Showing papers by "Warner L. Ecklund published in 1996"
TL;DR: The 915 MHz lower tropospheric wind profiler developed by the NOAA Aeronomy Laboratory has been used for measuring wind in the planetary boundary layer of the tropics as discussed by the authors.
Abstract: The NOAA Aeronomy Laboratory has developed a 915 MHz lower tropospheric wind profiler designed primarily for measuring wind in the planetary boundary layer of the tropics. In recent years the profiler has been used in many field programs worldwide. The profiler is being deployed by the Aeronomy Laboratory at several locations in the tropics to provide long-term measurements for the Tropical Ocean Global Atmosphere (TOGA) program and the Global Ocean Atmosphere Land Surface (GOALS) program. In the absence of precipitating cloud systems the profiler observes winds routinely up to altitudes of 3 to 6 km in the tropics depending primarily on humidity. In the presence of precipitating cloud systems, however, the profiler height coverage is substantially increased due to the presence of hydrometeors to which the profiler is sensitive at its wavelength of 33 cm. In this paper we examine the application of the 915 MHz profiler to the diagnosis and classification of precipitating cloud systems in the tropics. Preliminary results from Christmas Island confirm that at least half of tropical rainfall is stratiform in nature being associated with mesoscale convective systems. The 915 MHz profiler provides a means for the development of a climatology of tropical precipitating cloud systems. Such a climatology is needed to specify diabatic heating rates in large-scale numerical weather prediction and climate models. It should also help develop improved rain retrieval algorithms from satellite observations.
37 citations
TL;DR: In this paper, the authors derived a relationship between the vertical Doppler spectrum of the rain just below the radar bright band and that of the snow just above, assuming that each snowflake simply melts to form a raindrop of the same mass, disregarding other possible effects such as aggregation to form larger particles or breakup to create smaller ones.
Abstract: The authors derive a relationship between the vertical Doppler spectrum of the rain just below the radar bright band and that of the snow just above. It neglects vertical air motions and assumes that each snowflake simply melts to form a raindrop of the same mass, disregarding other possible effects such as aggregation to form larger particles or breakup to create smaller ones. The relationship shows that, regardless of the dependence of particle fallspeed on size, the product of the equivalent reflectivity factor and the mean Doppler velocity of the snow is proportional to the same product for the rain, with a constant proportionality factor of 0.23, which equals the ratio of the dielectric factors of ice and water. Observed values of the reflectivity and mean Doppler velocity above and below the melting layer sometimes agree with this theoretical prediction but more often deviate from it in ways that may be interpreted as indicating the predominance of either aggregation or breakup processes. T...
34 citations