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Shapiro (1984). Shapiro, M. A., 1984: Meteorological tower measurements of a surface cold front. Mon. Wea. Rev ., 112 , 1634-1639. BAO tower. WNW downslope flow. The passage of a strong cold front in eastern Colorado. We will be interested in the structure of this front as it passes the
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Shapiro (1984) Shapiro, M. A., 1984: Meteorological tower measurements of a surface cold front. Mon. Wea. Rev., 112, 1634-1639.
BAO tower WNW downslope flow The passage of a strong cold front in eastern Colorado We will be interested in the structure of this front as it passes the Boulder Atmospheric Observatory tower Temperatures (°C) winds (barb = 10 kts)
The Boulder Atmospheric Observatory Tower located in Erie, Colorado near I-25
Cross section of the cold front that passed the BAO tower on 24 March 1982 Based on a rawinsonde at Denver, a radiometer temperature profile, a lidar wind profile and surface data
300 meters superadiabatic lapse rate Two minutes!!! Potential temperature (K, solid) and front normal wind component (m/s, dashed)
Vertical motion (m/s) measured by sonic anemometers on the tower Frontal boundaries denoted by solid lines
Do the flow fields suggest that frontal contraction was occurring at the time the front passed the tower? Miller 2-D frontogenesis function (neglecting diabatic processes and turbulence) Change in potential temperature gradient following parcel Confluence acting on q gradient Shear acting on q gradient Tilting of vertical q gradient Can’t evaluate this - so assume negligible based on surface data
Miller 2-D frontogenesis function (neglecting diabatic processes and turbulence) confluence term Change in potential temperature gradient following parcel Confluence acting on q gradient Shear acting on q gradient Tilting of vertical q gradient
Miller 2-D frontogenesis function (neglecting diabatic processes and turbulence) Tilting term Change in potential temperature gradient following parcel Confluence acting on q gradient Shear acting on q gradient Tilting of vertical q gradient
Miller 2-D frontogenesis function (neglecting diabatic processes and turbulence) Total frontogenesis Frontogenetical Frontolytical Change in potential temperature gradient following parcel Confluence acting on q gradient Shear acting on q gradient Tilting of vertical q gradient