR SR
Jan 28, 2008 Symposium on Imaging
Matched images of a tropical storm in Bay of Bengal
GR (SHAR, India)
SR (TRMM-PR)
Jan 28, 2008 Symposium on Imaging
Summary
• The Radar research group works on a variety of problems all the way from
• Design and development of imaging sensors
• Analysis of images for interpretation and • Cross validation of images from multiple
platforms • Developing hardware, theory algorithms
and and novel applications