Search Results

You are looking at 1 - 6 of 6 items for :

  • Author or Editor: Charles Warner x
  • Journal of Applied Meteorology and Climatology x
  • Refine by Access: All Content x
Clear All Modify Search
Charles Warner

Abstract

No abstract available.

Full access
Charles Warner

Abstract

A new method is described for photogrammetry of clouds from aircraft side camera movies, to take into account cloud motion. In extreme circumstances of measurement, this leads to improvements of 500 m in cloud height. General use of the method is desirable when cloud measurements are related to other data.

On 10 December 1978 over the South China Sea, cumulus fractus were of depth ∼0.2 km, and updrafts were of width ∼0.25 km. For humilis the corresponding numbers were 0.7 and 0.4 km. Mediocris with tops at height (z) 2.2 km had updrafts of width (w) ∼1.3 km. Updrafts in congestus towers increased with height, with dw/dz ∼0.17, a figure similar to that found for day 245 of the GARP Atlantic Tropical Experiment.

Cloud number densities on 10 December varied over an order of magnitude over distances of 100 km, even in circumstances relatively uniform on the large scale. Order of magnitude estimates of percent area coverage by updrafts yield values up to 10% for fractus and humilis combined, up to a few percent for mediocris, and less than 1% for congestus in the mid-troposphere. An area measuring 1° latitude × 2° longitude was found to contain nine cumulonimbi, yielding ≈0.1% coverage by updrafts in the mid-troposphere.

Full access
Charles Warner

Abstract

Equations for photogrammetry from an aircraft nose camera movie are based on angles from a fixed point on the horizon toward which the aircraft is flying. The positions and dimensions of an arc of clouds occurring on day 261 of GATE are presented as an example. The accuracy of such measurements is a few kilometers in the horizontal and about 500 m in the vertical.

Full access
Charles Warner and K. L. S. Gunn

Abstract

A transmissometer has been used to provide a continuous record with good time resolution of falling snow. The pulsed light, of wavelength 0.45μ, traversed a path 71 m long about 20 m above ground level A total snow amount of 160 millimeters of water (mmw) from 20 storms through the 1966-67 winter season was recorded and analyzed, Attenuation by snow was found to be proportional to rate of snowfall, with the constant of proportionality 11 (db km-1) / (mmw hr-1). A previous experiment by Lillesaeter yielded 18 for this constant.

The attenuation from precipitation-free air was found to increase as the relative humidity increased above about 60%. Relative humidity increase between the beginning and end of a storm could lead to an increase in "clean air" attenuation of 4-5 db km-1. Lack of correction for this together with the effect of thermal fluctuations on Lillesaeter's narrower transmitted beam probably account for his higher value of the constant of proportionality.

Snow amounts for individual storms deduced from the attenuation record agreed with amounts measured by standard instruments to within a factor of 2. When depths on the ground were compared, agreement was within a factor of 1.5. Over the 20 principal storms of the season, the total snow amount from the attenuation records agreed to within 2% with the accumulation in a standard Nipher gage.

Full access
Robert D. Sharman, Yubao Liu, Rong-Shyang Sheu, Thomas T. Warner, Daran L. Rife, James F. Bowers, Charles A. Clough, and Edward E. Ellison

Abstract

Output from the Army Test and Evaluation Command’s Four-Dimensional Weather System’s mesoscale model is used to drive secondary-applications models to produce forecasts of quantities of importance for daily decision making at U.S. Army test ranges. Examples of three specific applications—a sound propagation model, a missile trajectory model, and a transport and diffusion model—are given, along with accuracy assessments using cases in which observational data are available for verification. Ensembles of application model forecasts are used to derive probabilities of exceedance of quantities that can be used to help range test directors to make test go–no-go decisions. The ensembles can be based on multiple meteorological forecast runs or on spatial ensembles derived from different soundings extracted from a single meteorological forecast. In most cases, the accuracies of the secondary-application forecasts are sufficient to meet operational needs at the test ranges.

Full access
Yubao Liu, Thomas T. Warner, James F. Bowers, Laurie P. Carson, Fei Chen, Charles A. Clough, Christopher A. Davis, Craig H. Egeland, Scott F. Halvorson, Terrence W. Huck Jr., Leo Lachapelle, Robert E. Malone, Daran L. Rife, Rong-Shyang Sheu, Scott P. Swerdlin, and Dean S. Weingarten

Abstract

Given the rapid increase in the use of operational mesoscale models to satisfy different specialized needs, it is important for the community to share ideas and solutions for meeting the many associated challenges that encompass science, technology, education, and training. As a contribution toward this objective, this paper begins a series that reports on the characteristics and performance of an operational mesogamma-scale weather analysis and forecasting system that has been developed for use by the U.S. Army Test and Evaluation Command. During the more than five years that this four-dimensional weather system has been in use at seven U.S. Army test ranges, valuable experience has been gained about the production and effective use of high-resolution model products for satisfying a variety of needs. This paper serves as a foundation for the rest of the papers in the series by describing the operational requirements for the system, the data assimilation and forecasting system characteristics, and the forecaster training that is required for the finescale products to be used effectively.

Full access