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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 K of synoptic scale motion V, the kinetic energy K′ of mesoscale motion V′, and the scalar product V·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 V·V′, which transfers kinetic energy to K and K′. The term V·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.

The kinetic energy balance and kinetic energy sources are studied for high latitudes north of 55 deg N with twice daily upper air observations during a seven-year period from 1973 to 1979. Energy variables are presented for 5 deg latitudinal zones from 55 to 75 deg N and for the polar cap north of 75 deg N. Spatial distributions of important energy variables are also presented. The upper level maximum of the cross-isobaric generation in high latitudes is observed in th lower stratosphere above the tropopause level in the winter and becomes insignificant during the summer. The flux convergence of potential energy from the source in lower latitudes is identified as the single major source for kinetic energy in higher latitudes. The contribution of the baroclinic conversion is minor. Examination during the First GARP Global Experiment winter indicates that the cold air outbreaks of the Asian winter monsoon are associated with noticeable changes in the hemispherical distributions of the fields of vertical motion and energetics in the high latitudes.

Currently available diagnostic studies on kinetic energy balance in the general circulation are reviewed as one of the basic scientific problems in GARP. The kinetic energy equation and several different approaches in the evaluation of energy variables are discussed in relation to real and modeled atmospheric data. Energy balance problems in the middle latitudes are examined in terms of linkages between processes from energy conversion to dissipation, balance within various systems of circulation, and interactions with sub-synoptic scale disturbances. The kinetic energy budget in large-scale disturbances and the general flow of the tropical circulation are contrasted with those in the middle latitudes. By clarifying the current essential problems in the energetics of the middle latitudes and tropics, ongoing diagnostic studies at the University of Missouri—Columbia and Purdue University are identified in the context of the GARP.

The spectral energetics of the Northern Hemisphere circulation during blocking episodes of the FGGE year is investigated with gridded analyses of observational data and parallel simulation experiments. The purpose of this study is to describe the energetics distinctions of the observed and simulated blockings in the context of the general circulation and to assess the capability of the model to simulate blockings. In the observed circulation a pronounced winter blocking is developed and maintained by the nonlinear wave-wave interaction L(1) from the kinetic energy source for n = 3-10, where L(n) is the transfer of eddy kinetic energy from all other wavenumbers to wavenumber n. In the case of the double blocking in the winter, both L(1) and L(2) support the blocking. The kinetic energy source of n = 10 for upscale input at n = 1 and 2 is supported by the baroclinic conversion at n = 3-10. The simulated winter circulation shows strong baroclinic conversion at all wavenumbers, including ultralong waves. However, the simulation fails to produce pronounced blocking for the absence of L(1), and the converted energy cascades down to shorter waves. The wave-mean transfer of kinetic energy from the large-scale disturbances to the zonal mean component further prevents the accumulation of the kinetic energy at the ultralong waves. In contrast to the winter situation, the summer blocking seems to be directly supported by both L(4) and baroclinic conversion at other planetary-scale waves. Consequently, the summer circulation is better simulated than the winter circulation.

The energy transformations ore studied with a subsynoptic-scale upper air network for three types of severe storm environments under convective, nonconvective and frontal situations. The environment of the convective storms is most active energetically with intense generation and dissipation of kinetic energy taking place in the upper layer of the atmosphere. In the case of the non-convective environment, a strong adiabatic destruction of kinetic energy through the cross-isobaric flow takes place in the upper layer of the atmosphere. In the frontal cases the upper layer of the atmosphere becomes energetically inactive for the observed scale in terms of the gross energy budget. Examination of the kinetic energy budget during the thunderstorm passage indicates the existence of subsynoptic-scale areas of adiabatic generation and destruction of kinetic energy with the maximum destruction in the middle and upper layers in the area of the maximum storm intensity. The eddy energy transformations in the ...

The spectral energetics of the general circulation are presented for the entire FGGE year based on the GFDL analyses of FGGE observations. The global energy balance and those of the Northern and Southern hemispheres show a reasonable agreement. However, examining the energy flow in the wavenumber domain reveals a marked contrast between the two hemispheres in both energy and energy transformations. The annual variations of energy variables are large, and there are also pronounced differences of seasonal characteristics between the hemispheres. With the one-year time series of energy variables, time spectra of transient waves are examined at 500 and 100 mb in order to evaluate their contribution to the time-averaged kinetic energy and baroclinic conversion. Characteristic distributions of power spectra for kinetic energy and available potential energy are described for the Northern and Southern hemispheres. In cyclone-scale disturbance almost the entire baroclinc conversion is supported by transie...

