Search Results

You are looking at 1 - 6 of 6 items for

  • Author or Editor: F. W. MURRAY x
  • Refine by Access: All Content x
Clear All Modify Search
F. W. MURRAY

Abstract

A perturbation of relative humidity is used as a trigger to start the convection in a two-dimensional numerical model of a cumulus cloud. The effects of varying the width and depth of the perturbation are studied. The rate of growth, eventual cloud height, liquid water content, and updraft strength are strongly dependent on depth of the impulse; but for realistically shallow depths, these values are in reasonable agreement with observations of real clouds. As in the case of one-dimensional models, the ultimate cloud height is dependent on the width of the impulse, but perhaps to a lesser extent.

Full access
F. W. MURRAY

Abstract

Two versions of a numerical model for cumulus convection are compared. One is symmetrical about a vertical plane, the other about a vertical axis. It is found that the axisymmetric model grows more vigorously than the other and more realistically represents the relations between updraft and downdraft, the shape, and other characteristics. The previous findings of Ogura are generally confirmed and extended.

Full access
F. W. Murray

Abstract

Full access
F. W. MURRAY and L. R. KOENIG

Abstract

An existing numerical model of cumulus growth, treating condensation but not precipitation, is modified by the incorporation of a parameterized treatment of liquid phase microphysics. This modification improves the realism of the results in several important respects; among them are maximum height of cloud growth, maximum liquid content, amount and distribution of temperature departure, cloud shape, and occurrence and strength of subcloud downdraft. We found that one of the most important controlling features is the rate of evaporation of droplets. In particular, the introduction of a class of large particles with relatively slow evaporation rate produces a smaller temperature deficit at the cloud summit, hence more vigorous cloud growth. In this model, the upper and lower parts of the cloud are, to a large extent, decoupled dynamically, the development of a strong subcloud downdraft by evaporation of precipitation having little effect on the ultimate extent of cloud growth.

Full access
Hermann B. Wobus, F. W. Murray, and L. R. Koenig

Abstract

Three mathematical expressions for the terminal velocity of water drops in still air as a function of equivalent radius are compared with the experimental data of Gunn and Kinzer. Two of them, derived by curve-fitting techniques, give excellent results over the full range of meteorological interest, including the Stokes's law regime. A formula to correct for non-standard pressure and temperature is given, and its results are compared with the experimental data of Beard and Pruppacher.

Full access
Chelsea R. Thompson, Steven C. Wofsy, Michael J. Prather, Paul A. Newman, Thomas F. Hanisco, Thomas B. Ryerson, David W. Fahey, Eric C. Apel, Charles A. Brock, William H. Brune, Karl Froyd, Joseph M. Katich, Julie M. Nicely, Jeff Peischl, Eric Ray, Patrick R. Veres, Siyuan Wang, Hannah M. Allen, Elizabeth Asher, Huisheng Bian, Donald Blake, Ilann Bourgeois, John Budney, T. Paul Bui, Amy Butler, Pedro Campuzano-Jost, Cecilia Chang, Mian Chin, RóISíN Commane, Gus Correa, John D. Crounse, Bruce Daube, Jack E. Dibb, Joshua P. Digangi, Glenn S. Diskin, Maximilian Dollner, James W. Elkins, Arlene M. Fiore, Clare M. Flynn, Hao Guo, Samuel R. Hall, Reem A. Hannun, Alan Hills, Eric J. Hintsa, Alma Hodzic, Rebecca S. Hornbrook, L. Greg Huey, Jose L. Jimenez, Ralph F. Keeling, Michelle J. Kim, Agnieszka Kupc, Forrest Lacey, Leslie R. Lait, Jean-Francois Lamarque, Junhua Liu, Kathryn Mckain, Simone Meinardi, David O. Miller, Stephen A. Montzka, Fred L. Moore, Eric J. Morgan, Daniel M. Murphy, Lee T. Murray, Benjamin A. Nault, J. Andrew Neuman, Louis Nguyen, Yenny Gonzalez, Andrew Rollins, Karen Rosenlof, Maryann Sargent, Gregory Schill, Joshua P. Schwarz, Jason M. St. Clair, Stephen D. Steenrod, Britton B. Stephens, Susan E. Strahan, Sarah A. Strode, Colm Sweeney, Alexander B. Thames, Kirk Ullmann, Nicholas Wagner, Rodney Weber, Bernadett Weinzierl, Paul O. Wennberg, Christina J. Williamson, Glenn M. Wolfe, and Linghan Zeng

Abstract

This article provides an overview of the NASA Atmospheric Tomography (ATom) mission and a summary of selected scientific findings to date. ATom was an airborne measurements and modeling campaign aimed at characterizing the composition and chemistry of the troposphere over the most remote regions of the Pacific, Southern, Atlantic, and Arctic Oceans, and examining the impact of anthropogenic and natural emissions on a global scale. These remote regions dominate global chemical reactivity and are exceptionally important for global air quality and climate. ATom data provide the in situ measurements needed to understand the range of chemical species and their reactions, and to test satellite remote sensing observations and global models over large regions of the remote atmosphere. Lack of data in these regions, particularly over the oceans, has limited our understanding of how atmospheric composition is changing in response to shifting anthropogenic emissions and physical climate change. ATom was designed as a global-scale tomographic sampling mission with extensive geographic and seasonal coverage, tropospheric vertical profiling, and detailed speciation of reactive compounds and pollution tracers. ATom flew the NASA DC-8 research aircraft over four seasons to collect a comprehensive suite of measurements of gases, aerosols, and radical species from the remote troposphere and lower stratosphere on four global circuits from 2016 to 2018. Flights maintained near-continuous vertical profiling of 0.15 – 13 km altitudes on long meridional transects of the Pacific and Atlantic Ocean basins. Analysis and modeling of ATom data have led to the significant early findings highlighted here.

Full access