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  • Author or Editor: W. L. Ecklund x
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K. S. Gage
,
C. R. Williams
, and
W. L. Ecklund

Uncertainty in the magnitude and distribution of diabatic heating associated with precipitating cloud systems is one of the major factors giving rise to uncertainty in the simulation of large-scale atmospheric circulations in numerical models of the atmosphere. A major international effort is under way to develop an improved parameterization of the hydrological cycle within numerical models. Progress will require better observations of the distribution of the diabatic heating associated with cloud systems in the Tropics. In this paper new observations are presented demonstrating the potential of UHF profilers for diagnosing the vertical structure of convective systems in the Tropics. These preliminary results indicate that while mesoscale convective systems are prevalent in the Tropics there are important contributions to rainfall from smaller-scale warm rain systems that do not extend above the freezing level. They also show that extensive regions of upper-tropospheric precipitating clouds often exist at times when no rain is detected at the surface. These observations provide important information that should prove useful in developing improved methods for estimating precipitation from satellite observations.

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R. R. Rogers
,
W. L. Ecklund
,
D. A. Carter
,
K. S. Gage
, and
S. A. Ethier

A small UHF radar wind profiler was operated over a 40-day period during the summer of 1990 at a site on the windward coast of the island of Hawaii. It provided continuous measurements of winds up to the height of the trade-wind inversion, which varied in altitude from about 2 to 4 km during the course of the experiments. The inversion was readily discernible in the data as an elevated layer of high reflectivity, caused by the sharp gradient of refractive index at that level. With a wavelength of 33 cm, the profiler has about the same sensitivity to light rain as to moderately reflective clear air. The data have provided unexpected information on rain development, wave motions on the inversion, sustained vertical air motions at low levels, and interactions between convection and the inversion echo. This paper gives examples of some of the observations, indicating the wide range of applications of boundary-layer profilers.

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B. B. Balsley
,
D. A. Carter
,
A. C. Riddle
,
W. L. Ecklund
, and
K. S. Gage

In this paper we provide a set of examples to demonstrate the potential of VHF radar wind profilers for studying tropical convection processes. Our examples were extracted from data obtained from the NOAA/CU Pacific Profiler Network, which has been in operation for a number of years and is currently being expanded.

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DA Carter
,
W.L. Ecklund
,
K.S. Gage
,
M. Spowart
,
H.L. Cole
,
W.F. Dabberdt
, and
J. Wilson

The Aeronomy Laboratory of the National Oceanic and Atmospheric Administration and the Atmospheric Technology Division of the National Center for Atmospheric Research are jointly developing Integrated Sounding Systems (ISS) for use in support of TOGA (Tropical Ocean Global Atmosphere) and TOGA COARE (Coupled Ocean–Atmosphere Response Experiment). Some of the ISS units will have to be operated on research ships during TOGA COARE's intensive observing period in late 1992 and early 1993. The greatest technical challenge in adapting the ISS to shipboard use is to stabilize the UHF wind profiler that is an integral part of the ISS. In June 1991 a UHF wind-profiling Doppler radar was installed on a stabilized platform aboard the NOAA research vessel Malcolm Baldrige on an eight-day cruise in the Atlantic Ocean. The wind profiler was gyrostabilized and profiler winds were corrected for ship motion utilizing the Global Positioning System. During the eight days at sea, CLASS (Cross-Chain LORAN Atmospheric Sounding System) and OMEGA Sounding System balloons were launched onboard ship for wind profile comparisons. Results of the comparisons show excellent agreement between wind profiles, with an rms difference of about 1 m s−1 in wind speed.

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B. E. Martner
,
D. B. Wuertz
,
B. B. Stankov
,
R. G. Strauch
,
E. R. Westwater
,
K. S. Gage
,
W. L. Ecklund
,
C. L. Martin
, and
W. F. Dabberdt

Several ground-based remote sensors were operated together in Colorado during February and March 1991 to obtain continuous profiles of the kinematic and thermodynamic structure of the atmosphere. Instrument performance is compared for five different wind profilers. Each was equipped with Radio Acoustic Sounding System (RASS) capability to measure virtual temperature. This was the first side-by-side comparison of all three of the most common wind-profiler frequencies: 50, 404, and 915 MHz. The 404-MHz system was a NOAA Wind Profiler Demonstration Network (WPDN) unit. Dual-frequency microwave radiometers that measured path-integrated water vapor and liquid water content were also evaluated. Frequent rawinsonde launches from the remote-sensor sites provided an extensive set of in situ measurements for comparison. The winter operations provide a severe test of the profiler/RASS capabilities because atmospheric scattering is relatively weak and acoustic attenuation is relatively strong in cold, dry conditions. Nevertheless, the lower-frequency systems exhibited impressive height coverage for wind and virtual temperature profiling, whereas the high-frequency units provided higher-resolution measurements near the surface. Comparisons between remote sensor and rawinsonde data generally showed excellent agreement. The results support more widespread use of these emerging technologies.

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Madison J. Post
,
Christopher W. Fairall
,
Jack B. Snider
,
Yong Han
,
Allen B. White
,
Warner L. Ecklund
,
Klaus M. Weickmann
,
Patricia K. Quinn
,
Daniel I. Cooper
,
Steven M. Sekelsky
,
Robert E. McIntosh
,
Peter Minnett
, and
Robert O. Knuteson

Twelve national research organizations joined forces on a 30-day, 6800 n mi survey of the Central and Tropical Western Pacific on NOAA's Research Vessel Discoverer. The Combined Sensor Program (CSP), which began in American Samoa on 14 March 1996, visited Manus Island, Papua New Guinea, and ended in Hawaii on 13 April, used a unique combination of in situ, satellite, and remote sensors to better understand relationships between atmospheric and oceanic variables that affect radiative balance in this climatically important region. Besides continuously measuring both shortwave and longwave radiative fluxes, CSP instruments also measured most other factors affecting the radiative balance, including profiles of clouds (lidar and radar), aerosols (in situ and lidar), moisture (balloons, lidar, and radiometers), and sea surface temperature (thermometers and Fourier Transform Infrared Radiometers). Surface fluxes of heat, momentum, and moisture were also measured continuously. The Department of Energy's Atmospheric Radiation Measurement Program used the mission to validate similar measurements made at their CART site on Manus Island and to investigate the effect (if any) of large nearby landmasses on the island-based measurements.

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