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 Microwave Profiling Radiometer Doppler sodar 915 MHz Doppler Profiler Lidar ceilometer Surface instrumentation 18 June 2002 Deployment 3 IR radiometer

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 Z (Knupp) –very dry air within the heat burst (T  35 °C, T d  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

15 June 2002 case summary 15 June 2002, 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

Data presentation - 15 June case 915 MHz Profiler (  z = 60 m,  t = s) –V h, W, SNR (Z and C n 2 ), Doppler spectra, T v (z)  m lidar ceilometer –cloud base & precip. properties (extinction), aerosols Microwave Profiling Radiometer (to 10 km) –T(z),  v (z), PW, ILW, cloud base T (  t = 14 min) Surface instrumentation (1 Hz) –T, RH, p, wind, solar radiation S-Pol Z GOES-11 visible images

GOES 11 overview Good definition in cloud field

Poor definition in cloud field

Anvil moves over the boundary

Intense storm with gust front over MIPS

deployments (surface data) T, T d Wind speed Wind direction Solar radiation Anvil overhead boundary

Radiometer values of PW and ILW (note time breaks) 123 mm Systematic increaseSystematic decrease Profile

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 12 boundary

+ MIPS Deployment 1

+ MIPS Deployment 2

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

Deployment 1Deployment 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) SNR W VV

Ceilometer: Cu cloud base near km, some variation in backscatter at low levels associated with boundary passage clouds Cloud base decrease following boundary passage 12

Radiometer T,  v profiles at westeast west east dd

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, T d Wind speed Wind direction pressure solar Gust front boundary?

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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

T,  v profiles at 2246: disappearance of the stable layer (same location) Deeper layer of water vapor within the boundary zone; 35% increase in integrated vapor

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  v profiles.

End Information on MIPS, with a (future) link to IHOP analysis efforts is at the following site:

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

Ceilometer backscatter: cloud structure, precipitation properties, BL structure

MIPS measurements of a boundary (dry line) during IHOP