Transcript WRF-STILT: Progress Report Jan 2007 Top-level slides provided by Janusz Eluszkiewicz and Thomas Nehrkorn Atmospheric & Environmental Research, Inc. 131 Hartwell Ave Lexington, Massachusetts 02421 www.aer.com Jan 2007

WRF-STILT: Progress Report
Jan 2007
Top-level slides provided by
Janusz Eluszkiewicz and Thomas Nehrkorn
Atmospheric & Environmental Research, Inc.
131 Hartwell Ave
Lexington, Massachusetts 02421
www.aer.com
Jan 2007
1
WRF-STILT Coupling: Current Tasks
Coupling of WRF with STILT
Mapping of variables and data format conversions
Use of time-averaged momentum flux variables
for improved mass conservation
Use of convective mass fluxes for vertical
particle redistributions
Sensitivity testing and model evaluation
Sensitivity of trajectories and footprints to:
Treatment of convection
Model resolution
Effects of different Met Drivers (WRF, BRAMS, FNL…)
Jan 2007
Atmospheric and Environmental Research, Inc.
2
WRF-STILT Coupling: Current Tasks
Sensitivity testing and model evaluation (cont)
Comparison of simulated and observed CO2
Effect of met drivers (trajectories) on fit to observations
Effect of other inputs on fit to observations:
• Computation of PBL height
• Computation of radiative forcing
• Vegetation type and other biosphere parameters
Evaluation of relative contributions of near- and far-field
GEE, respiration, and other sources and sinks
Jan 2007
Atmospheric and Environmental Research, Inc.
3
WRF-STILT Coupling: Future Tasks
Examine Role of Data Assimilation
WRF v2.2 supports analysis and observation nudging
+: Improved fit to observations
- : may degrade mass conservation of model solution
- : requires manual tuning of nudging parameters
WRF-4dvar (under development) provides a possible
alternative
+: Analysis is a model solution, satisfies mass conservation
+: Tuning can be based on climatological or ensemble-based
error statistics
- : requires significant personnel and computer resources
AER has experience in both approaches, has worked with
NCAR on (MM5) 4dvar development
Jan 2007
Atmospheric and Environmental Research, Inc.
4
WRF-STILT Coupling: Argyle Results
Obs exhibit nighttime
spikes not reproduced by
simulations
Sims exhibit occasional
lows (< 340 ppm)
Common to WRF and
BRAMS
NLDAS SWF tends to
lower them further
Artificially replacing
“mixed forest” with
“deciduous” eliminates
some lows
Jan 2007
Atmospheric and Environmental Research, Inc.
5
WRF-STILT coupling: Argyle Results
The spike on July 4, 02Z
caused by uptake in
mixed forest - a case of
extreme sensitivity to
surface typing
Jan 2007
Atmospheric and Environmental Research, Inc.
6
Footprints: WRF/Nested/BRAMS
Jan 2007
Atmospheric and Environmental Research, Inc.
7
Water, ice, urban, other
Grassland
Cropland
Savanna
Shrubland
Mixed Forest
Deciduous Forest
Subtropical evergreen
Dry temperate evergreen
Wet temperate evergreen
Boreal evergreen
Jan 2007
Atmospheric and Environmental Research, Inc.
8
SWF: WRF/Nested/BRAMS
WRF40 may have hit a sunny
spot, but…
BRAMS even sunnier
Replacing “mixed” with
“deciduous” reduces uptake
Jan 2007
Atmospheric and Environmental Research, Inc.
9
WRF/STILT Coupling: Reversibility
WRF dramatically
improved over FNL.
BRAMS runs not practical
(~ weeks to generate a
comparable figure).
Jan 2007
Atmospheric and Environmental Research, Inc.
10