Cirrus Production by a Mesoscale Convective System Sampled During TWP-ICE: Analysis via Water Budget Equations

Jasmine Cetrone and Robert HouzeUniversity of Washington

IntroductionThis study computes certain elements of the water budget of a MCS observed during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE). The precipitation efficiency can help relate global maps of precipitation to maps of global anvil coverage, and the amount of cirrus produced by the system affects the radiation budget of the MCS.

*

Ecd

Ccu

Csu

Esd

CT

Ac As

HEIGHT

MIXED ANVIL

Rc Rs

STRATIFORMCONV.

LW

LW

SW

ANVIL

Ece

XA

Ese

XSXC

ZA)I

XA)M XA)I

* *

* ****

*

*ICE ANVIL

ZA)M

**

*

Ccu = Rc + Ecd + Ac + CT

CT + Csu = Rs + Esd + As

MCS Overview

Condensation and Evaporation

Precipitation

dzdz

dqwAE

dzdz

dqwAC

t

b

t

b

z

z

z

z

Results over radar domain:

Ccu=3.3627×1013 kg

Ecd=1.8498×1013 kg

Csu=2.7560×1013 kg

Esd=3.8781×1013 kg

Results over radar domain:

Rc=2.8586×1012 kg

Rs=6.7226×1011 kg

R=Rc+Rs=3.5208×1012 kg

Anvil

• Ice water content (IWC) calculated for anvil seen by MMCR via a Z-IWC relationship: IWC=0.097Z0.59

• Histogram of ice water path (IWP) calculated for the anvil; applied to the area covered by anvil in the satellite to get the mass of total anvil (Ac+As)

• MMCR sensitivity was low during TWP-ICE, resulting in underestimation of IWC in anvil and thus total anvil mass

• Some anvil will not be accounted for as it evaporates

Results of anvil from satellite/MMCR method:

Ac+As=3.3244×1011 kg

Convective Rain Stratiform Rain

126 127 128 129 130 131 132 133°E

11°S

12

13

14

60

53

46

39

32

25

18

11

4

dBZ

16

0

4

8

12

20

19 Jan22:00

20 Jan00:00

20 Jan02:00

20 Jan04:00

20 Jan06:00

20 Jan08:00

20 Jan10:00

Time

Hei

gh

t (k

m)

Millimeter Cloud Radar 28

21

14

7

0

-7

-14

-21

-28

dBZ

151050Specific Humidity (g kg-1)

0

2

4

6

8

10

12

14

16

18

20

Hei

gh

t (k

m)

Distance from radar (km)

Dis

tan

ce f

rom

rad

ar (

km)

150

100

50

0

-50

-100

-150 -100 -50 0 50 100 150

Sto

rm R

ain T

otal (m

m)

200

0

160

40

0

80

120

Distance from radar (km)

150

100

50

0

-50

-100

-150 -100 -50 0 50 100 150

Sto

rm R

ain T

otal (m

m)

25

0

20

5

0

10

15

30

Acknowledgements

We would like to thank Stacy Brodzik for her invaluable efforts in processing this data.

ARM - DOE Grant DE-FG02-06ER64175

NASA ESS Grant NNG05GP07H

0 0.5 1.0 1.5 2.0 2.5

0.01

0.02

Fre

qu

ency

0

IWP (kg m-2)

Results of anvil as a residual of other terms:

Ac+As=Ccu+Csu-Ecd-Esd-Rc-Rs

between 3.077×1011 kg and 6.154 ×1011 kg(for areas between 1 and 2 times the radar area coverage)

Summary and Future Work• Anvil mass is approximately 10% of the total rain

precipitated out by the system in the radar domain

• Errors in MMCR data amplify in calculations of anvil mass

• Next steps: Extend to another MCS (23-24 Jan)

Determine error bars on calculations

Extend to other tropical regions

Visible Satellite and Radar Reflectivity at 03:30 on 20 January

• A large MCS moved toward the north over the radar sites on 19-20 January 2006

• MCS was mainly leading convective precipitation and trailing stratiform

• Anvil blown off toward the WNW by upper-level winds• Total precipitation area coverage of storm uncertain:

between 1 and 2 times the actual radar area coverage

• Humidity profile computed from Darwin radiosonde

• Vertical velocity profiles of updrafts and downdrafts in the convective and stratiform regions computed from dual-Doppler radar data

• Condensation and evaporation terms calculated from the following equations:

• Convective/stratiform maps computed from radar data

• Maps applied to reflectivity data to give convective and stratiform rain totals in the radar domain

ARM Science Team Meeting, Monterey, CA, 27 March 2007