04

812

2006 P

2006 PE/P vs E

P E/P

(mm

d-1)

0.0

0.2

0.4

0.6

05/02 05/11 05/16 05/21 05/26 05/31 06/05 06/10 06/15 06/20 06/25 06/3005/06

03

69

12E

mm

d-1

2006 PE/P vs IF/A

012

2436

48IF

/Am

md-1

SWATS Volumetric Soil Water at 5cm - Lamont, OK

x

m3

m-3

0.24

0.28

0.32

0.36

05/02 05/11 05/16 05/21 05/26 05/31 06/05 06/10 06/15 06/20 06/25 06/3005/06

05/02 05/11 05/16 05/21 05/26 05/31 06/05 06/10 06/15 06/20 06/25 06/3005/06

05/02 05/11 05/16 05/21 05/26 05/31 06/05 06/10 06/15 06/20 06/25 06/3005/06

mm

d-1P E/

P(m

md-1

)

0.0

0.2

0.4

0.6

0.62.04.0

8.0

PE/P

PE/P

E

IF/A

Variation of P, Recycling and Soil Moisture on a Daily Timescale

Source:Climate Prediction CenterGridded Rain Gauge Analysis

Investigation of Southern Great Plains Atmospheric Moisture Budget for CLASIC

1Cooperative Institute for Mesoscale Meteorological Studies, 2School of Meteorology, The University of Oklahoma,3Blaustein Institute for Desert Research, Ben Gurion University of the Negev, Israel

CLASIC Campaign SummaryMotivations

Record Breaking Rainfall during CLASIC

SM > 60 cm

40 cm < SM < 50 cm

30 cm < SM < 40 cm

20 cm < SM < 30 cm

SM < 20 cm

50 cm < SM < 60 cm

5/02 5/20 5/30 6/10 6/20 6/305/10

010

020

030

0 May-June 2006

mm

010

020

030

0

5/02 5/20 5/30 6/10 6/20 6/305/10

mm

May-June 2007

Cumulative Precipitation

Soil Moisture

June 2007 June 2006

CLASICACRF SGP Region

Moisture BudgetStudy Region

MJ MJ MJ MJ 8 2 6 7-4-2

02

46

E1998 2002 2006 2007 Mean

mm

d-1

MJ MJ MJ MJ 8 2 6 7-4-2

02

46

P1998 2002 2006 2007 Mean

MJ MJ MJ MJ 8 2 6 7-4-2

02

46

E-P1998 2002 2006 2007 Mean

mm

d-1

mm

d-1

MJ MJ MJ MJ 8 2 6 7

-4-2

02

46

HA1998 2002 2006 2007 Mean

MJ MJ MJ MJ 8 2 6 7-4-2

02

46

HD1998 2002 2006 2007 Mean

MJ MJ MJ MJ 8 2 6 7-4-2

02

46

MFD1998 2002 2006 2007 Mean

mm

d-1

mm

d-1

mm

d-1

MJ MJ MJ MJ 8 2 6 7

010

2030

IF/A1998 2002 2006 2007 Mean

mm

d-1

MJ MJ MJ MJ 8 2 6 7

0.0

0.10

0.20

PE/P1998 2002 2006 2007 Mean

MJ MJ MJ MJ 8 2 6 7-4-2

02

46

E1998 2002 2006 2007 Mean

mm

d-1

Monthly Mean Moisture BudgetMay-June 1998, 2002, 2006, 2007

Characteristics of Daily Recyclingwithin Precipitation Categories

Outflow(OF/A)

E P Inflow(IF/A)

PPE =

AIF

E

E

+Plocal + advective

Plocal =

whereE is the local source of moistureIF/A is the advective source of moisture

Based on this Tank Model, our recycling ratio is:

dPWA

IF

A

OFPE +-=-

Bulk formula for the moisture budget has 4 bound-ary fluxes (E, P, OF/A and IF/A):

Recycling on a Monthly Timescale

Conventional Form of the Moisture Budget Equation:E-P = MFD +dPW= HA + HD +dPW

where E is evapotranspiration, P is precipitation, MFD is Moisture Flux Divergence with its compo-nents HA (horizontal moisture advection) and HD (horizontal velocity divergence in the presenceof moisture), dPW is atmospheric moisture storage (which is negligible on a monthly timescale).

Using the conventional form of the Moisture Budget Equation,one might assume that if E-P ~0 (or MFD ~0), then most of theprecipitation (P) originates from evapotranspiration (E).

Over the SGP, E-P ~0 (except for the extremely wet May-June 2007 and the very dry May 1998).

However, using the bulk form of the Moisture Budget above,the ratio of precipitation originating from evapotranspirationto the total precipitation (PE/P) is much less than 1.0.

2<P<4 mm d-1

0.6<P<2 mm d-1

P< 0.6 mm d-1

4<P<8 mm d-1

P>8 mm d-1

2<P<4 mm d-1

0.6<P<2 mm d-1

P< 0.6 mm d-1

4<P<8 mm d-1

P>8 mm d-1

0

E

2.84

3.21

3.73

3.80

4.16

0

IF/A

19.12

20.82

22.10

23.22

24.85

0

PE/P

0.152

0.155

0.187

0.163

0.150

0

SR

30.93

29.54

27.95

26.61

24.75

0.0

PE

0.03

0.18

0.54

0.93

1.78

0

# Cases

84

43

38

49

26

P

P

Daily Mean Recycling and Related VariablesMay-June 1998, 2002, 2006, 2007

whereE is the local source of moisture (mm d-1); IF/A is the advective source of moisture (mm d-1)PE/P is the recycling ratio ; SR is the solar radiation (MJ m-2 d-1);PE is the recycled precipitation (mm d-1)

* Recycling ratio is maximized in the 2-4 mm d-1 P Category.

* Both E and IF/A increase with increasing P.

* Variation among the recycling related components on a dailytimescale is shown below for the dry year of 2006. The red boxindicates a period of very high recycling rates when advectedmoisture was low but there was still soil moisture available forevapotranspiration.

The Cloud and Land Surface Interaction Campaign wasconducted over the Southern Great Plains (SGP) ARMClimate Research Facility during June 2007. One ofCLASIC’s primary goals is to “improve understandingof the physics of the early stages of cumulus cloud con-vection as it relates to land surface conditions”.

Our moisture budget analysis, conducted over an expandedregion surrounding the SGP for CLASIC and three other con-trasting May-June periods, provides a bulk approach for relatingcloud properties to larger-scale atmospheric conditions. Moisturebudget analysis is an important tool for studying land-atmosphereinteractions, since the linkages among atmospheric dynamics,water vapor, surface conditions, and precipitation are constrainedby the moisture continuity equation.

O ver t he SG P , E ( E v apo t r a n s p i r a t i o n ) = ~P(Precipitation) for many monthly means. However, thisdoes not imply that E is the main moisture source formonthly P.On a daily timescale, the recycling ratio (PE/P) is maxi-

mized in the 2-4 mm d-1 P range. This is the P range ofmost interest for CLASIC clouds.

Recycling Method

Peter J. Lamb1,2, Diane H. Portis1, Avraham Zangvil3

Source:Climate Prediction CenterCPC Leaky Bucket Model