Grantee Research Project Results

Final Report: Development of Techniques for Assimilating GOES Satellite Data into Regional-Scale Photochemical Models

EPA Grant Number: R826770
Title: Development of Techniques for Assimilating GOES Satellite Data into Regional-Scale Photochemical Models
Investigators: McNider, R. T. , Norris, W. B. , Biazar, Arastoo
Institution: The University of Alabama in Huntsville
EPA Project Officer: Hahn, Intaek
Project Period: July 1, 1998 through June 30, 2001 (Extended to January 17, 2004)
Project Amount: $404,127
RFA: Air Pollution Chemistry and Physics (1998) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air , Safer Chemicals

Objective:

The objective of this research project was to enlist the methods of satellite remote sensing to reduce the uncertainty in the cloud, soil-moisture and land-use physical characteristics that meteorological models pass to their photochemical counterparts.

Summary/Accomplishments (Outputs/Outcomes):

During the period of performance of this study, we have continued the development of new techniques for assimilating satellite data into Mesoscale Meteorological Model (MM5) and the Community Multiscale Air Quality Model (CMAQ) to improve model performance in regulatory settings (e.g. State Implementation Plan [SIP] activities). Specifically, we have improved the quality of the insolation and albedo retrievals to include updates of sensor calibration data. We have refined the surface moisture retrieval through improved numerical techniques for handling radiation and through a dynamical nudging technique that avoids shocks and oscillations in the surface energy budgets during the morning assimilation period.

For new technique developments, we have defined a technique for recovering the surface bulk grid scale heat capacity using evening tendencies. This initiative was taken because of bias and RMS errors in nighttime temperatures. We have made initial tests of this recovery in the southeast United States, in particular during the Texas Air Quality Study (TexAQS) 2000 period. Implementation of the technique required a recoding of the soil temperature model in MM5 to include an implicit solver. Tests of the retrieval showed that nighttime bias and RMS errors were significantly reduced and daytime performance was improved as surface moisture availability retrievals were improved.

An independent review of the satellite assimilation results by Texas A&M recommended that the satellite assimilation be used for SIP strategy testing. The model code and satellite products were delivered to the Texas Commission on Environmental Quality and Texas A&M. The satellite assimilation run was used in Comprehensive Air Quality Model (CAMx) SIP runs evaluating control strategy options for the Houston area. Thus, we believe this demonstrates that the EPA research activities directly impacted regulatory decisionmaking.

Finally, we carried out CMAQ simulations using the satellite derived photolysis fields for the TexAQS 2000 intensive period. This was the first time that satellite derived photolysis fields have been used in a photochemical model. The results showed that ozone fields could be altered at a grid point by plus or minus 50 ppb as a result of using the satellite-derived cloud transmittance compared to the MM5 cloud transmittance.

Model Evaluations

Two major modeling periods were undertaken to test the satellite assimilation strategies.

1. The first coincided with major field program activities in 1999 both for Southern Oxidant Study (SOS) and NARSTO-NE. The MM5 simulations that are discussed here span a period of 52 days during the summer of 1999, from June 28 through August 20. This period coincides with the SOS intensive field campaign during the summer of 1999. During the previous years of this project, surface properties were retrieved from satellite images and control MM5 simulations were performed. In addition, MM5 source code was modified for the assimilation of satellite retrievals, preprocessors were developed to prepare the satellite data for use in MM5, and finally utilizing the satellite retrievals, MM5 simulations with satellite assimilation was performed. The results from these simulations were less than satisfactory. The model crashed during the simulations for the 8-km nest, and unreasonable skin temperatures were observed in the 32-km runs.

   During the period of this report, we performed simulations with satellite assimilation, analyzed the results, and investigated the deficiencies in our assimilation method. We revisited the assumptions used in McNider, et al., 1994, and examined the implementation of this technique in MM5. The process that led us to revisit our technique was costly. First, as a result of undesirable results, we noticed the problem of cloud contamination in the satellite retrievals. This problem was fixed and the simulations were redone. This time the examination of the results indicated that although there was an overall improvement in the model results with respect to skin temperature predictions compared to the control run, at certain grid points the results were unreasonable. Therefore, we had to redo part of the simulations and look at the problem in detail. This testing period provided invaluable feedback into the performance and difficulties with applying the satellite assimilation for an extended period. Despite the difficulties, it led to an improved assimilation system that was then applied to the TexAQS 2000 data evaluation period with very good results.

