Franco Einaudi

International Global Precipitation Measurement (GPM) Program and Mission: An Overview

Eric A. Smith , Ghassem Asrar , Yoji Furuhama , Amnon Ginati , Christian Kummerow , Vincenzo Levizzani , Alberto Mugnai , Kenji Nakamura , Robert Adler , Vincent Casse , Mary Cleave , Michele Debois , John Durning , Jared Entin , Paul Houser , Toshio Iguchi , Ramesh Kakar , Jack Kaye , Masahiro Kojima , Dennis Lettenmaier , Michael Luther , Amita Mehta , Pierre Morel , Tetsuo Nakazawa , Steven Neeck , Ken’ichi Okamoto , Riko Oki , Garudachar Raju , Marshall Shepherd , Erich Stocker , Jacques Testud , and Eric Wood 19

Wave-Turbulence Dynamics in the Stably Stratified Boundary Layer

Abstract New data obtained at the Boulder Atmospheric Observatory (BAO) has been compared with a linear stability analysis of the background atmospheric state as measured by rawinsonde ascents. Good agreement was obtained between measured wave parameters such as wavelength, period, and vector phase velocity, and the eigenvalues of the linear solution, but linear eigenvectors scaled by measured pressure at the base of the BAO tower agreed less well with measurement. An investigation of the wave kinetic energy budget revealed that buoyant production of wave energy was a significant gain despite the strong stability (Ri ≳ 5). Further analysis of the budgets of wave heat flux and temperature variance revealed the essential role of wave-turbulence interaction in maintaining a large amplitude temperature wave and countergradient wave heat flux. A consideration of the turbulent kinetic energy budget showed many of the same features as the wave budget. A comparison with earlier near-neutral and stable cases analy...

A Case Study of Gravity Waves–Convective Storms Interaction: 9 May 1979

Abstract An analysis is presented of a series of severe storms which occurred in the north central United States on 9 May 1979 and whose spatial distribution and movement correlate well with observed gravity waves. Two gravity wave trains of 2.1–3 mb amplitude, 2.5–3.3 h period and 240–265 km horizontal wavelength were isolated through power spectra analysis and cross-correlation techniques applied to National Weather Service barograph traces. The wave trains propagated in the 200° direction, which coincided with the jet axis, with a phase velocity of 20–30 m s−1C and within a 300 km wide band. The storms were identified on enhanced infrared GOES satellite pictures with the help of radar summaries. These convective systems initially developed in Nebraska and propagated north–northeast at 25 m s−1, revealing wave-like characteristics with a separation of 300–400 km. The convective systems were closely linked to the observed wave trains with cell intensity, height and associated rainfall maximized at the wa...

Solitary waves in the atmosphere

Abstract The weakly nonlinear theory for internal solitary waves is reviewed and theoretical results of the vertical and horizontal structure of temperature, vertical displacements, and vertical and horizontal perturbations to the wind field associated with steadily propagating solitary waves are presented in two idealized atmospheric configurations. One configuration is representative of solitary waves observed in the lower troposphere and the other of solitary waves that occupy the entire troposphere. The important results of the theory are presented in a form that can be readily used by observationalists. The results obtained are then analyzed using actual rawinsonde data for two well-documented observations of atmospheric solitary waves, which are analogous to the two idealized configurations. The importance and difficulties of properly identifying the waveguide within which the solitary wave is confined are discussed. The fundamental role of a critical level in ducting the disturbances and thus in de...

A Climatology of Gravity Waves and Other Coherent Disturbances at the Boulder Atmospheric Observatory during March–April 1984

Abstract We present a climatological study of gravity waves and other coherent disturbances at the Boulder Atmospheric Observatory, during the period mid-March-mid-April 1984. The data were collected by a network of microbarographs, and by sensors on the 300 m tower. The total observational period was divided into 522 time segments of 5120 s each. Coherent and incoherent motions were identified on the basis of a cross-correlation coefficient, calculated from the microbarograph network for each time segment and frequency band analyzed, using the assumption that the atmospheric state can be described by an equivalent plane wave. Five passbands were considered in the period range 1–20 min. The analysis indicates that the atmospheric state at these passbands displays highly coherent structure, most of the time. During the interval from 0800 to 1800 LST, coherent motions with cross-correlation coefficient larger than 0.5 are present about 25% of the time for periods between 1 and 5 min and more than 80% of the...

Atmospheric gravity waves and aircraft turbulence encounters

Abstract We describe aircraft turbulence-atmospheric gravity wave events which occurred during a 2-day period over the Continental Divide. The waves are observed by two microbarograph networks an each side of the divide and last for several hours at a time. We show them to be unstable modes of the jet stream, corresponding to propagating internal gravity waves. We also show that the position of aircraft-reported turbulence coincides with the critical levels of the waves.

Time and space variability of spectral estimates of atmospheric pressure

Abstract The purpose of this paper is to analyze the temporal and spatial behavior of atmospheric pressure spectra. The literature shows many examples of pressure, wind and temperature spectra whose shapes display a remarkable degree of universality. Theories relying either on turbulence or internal waves have been suggested to account for such spectra. While the former accounts for features at the observed synoptic scales and the latter for the local scales, several difficulties remain especially at the intermediate or the so-called mesoscale range. As a preliminary step for our understanding of the physical mechanisms underlying the spectral behavior, a detailed analysis of the surface pressure was carried out having in mind to test the temporal and spatial variability of these spectra. The source of the data were two microbarograph stations in the Po Valley, 276 km apart; one in the plains 50 km south of the Alps, the other in the foothills of the Dolomites. The 60-day record was part of the Alpine Exp...

Weather prediction improvement using advanced satellite technology

We discuss in this paper some of the problems that exist in the full utilization of satellite data to improve weather forecasts and we propose specific recommendations to solve them. This discussion can be viewed as an aspect of the general debate on how best to organize the transition from research to operational satellites and how to evaluate the impact of a research instrument on numerical weather predictions.

Environment Canada cuts threaten the future of science and international agreements

In August 2011, 300 Environment Canada scientists and staff working on environmental monitoring and protection learned that their jobs would be terminated, and an additional 400-plus Environment Canada employees received notice that their positions were targeted for elimination. These notices received widespread coverage in the Canadian media and international attention in Nature News. Environment Canada is a government agency responsible for meteorological services as well as environmental research. We are concerned that research and observations related to ozone depletion, tropospheric pollution, and atmospheric transport of toxic chemicals in the northern latitudes may be seriously imperiled by the budget cuts that led to these job terminations. Further, we raise the questions being asked by the international community, scientists, and policy makers alike: First, will Canada be able to meet its obligations to the monitoring and assessment studies that support the various international agreements inTable 1? Second, will Canada continue to be a leader in Arctic research.