65th IHC Booklet/Program (pdf - 4.9MB) - Office of the Federal ...

Pre-Genesis Monitoring of the 3-D Atmospheric and Oceanic Environment Via High
Altitude Aircraft Observations
Jeff Hawkins 1 , Peter Black 2 , Pat Harr 3 , Russ Elsberry 3
(Jeffrey.Hawkins@nrlmry.navy.mil)
1 Naval Research Laboratory; 2 Science Applications International Inc;
3 Naval Postgraduate School
The Tropical Cyclone Structure (TCS-08) and the Impact of Typhoons on the Ocean in the
Pacific (ITOP) field programs enabled the first two tests of high altitude (300 MB) deployment
of dropsondes and AXBTs into pre-genesis, incipient tropical cyclone (TC) systems within the
western North Pacific basin (WPAC). This sampling strategy enabled a unique view of the three
dimensional (3-D) atmospheric (winds, temperature and moisture) and oceanic thermal
environments. Data sets from both developing and non-developing tropical systems were intercompared
through the use of the Air Force WC-130J data sets, which include dropsondes,
Stepped Frequency Microwave Radiometer (SFMR), airborne radar, and flight level parameters,
MTSAT-derived automated cloud motion winds, NRL P-3 Eldora 3-D winds (TCS-08), and
satellite-derived ocean surface wind vectors (QuikSCAT – TCS-08 only, ASCAT, and WindSat).
Aircraft flights were designed to overlap with satellite over-pass times as close as possible. In
addition, satellite-derived total precipitable water (TPW), a measure of low/mid-level moisture
content which maps mesoscale and synoptic scale features, was utilized to observe the potential
of dry- and moist-air entrainment into the inner vortex. This combination of sensors allowed the
aircraft-derived observations to validate satellite-derived observations of ocean surface and midlevel
winds as well as sea surface temperature (SST) and subsurface ocean heat content (OHC).
During August 2008, TCS-08 candidate systems included many weak convective clusters as the
western Pacific basin experienced an unusual ‘TC drought’ and an anomalous circulation pattern.
Organized convective activity was suppressed and the monsoon trough was absent as low-level
easterly flow predominated. Several wave-like systems entered the TCS-08 Guam domain from
the east and were investigated by the WC-130J and NRL P-3 aircraft. ITOP conditions during
2010 included additional pre-genesis cases near Guam of several systems that later evolved into
significant TCs.
Passive microwave imagers were able to augment the TCS-08 and ITOP aircraft data sets by
mapping the rainfall and convective cloud cluster patterns during many daily overpasses. The
combination of both operational and research microwave satellite sensors (SSM/I, SSMIS, TMI,
AMSR-E, and WindSat) provided frequent temporal observations of convective system
evolution. The temporal sampling from the microwave imagers provided the large-scale context
in mapping convective organization of the three tropical systems using WC-130J recorded radar
video and NRL P3 Eldora Doppler radar data (TCS-08), but does not provide the 3-D structure,
nor spatial details needed to appropriately understand the full 3-D storm environment.
Preliminary analysis of the WC-130J dropsondes, AXBTs, and satellite digital data sets indicate
complicated 3-D atmospheric and oceanic structures can be monitored by the high altitude WC-
130J dropsonde square spiral flight patterns and effectively detail critical differences between
Session 9 – Page 4