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  • Author or Editor: Ernest C. Kung x
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Ernest C. Kung
and
Lester I. Merritt

Abstract

The maintenance of large-scale tropical disturbances has been examined with the source terms of kinetic energy generation utilizing the special 1958 upper-air observations in the Marshall Islands area. An optimized objective analysis scheme for the computation of kinematic vertical velocity as well as the method for evaluation of energy variables is presented.

The time mean budgets of kinetic energy source terms are presented in terms of vertical profiles and intensity of processes represented by each term. The eddy conversion of available potential energy has its primary maximum in the layer between 400 and 200 mb, whereas the eddy kinetic energy generation shows maxima in the lower boundary and upper troposphere between 200 and 100 mb. In terms of the time mean budget only a fraction of the released energy by eddy conversion contributes to the eddy generation of kinetic energy in the area.

Through examination of the time series of energy variables, it is revealed that horizontal eddy flux convergence of potential energy is the dominant term in determining the local generation of eddy kinetic energy. The migration pattern of the ITCZ further suggests that this horizontal eddy flux term is closely associated with the position of the ITCZ, with a significant divergence of eddy flux of potential energy when the ITCZ is located to the south of the area.

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DONALD H. McINNIS
and
ERNEST C. KUNG

Abstract

Kinetic energy transformations from the view-point of energetics of the large-scale circulation are investigated with a series of subsynoptic scale radiosonde network soundings. Individual terms of the kinetic energy equation are evaluated along with the gradient form of the Richardson number.

A bimodal character of the vertical profile of kinetic energy generation having maxima in the upper and lower troposphere that is similar to what we observe in the genera1 circulation-scale disturbances is observed in the subsynoptic scale disturbances studied. However, the inflow of kinetic energy into the area indicates that, on the average, more kinetic energy could be dissipated than generated even during intense thunderstorm activity. Large pulsations of kinetic energy generation and dissipation with time are observed. Extrema of upper level generation are observed to occur mainly in layers where the Richardson number is relatively low.

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Wayman E. Baker
,
Ernest C. Kung
, and
Richard C. J. Somerville

Abstract

The energetics in numerical weather forecast experiments with the NCAR general circulation model have been analyzed. The 6-layer, 5-degree, second-generation global model was used to make two 10-day forecasts with the same initial conditions. The two experiments differed primarily in the methods of convective parameterization.

Hemispheric integrals of the model energies and energy transformations are presented in the context of their approach to a quasi-equilibrium climatology. Spectral and spatial analyses of the eddy energies and transformations provide further insight into the model response to the initial conditions. After the initial adjustment, the eddy kinetic energy appears to lag the conversion from eddy available potential energy to eddy kinetic energy by at least 48 h in the long waves (wavenumbers 1–4) and by approximately 24 h in the baroclinic waves (wavenumbers 5–7), whereas little or no time lag is apparent in the short waves (wavenumbers 8–12).

The sensitivity of the forecast energetics to two different convective parameterizations is also examined. There is little appreciable difference between the two experiments in the eddy kinetic energy integrals during the first 36 h of the forecast, but temporal patterns of the eddy transformations are distinctly different after 12 h.

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Wayman E. Baker
,
Ernest C. Kung
, and
Richard C. J. Somerville

Abstract

A comprehensive energetics analysis has been performed on the NCAR general circulation model. The analysis involves January and July simulation experiments with the 6-layer, 5-degree, second-generation model with two different convective schemes. Spectral analysis of the energy transformations in the wave-number domain was performed separately on a global and hemispheric basis as well as for the tropics and mid-latitudes. Latitudinal distributions of energy variables were also examined.

A qualitative agreement with observational estimates is generally recognized in the transformations of eddy energies. Quantitatively, however, the eddy energies, conversions and energy transfer between wavenumbers are weaker than observational estimates. It is noteworthy that substantial differences exist in the energetics of the two versions of the model with different convective schemes.

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Ernest C. Kung
,
H. L. Tanaka
, and
Wayman E. Baker

Abstract

Four numerical simulations of the global atmosphere for January 1979 are analyzed to study the formation of blocking in terms of Northern Hemisphere energetics. The Goddard Laboratory for Atmospheres (GLA) 4° × 5° latitude-longitude grid general circulation model (GCM) and 2° × 2.5° grid GCM are employed with the GLA and Geophysical Fluid Dynamics Laboratory (GFDL) initial datasets.

The difficulty in simulating a realistic blocking due to inadequate wave–wave interaction can be attributed in part to inadequate grid resolution. Among four simulations, the simulations by the high resolution GCM produce realistically strong blockings with compatible spectral energetics as in the observed blocking episodes. The latitude–height cross sections of the energy variables of wavenumber 1 is presented to describe the dipole structure of blockings. Blocking development is also examined in time series of barotropic and baroclinic components of energy and associated conversions.

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Shou-Jun Chen
,
Le-Sheng Bai
, and
Ernest C. Kung

Abstract

To explicitly describe the energy exchange between meso and synoptic-scale motions, a diagnostic scheme of kinetic energy has been developed. By using a horizontal filtering technique, meteorological variables are separated into synoptic and mesoscale components. A set of budget equations are derived for the kinetic energy of synoptic scale motion V̂, the kinetic energy K′ of mesoscale motion V′, and the scalar product V̂·V′.

The scheme is applied to diagnose a severe rainstorm case over northern China during summer. The results show that the scale interactions between wind and height fields produce V̂·V′, which transfers kinetic energy to and K′. The term V̂·V′ thus acts as a medium in scale interactions conveying the energy between meso- and synoptic-scale motions and the potential energy source residing in the mass field.

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ERNEST C. KUNG
,
REID A. BRYSON
, and
DONALD H. LENSCHOW

Abstract

A series of 12 monthly flights along a fixed path in Wisconsin and a series of 4 long-range flights over extensive areas of the United States and Canada were performed during 1963 to measure systematically the surface albedo over various types of the earth's surface, using an instrumented light airplane operating at a low level. An approximate total of 24,000 mi. was flown and roughly 210,000 sets of the measurements were processed for this study. Techniques of measurement and data treatment are discussed.

It is shown, and discussed in detail, that the regional differences and seasonal variations of the surface albedo due to thc structure and state of the earth's surface cover are significant. The snow cover is the most important modification of the earth's surface, giving a significantly higher albedo. A quantitative relationship between the increase of surface albedo and snow cover is examined. The surface albedo measured during the flights over typical surface covers over North America, including cities, is presented. The surface covers and their textures over the North American Continent were studied mainly in terms of land use, vegetation type and phenology, soil type, and ground snow cover. The surface albedo values were estimated for various regions of the continent from the flight measurement data, considering the similarity and differences in surface structure among the regions. The resulting seasonal albedo maps of North America are presented and discussed, along with the seasonal variation of the meridional profile of thc continental surface albedo.

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