Chandrasekar, V.

Petersen, Walter A.

Wingo, Stephanie M.

English

NASA Technical Reports Server

Analysis of NASA GPM Ground Validation 
Multi-frequency Radar Observations
Stephanie M. Wingo1, Walter A. Petersen2, V. Chandrasekar3
1NASA Postdoctoral Program/USRA, University of Alabama in Huntsville
2NASA Marshall Space Flight Center
3Colorado State University
American Meteorological Society – Annual Meeting 2020
Boston, MA
16 January 2020
Image: Stacy Brodzik
https://ntrs.nasa.gov/search.jsp?R=20200000476 2020-03-11T12:41:21+00:00Z
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Motivation
• GPM GV Observation 
Diversity
• Core Observatory
• Constellation Partners
• Field Campaigns
Goals:
Focus on OLYMPEX 
Atmospheric River (AR) Events: 
• Integrative approach/building 
atmospheric column
• DPR LCFB often above 0°C in 
high terrain
• Compositing vertical slices
• Multi-frequency analysis via 
ground-based radars
Total accumulation
Oct–April (~8-16 feet)
(Zagrodnik et al. 2018)
Land/topo impact ice/liquid precipitation processes –
unblocked (large Froude) & warm sector flow regimes
(Hunzinger 2018/Petersen et al. 2018)
17 Nov 2001 UTC DPR HS LCFB
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Methodology
Case Criteria
• ARs with unblocked terrain-normal 
component flow:  WS, Fr > 1.3 
(Hunzinger 2018/Petersen et al. 2018)
• 6 AR cases, 8 GPM OPs
• 13 Nov 03-00 UTC (20%)
• 17 Nov 10-21UTC (10%)
• 3 Dec 14-00 UTC (10%)
• 6-7 Dec 00-02 UTC (25%)
• 8-9 Dec 13-10 UTC (20%)
• 17 Dec 08-00 UTC (15%)
Analysis:
• Vertical slice composites:
• Z, Dm, RR
• Dual-frequency ratios:
• NPOL (S-band) & D3R (Ku/Ka-band)
• 150 x 200 m range-height grid spacing
• Parse results by:
• NPOL-derived HID (Dolan et al. 2013)
• LIQ: drizzle, rain, big drops
• ICE: crystals, aggregates, hail
• MIX: wet snow, graupel
• Sea vs. terrain
• Individual HID type classes
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Composites
over all ARs
O
O
ZS
Dm
• Along NPOL RHI 
approaching, through 
Quinault River Valley
• Terrain, orographic 
enhancements
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
O
O
17 November 2015   10-21 UTC
3 December 2015  14-00 UTC
ZS
ZS
ZS – NPOL Composites
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
InlandOcean
InlandOcean NPOL
MRR
2DVD
APU
DPR NS
DPR HS
DPR MS
CMB NS
CMB MS
Dm Composite Profiles
Why Dual-Frequency Ratios for the ARs?
• Previous work:
• Column-based ARs analyses show 
best agreement among DPR, GMI, 
GV observations over ocean
• Discrepancies increase:
• As move up valley/into more 
complex terrain
• Terrain-normal flow magnitude
• Precipitation processes & satellite 
observations involve more than below 
0°C level
 Importance of identifying & quantifying ICE, LIQUID, and MIX phase hydrometers to 
better discern processes, improve observing
17 Nov 
Westerly 
flow
3 Dec
Southerly 
flow
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
DFRS-Ku
2 Events
• S-Ku DFR 
composite, 
includes all 
NPOL HID 
types
• More ocean-
side variation 
in westerly 
flow case
• DFR layering 
complexity 
increases as 
approach 
terrain
17 November 2015  10-21 UTC – westerly flow
3 December 2015  14-00 UTC – southerly flow
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
DFRS-Ku ALL ARs  Land Side Scans
DFRS-Ku ALL ARs  Ocean Side Scans
ALL
ALL LIQ ICE MIX
LIQ ICE MIX
S-
Ku
 D
FR
 [d
B]
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ku:  Liquid phase HID type classesLIQ
drizzle rain big drops
LAND
OCEAN
• S-band Z / 
Rayleigh regime 
dependence on 
hydrometeor size 
evident
• DFRS-Ku values 
positive & 
negative
• OLYMPEX region 
well known for 
copious numbers 
of small drops
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ku:  Mix-phase HID type classesMIX
