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Primary data sources for paper

Detail study of a cold front and dry line prior to precipitation development during the International H 2 O Project.

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Primary data sources for paper

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  1. Detail study of a cold front and dry line prior to precipitation development during the International H2O Project Friedrich, K., D.E. Kingsmill, C. Flamant, H.V. Murphey, and R.M. Wakimoto, 2008: Kinematic and Moisture Characteristics of a Nonprecipitating Cold Front Observed during IHOP. Part I: Across-Front Structures.Mon. Wea. Rev., 136, 147–172. Friedrich, K., D.E. Kingsmill, C. Flamant, H.V. Murphey, and R.M. Wakimoto, 2008: Kinematic and Moisture Characteristics of a Nonprecipitating Cold Front Observed during IHOP. Part II: Alongfront Structures.Mon. Wea. Rev., 136, 3796–3821.

  2. Primary data sources for paper Wyoming King Air NRL P3 with ELDORA radar Learjet with Dropsondes

  3. side view P-3 Aircraft plan view

  4. We will be interested in the area inside the red box Note times

  5. Surface observations overlaid on GOES-11 visible satellite image (1-km resolution) at (a) 1900 and (b) 2200 UTC. Note times

  6. Reflectivity and Radial Velocity from Dodge City WSR-88D radar Points to note: SW flow Radar fine line at cold front Directional shear at both Boundaries Winds light (big barb = 5 m/s) Note scale 1 degree long = 86 km Fronts are about 40 km Apart in Box B Note times Note dropsonde x-secs

  7. DDC radar reflectivity at 1.5 km MSL between 1829 and 2026 UTC within box B Note: solid red lines for the NRL-P3 aircraft Note: dashed red lines for the UW King Air aircraft. Note: The path of the MMR Mobile Microwave Radiometer) is depicted by solid gray lines Note: Locations of dropsondes deployed between 1930–1939 and 2048–2100 UTC are indicated by dots in (d) and (g). Note three boundaries in the reflectivity field Note times

  8. Note times bad sonde Northern vertical cross section across the cold front from dropsondes Stable layer Contours of virtual potential temperature and mixing ratio (dashed estimated, mixing ratio >11 g kg−1 is shaded gray) Warm pocket Denser air Surface cold front Contours of equivalent potential temperature and mixing ratio Convectively Unstable but capped Note that this cross section is north of the intersection of the dry line with the cold front (see 2 slides back)

  9. Note times Soutern vertical cross section across the cold front and dry line from dropsondes Contours of virtual potential temperature and mixing ratio (dashed estimated, mixing ratio >11 g kg−1 is shaded gray) Warm Dry air Surface cold front and dry line Contours of equivalent potential temperature and mixing ratio Similar features, but warm dry pocket more prominent between dry line and cold front

  10. Cross section along red line Neutral stability in boundary layer (well mixed) Vertical cross section of contoured (a) virtual potential temperature and (b) equivalent potential temperature from the UW King Air aircraft data at 0.9, 1.1, 1.5, and 1.9 km MSL between 2006 and 2053 UTC.

  11. wind direction (solid black lines) and wind speed (solid gray lines) at each UW King Air flight level. vertical velocity (solid black lines) and mixing ratio (solid gray lines) Lots going on here in the boundary layer!

  12. Across front front-relative wind (derived from averaging winds recovered from dual Doppler syntheses along line from each Flight leg of NRL-P3 aircraft) Vertical velocity is indicated by solid (dashed) lines (derived from DD synthesis and averaged along line) -5 dBZ contour The position of surface cold front is indicated by a filled black triangle at the bottom of (a)–(f). Flow increases with time over front

  13. convergence field vertical velocity (black lines), vertical vorticity (red lines) Vertical vorticity indicative of shear along front

  14. Note gray line Surface mixing ratio (black lines), Integrated water vapor (medium gray Integrated liquid water (light gray lines) Thin, downward-pointing arrows highlight local maxima in IWV. cl are clouds Note periodicities in IWV at later times

  15. 15 km segments 1.3-km MSL horizontal cross sec. dual-Doppler horizontal winds reflectivity LEANDRE II mixing ratio In-situ virtual potential temperature, mixing ratio and wind Close-up measurements of front at one altitude Note scale

  16. Can the cold front be considered a gravity current? Froude number requirement “Densiometric current speed” Based on equations in papers by Benjamin (1968) and Simpson and Britter (1980) Answer: can’t tell – measurement errors to large to be certain -Conceptual model of the kinematic structures in an atmospheric gravity current (modified from Smith and Reeder 1988). -Reflectivity -Radial velocity -

  17. Schematic diagram showing the kinematic and moisture structures across the cold front during the (a) early (1800–2000 UTC) and (b) late (2000–2200 UTC) afternoon on 10 Jun 2002.

