1. This is tes box Multi-scale Analyses of Moisture and Winds during the 3 and 9 June IHOP Low-Level Jet Cases Edward Tollerud, Fernando Caracena, Adrian Marroquin, Brian Jamison *, and Steve Koch NOAA Forecast Systems Laboratory and Cooperative Institute for Research in the Environmental Science (CIRES) * DLR Falcon Dropsonde Sections Along the Northern Leg of the June 9 Flight Track MODELING STUDY, JUNE 3 CASE The RAMS model was initialized with LAPS analyses fields for 1500 UTC 3 June 2002 over the IHOP area with lateral boundary fields taken from the RUC20 model. For verification, we use the NOWRAD patterns for 3 June 2002, valid at 1800 UTC shown below. The model was run in a two-nested grid configuration with the innermost grid spacing of 4 km and an external grid of 12 km. A horizontal cross section of wind vectors, isotachs (red), and precipitation (black) from a 3-h forecast is shown at the right. The initial fields are from LAPS analysis with conventional data (no IHOP observations) and include the "hot start" diabatic initialization procedures (which includes moisture and consistent vertical velocities) to describe Radiosonde Processing and IHOP Observations Dropsonde data taken during Ihop has allowed us to see the vertical structure of low-level jets that developed over the area of the field experiment with a vertical sample interval better than 5 m. The terminal speeds of these dropsondes was about 7 m/s and the wind sample rate was 0.5 s. Contrast these values with those of radiosondes, which rise at 5 m/s and wind samples are taken every 6 s. During IHOP, an archaic procedure used by NWS in coding transmitted wind data described by Doswell (http://www.cimms.ou.edu/ ~doswell/NWSwinds/NWS_Winds.html), futher degraded wind measurements, resulting in a corresponding degradation of initial wind data in the Eta model.http://www.cimms.ou.edu/ ~doswell/NWSwinds/NWS_Winds.html The figure shows a comparison of two vertical wind profiles (80 km Eta initial field, dashed and dropsonde data, solid) taken at the first dropsonde release point on 1104 UTC 3 June 2002. The Eta wind profile was obtained from the grid point nearest to the dropsonde location, and includes the boundary layer level output as well. Note that the boundary layer resolution of the model is not manifest in the initial fields because the model has been fed coarse, "minute" wind information from the radiosondes. The coarser radiosonde wind data has resulted in a 15- 20 % maximum wind error in the wind speed at and below the level of maximum winds. The effect is magnified in the horizontal moisture transport, which is computed from the product of the mixing ratio and wind speed (profiles shown in bottom figure). The sharp peak in vertical profile of moisture transport by the LLJ is located at about 300 m above ground level (AGL). Looking at the structure of the Eta wind profile, one can see that there would be a large error in moisture transport below 800 m AGL. Description and Comparisons of LLJ Wind and Moisture Structure vis-à-vis Mission Science Objectives HRDL observations of windspeed normal to the Falcon flight track during the June 9 mission, combined with simultaneous DIAL measurements of specific humidity, will provide highly-resolved estimates of transport by the LLJ. When compared with computations using dropsonde measurements at a larger scale (roughly 60 km separation of observations) and with radiosonde observations made at even larger scales, the lidar flux computations can begin to address questions about the utility of moisture measurements at these fine scales. Specifically, the presence of correlations of the windfields with the moisture fields at scales below that resolved by the operational network of radiosondes and profilers may be determined. Model runs that incorporate research observations by dropsondes will also be compared with existing runs that do not to get another assessment of the impact of mesoscale observations on forecasts of LLJ transport. June 9 Aircraft Tracks and Dropsonde Observation Locations June 3 Aircraft Tracks and Dropsonde Observation Locations Jet Core Dropsonde Profile S-POL Radar Doppler Velocities Two IHOP Morning Low Level Jet (LLJ) Missions On the mornings of June 3 and June 9, aircraft missions were flown in the IHOP domain to observe LLJ circulations and moisture structure. The primary instrumentation included extra standard radiosonde launches, aircraft-launched dropsondes, and airborne lidar wind and moisture measurements from the DLR Falcon and Learjet. Using data observed from these platforms it is possible to describe the moisture structure and transport in the LLJ in unprecedented detail and at multiple scales. We describe the observations made in these missions and the flight tracks designed to observe them. Some initial model results from a detailed MM5 run are also discussed. Sections of dropsonde and lidar moisture and wind observations are shown. Finally, an application of detailed dropsonde profiles to assessment of radiosonde processing accuracy are presented. NAST Lidar data Proteus aircraft LASE Data from DC-8 Windspeed (m/s). The core of the LLJ is indicated near the eastern end of the flight leg at a pressure of about 820 mb. Mixing Ratio (r) in g/kg. The depth of the moist boundary layer increases eastward. The mid-boundary layer dryness at the extreme east end is relected also in the DIAL sections above Moisture Transport across the northern side of the flight box as given by v. r, where v is the wind component transverse to the flight leg.. DIAL (onboard lidar, DLR Falcon) observations of specific humidity. Compare with dropsonde-observed section below. Anomalous rectangular regions near east end of section suggest cloud contamination. Jet Core Dropsonde Profile, June 9 the initial cloud field. The wind barbs and isotachs in the figure seem to suggest that the LLJ splits into two branches (upper right of figure), with one branch feeding the convective activity over Kansas and the other continuing to the northeast (upper right of figure). The precipitation pattern correlates with the NOWRAD radar shown to the lower left. NOWRAD radar mosaic valid 1800 UTC 3 June 2002. Notice the radar pattern across New Mexico-Texas border, which suggests convective activity forecasted by RAMS Terra Modis Satellite Image, 1641 UTC 3 June 2002 LLJ Mission Forecasting Issues involved with forecasting LLJ occurrences for IHOP mission planning are revealed in the two RUC 10 km 12h forecasts for 1200 UTC June 9 shown above and to the right. A jet with good moisture that met windspeed criterion was suggested in the surface fields in central and western KS and OK. Secondly, for optimum performance of the lidar sensors on the Falcon, essentially cloud-free conditions were required. The forecast of cloudtops (above) suggested possible trouble, and indeed some slight cloud contamination was encountered.