Studying present day and future air quality in California using WRF, CMAQ and satellite data

National Aeronautics and Space AdministrationJet Propulsion LaboratoryCalifornia Institute of Technology

Tropospheric Emission Spectrometer

Studying present day and future air quality in California using WRF, CMAQ

and satellite data

Greg Osterman1,3

Jinwon Kim2,3

Annmarie Eldering1,3

Yunsoo Choi1

1 Jet Propulsion Laboratory/California Institute of Technology2University of California, Los Angeles3UCLA Joint Institute for Regional Earth System Science and Engineering (JIFRESSE)



Project Goals

• Construct a coupled regional climate and air quality modeling system

– Part of a larger joint JPL/UCLA effort to build coupled models to study effects of climate change on California environmental issues (air quality, water resources, snow cover)

• Study the potential effects of anthropogenic climate change on air quality in the mid-21st century

– Do this by running the model for current time periods and future time periods using projected meteorological conditions from climate models

– Focus on the changes in meteorological values have on ozone in 2044 (no emissions changes).

• Evaluate the present day model results using meteorological analysis results, surface monitor and satellite data



Model Description

• Study focuses on July 2006– WRF model is used to compute met fields (initiated by NCEP

Reanalysis)– SMOKE is used to determine emission data– CMAQ is used for air quality simulations– Models are one way nested

• Climate change signal by dynamically downscaling results from NCAR-CCSM3 (SRES-A1B) using the WRF model

– Two time periods calculated: 2004-2008, 2040-2044– Monthly mean differences in temperature and specific humidity are

calculated from those time periods

• Climate change signal in temperature and specific humidity is the added to the WRF results from July 2006

• CMAQ is run for July 2044



Model Calculation Scheme



Model Evaluation



Evaluation: WRF over CA for July 2006

• Evaluation using NCEP North American Reanalysis (NARR) with 30 km resolution

• Monthly mean 2m temperature with 12 km resolution from WRF

• Model tends to underestimate temperatures in most of CA, particularly the central valley

• High biases along the coast possibly due to difference in resolution in the models



Evaluation of CMAQ: TES Tropospheric O3

Step & Stare footprints45 km apartSpecial observation

Global Survey footprints180 km apartEvery 2 days… ~767 and counting

Transect footprints12 km apartSpecial observation

TES nadir footprint is 5 x 8 km



Evaluation: TES Tropospheric O3

Must take into account vertical sensitivity of TES measurements when comparing profiles to the model



Evaluation: TES Tropospheric O3

Looked at mean of TES profiles for July in three areas:

• Northern CA/NV and Southern Oregon• Southern CA Desert• Pacific off CA Coast



Evaluation: Northern California

• TES shows reasonable comparison with model throughout the troposphere

• Surface monitor data higher than CMAQ for month at Lassen and Yreka



Evaluation: Southern California Desert

• TES shows higher tropospheric ozone than the model in the lower troposphere (15-20 ppb)

• Good comparison in the upper troposphere• Surface monitor data higher than CMAQ for month at Death

Valley, Palm Springs and Joshua Tree



Evaluation: Ocean

• TES Step & Stare observation July 18, 2006

• TES data used with models can provide information on transport of data across the Pacific



Evaluation: Ocean



Evaluation: Ocean



Evaluation: Ocean

• TES shows lower tropospheric ozone than the model in the lower troposphere (5-15 ppb)

• Good comparison in the upper troposphere



Preliminary Study Results



2 m Temperature (K) 2 m RH (%) 2 m Qv (g/kg)

Changes in Temperature and Humidity

• Good statistical significance found in temperature and humidity but not in other meteorological variable (winds, PBL heights)

• Focus primarily on changes in 2 m temperature and humidity• Significant warming and drier air over the Sierra Nevada and

Western Nevada

06 UT

00 UT18 UT

12 UT 06 UT

00 UT18 UT

12 UT 06 UT

00 UT18 UT

12 UT


Tropospheric Emission SpectrometerEffects on O3 of Changes in all

Meteorological Variables

• Adding effects of changes in winds and PBL lead to larger changes in ozone

• Largest effects concentrated in more populated regions

• Keeping ozone within EPA standards could be more difficult under warmer surface conditions

• Looking at the effects of changes in individual meteorological variables show results can be nonlinear

06 UT

00 UT18 UT

12 UT



Conclusions

• WRF/CMAQ model run for July 2006:– Reasonable comparison in free troposphere with mean TES ozone

in Northern CA– Model sees lower mean ozone compared to TES in the lower

troposphere over desert scenes in Southern California– Model compares well with TES in the upper troposphere over the

ocean but is higher than TES in the lower troposphere

• Climate run of WRF/CMAQ:– Statistically significant warming and drier air over the Sierra Nevada

and Western Nevada– Increases in surface ozone seen over large parts of CA, particularly

heavily populated regions– Increases in surface ozone due to temperature increases offset

somewhat by changes in humidity.



Future Work

• Further evaluation of the July 2006 control run using satellite and surface data:

– TES CO– OMI NO2 and OMI/MLS tropospheric O3 residual– Comparison with GEOS-Chem assimilation of TES data

• Better understanding of the reasons for the changes suggested by the model for the middle 21st century

• Put results into context of other similar studies on future climate/air quality over CA and West coast



Thank you!



Effects on O3 of T and Q Changes

Mean 12 UT

Sigma 00 UTSigma 12 UT

Mean 00 UT 06 UT

00 UT18 UT

12 UT

Mean Surface O3 in ppm – July 2006 Changes in O3 in ppm – July 2040


Tropospheric Emission SpectrometerEffects on O3 of changes in T and Q

Separately

Studying present day and future air quality in California using WRF, CMAQ and satellite data

Documents