  18. What about along front structure?.....Part II

  19. 1.5 km MSL of ELDORA-derived dual-Doppler horizontal winds (arrows with scale indicated at bottom) ELDORA reflectivity (scale at the bottom). The dryline is indicated as a blue line with two unfilled semicircles reflectivity thin line is indicated as a dashed blue line.

  20. Altitude where the front relative winds reverse (top of the advancing air) Note the extreme variability What is going on?

  21. Horizontal projection of maximum ELDORA reflectivity within the vertical column below 2.3-km height [gray-shade scale in (d)] maximum vertical velocity [blue lines; scale in (a maximum vertical vorticity [red lines; scale in (a)]. Locations of the vortex lines are indicated as thin black thin lines oriented 65° off the cold front leading edge. Note kinks in front, updrafts and vorticity tubes: vorticity due to shear along front is concentrated in kink region and transported aloft as a vortex tube

  22. Horizontal cross section at 1.5 km of the ELDORA-derived alongfront wind component (gray-shade scale at the bottom). Positive winds are from the south. Plotting conventions for cold front, dryline, reflectivity thin line, and NRL P3 flight path are as in Fig. 2.

  23. Horizontal cross section at 1.5 km reflectivity indicated by the −1- and 3-dBZ contours (black lines), vertical velocity (areas with light-gray shading), vertical vorticity (areas with dark-gray shading)

  24. Color-coded maximum horizontal vorticity contours maximum vertical vorticity contours (black lines) horizontal wind vectors at 1.5 km (arrows with scale indicated at the bottom). Mean wind shear vector between 1.05- and 2.55-km height during 1844–2023 UTC is shown. cold front leading edge is indicated by the vertically oriented blue line. The location of the vortex lines is indicated by blue lines oriented almost perpendicular to the cold front leading edge. Vertical black lines indicate alongfront vertical cross sections from (a) I–I′ and (b) II–II′ shown in Fig. 14; horizontal black lines in (b) indicate the across-front vertical cross sections A–A′, B–B′, C–C′, and D–D′ shown in Fig. 15.

  25. Southwest–northeast vertical cross section within the postfrontal region during P3 (a), (b) leg 2 and (c), (d) leg 4. location of the cross sections is indicated in previous figure Color-coded ELDORA reflectivity (scale at the bottom) overlaid by wind vectors (arrows with asymmetric scale indicated) in the plane of the cross section. Gray-shaded magnitude of horizontal vorticity (scale at the bottom), vertical velocity contours (red lines; scale at the bottom), convergence contours (turquoise lines divergence contours (green lines). Updraft areas are indicated by red, solid lines and upward-pointing arrows; downdrafts are indicated by red, dashed lines and downward-pointing arrows. kinematic boundary is indicated as a thick black line and the flight level at 1.3 km MSL as a horizontal, thin black line with the aircraft symbol.

  26. Northwest–southeast vertical cross section for P3 leg 4 as indicated in Fig. 13b with (a) A–A′, (b) B–B′, (c) C–C′, and (d) D–D′. What are all these fluctuations associated with? Possibilities: Horizontal convective rolls KH waves at interface of front

  27. Horizontal profile of vertical velocity (black line) and mixing ratio (gray line) at 1.3 km MSL within the postfrontal air measured between 2020 and 2023 UTC (P3 leg 6) by in situ instruments mounted on the P3 aircraft. Thick arrows indicate the probable location of Kelvin–Helmholtz waves.

  28. Schematic diagram combining the results of this study – the structure of this “simple” cold front on the high plains of Oklahoma

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