It is shown that the recorded onset dates of the summer monsoon in southwestern India can be closely related functionally to the antecedent upper air conditions. The antecedent upper air conditions are represented by April mean values of the daily upper air parameters at 100 and 700 mb from 1958 to 1978. It is further demonstrated that the multi-regression scheme on the basis of such a functional relationship may be utilized in an objective forecast of the onset date. The forecasted dates are shown to be reasonably close to the recorded onset dates. Various aspects of the approach and scheme are discussed. Because of the time variations of the patterns of the general circulation, a constant updating of the regression equation should be an integral part of the multi-regression forecasting scheme.

The large-scale sensible and latent beat budgets in the intense winter monsoon over the Kuroshio region are studied with the AMTEX 74 and 75 observations. Energy variables involved in the sensible heat balance and latent beat balance are computed and examined from the surface to 100 mb. They are also compared with the sensible and latent heat supplies from the sea surface, which are independently estimated. The large-scale vertical and horizontal transport processes are important in the local balance of sensible and latent heat. The adiabatic conversion term is also significant in the balance of sensible heat. The boundary layer of the atmosphere appears to be a persistent source of sensible and latent beat. The existence of the apparent sensible and latent heat sources above the boundary layer seems to be related to the prevailing synoptic pattern and existing meso-convective systems. When the winter monsoon dominates over the warm sea, considerable heat energy is transferred from the sea surfac...

Eigenvector and harmonic analyses have been performed with monthly mean values of upper air parameters of the Northern Hemispheric circulation for the period from April 1955 to December 1974. The parameters used involve the 700 and 500 mb temperatures, the 700–500 mb thickness, the 300 mb kinetic and eddy kinetic energies, and the 700, 500 and 300 mb zonal/meridional flow indicators. The zonal/meridional flow indicator is defined as the ratio |u|/|v|, where the bar indicates the monthly mean. The first eigenvectors of the normalized parameters are associated with the annual variation of the basic patterns. For the temperature field the first eigenvector overwhelmingly dominates. It reflects the annual variation of temperature in the mid and higher latitudes with an effect of the land-ocean configuration. The second eigenvector shows a land-ocean contrast. The long-term variation of temperature in the lower latitudes also stands out. For the kinetic energy and zonal/meridional flow indicator the f...

A global energetics analysis is presented for the FGGE SOP-1 and SOP-2 with ECMWF and GFDL data sets. Both global integral properties and spectral characteristics are examined. There is a large discrepancy between the present FGGE analysis and previously available estimates concerning the level of available potential energy and kinetic energy. This discrepancy is attributable to an earlier restriction of data coverage. There is a significant seasonal difference in the energy reservoir of the Northern Hemisphere, whereas the diference is minor in the Southern Hemisphere. This leads to a seasonal contrast of the globally integrated energy budget which comes mostly from the Northern Hemisphere. Both the global energy level and the intensity of the general circulation are more pronounced during SOP-1 than during SOP-2. One major focus of attention in this study is an energetics comparison of ECMWF and GFDL data sets. There is a twofold difference in the intensity of the general circulation as measured with these two data sets. The energetics diagnosis indicates that the operational modes of the general circulation as described by these two data sets also differ considerably. The contrasts between SOP-1 and SOP-2 and between the ECMWF and GFDL versions of the data sets are apparent in the pattern of energy flow in the wavenumber domain.

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 conve...

Energetics characteristics of the Asian winter monsoon are studied with twice-daily upper air data during a 20-year period over its source region. It is found that the energetics features over Siberia, North-eastern Asia, China Main and the Japan Sea, are distinctly different reflecting the different roles and characteristic flow patterns of these regions in the system of the winter monsoon. Siberia, under the dominance of the anticyclonic flow, shows a general adiabatic destruction of kinetic energy through cross-isobaric motion. Northeastern Asia, under the influence of a major cyclonic system, is dominated by typical patterns of energy transformations as observed in most areas of transient synoptic disturbances. The strong westerlies dominate over the general area of the China Main, East China Sea and Japan Sea and the kinetic energy is intensely generated in this portion of the flow. Most of the kinetic energy generated over China Main is exported. Over the Japan Sea area where the series of ...