wet snow low density graupel high density graupel
LAND
OCEAN
• Wet snow 
shows most 
variation, and 
more dispersed 
over ocean
• Graupel classes 
more similar to 
rain, hail; more 
dispersed over 
land
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ku:  Ice phase HID type classesICE
aggregates ice crystals vertical ice
LAND
OCEAN
• Aggregates: 
different land/
ocean modes
• Ice crystals: 
land/ocean 
similar
• Vertical ice: 
slightly lower 
DFR
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
DFRS-Ku ALL ARs  Land + Ocean
DFRS-Ka ALL ARs  Land + Ocean
ALL LIQ ICE MIX
ALL LIQ ICE MIX
S-
Ka
DF
R 
[d
B]
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
S-
Ka
DF
R 
[d
B]
S-
Ka
DF
R 
[d
B]
S-
Ka
DF
R 
[d
B]
S-
Ku
 D
FR
 [d
B]
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
LIQ
drizzle rain big drops
LAND
OCEAN
S-Ka:  Liquid phase HID type classes
• S-band Z / 
Rayleigh regime 
dependence on 
hydrometeor size 
evident
• Almost all DFRS-Ka
values positive
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ka:  Mix-phase HID type classes
MIX
wet snow low density graupel high density graupel
LAND
OCEAN
• Wet snow most 
varied, more 
dispersed over 
ocean
• Graupel classes 
more similar to 
rain, hail; more 
dispersed over 
land
• Almost all DFRS-Ka
values positive
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ka:  Ice phase HID type classes
ICE
aggregates ice crystals vertical ice
LAND
OCEAN
• Aggregates & ice 
crystals: slightly 
more compact over 
ocean
• Vertical ice: similar 
to other ICE HID 
type classes
• Modes more 
consistent  (vs. S-Ku)
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
DFRKu-Ka vs Ku
Land
DFRKu-Ka vs S
Land
DFRS-Ku vs DFRS-Ka
Land
DFRKu-Ka vs Ku
Ocean
DFRKu-Ka vs S
Ocean
DFRS-Ku vs DFRS-Ka
Ocean
DFRKu-Ka:  All HID Types – Distribution Space
DFRKu-Ka vs Ku-band Z:
• Triangular, almost 
parabolic shape
DFRKu-Ka vs S-band Z:
• More broad 
triangular shape
DFRS-Ku vs DFRS-Ka:
• Most confined 
distribution
All:  
• Ocean distribution 
more compact 
than land
Ku-band Z [dBZ] S-band Z [dBZ] S-Ka DFR [dB]
Ku
-K
a
DF
R 
[d
B]
Ku
-K
a
DF
R 
[d
B]
S-
Ku
 D
FR
 [d
B]
Ku-band Z [dBZ] S-band Z [dBZ] S-Ka DFR [dB]
Ku
-K
a
DF
R 
[d
B]
Ku
-K
a
DF
R 
[d
B]
S-
Ku
 D
FR
 [d
B]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Liquid phase HID type classes
LIQ
drizzle rain big drops
LAND
OCEAN
• No negative 
DFRKu-Ka values
• Ocean 
distributions 
more compact
• Modes & size 
separation more 
pronounced in 
S-band space
Ku-band Z [dBZ] Ku-band Z [dBZ] Ku-band Z [dBZ]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Liquid phase HID type classes
LIQ
drizzle rain big drops
LAND
OCEAN
• No negative 
DFRKu-Ka values
• Ocean 
distributions 
more compact
• Modes & size 
separation more 
pronounced in 
S-band space
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Mix-phase HID type classes
MIX
wet snow low density graupel high density graupel
LAND
OCEAN
• Wet snow: more 
compact over 
ocean
• Graupel: more 
compact over 
land (vs. Ku-
band Z)
• Modes & size 
separation more 
pronounced in 
S-band space
Ku-band Z [dBZ] Ku-band Z [dBZ] Ku-band Z [dBZ]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Mix-phase HID type classes
MIX
wet snow low density graupel high density graupel
LAND
OCEAN
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
• Wet snow: more 
compact over 
ocean
• Graupel: more 
compact over 
land (vs. Ku-
band Z)
• Modes & size 
separation more 
pronounced in 
S-band space
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Ice phase HID type classes
ICE
aggregates ice crystals vertical ice
LAND
OCEAN
Ku-band Z [dBZ] Ku-band Z [dBZ] Ku-band Z [dBZ]
• Ku-band:
•more consistent 
distribution shape 
among all ice types 
(but hail – not shown)
• S-band:
