Turbulence and turbulent fluxes over the Indian Ocean

Originally issued as Reference No. 68-62, series later renamed WHOI-.A C-54Q aircraft equipped with meteorological instruments was flown three times to India to participate in the International Indian Ocean Expedition. Flights were made out of Bombay, Gan, and Aden to observe winds, temperatures, humidities, clouds, radiation, carbon dioxide, tritium, turbulence, and turbulent fluxes of heat, water vapor, momentum and kinetic energy. The present paper reports the values of 405 measurements of the turbulence and turbulent fluxes and interprets them in terms of the monsoon circulation and the effect upon currents and temperatures of the Arabian Sea. Analyses of other data have been reported and interpreted elsewhere. The aircraft turbulence measuring system used was developed earlier by Bunker (1955) (1960). It consisted of a vertical accelerometer, a strain-guage air-speed transducer, a vertical gyro, a platinum wire thermometer and a microwave refractometer for humidity measurements. The data was recorded on a nine-channel oscillograph. A digitizing reader was used to read and punch the data on cards. The turbulent quantities and fluxes were computed and tabulated by machine. The accuracy and limitations of the system are discussed. While much is left to be desired in terms of accuracies and spectral range, the results are meteorologically useful and comparison shows good agreement with other techniques.Submitted to the National Science Foundation under Grants G-22389 and GA-1490

Stress, turbulence, and heat flow measurements over the Gulf of Maine and surrounding land

Originally issued as Reference No. 56-65, series later renamed WHOI-.This report presents turbulence, flux, temperature and water vapor data obtained from an airplane flying over the Gulf of Maine and adjacent shores. Measurements of the root-mean-square turbulent deviation velocities, shearing stresses, and heat flows were made at many heights and offshore distances in air masses moving from land to water. Stability effects on the turbulence and fluxes of heat and momentum have been Observed over a wide range of conditions as air flowed over cooler or warmer surfaces. The following conclusions have been drawn from a study of the data: (1) The magnitudes of the root-mean-square turbulent deviation velocities δw and δu 3 increases with height in the lowest 100 meters and then decreases slowly with height up to the inversion where the velocities drop to very low values. (2) Shearing stresses were found to increase with height up to the 100 to 200 in level and then drop off with height. This height variation is in contrast to the generally accepted notion of a decrease of the stress from the surface to the geostrophic level. These observations confirm the findings of Scrase (1930) and others and demand an investigation of the acceleration of the air and the effects of thermal winds. (3) Both the horizontal and vertical components of the turbulent wind are increased by hydrostatic instability and decreased by stability. The horizontal component is affected less than the vertical component by stability differences. (4) The decrease in the turbulent velocities as air passes from land to cooler water is great and rapid while the increase in turbulent velocities as the air passes over warmer water is slight and slow. (5) The observed heat fluxes also first increase and then decrease with height and usually become negative near the top of the mixed ground layer where the potential temperature gradient becomes strongly positive. (6) The stability of the air above about 50 m is a very poor indicator of the temperature difference existing between the underlying surface and the air of the main mixed layer. Diffusion of heat downward from a layer of warm air above the ground layer frequently is the cause of a stable lapse rate regardless of the relative temperature of the surface below. (7) No comparison of the coefficient of turbulent mass exchange for water vapor, heat flow and momentum could be made since the temperature gradient was stable even when heat was flowing upward, and no wind profiles were made over the water.Office of Naval Research under contract Nonr-1721(00) (NR-082-021

Air-sea interaction for the International Indian Ocean Expedition

Originally issued as Reference No. 68-8, series later renamed WHOI-A C-54Q aircraft was bailed to the Woods Hole Oceanographic Institution to participate in the International Indian Ocean Expedition and other research projects in the fields of meteorology and oceanography. With the joint support of the Office of Naval Research and the National Science Foundation, the aircraft was modified and instrumented for meteorological research.Submitted to the National Science Foundation on Work Accomplished under Grant G 22389 to the Woods Hole Oceanographic Institution

Measurements of the vertical water vapor transport and distribution within unstable atmospheric ground layers and the turbulent mass exchange coefficient

The series of observations described in this report were planned with the double purpose of measuring the evaporation and transport of water vapor from the ocean into an unstable atmosphere, and of studying the diffusion processes operating in air of this stability class. Measured values of the evaporation from ocean surfaces were conspicuously absent from the meteorological literature until Craig and Montgomery (1949) published values for hydrostatically stable air. The present set of measurements extends our knowledge to include evaporation into a hydrostatically unstable air mass. In addition to evaporation values at the surface, net transports of water vapor at many levels up to 2000 meters have been measured

New Star Forming Galaxies at z\approx 7 from WFC3 Imaging

The addition of Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) has led to a dramatic increase in our ability to study the z>6 Universe. The increase in the near-infrared (NIR) sensitivity of WFC3 over previous instruments has enabled us to reach apparent magnitudes approaching 29 (AB). This allows us to probe the rest-frame ultraviolet (UV) continuum, redshifted into the NIR at $z>6$. Taking advantage of the large optical depths at this redshift, resulting in the Lyman-alpha break, we use a combination of WFC3 imaging and pre-existing Advanced Camera for Surveys (ACS) imaging to search for z approx 7 over 4 fields. Our analysis reveals 29 new z approx 7 star forming galaxy candidates in addition to 16 pre-existing candidates already discovered in these fields. The improved statistics from our doubling of the robust sample of z-drop candidates confirms the previously observed evolution of the bright end of the luminosity function.Comment: 15 pages, accepted in MNRA