Three-dimensional normal mode functions are applied to the analysis of the energetics of the general circulation during the FGGE year. The GFDL FGGE data are used for the computation of both the normal mode energetics and the standard spectral energetics. The normal mode energetics of the global circulation are presented in a barotropic and baroclinic decomposition for the zonal mean and eddy energies for the stationary and transient components of the flow. The energy generated in the zonal mean baroclinic component is first transformed to the eddy baroclinic component through the process of atmospheric baroclinic instability. It is then further transformed to eddy and zonal mean barotropic components by the nonlinear up-scale cascade of kinetic energy. The zonal mean kinetic energy thus maintains its barotropic structure by the activities of baroclinic waves. The time series of energy variables during the FGGE Northern Hemisphere winter clearly indicates a sequence of energy transformations from...

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 ene...

Energy source terms in various types of mid–latitude synoptic–scale disturbances are examined with wore than 3400 computed synoptic cases during a 5–year period over North America. It is shown that cyclones and cyclone vicinities serve as the baroclinic energy source regions, although the released energy through the eddy conversion process may be transported to other regions for generation of the kinetic energy. In the development and mature stages of cyclonic disturbances the eddy energy conversion is very active both within the cyclones and their vicinities. When cyclones are occluded the cyclone vicinities lose their importance as the baroclinic source region. In contrast to cyclonic disturbances, anticyclonic disturbances destroy kinetic energy. In intermediate type disturbances there is a significant generation of kinetic energy. However, there is no internal energy source through the eddy conversion in these disturbances, and they depend on imported potential energy for their kinetic energy...

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 x 5 deg latitude-longitude grid general circulation model (GCM) and 2 x 2.5 deg grid GCM are employed with the GLA and Geophysical Fluid Dynamics Laboratory initial datasets. Among four simulations, the simulations by the high resolution GCM produce realistically strong blockings with compatible spectral energetics as in the observed blockings 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.

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.

The vertical distribution and seasonal variation of the kinetic energy balance of the atmosphere are studied. From 11 months' daily wind and geopotential data during 1962 and 1963 over North America, the generation due to the work done by the horizontal pressure force, the local change, the horizontal outflow, and the vertical transport, are evaluated for 20 pressure layers from the surface to 50 mb. The dissipation is then obtained as the residual to balance the kinetic energy equation. The generation and dissipation are at a maximum in the planetary boundary layer. They decrease gradually to a minimum in the mid-troposphere, increase again to the second maximum in the upper part of the atmosphere, then decrease again farther upward. The generation and dissipation are approximately balanced in the lower troposphere, particularly in the boundary layer, for the large-scale domain of analysis. The generation and dissipation of the kinetic energy are significantly large both in the lower troposphere...

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, includ...

The design of an optimized computation of bias error accumulation in the kinematic w profiles seems scheme for kinematic vertical motion fields with an upper to have been practically overcome. The discussions air network is discussed with a scheme that incorporates include the general construction of the scheme in terms 14 degrees of optimization in the evaluation of divergence. of the sequential flow of the computation, the quality The provided range of optimization enables the computa- of the vertical motion field over the synoptic network tion scheme to suit wide varieties of data dispostion in through the depth of the atmosphere, and the utilization the observation network, and the well-known problem and application of the scheme under various circumstances. As an integral part of our observational study of at- mospheric energetics, the development of a scheme for the kinematic estimate of the vertical motion field is under way. Since it is based on no assumptions about the nature of the atmospheric circulation except the hydro- static relationship, the kinematic estimate of the vertical p velocity, w, has paramount importance in the objective energy diagnosis. In a preceding paper (Kung 1972), a new approach to the kinematic estimate of the vertical motion field with an upper air network was presented. The scheme has been designed under the presumption that the vertical profile of w should converge to a near-zero value at the top of the atmosphere without being so required when a sensitive balance between the analysis scheme and the data dis- position is achieved. Thus, a range of optimization is provided in a computation scheme to suit wide varieties of data disposition in the observation network. The pre- liminary computation with eight degrees of optimization in a scheme, as reported in the previous paper, has sup- ported this presumption, and our extensive computational studies subsequent to the paper also confirm the approach. Thus, it may be concluded that the well-known problem of bias error accumulation in the kinematic w profiles can be practically overcome, and meaningful fields of kinematic vertical p velocity can be obtained through the depth of the atmosphere with observed mind data over a

The latitude-height distributions of the kinetic energy generation and dissipation over North America are presented in a series of cross sections from 25° to 70° N, and from the surface to the 50-mb level. The generation was computed using the twice-daily observed wind and geopotential data for a 1-yr period. The dissipation was obtained for a 3-mo summer period as the residual term of the kinetic energy equation. Throughout all latitudes, the generation and dissipation have a maximum in the planetary boundary layer. They gradually reach a minimum in the mid-troposphere, then increase to another maximum at the jet stream level except in middle latitudes. In the upper troposphere, there seems to be a characteristic meridional distribution both for generation and dissipation. The generation is significantly large north and south of the middle latitude where the kinetic energy is adiabatically destroyed. Those latitudes of large generation in the upper troposphere are also characterized by high fric...

