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Kevin Knupp University of Alabama in Huntsville IHOP_2002 Spring Science Workshop 3/24/03-3/26/03

Mobile Integrated Profiling System (MIPS) Observations of Boundary Layer and Water Vapor Variations around Boundaries and Storms. Kevin Knupp University of Alabama in Huntsville IHOP_2002 Spring Science Workshop 3/24/03-3/26/03. MIPS - Mobile Integrated Profiling System. IR radiometer.

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Kevin Knupp University of Alabama in Huntsville IHOP_2002 Spring Science Workshop 3/24/03-3/26/03

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  1. Mobile Integrated Profiling System (MIPS) Observations of Boundary Layer and Water Vapor Variations around Boundaries and Storms Kevin Knupp University of Alabama in Huntsville IHOP_2002 Spring Science Workshop 3/24/03-3/26/03

  2. MIPS - Mobile Integrated Profiling System IR radiometer Microwave Profiling Radiometer Lidar ceilometer Surface instrumentation 915 MHz Doppler Profiler Doppler sodar 18 June 2002 Deployment 3

  3. Analysis activities at UAH • Examination of the characteristics of all boundaries that passed over the MIPS (Ph.D. student) - see poster • 15 June case study (M.S. student, this presentation) • Heat burst event on 20 June around 0200-0230 Z (Knupp) • very dry air within the heat burst (T  35 °C, Td 0 °C) • combination of multiple microbursts and vortices • Highly variable wind, peak gust to 33 m s-1, near encounter with a vortex • Examination of a boundary layer entrainment event on 19 June; observed at the end of the CI experiment • Examination of the performance of the microwave profiling radiometer (entire research team) • focus on the BLE days

  4. 15 June 2002 case summary • 15 June 2002, 1900-2400 UTC • Observations of a complicated, diffuse boundary with small thermodynamic contrast. Three deployments were made around this boundary. • Continuous observations were acquired as the eastward-moving boundary intersected the inflow zone of an existing intense thunderstorm • the boundary assumed a much better definition • enhanced inflow into the storm (blowing dust) was observed • a strong gust front and outflow occurred 30 min later

  5. Data presentation - 15 June case • 915 MHz Profiler (Dz = 60 m, Dt = 30-60 s) • Vh, W, SNR (Z and Cn2), Doppler spectra, Tv(z) • 0.905 mm lidar ceilometer • cloud base & precip. properties (extinction), aerosols • Microwave Profiling Radiometer (to 10 km) • T(z), rv(z), PW, ILW, cloud base T (Dt = 14 min) • Surface instrumentation (1 Hz) • T, RH, p, wind, solar radiation • S-Pol Z • GOES-11 visible images

  6. GOES 11 overview Good definition in cloud field 1934 2003

  7. Poor definition in cloud field 2034 2103

  8. Anvil moves over the boundary 2134 2203

  9. Intense storm with gust front over MIPS 2255 2334

  10. 3 deployments (surface data) 2 3 1 T, Td Wind speed Wind direction boundary Anvil overhead Solar radiation

  11. Radiometer values of PW and ILW (note time breaks) mm 1 2 3 Profile Systematic decrease Systematic increase

  12. Deployments 1 and 2 Dep 1: Primarily west of boundary Dep 2: Boundary passage - wind direction change Lack of thermodynamic contrast in both cases More significant clouds during boundary passage at 2055 UTC 1 2 boundary

  13. Deployment 1 + MIPS

  14. Deployment 2 + MIPS

  15. Winds from one set of 3 beams, plotted every 5 min Red arrows indicate boundary location

  16. Deployment 1 SNR Deployment 2 915 MHz profiler Updraft with bndy at 1910? (deployment 1) Enhanced SNR during bndy passage near 2050 Appears to be a difference in CBL properties for 1 and 2 (all moments) W sV

  17. Ceilometer: Cu cloud base near 1.8-2.0 km, some variation in backscatter at low levels associated with boundary passage 1 2 clouds clouds Cloud base decrease following boundary passage

  18. Radiometer T, rv profiles at 1933 Gd 1922 1921 500 west east 700 east west 1000

  19. Deployment 3 Boundary passage near 2205 UTC? Oscillation? Intense vortex observed 2 km to the west. Anvil passage overhead rapidly reduced surface heating. As a result, the CBL turbulence weakened. Enhanced inflow into the approaching storm Gust front passage at 2256 UTC. 2 mb pressure rise prior to arrival T, Td Wind speed Wind direction boundary? pressure solar Gust front

  20. + MIPS MIPS

  21. + MIPS

  22. + MIPS

  23. + MIPS

  24. Deployment 3 Reduction in CBL turbulence due to cessation of surface heating. Updraft activity near 2240 UTC Acceleration of flow into the storm Gust front passage at 2256 UTC - max updraft > 10 m s-1 and peak gust to 28 m s-1

  25. T, rv profiles at 2246: disappearance of the stable layer Deeper layer of water vapor within the boundary zone; 35% increase in integrated vapor 2137 2220 (same location) 500 700 1000

  26. Summary & future work • Subtle variations in ABL properties were measured across the diffuse boundary. • A strong cap existed near 2 km AGL initially. • The cap eroded within the “sharpened” boundary zone near an approaching storm. Low-level water vapor increased significantly within the boundary zone. • The (main?) boundary appeared to contract as the storm approached, following a rapid reduction in solar heating. The storm intensified in the region where it intersected the boundary. What were the physical mechanisms? • Future: comprehensive case study; combine sensors to retrieve more detailed T and rv profiles.

  27. End Information on MIPS, with a (future) link to IHOP analysis efforts is at the following site: http://vortex.nsstc.uah.edu/mips

  28. 915 MHz SNR - varied examples, 2/16/01

  29. Ceilometer backscatter: cloud structure, precipitation properties, BL structure

  30. MIPS measurements of a boundary (dry line) during IHOP

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