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