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Peter R. Bannon
,
Jeffrey M. Chagnon
, and
Richard P. James

Abstract

Numerical anelastic models solve a diagnostic elliptic equation for the pressure field using derivative boundary conditions. The pressure is therefore determined to within a function proportional to the base-state density field with arbitrary amplitude. This ambiguity is removed by requiring that the total mass be conserved in the model. This approach enables one to determine the correct temperature field that is required for the microphysical calculations. This correct, mass-conserving anelastic model predicts a temperature field that is an accurate approximation to that of a compressible atmosphere that has undergone a hydrostatic adjustment in response to a horizontally homogeneous heating or moistening. The procedure is demonstrated analytically and numerically for a one-dimensional, idealized heat source and moisture sink associated with moist convection. Two-dimensional anelastic simulations compare the effect of the new formulation on the evolution of the flow fields in a simulation of the ascent of a warm bubble in a conditionally unstable model atmosphere.

In the Boussinesq case, the temperature field is determined uniquely from the heat equation despite the fact that the pressure field can only be determined to within an arbitrary constant. Boussinesq air parcels conserve their volume, not their mass.

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Richard A. Fulton
,
Jay P. Breidenbach
,
Dong-Jun Seo
,
Dennis A. Miller
, and
Timothy O’Bannon

Abstract

A detailed description of the operational WSR-88D rainfall estimation algorithm is presented. This algorithm, called the Precipitation Processing System, produces radar-derived rainfall products in real time for forecasters in support of the National Weather Service’s warning and forecast missions. It transforms reflectivity factor measurements into rainfall accumulations and incorporates rain gauge data to improve the radar estimates. The products are used as guidance to issue flood watches and warnings to the public and as input into numerical hydrologic and atmospheric models. The processing steps to quality control and compute the rainfall estimates are described, and the current deficiencies and future plans for improvement are discussed.

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L. Illari
,
J. Marshall
,
P. Bannon
,
J. Botella
,
R. Clark
,
T. Haine
,
A. Kumar
,
S. Lee
,
K. J. Mackin
,
G. A. McKinley
,
M. Morgan
,
R. Najjar
,
T. Sikora
, and
A. Tandon

A collaboration between faculty and students at six universities in a project called Weather in a Tank is described, in which ways of teaching atmosphere, ocean, and climate dynamics are explored that bring students into contact with real fluids and fundamental ideas. Exploiting the use of classic rotating laboratory experiments, real-time meteorological data and associated theory, teaching tools, curricular, and evaluation materials have been developed that focus on fundamental aspects of atmospheric and oceanographic dynamics for use in undergraduate teaching. The intent of the project is to help students learn how to move between phenomena in the real world, theory, and models.

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