Anvil Generation in Relation to Cloud System Water Budget: TWP-ICE Case of 19-20 January 2006
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Transcript of Anvil Generation in Relation to Cloud System Water Budget: TWP-ICE Case of 19-20 January 2006
Anvil Generation in Relation to Cloud System Water Budget:
TWP-ICE Case of 19-20 January 2006
Jasmine Cetrone and Robert HouzeUniversity of Washington
8 November 2006, ARM Cloud Processes Working Group, Annapolis, MD
Water Budget of an MCS
*
Ecd
Ccu
Csu
Esd
CT
Ac As
HEIGHT
MIXED ANVIL
Rc Rs
STRATIFORMCONV.ANVIL
Ece
XA
Ese
XSXC
ZA)I
XA)M XA)I
* *
* **** *
*ICE ANVIL
ZA)M
**
*
Water Budget Equations
*
Ecd
Ccu
Csu
Esd
CT
Ac As
HEIGHT
MIXED ANVIL
Rc Rs
STRATIFORMCONV.ANVIL
Ece
XA
Ese
XSXC
ZA)I
XA)M XA)I
* *
* **** *
*ICE ANVIL
ZA)M
**
*
Ccu =Rc + Ecd + Ac +CT
Convective region water budget equationRc = εcCcu
Ecd= αCcu
Ac = βCcu
CT = ηCcu
εc+α+β+η=1
Water Budget Equations
*
Ecd
Ccu
Csu
Esd
CT
Ac As
HEIGHT
MIXED ANVIL
Rc Rs
STRATIFORMCONV.ANVIL
Ece
XA
Ese
XSXC
ZA)I
XA)M XA)I
* *
* **** *
*ICE ANVIL
ZA)M
**
*
Csu +CT =Rs + Esd + As
Stratiform water budget equation
Rain not simply related to condensation
Rs = εs(Csu+CT)Esd= a(Csu+CT)As = b(Csu+CT)
εs+a+b=1
*
Ecd
Ccu
Csu
Esd
CT
Ac As
HEIGHT
MIXED ANVIL
Rc Rs
STRATIFORMCONV.ANVIL
Ece
XA
Ese
XSXC
ZA)I
XA)M XA)I
* *
* **** *
*ICE ANVIL
ZA)M
**
*
PRECIPITATING CLOUD
ANVIL
Rc Rs
Ac + As* ** **
**
*
*
*ZA
** *
XAXSXC
XA)M XA)I
HEIGHT
Simplified Water Budget Model
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
19-20 January MCS
Finding anvil amounts from water budget equations
• Assume portion of cloud system passing over radar was representative of whole system (not true)
• Compute total convective and stratiform rain amounts from C-Pol radar (in radar domain)
• Use a range of assumed values of the water budget parameters εc,α,η,εs,a (from Houze and Cheng 1981)
• Compute Ac + As
Results using water budget
Rc=2.8586 x 1012 kg, Rs=6.7226 x 1011 kg
α a εc Ac + As
0.13 0.35 0.38 1.0538 x 1012 kg
0.13 0.20 0.49 6.9538 x 1011 kg
0.13 0.15 0.50 6.6096 x 1011 kg
0.13 0.08 0.54 5.6997 x 1011 kg
0.13 0 0.50 6.2993 x 1011 kg
0.13 0 0.61 4.4759 x 1011 kg
Realistic Values, acc. to Houze and Cheng 1981
19-20 January MCS
dBZ
Convective Stratiform Anvil
Cloud Radar
Finding anvil amounts from MMCR and C-Pol
• Find a relationship between cloud thickness and IWP (MMCR)
• Compute the average area and thickness of anvil clouds in radar range using C-Pol
• Calculate the amount of anvil water/ice (Ac + As) that is in range of C-Pol
IWP=0.026∆z3.0434
R2=0.9101
IWP [kg/m2]
Thic
knes
s [k
m]
Ac + As = 4.2730 x 1010 kg
We’re only getting about 10% of the anvil calculated by the water
budget equations
MMCR
Why such a difference??
1. The CPol will miss some anvil because of it’s lower sensitivity
4
0
8
12
16
20
00 1206
Why such a difference??
2. Above about 8-km, the winds were easterly, shearing much of the anvil to the west instead of it trailing behind the system (i.e. out of CPol’s range)
Future Improvements
• Use dual-Doppler velocities, cloud radar, and sounding data to compute other values (CT, Ccu, Ecd, Csu, Esd) to calculate the water budget parameters
• Use satellite data to extend water budget to the whole system, rather than just radar area
• Use model simulations to help close the water budget
• Connect water budget to the TRMM PR overpass
• Find other casesJASMINE, KWAJEX
JASMINE Ship RadarData
TRMM PrecipitationRadar Swath
23 May 1999 0650 LST
JASMINE
Bay of Bengal
India
Cloud Radar
Cloud radar on ship shows anvil
Cloud RadarTRMM PR
TRMM PR
Also: Scanning radar and ship soundings
KWAJEX•TRMMTRMM
•Scanning C- and S-band Doppler radarsScanning C- and S-band Doppler radars•Vertically Pointing S-band radarVertically Pointing S-band radar
•Sounding NetSounding Net
Thanks!
KWAJEX