Mission Plan :

NOAA 43RF will participate in an EMC Tail Doppler Radar mission (with an option to conduct HRD's TC-Ocean Interaction Experiment) into Hurricane Ike. The flight called for a rotated figure four pattern with an IP WNW of the center. The leg lengths were to be ~105 nm flown at 8,000 ft (pressure altitude) and GPS dropsondes would be launched in the center, in areas with insufficient scatterers to derive Doppler winds, in selected locations where AXBTs will be launched and in combination with AXBTs at the IP and second drop point (in support of Joe Cione's inner core SST cooling research). AXBTs and AXBT/GPS dropsonde combos will be targeted in areas coincident with a pre-storm ocean survey mission flown on 08 September as well as with NOAA drifting buoys in the area. Doppler wind and Super Ob analyses will be transmitted off the plane in real-time, if possible. The flight track, 12 GPS dropsonde points and 22 AXBT points are shown in Fig. 1. The flight track with overlaid tracks and positions of NOAA drifting buoys that were deployed ahead of the storm are shown in Fig. 2.

Fig. 1: Flight track (red line) for EMC Tail Doppler Radar mission 20080911I1. GPS dropsondes, AXBTs and AXBT/GPS dropsonde combos that were launched are indicated by black circles, white circles and circled crosses respectively. Blue circles indicate positions of NOAA drifting buoys that were overflown with GPS dropsonde/AXBT combos.

Fig. 2: Flight track (white line) for EMC Tail Doppler Radar mission 20080911I1. The black curves (blue circles) show the tracks (positions) of several NOAA drifting buoys that were launched ahead of the storm. Hurricane Ike's forecast track is shown by the blue line with forecast points shown by black circles. Altimeter-derived ocean heat content values are indicated by the colored shading.

Mission Summary :

1. Synoptic Situation

   On 11 August, Hurricane Ike was positioned around the western periphery of a large deep layer ridge and the remains of a weakening ridge to the NW (Fig. 3, left). Vertical wind shear analyses from UW-CIMSS indicated ~10-15 kt of shear over Ike (Fig. 3, right). Figures 3 and 4 also indicate that northwesterly shear was still present over the storm and that upper-level outflow around the western semicircle was still restricted (though perhaps somewhat less so).

   
   Fig. 3: (Left) plot of 250-850 hPa deep layer mean steering [magnitude (direction) of the steering flow is indicated by colored shading (white streamlines) and the storm center is shown by the red hurricane symbol] for 11 Sept 1200 UTC. (Right) vertical wind shear [magnitude (direction) of the wind shear is indicated by yellow contours (orange streamlines)]) for 11 Sept 1200 UTC. Images courtesy of UW/CIMSS.
   
   Fig. 4: Plot of mid to upper-level GOES water vapor winds for 11 Sept 1200 UTC. Image courtesy of UW/CIMSS.

2. Mission Specifics

   Take-off was from MacDill at 0810 UTC. Hurricane Ike was located at ~25.2° N 87.6°W, its intensity was 85 kt (946 hPa) and its forward motion was 295 ° at 8 kt. Figure 5 (left) shows an overpass by the SSMIS (91 GHz) satellite and indicates that Ike's convection was still quite asymmetric. Ike had a broad crescent shaped outer eyewall that was confined to the SE quadrant. Also evident in the SSMIS image (and confirmed by 43's LF radar) was a small inner eyewall located ~20 nm inside the outer eyewall. The size and location (SE quadrant) of the larger outer eyewall and small inner eyewall were quite consistent throughout the 8.75 hr mission. A 1330 UTC H*Wind surface wind analysis confirmed that the asymmetry of the surface wind field was similar to the asymmetry seen in the SSMIS 91 GHz imagery (Fig. 5). Also of interest was the atypical flight-level to surface reduction factor for the winds. At one point during the mission, ~100 nm NNE of the center, the P-3 measured 103 kt flight-level winds, while the SFMR only reported 65 kt at the surface. This 63% surface wind reduction factor suggests that Ike's winds at the flight level were highly decoupled from those at the surface.

   
   Fig. 5: Plots of (left) SSMIS 91 GHz imagery for 11 Sept 1354 UTC and (right) a HRD H*Wind surface wind analysis for 11 Sept 1330 UTC. Images courtesy of NRL/Monterey and NOAA/AOML/HRD.

   The flight pattern was executed as planned. There were ten GPS dropsonde/AXBT combos and two overflights of NOAA drifting buoys (with GPS dropsonde/AXBT combos) were made at drops #9 and #12. Additionally, GPS dropsonde/AXBT combos were made at the IP and at drop #2 in support of Joe Cione's inner core SST cooling research. The lowest GPS dropsonde pressure observed during the mission was 945.1 hPa at drop #5, during a pass through the center at 1118 UTC. Five Doppler wind and three Super Ob analyses were transmitted off the P-3 in real-time during this mission.

Problems :

There were no major problems related to this flight. A few minor issues included:

• FTPing of the Doppler data off the plane was unreliable during the flight once again
• 3 of the 22 AXBTs failed and one of the CADS failed to launch

Jason Dunion
29 April 2009

Mission Data :