Short-period cycles in the large-scale atmospheric circulation were investigated with time series of kinetic energy, its generation and outflow, which were computed twice a day for a 5-year period over the North American Continent. The spectra were computed from the autocorrelation curves, and were compared with the red noise spectra to evaluate the statistical significance of the energy cycles. The maxima of time spectra of different energy parameters show frequent agreement. The commonly reported kinetic energy cycles with periods of one to two weeks are observed; however, they are not statistically significant and also show very high year-to-year irregularity. Significant cycles with periods around 40 days and 2–4 days are also noted.

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.

The diurnal variation and long-term variation of the kinetic energy generation and dissipation are investigated with the wind and geopotential data observed twice a day at 00 and 12 gmt over North America during a 5-yr. period. The generation from the work done by the horizontal pressure force and the dissipation are significantly and consistently greater at 00 gmt than at 12 gmt. The diurnal variation is especially pronounced during the summer. The annual march of the seasons and the year-to-year variation of the kinetic energy parameters are also significant. By the use of twice-a-day observations for an extended period, the study over North America is increased in generality as an approximation to hemispherical features. However, some uncertainty remains in this respect because of the possible effects of the semidiurnal variations and unconfirmed radiation errors in the radiosonde observations. The previously reported double maxima of the generation and dissipation in the planetary boundary la...

This is an attempt to employ a pertinent boundary layer model and proper frictional parameters in the numerical analysis of the angular momentum budget of the atmosphere. The mean zonal surface stress due to friction is examined utilizing Lettau's boundary layer model and the earth's roughness study by the writer and Lettau for the period 1945–1955. The meridional and seasonal variations of the mean zonal surface stress are described; the mountain effect is derived indirectly; the stresses over the continent and ocean are compared; and finally the sensitivity of the numerical analysis to the prescribed frictional parameters is briefly discussed.

The kinetic energy budget and dissipation are studied in their various partitionings, using daily aerological (wind and geopotential) data from the network over North America for six months. The total kinetic energy dissipation is partitioned into vertical mean flow and shear flow and also into planetary boundary layer and free atmosphere. Furthermore, the dissipations in the vertical mean flow and shear flow are partitioned separately into components contributed by the boundary layer and free atmosphere. Two important terms in the total kinetic energy equation in determining the total dissipation are the generation and outflow. TWO important terms in the mean flow kinetic energy equation in determining the mean flow dissipation are the conversion between the vertical shear and mean flows and the outflow. The mean flow and shear flow dissipations seem to have numerical values of the same order of magnitude. The evaluated boundary layer dissipation and free atmosphere dissipation indicate that the latter is at least as important as the former. It is also shown that the mean flow dissipation is mainly contributed from the free atmosphere while the shear flow dissipation is contributed fromthe boundary layer and free atmosphere in the same order of magnitude. The evaluated dissipation values and related kinetic energy parameters are presented and examined in detail. Of special interest in this study is the direct evaluation of the kinetic energy generation due to the work done by the horizontal pressure force. Daily variation of the generation at different pressure levels seems to suggest three different modes of the generation cycle in the upper, mid, and lower troposphere. Clear vertical profiles of the generation from the surface to the 100-mb. level are obtained; it is shown that strong generation takes place in the upper and lower troposphere while the generation in the mid troposphere is very weak. It is also suggested that there may be an approximate balance of the kinetic energy generation and dissipation in the boundary layer.

Various aspects of our studies of the kinetic energy balance are discussed, using an improved scheme of computing the horizontal and vertical transports of the kinetic energy with the observed wind and geopotential data over North America. On a firmer basis than before, it has been shown that there is a considerable amount of kinetic energy dissipated outside the planetary boundary layer, particularly at the jet-stream level. This also may imply that intensity of the atmospheric general circulation is significantly higher than is being assumed in most of the numerical models of the atmosphere.