the nature of rain events in summer vs. winter at the sgp arm facility
DESCRIPTION
The nature of rain events in summer vs. winter at the SGP ARM Facility. MPO 581 Class Project Emily Riley, Siwon Song, & Brian Mapes. Background. ARM – Atmospheric Radiation Measurements Several Sites (facilities) funded by DOE. Background. ARM – Atmospheric Radiation Measurements - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/1.jpg)
The nature of rain events in summer vs. winter at the SGP
ARM Facility
MPO 581 Class ProjectEmily Riley, Siwon Song, & Brian Mapes
![Page 2: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/2.jpg)
Background• ARM – Atmospheric Radiation Measurements
– Several Sites (facilities) funded by DOE
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Background• ARM – Atmospheric Radiation Measurements
– SGP-Southern Great Plains
![Page 4: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/4.jpg)
Data• Climate Modeling Best Estimate (CMBE) Data
– 1996 – 2009– Data averaged over one hour time intervals
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Data• Climate Modeling Best Estimate (CMBE) Data
– 1996 – 2009– Data averaged over one hour time intervals
* Cloud fraction profiles* Total, high, middle, and low
clouds* Liquid water path and
precipitable water vapor* Surface radiative fluxes* TOA radiative fluxes
* Soundings* NWP analysis data* Surface sensible and latent heat fluxes* Surface precipitation* Surface temperature, relative humidity, and horizontal winds
![Page 6: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/6.jpg)
Methods
• Composite • Weighted Composite• Regression
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July 1996 – RH and PrecipitationRelative Humidity (RH) at surface – ψ(t)
Days on July 1996
Days on July 1996
[mm
/hr]
[%]
Precipitation Rate at surface – p(t)
: Rain Event
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non-weighted composite method
• non-weighted composite
€
ψi(tlag )i= 0
N
∑N
=ψ (tlag )
tlag = [-7*24, 7*24] hoursN = total number of selected rain events
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non-weighted composite
-7 days +7 days
Relative Humidity (RH) at surface – ψ(t)
Days on July 1996
[mm
/hr]
[%]
Precipitation Rate at surface – p(t)
-7 days +7 days-7 days +7 days-7 days +7 days-7 days +7 days-7 days +7 days
: Rain Event
![Page 10: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/10.jpg)
Weighted composite method
• weighted composite
tlag = [-7*24, 7*24] hoursN = total number of selected rain events
€
pi(t0)ψ i(tlag )¡=1
N
∑
pi(t0)i=1
N
∑
Non-weighting
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Weighted composite
-7 days +7 days
Relative Humidity (RH) at surface – ψ(t)
Days on July 1996
[mm
/hr]
[%]
Precipitation Rate at surface – p(t)
-7 days +7 days-7 days +7 days-7 days +7 days-7 days +7 days-7 days +7 days
: Rain Event
![Page 12: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/12.jpg)
Composite vs. Weighted Compositem
m/h
rm
m/h
r
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Regression method
• Regression Coefficient
€
cor p(t),ψ (t + tlag )( )sd ψ (t)( )sd p(t)( )
t = whole time series tlag = [-7*24, 7*24] hours
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Regression method: t = 0 hourRelative Humidity (RH) at surface – ψ(t)
Days on July 1996
[mm
/hr]
[%]
Precipitation Rate at surface – p(t)
![Page 15: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/15.jpg)
Regression method: t = -10 hourRelative Humidity (RH) at surface – ψ(t)
Days on July 1996
[mm
/hr]
[%]
Precipitation Rate at surface – p(t)
![Page 16: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/16.jpg)
Regression method: t = +10 hourRelative Humidity (RH) at surface – ψ(t)
Days on July 1996
[mm
/hr]
[%]
Precipitation Rate at surface – p(t)
![Page 17: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/17.jpg)
Comparison: Regression vs. weighted composite
• Regression Coefficient
• Weighted composite€
cor p(t),ψ (t + tlag )( )sd ψ (t)( )sd p(t)( )
=cov p(t),ψ (t + tlag )( )
sd p(t)( )2 =
cov p(t),ψ (t + tlag )( )
sd p(t)( )2 =
′ p (t) ′ ψ (t + tlag )
′ p (t)2
€
pi(t0)ψ i(tlag )¡=1
N
∑
pi(t0)i=1
N
∑=
p(t0)ψ (tlag ) + ′ p (t0) ′ ψ (tlag )
p(t0)=ψ (tlag ) +
′ p (t0) ′ ψ (tlag )
p(t0)=ψ (tlag ) +
cov p(t0),ψ (tlag )( )
p(t0)
t = whole time series tlag = [-7*24, 7*24] hoursN = total number of selected rain events
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Weighted Composite vs. Regression %
RH on precipitation
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Weighted Composite vs. Regression
SAME, except for units
%
RH on precipitation
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Relative Humidity Perturbation
Weighted[%]
Regression[%/(mm/hr)]
Non-weighted[%]
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Time for some results….
• Oklahoma JJA vs. DJF precipitation
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Cumulative Fraction of Rain Events
JJA
DJF
• DJF - ~45% time not raining • JJA - ~32% time not raining
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Cumulative Fraction of Rain Events
JJA
DJF
• DJF - ~45% time not raining • JJA - ~32% time not raining
5
~20% rain events > 5 mm/hr
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Cumulative Fraction of Rain Events
JJA
DJF
• DJF - ~45% time not raining • JJA - ~32% time not raining
5
~5% rain events > 5 mm/hr
![Page 25: The nature of rain events in summer vs. winter at the SGP ARM Facility](https://reader033.vdocument.in/reader033/viewer/2022051821/568159e9550346895dc736f4/html5/thumbnails/25.jpg)
Summer vs. Winter Precipitation
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Summer vs. Winter Temperature
Strong Diurnal Cycle
Weak Diurnal Cycle
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Summer vs. Winter Temperature
Strong Diurnal Cycle
Weak Diurnal Cycle
Frontal Precip
Afternoon Convection
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Seasonal:
Temperature perturbation [K]
DJF: Winter
JJA: Summer
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Summer vs. Winter Surface Pressure
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Seasonal:
Relative Humidity perturbation [%]
DJF: Winter
JJA: Summer
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Seasonal:
Relative Humidity perturbation [%]
DJF: Winter
JJA: Summer
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Summer vs. Winter LWP
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Seasonal:
All Cloud Fraction perturbation [%]
DJF: Winter
JJA: Summer
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Summer vs. Winter Cloud Top Height
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Seasonal:
Omega perturbation [Pa/s]
DJF: Winter
JJA: Summer
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Summary• Summer (JJA):
– More rain events– Heavier, but shorter rain events– Stronger diurnal cycle– Higher cloud tops
• Winter (DJF):– Tilted vertical structure for RH and Cloud Fraction
• THOUGH, hourly time composites might reveal tilted structure in summer