The Turbulence Characterization and Detection (TCAD) Program

The TCAD field program was conducted near Greeley, Colorado during June 1999. Participating agencies included the National Aeronautical and Space Administration (NASA), the National Center for Atmospheric Research (NCAR), the AlliedSignal Corporation, the Rockwell-Collins Corporation, the Colorado State University (CSU) and the South Dakota School of Mines and Technology (SOM). Three aircraft participated: the Rockwell-Collins Sabreliner, the South Dakota T-28, and the AlliedSignal Convair 580. The CSU CHILL and Pawnee Doppler radars provided ground-based radar support. The NCAR Mobile CLASS van took daily soundings.

General information about the TCAD data sets

Radar Plots

CHILL data are shown on a Cartesian grid at altitudes that most closely match the aircraft altitudes. The Cartesian interpolation for the CHILL radar data is done using a closest point analysis. Discontinuities are visible in the data. A better interpolation method for generating the Cartesian plots is under investigation, but it will only be used for high priority cases. The radar plots currently shown are good for a quick look at the data. Fields shown are reflectivity (dBZ), radial velocity (m/s) and spectrum width (m/s).

**VERY IMPORTANT** The CHILL radar data shown in the closest point Cartesian files are NOT edited, therefore the radial velocity and spectrum width fields are invalid in low signal regions.

Vertical cross-sections are taken along the flight paths for the high priority flights. The cross-sections can have multiple segments. This ability is used to create a cross-section that closely parallels the aircraft flight track. Each set of cross-sections has a horizontal and 3 vertical plots. The horizontal plot is used to show the location of the vertical cross-section (solid yellow line) with the aircraft flight tracks and the CHILL reflectivity. The three vertical plots show the reflectivity (dBZ), radial velocity (m/s) and the spectrum width (m/s) fields of the cross-section. On these three plots, the vertical lines (dashed yellow) denote inflection points along the flight path; the horizontal line (dashed yellow) is the approximate flight altitude. The X-axis shows the distance along the cross-section (km); the y-axis is the altitude (km MSL).

Aircraft data

**VERY IMPORTANT** More aircraft data processing may be required.

The aircraft time (UTC) and the altitude (km MSL) fields are color-coded by aircraft along each flight track: magenta is SOM T-28, sky blue is the AlliedSignal Convair 580, and green is the Rockwell-Collins Sabreliner.

For the accelerometer data (g) and the cube root of the eddy dissipation rate (m2/3 s-1) fields, the data are color-coded by turbulence intensity as shown in the following table. Accelerometer variables shown include the Vertical Acceleration (AZ) and the Humphrey (gyro-stabilized) accelerometer (HACC) from the T-28, and the INS Vertical Acceleration (INS Vertical Accel) from the Sabreliner. Extracting flight data from the AlliedSignal Convair is not yet complete. Variables that will be shown include the INS Vertical Acceleration (INS_VERTACC) and the INS Vertical Plate Accelerometer (INS_VERTPLATACC). Other variables will be added as analyses are completed.

Dual Doppler plots

Sounding Plots and Data Files

Profiler Data Files

Metar Plots