Impact of vegetation roughness parameters

1
Impact of vegetation roughness parameters
changes in boundary layer variables.
Arturo I. Quintanar and Rezaul Mahmood. Kentucky
Climate Center Department of Geography and
Geology, Western Kentucky University, Bowling
Green, KY 42101 USA John Loughrin and Nanh C.
Lovanh USDA-ARS, Animal Waste Management
Research Unit Bowling Green, Kentucky, 42101, USA
2
OUTLINE

• Objectives
• The experiment design
• The vegetation roughness length impact
• Comparisons with a soil moisture sensitivity
  experiment
• Preliminary conclusions
• Future work

3
GENERAL OBJECTIVES

• Construct ensemble simulations from different
  regional atmospheric models to produce air
  quality scenarios where the uncertainty to
  vegetation and soil moisture specification is
  included.
• To study the sensitivity of each model to the
  specification of vegetation and soil properties

4
OBJECTIVES

• In particular we want to study the sensitivity of
  boundary layer variables to
• Soil moisture perturbations
• Aerodynamic roughness lengths from vegetation
  cover.

5
EXPERIMENTAL DESIGN
The Penn State/NCAR MM5 v.3 coupled to the Noah
LSM 2 two-way nested domains at 18km and 6km
resolution Kain-Fritsch cumulus
parameterization. NCAR FNL data at 10 x 10
horizontal resolution.

• Period of integration June 2006
• June 12 moderate synoptic forcing
• June 18-19 strong synoptic forcing
• June 23 weak synoptic forcing

6
EXPERIMENTAL DESIGN
7
Control Run and perturbed Roughness Length Z 0
(cm) experiments
8
Region of roughness modification (tones of gray)
for cropland, pasture and grassland in mother
domain
9
CONTROL Run 12 Hour Accumulated Precipitation (mm)
MM5
NARR
JUNE 12 2006
Moderate Synoptic forcing
JUNE 18 2006
Strong Synoptic forcing
10
CONTROL Run 12 Hour Accumulated Precipitation (mm)
NARR
MM5
JUNE 19 2006
Strong Synoptic forcing
JUNE 23 2006
Weak Synoptic forcing
11
12 Hour Total PRECIPITATION AND WIND FIELD
DIFFERENCES
CTRL MINUS EXPERIMENT WITH Z0 2 cm
JUNE 12
JUNE 18
JUNE 23
JUNE 19
12
12 hour Total PRECIPITATION AND WIND FIELD
DIFFERENCES
CTRL MINUS EXPERIMENT WITH Z0 5 cm
JUNE 12
JUNE 18
JUNE 23
JUNE 19
13
12 Hour Total PRECIPITATION AND WIND FIELD
DIFFERENCES
CTRL MINUS EXPERIMENT WITH Z0 10 cm
JUNE 12
JUNE 18
JUNE 23
JUNE 19
14
12 Hour Total PRECIPITATION AND WIND FIELD
DIFFERENCES
CTRL MINUS EXPERIMENT WITH Z0 20 cm
JUNE 12
JUNE 18
JUNE 23
JUNE 19
15
(No Transcript)
16
A COMPARISON WITH A SOIL MOISTURE
EXPERIMENT DIFFERENCES IN EQUIVALENT POTENTIAL
TEMPERATURE JUNE 12 2006
CTRL-EXP (Z0 5 cm)
CTRL-DRY( SM decreased by .1)
17
A COMPARISON WITH A SOIL MOISTURE
EXPERIMENT DIFFERENCES IN EQUIVALENT POTENTIAL
TEMPERATURE JUNE 18 and 19 2006
CTRL-EXP (Z0 5 cm)
CTRL-DRY( SM decreased by .1)
18
A COMPARISON WITH A SOIL MOISTURE
EXPERIMENT DIFFERENCES IN EQUIVALENT POTENTIAL
TEMPERATURE JUNE 23 2006
CTRL-EXP (Z0 5 cm)
CTRL-DRY( SM decreased by .1)
19
A COMPARISON WITH A SOIL MOISTURE
EXPERIMENT DIFFERENCES IN VERTICAL AND HORIZONTAL
WIND COMPONENT JUNE 12 2006
CTRL-EXP (Z0 5 cm)
CTRL-DRY( SM decreased by .1)
20
A COMPARISON WITH A SOIL MOISTURE
EXPERIMENT DIFFERENCES IN VERTICAL AND HORIZONTAL
WIND COMPONENT WITH RESPECT TO CONTROL JUNE 18
and 19 2006
CTRL-EXP (Z0 5 cm)
CTRL-DRY( SM decreased by .1)
21
A COMPARISON WITH A SOIL MOISTURE
EXPERIMENT DIFFERENCES IN VERTICAL AND HORIZONTAL
WIND COMPONENT WITH RESPECT TO CONTROL JUNE 23
2006
CTRL-EXP (Z0 5 cm)
CTRL-DRY( SM decreased by .1)
22
PRELIMINARY CONCLUSIONS

• As a first step in studying the response of the
  model atmosphere we have changed uniformly the
  values of roughness length for cropland,
  grassland and pastures which dominate
  southwestern Kentucky.
• Smaller roughness lengths than the average values
  in the control, result in larger changes in
  precipitation rates over the affected region.

23
PRELIMINARY CONCLUSIONS

• The changes in precipitation are linked to
  changes in near-surface wind fields near the time
  and location of convective events.
• The timing of precipitation is also affected by
  changes in roughness length values over the
  domain.
• The response to roughness length changes is about
  3 or 4 orders of magnitude smaller than that
  found for a soil moisture experiment.

24
FUTURE WORK

• To study the sensitivities and biases of MM5, WRF
  and RAMS to vegetation parameters such as albedo,
  LAI, roughness length, canopy resistance and soil
  moisture specification.
• To study the impact on transport and dispersion
  of pollutants under different meteorological
  synoptic conditions.