Mission Plan :

The plan for this EMC-tasked mission was to fly a butterfly pattern (Fig. 1) with three passes through the center, but to first drop an AXBT at the 24-h forecast location to sample changes in the ocean as the hurricane passed. Further modules, such as one for stepped-frequency microwave radiometer circles, and for a gravity-wave module, were at the discretion of time and crew.

Mission Summary :

At the mission start time, Hurricane Lane was a major hurricane with estimated maximum sustained wind of 135 kt, moving westward. The previous intensity forecast was for Lane to remain steady state of slowly weaken, but instead, it rapidly intensified to the cusp of category 5. The forecast was for it to pass well south of the Big Island of Hawai'i and then turn north (Fig. 2). At this point, a clear, circular eye was seen on both visible and infrared satellite imagery, and an eye was also seen on microwave imagery, though it may have been open to the north (Fig. 3).

The IP was reached, and an AXBT was launched, reporting a sea-surface temperature of about 27.9C, which was slightly warmer than the previous day. The butterfly pattern was completed largely as planned, and circles for the stepped-frequency microwave radiometer were conducted in approximately 20 m/s surface winds before the third pass into the center. A final pass was conducted as part of a gravity-wave module. Four radar analyses were transmitted. During the mission, Lane's central pressure fell by 4 mb to a still high (for such a strong hurricane wind-wise) 951 mb, suggesting that the intensity forecast was correct, at least in the short term; Lane was 20 mb deeper than during the previous day's mission. Lane was moving just north of due west during the period.

During this flight, the radar showed a closed eyewall during all passes. One interesting aspect of the radar data was the display of surface mode, which showed more structure at further distances than the standard weather mode. (Fig. 4). The figure also shows the attenuation limitations of the new radar.

Radar analyses also showed that the strongest winds remained on the northern side of the eyewall, as well as strong upper-level outflow, though not as strong as during the previous day (Figs. 5 and 6). Multiple AXBTs were dropped in storm. The SST was reported to be 27.3C in the core, which was more than one degree lower than was reported the previous day.

The wind-speed reports from various instruments suggested that Lane continued to be a healthy hurricane. One dropwindsonde reported 176 kt at 192 m above the surface in the northeastern eyewall. In that same location, a sonde reported a 21.3-m/s updraft at about 1000 m and a 9.1-m/s downdraft at 532 m. This is one of the five largest updrafts measured by dropwindsondes in a hurricane. The strongest surface wind speed reported by the SFMR was 133 kt, and the highest flight-level wind speed was 132 kt.

Problems :

There were numerous problems during this flight. Most importantly, the NOAA Gateway went down during the flight, stopping all data transmission. The only way to contact CARCAH and CPHC was by satellite phone. This also prevented download of Doppler Wind Lidar data. The flight director was on the phone with CARCAH and CPHC telling them what we were seeing for significant parts of the flight. Because of this, the flight director was not always available ro ready for the science mission. Recommendation: Either the flight director of the lead project scientist should not be shy about calling for a time out so that everyone can catch up to what is happening on the flight.

Before the Gateway issue was diagnosed, we tried to contact John Hill to see if there was an issue at AOC preventing transmission. AOC did not have (or utilize) a way to contact John Hill, so John Gamache had to do it.

The pilots were conducting slightly curved legs instead of straight legs. Straight legs are important for many reasons, including the DWL. This was discussed at the post-flight brief, but should be clearly communicated before each flight. In addition, the lead project scientist requested straight legs during the gravity-wave module, but the flight director started turns to improve the fix; this was caught before it created problems.

There were multiple issues with the SFMR circles. First, the flight director insisted on doing the circles outside a rainband where the winds were too low, even though the pilots were fine with the area that the lead project scientist designated inside that band; ultimately, they were conducted inside the band. Second, it was requested that an AXBT and sonde be dropped at the beginning of the circles so that, if either failed, they could be backed up at the end of the circles and the mission could proceed; this advice was ignored. Finally, at the end of the circles, the pilots rolled out of the turns directly and immediately into the eye of this category-4 hurricane; this left very little time for the pilots to safely maneuver, and prevented the plane from returning to the inbound azimuth. Due to constraints on the aircraft, the lead project scientist could not hear that the pilots were planning this maneuver, so could not help. Some recommendations are to reposition to the start location at the start of each set of circles and to clearly communicate safety issues during the maneuvers.

SVN locked up for radarsync; this reason for this is unknown, but it worked by the time the plane reached the IP.

The area of the aircraft near the head started vibrating intensely during the last pass through the center of Lane. Cause remains unknown.

Flight track with winds

Timeseries wind, SFMR wind, rain rate, altitude and pressure plots

Flight track	Temperature and Moisture	Wind and Atlitude
Flight track

Flight Director's log | Flight Director's manifest | SFMR data | NetCDF data | serial data | 1 second data
LPS log | DWL log | Drop log

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