2. The TexAQS 2000 period provided an excellent opportunity to test the improved assimilation system because of the quantity and quality of extra observable data and the focus of the national air quality research community. The MM5 model was run from August 20-September 1, 2000, which was part of the intensive period elected to be analyzed by the TexAQS national community. Part of the funding for this study was provided by the State of Texas. The model was run using the improved satellite assimilation system for insolation and moisture availability. The model showed considerable improvement in bias and root-mean-square error over the control simulation. This period was an exceptionally dry, hot period in the Southwest and coastal Southeast. The satellite assimilation did dry down the region considerably and, in fact, dried the model to a level near an ad hoc domain adjustment TexAQS modelers had made to improve model performance. An independent review of the satellite assimilation results by John Nielson-Gammon of Texas A&M concluded that the results were superior to any previous model run in terms of wind direction and mixing heights. A joint manuscript with Texas A&M researchers is being developed.

   More recently, an evaluation of model wind performance against profiler and surface wind data was made by Harvey Jeffries of the University of North Carolina. This evaluation showed that the MM5 run with satellite assimilation improved model performance compared to those without satellite assimilation especially in the first 7 days of the episode period.

   In addition to the base satellite insolation and moisture availability satellite retrievals, we were able to carry out the first test of employing photolysis fields using satellite derived broadband cloud transmittance and cloud top temperature into the CMAQ model. CMAQ ozone fields using the satellite photolysis fields were compared to control ozone fields using MM5 derived cloud transmittance and depth. The results showed that grid point ozone could change plus or minus 50 ppb between the satellite and control cases. This clearly illustrates the importance of using real cloud properties to calculate the photolysis values which are of first order importance in the chemical processes (Biazar, et. al., 2004).

   Although the model results using the base satellite assimilation were an improvement over the control cases, an examination of the model performance showed that considerable error was showing up in the nocturnal temperatures, and, in some locations, the satellite assimilation was overdoing the surface drying. In response to this, we implemented techniques for using evening skin tendencies to recover the model bulk grid-scale heat capacity. Although postulated in McNider et al. 1994, this technique had not been implemented or tested. Even though we encountered stability issues (which should be the basis of a more fundamental nature) by using time-step control, we were able to successfully recover a bulk grid scale heat capacity (the grid scale heat capacity is more a model heuristic than a physical quantity). By using this heat capacity in the model assimilation, we were able to drastically reduce the nighttime error and also reduce the daytime error (McNider, et. al., 2005; Shi, et. al., 2005).

Practical Application

The satellite assimilation techniques have matured to the point that they are now ready to be considered for use in SIP and other air quality planning activities. Based on independent reviews, the State of Texas selected the satellite assimilation TexAQS 2000 run for part of its SIP strategy testing. In discussions with U.S. Environmental Protection Agency National Exposure Research Laboratory colleagues it appears that the key issue on the use of the satellite products is developing a strategy for transitioning the products from a case-by-case research use to broad application. We are working with the National Aeronautics Space Administration and the National Oceanic and Atmospheric Administration to help develop a transition plan.

Journal Articles on this Report : 3 Displayed | Download in RIS Format

Publications Views

Other project views:	All 4 publications	3 publications in selected types	All 3 journal articles

Publications

Type	Citation	Project	Document Sources
Journal Article	McNider RT, Lapenta WM, Biazar AP, Jedlovec GJ, Suggs RJ, Pleim J. Retrieval of model grid-scale heat capacity using geostationary satellite products. Part I: First case-study application. Journal of Applied Meteorology 2005;44(9):1346-1360.	R826770 (Final)	Full-text: AMS Journals - Full Text HTML Exit
Journal Article	Pour-Biazar A, McNider RT, Roselle SJ, Suggs R, Jedlovec G, Byun DW, Kim S, Lin CJ, Ho TC, Haines S, Dornblaser B, Cameron R. Correcting photolysis rates on the basis of satellite observed clouds. Journal of Geophysical Research-Atmospheres 2007;112, D10302, 17 pp.	R826770 (Final)	Abstract: AGU Abstract Exit
Journal Article	Shi XZ, McNider RT, Singh MP, England DE, Friedman MJ, Lapenta WM, Norris WB. On the behavior of the stable boundary layer and the role of initial conditions. Pure and Applied Geophysics 2005;162(10):1811-1829.	R826770 (Final)	Abstract: SpringerLink Exit

Supplemental Keywords:

air quality, photolysis, land-use, ambient air, precipitation, oxidants, satellite data, modeling, remote sensing,, RFA, Scientific Discipline, Air, Ecology, particulate matter, Environmental Chemistry, Environmental Monitoring, Environmental Engineering, Engineering, Chemistry, & Physics, air quality standards, GOES satellite, remote sensing, cloud condensation, PM 2.5, air modeling, latent heat flux, boundary layer, soil, regional scale, photolysis wavelength, PM2.5, actinic flux, biogenic emissions, meterology

Progress and Final Reports:

Original Abstract

1999 Progress Report

2000 Progress Report

2001 Progress Report

2002 Progress Report

2003