Shoaling Waves Experiment (SHOWEX)

   Participants:

         Jielun Sun, NCAR, Boulder, CO
         Sean Burns, NCAR, Boulder, CO
         Larry Mahrt, Oregon State University, Corvallis, OR
         Tim Crawford, FRD/NOAA, Idaho Falls, ID
         Jerry Crescenti, FRD/NOAA, Idaho Falls, ID
         Jeff French,  FRD/NOAA, Idaho Falls, ID
         Ed Dumas, NOAA/ATDD, Oak Ridge, TN
         Douglas Vandemark, NASA/GSFC. Wallops Island, VA
         Dean Vickers, Oregon State University, Corvallis, OR
         Erin Moore, Oregon State University, Corvallis, OR

 Shoaling Waves Experiment (SHOWEX) is designed to study the
 properties and evolution of surface gravity waves in intermediate
 and shallow water depths.  As part of the group effort to study
 the shoaling waves sponsored by Office of Navy Research, the
 NOAA aircraft LongEZ was deployed to study the interaction between
 the atmosphere and the sea surface in the shoaling zone, which is
 an important factor for the generation of the oceanic waves.

 The field campaign focused on several scientific issues: a)
 spatial variations of the air-sea interaction, b) the internal
 boundary layer associated with the heat-island, c) SST thermal
 fronts, and d) air-sea interaction under very weak and very strong
 wind conditions.

 The field campaign of SHOWEX was conducted at Duck, North
 Carolina. The field campaign for the LongEZ group is between
 November 10 and December 5, 1999.  All the instruments on board
 operated well. In addition, Melville's camera was mounted on the
 LongEZ for investigating breaking waves. For several flight missions,
 an infrared imager was added to the Melville's camera package. At the
 end of the field experiment, a digital video camera from Doug Vandemark
 was installed to monitor sea surface waves.

 During the field campaign, joint missions were conducted between
 the LongEZ and the SURPAS TwinOtter, and between the LongEZ and
 the SWATH ship, Fred G. Creed.  Five formation flights between the
 LongEZ and the TwinOtter were conducted within the SHOWEX domain
 (Fig.\ref{fig1}). In addition, one formation flight between the two
 aircraft was done on a big box to study clearly-defined roll vortices
 (Fig.\ref{fig1}). Furthermore, the comparison between the
 LongEZ and the OSU sonic anemometers at the end of the pier was
 also conducted. During the field experiment, three SAR flights were
 accomplished, two of them were with the TwinOtter.

Several flights were flown across the coastline, both on the ocean
coast and the inland water coast.  These flights were designed to
study adjustment of the flow after crossing surface
discontinuities in surface heat flux and roughness.  Repeated
passes were flown at several levels perpendicular to the shoreline
to study the evolution of the vertical structure downstream from
surface discontinuities.


 The field experiment covers a large range of wind conditions, from
 very weak wind days, about 1-2 m/s, to very strong wind days, about 16 m/s.
 During the weak wind period, the sea surface was very smooth.
 Radar signal dropouts due to the smooth sea surface were
 reported from the TwinOtter group.

 In addition to the LongEZ aircraft measurements, ground
measurements over the land tower and on the pier were collected
during the same period. The land tower observations included 12
thermolcouples. The pier measurements included two 3-d campbell
CSAT-3 sonic anemometers.