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D. R. Johnson
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R. G. Gallimore
and
D. R. Johnson

Abstract

The impact of GWF satellite data on GLA analyses of the thermal structure of two oceanic extratropical cyclones are presented. The two storms developed nearly simultaneously in the western Pacific and Atlantic oceans during January 1979. In addition to describing the satellite data impact on temperature and static-stability distributions within each storm, implications of the impact on available potential energy and on the baroclinic growth of the cyclone are discussed.

In the comparison of CLA analyses with (SAT) and without (NOSAT) the satellite temperature soundings produced by 1,be NOAA/NESS retrieval method, the results show sizable temperature differences between the two analyses for both storms. Characteristic features include the following: 1) warmer SAT temperature within NOSAT thermal through and colder SAT temperatures within NOSAT thermal ridges 2) a difference in sign or magnitude of the temperature impact between the upper troposphere and the lower troposphere, and 3) an evolution of a significant, satellite-data cold bias located within and paralleling the evolution of the low-tropospheric thermal ridge close to the cyclone center. The satellite temperature impact in the low troposphere increases tropospheric static in the central storm area and decreases troposhperic stability in the cold troughs both to the rear and ahead of the cyclone.

Although the net effect of area-averaged satellite temperature impact for the storms is small, the association of warmer temperature with NOSAT thermal trough and colder temperatures with thermal ridges reduces the areal temperature stability variance within the Pacific storm area. The reduction for the Atlantic storm region is less. For the Pacific storm the satellite temperature impact led to a 10% reduction of available potential energy, a significant reduction in vertical phase tilt of the tropospheric temperature structure, and a potentially greater than 10–20% reduction of the baroclinic rate of cyclone-scale waves. The decreased baroclinic amplification is inferred from stabilization of the highest lapse rates and a reduction of the largest vertical thermal-wind shears in the low troposphere of the storm area. Overall the results stress the need to identify characteristics of satellite temperature-sounding impacts on the baroclinic structure of cyclone waves, which potentially degrade numerical weather prediction of cyclogenesis.

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Ronald D. Townsend
and
Donald R. Johnson

Abstract

The mass circulation of the zonally averaged global circulation is investigated in isobaric and isentropic coordinates through the use of a FGGE Level IIIa data set. The isobaric mass circulation during the First GARP Global Experiment is consistent with previous results, i.e., direct Hadley cells in low latitudes and indirect Ferrel cells in midlatitudes of both hemispheres.

Within the isentropic framework, the combination of a geostrophic mean mode of mass transport within the baroclinic wave structure of extratropical latitudes, and an ageostrophic mean mode in tropical latitudes, yields an isentropic mass circulation spanning the hemisphere. The asymmetric structure of midlatitude baroclinic waves provides the degree of freedom for a geostrophic mode of mass transport that is fundamental to the direct Hadley-type circulation in isentropic coordinates. This direct Hadley-type circulation is explicitly linked to heat sources and sinks on a planetary scale. The diabatic heating estimated from the mean meridional mass transport through the isentropic continuity equation reveals a realistic distribution for the zonally averaged atmosphere. Within the isentropic perspective, the scale of thermodynamic forcing by diabatic beating explicitly determines the hemispheric scale of atmospheric response for the mean meridional circulation.

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J. D. McQuigg
,
S. R. Johnson
, and
J. R. Tudor

Abstract

A method is developed which can be used to produce estimates of electric power load diversity from samples of ambient daily mean temperature observations from a large interconnected power system. This method has several advantages, the most important of which is the comparative case with which homogenous samples of temperature data can be located. The method is believed to have important applications in long-term planning of large interconnected electric power systems.

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D. Johnson
,
R. Stocker
,
R. Head
,
J. Imberger
, and
C. Pattiaratchi

Abstract

The design of small, compact, low-cost GPS drifters that utilize “off the shelf” components is described. The drifters are intended for use in confined or nearshore environments over time scales of up to several days and are a low-cost alternative for applications that do not require drifters with full ocean-going capabilities.

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J. M. Vergin
,
D. R. Johnson
, and
R. Atlas

Abstract

The results of a quasi-Lagrangian diagnostic study of two 72 h Goddard Laboratory for Atmospheric Sciences (GLAS) model cyclone predictions from 0000 GMT 19 February 1976 are presented and compared with observed results. One model forecast (SAT) was generated from initial conditions which included satellite sounding data, and the other model forecast (NOSAT) was generated from initial conditions that excluded satellite sounding data. Examination of the mass and angular momentum budget statistics for the SAT and NOSAT forecasts reveals substantial differences. The improvement in the SAT forecast is established from the more realistic SAT budget statistics, and results from the modifications of initial atmospheric structure due to satellite information.

The assimilation of satellite data caused modifications of the horizontal mass and eddy angular momentum transports at the zero hour. The assimilation of satellite data resulted in colder temperatures and weaker stabilities in the lower layers of the northwest quadrant of the budget volume, and thus an improved structure of the cold polar air mass over a relatively warm ocean surface. In the southwest quadrant of the budget volume, the SAT assimilation produced an increase in the stability of the middle and lower layers and an increase in temperatures throughout much of the troposphere. These modifications in the temperature structure were the primary reasons for the improved mass and eddy angular momentum transports which contributed to the better SAT forecast for the cyclone event.

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R. L. Johnson
,
D. E. Janota
, and
J. E. Hay

Abstract

During the spring-summer of 1979, six lightning warning devices were evaluated in a side-by-side comparison study at three test sites. Stock commercial devices were selected based upon distinct concepts of operation. The devices tested included a sferics counter, a corona point, a radioactive probe, a field mill, an azimuth/range locator and a triangulation locator. The test sites were chosen to provide varied thunderstorm conditions: 1) San Antonio, Texas (cold air advection), 2) Kennedy Space Center, Florida (localized surface heating) and 3) Langmuir Laboratory, New Mexico (orographic effects). The evaluation parameters were advance warning time, time to clear after hazard, alarm reliability, and false alarm and failure to alarm probabilities. The triangulation locator provided the best overall performance; however, all systems indicated a need for improvement in the failure to alarm rate.

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K. V. Beard
,
D. B. Johnson
, and
A. R. Jameson

Abstract

An energy model is formulated to compare collisional kinetic energy with viscous dissipation for oscillating raindrops as a function of size, raindrop distribution and rainfall rate. A potential energy model is used to calculate oscillation energies, and is coupled with results from a potential flow model to determine the time-average axis ratios for fundamental mode oscillations. The model findings are found to be consistent with observations of mean and extreme axis ratios. It is concluded that there is sufficient collisional energy to produce large-amplitude oscillations in moderate-to-heavy rainfall, and that time-average axis ratios should depart significantly from equilibrium, thereby altering the radar polarization characteristics of rain.

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S. R. Johnson
,
James D. McQuigg
, and
Thomas P. Rothrock

Abstract

The electric power industry has long been known to be sensitive to weather events. In particular, daily temperatures in distribution areas are known to affect electric power consumption. In this paper the relationship between power consumption and daily temperatures is estimated using simple regression techniques. The resulting relationships permit an investigation of the consequences of temperature modification for 14 midwestern electric power production companies. Comparisons between power production costs for observed and modified historical and experimentally generated temperature series suggest that changes of 3–5F in average daily temperature can reduce costs substantially. Exact differentials in production cost which can be attributed to temperature modification are presented so as to be useful in firm, industry and public policy decisions.

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H. D. Ausfresser
,
A. C. Johnson
, and
R. A. Kowalski
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