A time-height cross-section of wind profiler observations from Appledore Island.

A time-height cross-section of wind profiler observations from Appledore Island, Maine (upper panel) together with predicted winds from the operational Eta model (lower panel), collected during the New England Pilot Studies - Temperature and Air Quality (NEPS-TAQ) 2002 program. Black dots in the model data indicate levels where the model TKE passes a threshold, indicating the PBL depth. The model shows a high degree of skill in forecasting the passage of a shallow, low-level wind reversal feature.

Model Assessment Team

Dr. James Wilczak, Lead

Many of ESRL's developmental instruments provide unique, detailed insights into physical processes occurring within the atmosphere that cannot be obtained by any other means. The role of the Model Assessment Team is to use data collected from these instruments to critically evaluate algorithms for the parameterization of physical processes within operational and research numerical weather prediction models, and to develop and test new parameterization schemes. The goal of the parameterization evaluation, development, and testing is to improve the accuracy of operational weather forecast models, and requires a close collaboration between ESRL, NOAA's National Centers for Environmental Prediction (NCEP), and other NOAA Research Laboratories. The evaluation and development process requires an understanding of state-of-the-art instruments, access to field data taken with these instruments, and a thorough understanding of physical processes and parameterization schemes. It also requires iterative interactions between expert weather prediction modelers and observationalists. These model assessment tasks bridge the divide between the observational focus of ESRL and the numerical modeling that occurs at NOAA's research and operational modeling centers. They also create an opportunity for ESRL's instrumentation to have an immediate and direct impact on NOAA's operational services, and can provide feedback to ESRL on what new kinds of instrumentation could have the biggest impact on operational models.

Recent work by the Model Assessment Team has focused on broad areas including: air quality, surface temperature, and precipitation. Related work includes coupled atmosphere-ocean modeling, and numerical model physics development and verification.

Air Quality

Our air quality research largely has been directed through NOAA's Health of the Atmosphere program, including the

In addition, ESRL has been involved in NOAA sponsored research evaluating the meteorological aspects of air quality simulation models as part of the Central California Ozone Study (CCOS). These studies have focused on the ability of numerical models to properly simulate transport and mixing within the atmospheric boundary layer. These studies have utilized special networks of radar wind/temperature/turbulence profilers, surface radiation and aerosol measurements, and surface sensible and latent heat fluxes. As part of these studies ETL has evaluated the meteorological aspects of the developmental Eta/CMAQ air quality model, which is slated to become the NCEP operational ozone forecast model during the summer of 2004, and has evaluated the WRF-CHEM model which is the "next generation" air quality model under development within NOAA.

Surface Temperature

Our surface temperature forecast research has taken place under the auspices of the 2002 New England Pilot Studies-Temperature and Air Quality (NEPS-TAQ), and the follow-on 2003 New England High Resolution Temperature Program (NEHRTP). A central goal of these NOAA programs has been to reduce the costs of energy production by increasing the accuracy of surface (2m) temperature forecasts. On a nationwide basis, it has been estimated that the annual cost of electricity could decrease by $1 billion per year if the accuracy of temperature forecasts is improved by only 1 degree Fahrenheit. Under these programs ETL has deployed its instrumentation throughout New England, and has used that instrumentation to provide real-time evaluations of NCEP's Eta, GFS, RUC, NMM, and SREF models. We continue to work in collaboration with NCEP in using these measurements to identify weaknesses in model parameterizations of radiation, the surface energy balance, and boundary layer dynamics, and in seeking improved parameterizations that will increase the accuracy of surface temperature forecasts.

Precipitation Processes

The Model Assessment Team's research into precipitation processes has focused on the west coast of the United States. Under NOAA's Climate-Weather Connection program and the PACJET experiments, we have used numerical models to assess the origin of moisture in wintertime extra-tropical cyclones, which produce most of the U.S. West Coast's annual precipitation, finding that during ENSO years tropical moisture can be entrained into these winter storms. We have also utilized ETL's S-band radar measurements to evaluate the microphysical evolution of precipitating clouds simulated in research and operational models. During the winter of 2003-2004 this work will continue as part of the Hydro-Meteorological Testbed (HMT) deployment on the U.S. west coast, during which we will assess cloud and precipitation forecasts and cloud parameterization schemes from several NCEP operational models.

Precipitation Processes Results

Understanding the Dynamic Link Between Tropical Climate Variation and Winter Storms Along the US West Coast Satellite observations of the Pacific reveal bands of enhanced water vapor associated with the wintertime extratropical cyclones which produce most of the precipitation on the U. S. West Coast. Understanding the origins and development of these bands may aid regional short-term weather forecasting and seasonal precipitation predictions.

Coupled Atmosphere-Ocean Model

In traditional models of the atmosphere, the influence of the ocean on the atmosphere is limited to providing the bottom boundary condition in terms of sea surface temperature (SST). It has become increasingly clear that the the two-way interaction between the ocean and the atmosphere must be accounted for in order to better predict environmental events in coastal regions.

A Numerical Investigation of the Impact of Air-Sea Interaction on Hurricane Intensification
In this study, a coupled atmosphere-ocean-wave modeling system is used to simulate air-sea interaction under the high wind conditions of a hurricane. Results from these studies with and without sea-spray effect show that the inclusion of sea-spray evaporation can significantly increase hurricane intensity.

Development and Testing of Parmeterizations of Air-Sea Energy Fluxes under High Wind Conditions

Numerical Model Physics Development and Verification

Numerical models are computer approximations of the natural environment. In order to apply these models to increasingly complex issues, they must be tested and tuned. ETL is applying its extensive experience in Boundary Layer (BL) observation to improve the accuracy of boundary layer modeling.

Development and Testing of a New Atmospheric Boundary Layer (ABL) Scheme in WRF

Development of the Atmospheric Boundary Layer (ABL) Parametrizations for Weather and Air-Quality Predictions on Fine Scales