the effect of sw drought on precipitation of evapotranspired origin
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The Effect of SW Drought on Precipitation of
Evapotranspired Origin
1.Hydrology and Water Resources 2.Atmospheric Sciences 3.School of Natural Resources 4.Universidad de Antioquia, Colombia
Francina Dominguez1,2
Juan Camilo Villegas3,4
David D. Breshears3
The goal is to understand how hydrologic variability in the Southwest affects the export of moisture
Dynamic precipitation recycling model
Effect of SW Drought on subsequent Precipitation
R1 exp wd '
0
Export of Moisture from the SW Region
“Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. (Pringle, 2001)
The atmospheric paths of moisture that connect hydrologic units are poorly understood.
What are the effects of changes in atmospheric hydrologic connectivity?
atmospheric
surface
sub surface
Dynamic Precipitation Recycling Model
Dynamic Recycling Model
Dominguez, F. et al., 2006. J. Climate
R1 exp wd '
0
PEywv
xwu
tw
)()(
The principle for all analytic recycling models is the conservation of atmospheric moisture
In the past, recycling models have assumed that the change in moisture storage is negligible.
New model relaxes this assumption
Dynamic Recycling Model
R = (local recycling ratio) w(precipitable water)E(evapotranspiration)
R1 exp wd '
0
In order to solve the equation we change the coordinate system to follow the motion of the air.
0
'exp1 dR
utx
t
To solve, change coordinate system.
vty We basically follow the path of the air.
)1()1( RR
The equation becomes a simple ODE.
mmmm PEyvw
xuw
tw
)()(
R = (local recycling ratio) w(precipitable water)E(evapotranspiration)
Dynamic Recycling Model
In addition to recycling ratios, we can calculate source-sink regions of atmospheric moisture.
Dynamic Recycling Model
R1 exp wd '
0
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
What is the spatial extent of precipitation originating as ET from the South Western US?
Export of SW ET
?
North American Regional Reanalysis (NARR) data. Warm season (Apr-Sep)
Jul 1-15 (1996-1999)
Evapotranspiration from the South West affects precipitation across the United States.
Precipitation originating as ET from SW region.
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Percent of total Precipitation (falling in each pixel) that originates as ET from SW region.
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Export of SW ET
0.15
0.25
Jul_a
Jul_b
Aug_
a
Aug_
b
Sep_
a
Sep_
b
ET 4
-Cor
ners
(mm
/day
)
Jul 16-31 (1996-1999)
Evapotranspiration from the South West affects precipitation across the United States.
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
Precipitation originating as ET from SW region.
Percent of total Precipitation (falling in each pixel) that originates as ET from SW region.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Export of SW ET
0.15
0.25
Jul_a
Jul_b
Aug_
a
Aug_
b
Sep_
a
Sep_
b
ET 4
-Cor
ners
(mm
/day
)
Aug 1-15 (1996-1999)
At the peak of the Monsoon season, we see a peak in recycled precipitation.
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
Precipitation originating as ET from SW region.
Percent of total Precipitation (falling in each pixel) that originates as ET from SW region.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Export of SW ET
0.15
0.25
Jul_a
Jul_b
Aug_
a
Aug_
b
Sep_
a
Sep_
b
ET 4
-Cor
ners
(mm
/day
)
Aug 16-31 (1996-1999)
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
At the peak of the Monsoon season, we see a peak in recycled precipitation.
Precipitation originating as ET from SW region.
Percent of total Precipitation (falling in each pixel) that originates as ET from SW region.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Export of SW ET
0.15
0.25
Jul_a
Jul_b
Aug_
a
Aug_
b
Sep_
a
Sep_
b
ET 4
-Cor
ners
(mm
/day
)
Sep 1-15 (1996-1999)
Toward the end of the Monsoon, RP diminishes.
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
Precipitation originating as ET from SW region.
Percent of total Precipitation (falling in each pixel) that originates as ET from SW region.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Export of SW ET
0.15
0.25
Jul_a
Jul_b
Aug_
a
Aug_
b
Sep_
a
Sep_
b
ET 4
-Cor
ners
(mm
/day
)
Sep 16-30 (1996-1999)
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
Toward the end of the Monsoon, RP diminishes.
Precipitation originating as ET from SW region.
Percent of total Precipitation (falling in each pixel) that originates as ET from SW region.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Export of SW ET
0.15
0.25
Jul_a
Jul_b
Aug_
a
Aug_
b
Sep_
a
Sep_
b
ET 4
-Cor
ners
(mm
/day
)
Effects of Southwest drought on subsequent precipitation of evapotranspired origin.
Even though NARR doesn’t account for vegetation variability, ET varies as NDVI.
0.1
0.15
0.2
0.25
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Flux
es F
our
Cor
ners
Jul
-Sep
(mm
/day
)
ETPP
Jul – Sep ET and PP
NDVI for late May-June the region encompassing P. edulis (Breshears et al.,2005)
NDVI
0.1
0.15
0.2
0.25
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
ET F
our C
orne
rs J
ul-S
ep (m
m/d
ay)
Precipitation originating as ET from 4-Corners Region varies in agreement with evapotranspiration.
Drought and Recycling
0
0.05
0.1
0.15
0.2
0.25
0.3
0.3519
96
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Prec
ip. O
rigin
atin
g as
ET
from
SW
(m
m/d
ay)
LocalNon-Local
0
0.5
1
1.5
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Rat
io L
ocal
/Non
Loc
al
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Prec
ip. O
rigin
atin
g as
ET
from
SW
(mm
/day
)
LocalNon-Local
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
The drought period presented a sharp decrease in precipitation originating as ET.
Drought and Recycling
Pre-Drought Severe Drought
Legenddgtv13<VALUE>
0 - 0.1
0.2
0.3
0.4
Drought Transition
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Prec
ip. O
rigin
atin
g as
ET
from
SW
(mm
/day
)
LocalNon-Local
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
This meant that the % of precipitation originating as SW-ET considerably diminished during the drought.
Drought and Recycling
Legenddgtv11<VALUE>
0 - 0.025
0.026 - 0.05
0.051 - 0.075
0.076 - 0.1
0.101 - 0.15
Pre-Drought Severe Drought Drought Transition
2%
6%
10%
14%
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
% o
f Pre
cip.
orig
inat
ing
as S
W E
T Ju
l-Sep
NESDWYKSSW
Adjacent states receive approximately 10% of their Jul-Sep precipitation from the Southwest.
Drought and Recycling
This value dropped to around 6% during the drought
The Dynamic Recycling Model has enabled us to analyze the regions where ET from the Southwest contributes to precipitation.
Including intraseasonal variability.
Conclusions
In conclusion…
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Pre
cip.
Orig
inat
ing
as E
T fro
m
SW
(mm
/s)
LocalNon-Local The recent SW drought had a
significant impact on the precipitation originating as ET from the SW region.
Further Thoughts…
NARR doesn’t include vegetation variability, hence doesn’t account for the regional-scale die-off.
Could the vegetation die-off amplify the effect of the drought on remote precipitation?
Questions?Questions?
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