AL03 /CHRIS MISSION HIGHLIGHTS

Four operationally tasked (by EMC) NOAA P-3 missions were flown into Tropical Storm Chris (AL03) to provide airborne Doppler radar and dropsonde observations to initialize the operational Hurricane Weather Research and Forecasting (HWRF) Model, spaced every 12 hours, operating out of Lakeland, from approximately 0830 UTC (0430 AM EDT) 8 July 2018 to 0430 UTC (12:30 AM EDT) 10 July 2018. Chris remained nearly stationary off the U.S. east coast, just to the east of the Carolinas. Mission IDs, approximate mission times, and accompanying GOES East infrared satellite imagery are provided below:

Mission 1: 20180708H1 (0833- 1703 UTC)	Mission 2: 20180708H2 (2332 - 0452 UTC)
Mission 3: 20180709H1 (2030 - 0430 UTC)	Mission 4: 20180709H2 (o832 - 1552 UTC)

• Participating HRD Crew Sim Aberson (Radar Scientist), Ghassan Alaka (LPS/Dropsonde Scientist), Bachir Annane (Dropsonde Scientist), Hui Christophersen (LPS/Dropsonde Scientist), John Gamache (Ground Radar Scientist), Nancy Griffin (Ground Radar Scientist), Frank Marks (Radar Scientist), Paul Reasor (Ground Radar Scientist), Kelly Ryan (LPS), Jon Zawislak (FPD). Three interns flew on missions: Miguel Cortez (NCAPS), Erin Jones (Hollings), and Tyler Young (Hollings).

• A total of 55 dropwindsondes were launched over the 4 missions into Chris (13 in 20180708H1, 6 in 20180708H2, 15 in 20180709H1, and 21 in 20180709H2). Most of the sondes were released from an altitude of 8000-10000 ft. 7 sondes were released from over 20 kft during a circumnavigation at 70 nmi from the center during the 20180708H1 mission, while 4 sondes were released from 12 kft during a Figure 4 in the 20180709H2 mission.

• Significant progress was made on the implementation of new Multi-mode Radar (MMR) (replacement for the lower fuselage) for situational awareness, thanks to the work by engineers from Harris and Elta onboard 20180709H1. The improvement was significant enough that the MMR was subsequently used for situational awareness by the Flight Directors and Pilots during that flight and 20180709H2 (see figures below). Missions into Chris were also completed in time for the MMR training to proceed at AOC. Numerous images of the MMR, compared against the nose radar, are provided in the 'Mission Reports/Media" folder under AL03/Chris in the HFP Document Repository.

  Mission 2: 20180708H2	Mission 4: 20180709H2<
  MMR images in the eye of TS Chris before and after the engineers fixed the settings.

• All radar data was successfully transmitted to EMC for assimilation into HWRF. Missions on 9 July were also the first to assimilate NOAA P-3 data i nto H218, implemented for the 12Z cycle. Unfortunately, due to a missing semicolon delimiter at the end of the ASPEN-generated WMO TEMPDROP messages, some dropsondes from the 20180709H1 and 20180709H2 were not assimilated by HWRF despite successful transmission off the aircraft. In 20180709H2, HRD scientists on the ground discovered and then communicated the problem to HRD scientists aboard the P-3, who proceeded to test a temporary fix. The onboard P-3 dropsonde scientist appended the WMO messages with a semicolon, and those 5 sondes were all found to be successfully assimilated. Sondes without semicolons failed to assimilated. The issue is now being discussed among all relevant parties (HRD, AOC, and EMC).

• While data transmission to EMC was the primary objective, there is some relevant research that could be accomplished with the mission data. Chris met the requirements for the HFP-IFEX "Early Stage Experiment", Science Objective #1: Analysis of Intensification Processes Experiment. The storm experienced gradual strengthening during the period of the missions. During 20180708H1, the NHC intensity estimate increased from 35 to 40 kt. During 20180708H2, the NHC intensity increased to 50 kt. During 20180709H1, the NHC intensity remained at 50 kt. During 20180709H2, the intensity had recently increased to 60 kt and remained steady during the mission.

• As seen in the Figure 1, Chris slowly intensified and became more organized during the flight period, supported by an expanded, more symmetric wind field. During the first mission (20180708H1), the precipitation distribution (Figure 2) was asymmetric and the vortex was tilted to the east with height (Figure 3). Subsequent missions found less vortex tilt, and a more symmetric precipitation distribution (Figure 2). In the second mission (20180708H2), convective burst activity was impressive and the circulation became more organized, supported by a more symmetric distribution of precipitation (Figure 2). Over the 2 mission days, the development of deep convection was observed in only one quadrant of the storm, and this convection typically rotated around to the other quadrants. Despite decreasing deep vertical wind shear (Figure 3), a vertically-aligning vortex (Figure 3), and increased precipitation symmetry (Figure 2), Chris did not intensify rapidly. One factor could be the intrusion of dry air on 9 July. During the duration of the 20180709H1 mission, precipitation distribution changed dramatically where heaviest convection existed in the south and west quadrants at the beginning, whereas by the end of the mission, the heaviest precipitation occurred in the east and north quadrants. During the 20180709H2 mission, less precipitation was consistently observed to the north. Cooling SSTs underneath the storm due to upwelling while it remained stationary could be another factor limiting a more substantial increase in intensity during the flight period (see Figure 4, buoy SST time series).

  Figure 1. Sequence of composite storm-relative maps of 0.5-km windspeed from each mission

  Figure 2. Sequence of composite reflectivity at 2 km from each mission

  Figure 3. Sequence of composite wind at 2 km (color) and streamlines at 2 (black) and 5 km (gray) from each mission

  Figure 4. Water temperature at buoy 41002 in the storm, showing a decrease, possibly due to upwelling

• A nearly full circumnavigation was executed during the first mission (20180708H1), while the cloud and precipitation distribution was still asymmetric. Unfortunately due to icing conditions, the P-3 had to descend to a lower altitude for the eastern portion of the circumnavigation after climbing and maintaining altitude above 20 kft on the southern side of the storm. However, after reaching the northern side, the P-3 was able to ascend back to 20 kft and complete the circumnavigation through the western side. 7 out of 8 dropsondes were successfully deployed at 20 kft during this time.

• The WSRA and 2nd SFMR (mounted in the belly) were functional during these missions. However, the Doppler Wind LIDAR was not functional.

• Numerous issues with science workstations were encountered and addressed during the 20180708H1 and 20180709H1 missions. HRD scientists worked efficiently with other P-3 Crew to assure the success of data retrieval and/or transmission.

• The importance and value of in-situ observations was highlighted by these missions, as maximum wind measurements from the P-3 (e.g., dropsondes and SFMR) validated satellite-based estimates, including the Automated Dvorak Technique (ADT; Figure 5).

  Figure 5. Advanced Dvorak Technique time series intensity estimates

Jon Zawislak
Field Program Director

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