National Aeronautics and Space Administration

Wallops Flight Facility

Rain-Sea Interaction

RAIN-SEA INTERACTION PROGRAM

Our goal is to improve measurements of air-sea gas exchange, rain, and wind over the open oceans and coastal regions. Measurement of these processes contributes to improved weather prediction; climate modeling and air-water CO2 flux estimates. We investigate (a) rain generated air-sea interaction processes and (b) microwave scattering from rain-roughened water surfaces. Our approach is to develop physical models that are supported by data, and to incorporate these results into algorithms so that the findings can be broadly tested and applied. The rain-sea interaction team welcomes collaborative studies with investigators who are engaged in measuring and modeling rain-sea interaction processes. We conduct experiments in the Rain-Sea Interaction Facility at NASA Wallops Flight Facility, in other laboratories and in the field.

Present Activities:

(a) Characterization of rain induced sea-surface roughness and modeling of radar backscatter from rain and wind roughened seas. Collaborator: Prof. P. Sobieski, U of Belgium.

(b) Characterization of rain induced air-sea gas fluxes, especially CO2. Collaborator: Dr. D. Ho, Columbia U, Dr. D. Dacey of WHOI.

(c) Development of a novel rain algorithm for scatterometry. Collaborator: Prof. D. Weissman, Hoffstra U.

(d) Real-time applications of scatterometry for ocean current modeling and for atmospheric surface pressure and wind maps. Collaborators: Prof. J.J. O’Brien and Prof. M. Bourassa, Florida State U.

(e) Development of Rain Imaging System for measurement of rain rate as well as drop size and shape distributions. Collaborator: Prof. J Saylor, Clemson U

Our studies of the basic processes—wind, rain, air-sea gas flux, and real-time ocean circulation – have broad potential for coastal zone research; especially for storm related processes. Our rain induced gas flux research can help quantify air-water gas exchange in coastal marshes and the Everglades.

Future/Planned Activities:

Winter Coastal Storms Project

NOAA is addressing severe storms with active programs for hurricanes that impact the East and Gulf coasts and with the Pacjet program that focuses on winter storms on the West coast. However there is no program that focuses on winter storms that can cause significant problems on the East coast from the Carolinas to Maine. We propose the development of such a program, which we call the Winter Coastal Storms project, i.e. the Wics Project. We envision that the Wics Project will be a coordinated effort that is supported mainly by NASA and NOAA and that will include participants from other government agencies and universities.

The Wics project would be comprised of several primary components that are listed for consideration. (1) Real-time Ocean-Atmospheric Models that uses satellite data such as Quikscat scatterometer data to update the wind field every 12 hrs. The model will provide products such as the surface wind field, ocean surface currents, and atmospheric surface pressure field and storm forecasts, (2) Real-time rain data from satellite sensors such as radiometers and the TRMM rain radar. (3) Real-time ground based rain measurements from Nexrad single-pol radars and from NPOL, which is a new mobile dual-polarization S-band radar located at WFF. (4) Real-time surface current measurements from a CODAR system to be located at WFF. (4) NOAA aircraft have recently flown East coast winter storms with their normal complement of instruments and this would be a component of the Wics project. During special studies with the Wics project, the NOAA aircraft will fly with the enhanced set of instruments that are flown annually in hurricane studies. This includes microwave systems to measure surface waves, storm surge, and to map rain. Since the winter storm season follows the hurricane season, the enhanced instrumentation can be left onboard the NOAA aircraft.

The purpose of the Wics project is to improve our understanding the conditions for winter storm formation on the East coast and to improve predictions of storm tracks. We believe that data from satellites, aircraft and ground based radars are useful tools for this study because they can provide regional coverage in the coastal zone where normal ground based weather observations are sparse. In addition to storm characterization, the synergy of instrumentation and human resources will enable important studies, such as (a) mapping of ocean waves and beach erosion modeling, (b) measurement and modeling of sea-surface currents, (c) measurement and modeling of storm surge, (d) measurement and modeling of rainfall. These resources are presently available and only require a modest investment of human resources to make them operational.

Air-Water Gas Fluxes in Marshes

Wind is the dominant forcing function for air-water gas transfer in open water regions. Water from land sources, however, often passes through marshes as it flows to the coast. Marsh grasses shelter the air-water surface from wind mixing and thus rain maybe an important process governing gas fluxes in marshes. We have conducted extensive pioneering laboratory investigations of rain induced gas fluxes. To better understand air-water gas fluxes in the coastal zone, we propose field studies to investigate rain induced air-water gas fluxes in marshes and the Everglades.

Rain Characteristics

Radars are used to provide rain information over large areas, yet the quality of rain estimates is limited by lack of data to characterize regional and seasonal variations of rain drop size and shape distributions. We have developed the Rain Imaging System to measure these distributions. We propose to deploy RIS at coastal sites in collaboration with field studies, such as PACJEET, TRMM cal/val, hurricane research and the proposed Wics project. RIS can also be miniaturized to fit on UAV’s to measure drop characteristics aloft in convective storms where pilots are unwilling to fly.

Contributors:

Lead Investigator: Larry Bliven