Objectives:

Study the effects of land surface processes (land use data, land surface related parameters) on the meteorological condition and on Houston’s high ozone concentration problem.

Previous Work

Meteorological simulations for the HGA provided by the Texas A&M (Dr. John Nielsen-Gammon) accurately predict maximum temperatures and reproduce the large-scale temperature patterns using simple 5-layer slab soil model.
The model performance is good, but is less successful for the PBL heights in rural areas.
To better understand Houston high ozone problem, and to understand the impact of urban vegetation, we use NOAH LSM in order to provide better meteorological simulations.

Configuration

• Analysis nudging for d1,d2,d3; observation nudging(wind vector)for d4
• d1, d2 2way nesting;
• d3,d4 continuous one-way nesting
• MRF PBL Parameterization
• Dudhia explicit moisture scheme
• RRTM radiation scheme
• Slab land-surface model (LSM)

Dominant landuse data used in MM5: Urban : 10 sites Rural : 18 sites

Design of Meteorological Simulation: S2(NOAH)

Experiment: Use the recently developed NOAH Land Surface Model (NOAH LSM) (EK, 2001) with identical inputs and model configurations as in S1 case except using different land-surface parameterizations (S2).

Scattered Diagram of 2-m Temp with (a) S1; (b) S2 simulations.

Summary of MM5 simulation

1. Original NOAH/USGS data for HGA: Urban area was treated as if it were totally covered with impervious surface. Therefore, we have large diurnal variations in temp and very low latent/sensible heat flux ratio in urban areas.
2. Bias in daytime temperature mostly fixed with added canopy water for the urban LU.
3. Min. temperature bias was fixed with the modified heat capacity at urban sites; and fixed with the added emissivity value at rural sites.
   

   Future MM5 simulation at IMAQS

• Continue to test MM5/NOAH
• Need to look at development of daytime wind speed build up.
• Need to continue to improve meteorological simulations especially for August 30 and 31 for wind development and moisture advection
• Use improve land use and land cover data
  - compare w/ TCEQ LU/LC used for biogenic emissions
  - develop methods to incorporate fractional LU/LC effects
• Future study will focus on the urban canopy parameterization (UCP) in meteorological modeling. By implementing the urban canopy parameterization into MM5, the meteorological simulation will be expected to have more accurate results on urban area simulation.