•all ice: slightly 
broader distributions
•Size separation more 
pronounced
•Less linear
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Ice phase HID type classes
ICE
aggregates ice crystals vertical ice
LAND
OCEAN
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
• Ku-band:
•more consistent 
distribution shape 
among all ice types 
(but hail – not shown)
• S-band:
•all ice: slightly 
broader distributions
•Some size separation
•Less linear
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Only LIQ HID Types:  DFRS-Ka vs. 10*Dm
ALL LAND OCEAN
• Little trend, somewhat more compact over ocean
• Many very small drops
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
LIQ
ICE
MIX
LIQ
ICE
MIX
LIQ
ICE
MIX
LIQ
ICE
MIX
LIQ
ICE
MIX
LIQ
ICE
MIX
DFRS-Ku
DFRS-Ku
DFRS-Ka
DFRS-Ka
DFRKu-Ka
DFRKu-Ka
DFRs
All ARs
• S-Ku DFR has 
largest LIQ and 
ICE overlap
• MIX overlaps 
in all 3 spaces
• Ocean regime 
is slightly more 
compact
S-Ku
S-Ka
Ku-Ka
(vs. ZS)
Land Scans
O
cean Scans
*Histograms include 
all HID phases
*Contours at densities of 0.1, 0.3 for each HID phase
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
This work was partially supported by an appointment to the NASA Postdoctoral Program at Marshall Space 
Flight Center, administered by Universities Space Research Association through a contract with NASA.
• OLYMPEX AR composite RHIs show enhancement 
as approach terrain, mean flow orientation control
• DFR layering consistent with terrain complexity
• Magnitude of terrain-normal flow influences DFR 
enhancement location, severity
• DFRS-Ka shows most difference among HID phases
• DFRKu-Ka vs S-band Z gives most space for comparing 
individual HID type classes
• Ocean DFR distributions in general are slightly 
more compact
• Indicates more complex processes over land
• But there are exceptions: wet snow (S-Ku, S-Ka), 
graupel (Ku-Ka vs. Ku-band Z)
• Inexact beam matching
• Implications for future spaceborne radar concepts
LIQ
ICE
MIX
LIQ
ICE
MIX
LIQ
ICE
MIX
DFRS-Ku DFRS-Ka
DFRKu-Ka
Summary
*Histograms include all HID phases
*Contours at densities of 0.1, 0.3 for each HID phase
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
DFRS-Ku
All ARs
• S-Ku DFR 
composite, 
includes all 
NPOL HID 
types
• Histograms: 
land + ocean
ALL LIQ ICE MIXDFRS-Ku
S-
Ku
 D
FR
 [d
B]
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
S-
Ku
 D
FR
 [d
B]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ku:  Ice phase HID type classesICE
aggregates ice crystals hail
LAND
OCEAN
• Aggregates: 
different land/
ocean modes
• Ice crystals: 
land/ocean 
similar
• Hail: see Rayleigh 
dependence
• Vertical ice: 
slightly lower DFR
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
S-Ka:  Ice phase HID type classes
ICE
aggregates ice crystals hail
LAND
OCEAN
• Aggregates & ice 
crystals: slightly 
more compact 
over ocean
• Vertical ice: 
behavior in this 
space very similar 
to other ICE HID 
type classes
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Ice phase HID type classes
ICE
aggregates ice crystals hail
LAND
OCEAN
• Ku-band:
•more consistent 
distribution shape 
among all ice types 
(but hail)
• S-band:
•all ice more 
dispersed
•Size separation 
more pronounced
•Less linear Ku-band Z [dBZ] Ku-band Z [dBZ] Ku-band Z [dBZ]
AMS 100th Annual Meeting • 13B.3 • stephanie.m.wingo@nasa.gov
Ku-Ka:  Ice phase HID type classes
ICE
aggregates ice crystals hail
LAND
OCEAN
S-band Z [dBZ] S-band Z [dBZ] S-band Z [dBZ]
• Ku-band:
•more consistent 
distribution shape 
among all ice types 
(but hail)
• S-band:
•all ice more 
dispersed
•Size separation 
more pronounced
•Less linear


Analysis of NASA GPM Ground Validation Multi-Frequency Radar Observations

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