Joint Urban 2003 - Oklahoma City | NCAR Research Applications Laboratory

Projects

Overview

Objective

In the summer of 2003, a field program was conducted in Oklahoma City to study atmospheric transport and diffusion in an urban environment. NCAR provided mesoscale modeling support for field-program operations.

Description

Joint Urban 2003 was the largest urban field program ever undertaken and the NCAR modeling activities provided forecasts for planning intensive observation periods. These forecasts were used to develop improvements in the model’s ability to realistically render urban boundary-layer properties. Five MM5-model grids were used in the nested modeling system, with the highest-resolution grid having a grid increment of 500 m. In addition to the MM5 model, the Variational Doppler Radar Assimilation System (VDRAS) was used to assimilate local NEXRAD radar data to produce analyses and 1-hour forecasts of boundary layer winds and other properties. Both MM5 and VDRAS winds were used as input to a transport and dispersion model to permit field-program managers to anticipate the transport of releases of chemical tracers used in the study.

Operations

The ATEC 4DWX system was adapted for use over metropolitan areas, and this capability was tested during the Joint Urban 2003 urban field study in Oklahoma City in July. A version of the GlobalMOD system with five nested grids employed the highest-resolution grid that spanned the limits of the city, with a horizontal resolution of 500 m. The Urban Wind Module (UWM) from the Defense Threat Reduction Agency (DTRA) was embedded in this inner grid. The UWM winds were used as input to the DOD SCIPUFF transport and dispersion model.

RTFDDA modeling study of OKC UHI

An analysis of three-dimensional atmospheric structures, based on model analyses for eight clear-sky days during the field program, reveals some interesting features of the Oklahoma City urban BL, including complex thermally induced circulations and associated convergence/divergence zones, a nocturnal thermal shadow downwind of the urban area, and the reduction of low-level-jet wind speeds by more-vigorous nocturnal mixing over the city. Figure on right show the mean 2-m temperature and 10-m winds of RTFDDA model output on eight clear-sky days. OKC urban regions are marked with think solid lines.

The ATEC 4DWX system was adapted for use over metropolitan areas.

Technology

Real-Time Four Dimensional Data Assimilation (RTFDDA)

The Real-Time Four Dimensional Data Assimilation (RTFDDA) system is a computer-model that was originally developed by NCAR for producing analyses of current meteorological conditions and forecasts for U.S Army test ranges. Since then, the system has been adopted by other DoD and government agencies for support of special missions and for homeland-security applications.

RTFDDA focuses its computational resources on forecasting for specific geographic areas - not the entire continent, for example. This narrow focus enables the model to resolve a greater number of meteorological features while maintaining accuracy. The forecasting system can be deployed worldwide to address threats of a human or man-made nature. For example, RTFDDA has been used for counter-terrorism support for both the Athens and Salt Lake City Olympics and to forecast the movement of hazardous material potentially released into the atmosphere. The system was used by the Army to support operations in Afghanistan and Iraq and it provided superior forecasts of Hurricane Rita in September 2005. In summary, the system excels at representing the details of the day-to-day weather in urban areas, as well as the extreme weather associated with hurricanes and thunderstorms.

Variational Doppler Radar Assimilation System (VDRAS)

Developed by Jenny Sun and Andrew Crook (both MMM/RAL), it provides detailed and frequently updated information on wind, rain, and other real-time weather developments. VDRAS is the first real-time system to diagnose low-level wind and temperature over a wide region using four dimensional data assimilation of Doppler radar data.

Operational Algorithms

Multiscale model blending
Source term reconstruction
Locating sources
Sensor placement

Resources

Journal Publications

Grossman-Clarke, S., J.A. Zehnder, W.L. Stefanov, Y. Liu and M.A. Zoldak,2005: Urban Modifications in a Mesoscale Meteorological Model and the Effects on Near Surface Variables in an Arid Metropolitan Region.J. Appl. Meteor, Vol. 44, 1281-1297. (abstract)

Conference Publications and Presentations

Chen, F., Y. Liu, H., Kusaka, M. Tawari, J. Bao, C. Lo and K. Lau, 2004:Recent Progress in Urban Landuse Modeling for the Community MM5 and WRF Models. Mesoscale and CFD Modeling for Military Appli., May 25 - 26, 2004. Jackson, MS.
(pdf) (html)

Halvorson, S., Y. Liu, R. Sheu, J. Basara, J. Bowers, T. Warner, and S. Swerdlin, 2004: Mesoscale and urban-scale modeling support for the oklahoma city JOINT-URBAN 2003 field program. Symposium on "Planning, Nowcasting, and Forecasting in the Urban Zone", Seattle, Washington. January, 2004.
(pdf) (html)

Liu, Y., F. Chen, T. Warner and S. Swerdlin, 2004: Improvements to surface flux computations in the MRF PBL scheme, and refinements to urban processes in the Noah Land-Surface model with the NCAR/ATEC Real-Time FDDA and forecast system. The 5th WRF / 14th MM5 User's Workshop , Boulder, CO. June 22-25, 2004.
(pdf) (html)

Links

Joint Urban 2003 data server: Measurements from existing and special sensors and platforms through the field experiment period, including RAL RTFDDA model final analysis data can be obtained from https://ju2003-dpg.dpg.army.mil/

Participants

Sponsor

Defense Threat Reduction Agency (DTRA)
The Defense Threat Reduction Agency safeguards America and its friends from weapons of mass destruction (chemical, biological, radiological, nuclear and high explosives) by reducing the present threat and preparing for the future threat.

Collaborator

U.S. Army Test and Evaluation Command (ATEC)
The U.S. Army Developmental Command (DTC) is the developmental testing arm of the U.S. Army Test and Evaluation Command (ATEC) and the Army's premier organization for conducting developmental testing of weapons and equipment. With the largest, most diverse array of testing capabilities in the Department of Defense , DTC tests military hardware of every description under precise conditions across the full spectrum of arctic, tropical, desert and other natural or controlled environments on highly instrumented ranges and test courses.

OU, Oklahoma Climatological Survey
The Oklahoma Climatological Survey was established in 1980 to provide climatological services to the people of Oklahoma, conduct research on the impacts of climate on human activities, and serve as a support facility for the State Climatologist. OCS has a legislative mandate to acquire, process, and disseminate climate and weather data and information for use by the state's citizens. The Survey maintains an extensive array of climatological information, operates the Oklahoma Mesonet, and hosts a wide variety of educational outreach and scientific research projects. The Oklahoma Climatological Survey is a research unit of the College of Geosciences at the University of Oklahoma.

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Joint Urban 2003 - Oklahoma City