Search Results

You are looking at 1 - 3 of 3 items for :

  • Author or Editor: Andrew Johnson Jr. x
  • Refine by Access: All Content x
Clear All Modify Search
Andrew Johnson Jr. and James J. O'brien

Abstract

A series of meteorological observations including aircraft, pilot balloon (pibal), rawinsonde, surface buoy, and special land-based surface observations was taken on 23–24 August 1972, on the central Oregon coast, to investigate the mesoscale thermal and kinematic responses of the lowest 4 km of the atmosphere during a sea breeze event.

A description of those field observations is given. Vertical cross sections of the wind field on a line perpendicular to the coast, extending 60 km inland from data obtained at three pibal stations, are presented and discussed. Time sections of the wind field and temperature fields at the coast are discussed. Mesoscale features are presented and related to prevailing synoptic-scale changes occurring aloft during the observational period.

The sea breeze event on 23 August exhibited the following important characteristics: 1) a sea breeze front, distinguishable in the zonal wind field, which penetrated more than 60 km inland; 2) a distinct wind maximum which followed the front inland; 3) the surface onshore flow at the coast which took place below the main inversion, deepening the marine layer at the onset; and 4) a return flow above the inversion which appeared in quasi-periodic surges in response to surges in the sea breeze flow.

Full access
William I. Gustafson Jr., Andrew M. Vogelmann, Zhijin Li, Xiaoping Cheng, Kyle K. Dumas, Satoshi Endo, Karen L. Johnson, Bhargavi Krishna, Tami Fairless, and Heng Xiao
Full access
William I. Gustafson Jr, Andrew M. Vogelmann, Zhijin Li, Xiaoping Cheng, Kyle K. Dumas, Satoshi Endo, Karen L. Johnson, Bhargavi Krishna, Tami Fairless, and Heng Xiao

Abstract

The U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) user facility recently initiated the Large-Eddy Simulation (LES) ARM Symbiotic Simulation and Observation (LASSO) activity focused on shallow convection at ARM’s Southern Great Plains (SGP) atmospheric observatory in Oklahoma. LASSO is designed to overcome an oft-shared difficulty of bridging the gap from point-based measurements to scales relevant for model parameterization development, and it provides an approach to add value to observations through modeling. LASSO is envisioned to be useful to modelers, theoreticians, and observationalists needing information relevant to cloud processes. LASSO does so by combining a suite of observations, LES inputs and outputs, diagnostics, and skill scores into data bundles that are freely available, and by simplifying user access to the data to speed scientific inquiry. The combination of relevant observations with observationally constrained LES output provides detail that gives context to the observations by showing physically consistent connections between processes based on the simulated state. A unique approach for LASSO is the generation of a library of cases for days with shallow convection combined with an ensemble of LES for each case. The library enables researchers to move beyond the single-case-study approach typical of LES research. The ensemble members are produced using a selection of different large-scale forcing sources and spatial scales. Since large-scale forcing is one of the most uncertain aspects of generating the LES, the ensemble informs users about potential uncertainty for each date and increases the probability of having an accurate forcing for each case.

Free access