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Study of the latent heat energy and the sensible heat energy in the atmosphere over Yangtze-Huaihe River valley during summer flood and drought
Abstract
The physical causes leading to the occurrence of drought and flood disasters are mainly due to the anomaly of water and heat budget and circulation resulting from the abnormal energy transport in the atmosphere and on earth. Taking the data of water and heat in the years with summer flood and drought, the latent heat energy and sensible heat energy in the whole atmosphere column over Yangtze-Huaihe area and in each of the ten atmosphere layers in the column from the ground to 150 hPa are calculated. The features of the temporal and spatial distribution of the energy, its transport and convergence (divergence) are analyzed and compared. Thus the causes of disaster formation are explored.
... anomalies during the life cycle of UB events ( Figure 5). Here, we use the definition of sensible heat energy presented by Lu, Gao, and Zhai (1996), in the form E s = c p ∫ p T dp, to calculate the sensible heat energy in the whole troposphere, where c p = (1 + 0.837q) × 1.005, q is the specific humidity, T is the temperature, and p is the pressure. ...
The physical cause of amplified deep Arctic tropospheric warming in winter in the Barents–Kara Seas (BKS) is examined. The authors propose that changes in the atmospheric circulation patterns are important for deep Arctic tropospheric warming in winter. It is found that the retrograde Urals blocking (UB) event concurrent with a negative North Atlantic Oscillation (NAO⁻) that arises from a prior negative Arctic Oscillation (AO⁻) is not favorable for tropospheric warming because of less water vapor over the BKS. Such UB events are related to more winter BKS sea ice associated with the negative sea surface temperature (SST) anomaly in the BKS. In contrast, a UB occurring together with a positive North Atlantic Oscillation (NAO⁺) shows less movement and can significantly enhance tropospheric warming over the BKS through increasing tropospheric sensible heat energy due to a persistent BKS water vapor increase. This type of quasi-stationary UB event is related to prior less BKS sea ice associated with a positive BKS SST anomaly that coexists with the North Atlantic SST tripole structure. In summary, because warm, wet and low sea-ice winters in the BKS are related to UB events with an NAO⁺, and depend on the winter prior sea-ice condition, the tropospheric warming is to some extent a manifestation of the sea-ice–blocking–moisture feedback in the BKS.
Eulerian kinetic energy budgets for the synoptic-scale flow over North America were computed for two cases of cyclone development associated with severe prefrontal convection. Horizontal flux convergence constitutes the major energy source in both cases and assumes major importance in maintaining the strength of the upper tropospheric jet maxima. Generation of kinetic energy via cross-counter flow is, surprisingly, a persistent sink in one case and only a weak energy source for the cyclone in the second case. Cross-contour flow toward higher heights is generally found ahead of the upper level troughs, where the jet stream is moving through regions in which the contour gradient weakens downstream. Generation of kinetic energy is largely confined to the lower troposphere, reflecting frictional influence near the earth's surface. Dissipation of kinetic energy, computed as a residual, has local maxima both in the lower troposphere (nearly balancing the generation) and near the jet stream level. Subgrid-scale sources of kinetic energy are apparent in both cases and, at times, are particularly important in regions of widespread deep convection. These sources are associated with longitudinal shear in the polar jet stream and with the presence of deep convection. Convective region budgets show that the maximum rate of kinetic energy gain occurs during periods when the convection increases most rapidly both in intensity and in areal extent.
The derivations of the energy budget equations for divergent and rotational components of kinetic energy are provided. The intense convection periods studied are: (1) synoptic scale data of 3 or 6 hour intervals and (2) mesoalphascale data every 3 hours. Composite energies and averaged budgets for the periods are presented; the effects of random data errors on derived energy parameters is investigated. The divergent kinetic energy and rotational kinetic energy budgets are compared; good correlation of the data is observed. The kinetic energies and budget terms increase with convective development; however, the conversion of the divergent and rotational energies are opposite.