OLR(1987)34(11) B. MarineMeteorology 941

New developments of a cloud classification scheme based on histogram clustering by a statistical method are presented. Use of time series of geostationary satellite pictures for construction of composite images representative of the surface properties, and for the identification of significative cloud classes is discussed. Spatial variances are introduced as addi- tional parameters of the classification, to better separate clouds from the surface and the different kinds of more or less homogeneous cloud classes. LMD/CNRS, 91128 Palaiseau Cedex, France.

B270. Precipitation 87:6190

Joussaume, Sylvie, Robert Sadourny and Charly Vignal, 1986. Origin of precipitating water in a numerical simulation of the July climate. Ocean- air Interactions, 1(1):43-56.

An atmospheric general circulation model, based upon a 'macro-Lagrangian dynamic analysis of the atmospheric water cycle,' is developed which iden- tifies the water vapor according to its origin and traces it through turbulent boundary layer diffusion, large-scale transport, convection, and precipitation. The method uses perpetual July simulations to obtain an estimate of the continentality of regional July climates. Lab. de Meteorol. Dynamique du CNRS, Ecole Normale Superieure, 75231 Paris Cedex 05, France. (hbf)

B280. Storms, disturbances, cyclones, etc.

87:6191 Betts, A.K. and Joanne Simpson, 1987. Thermo-

dynamic budget diagrams for the hurricane subcloud layer. J. atmos. Sci., 44(5):842-849.

We reexamine the idealized hurricane boundary layer budget from Malkus and Riehl using vector diagrams for thermodynamic budgets in the light of recent observational studies. We conclude that a large air-sea temperature difference can only be maintained with both large fluxes through cloud- base level and a large evaporative cooling of the subcloud layer. The high 0E values observed in hurricane eyewalls can be reached if these cloud- base and evaporative fluxes are reduced and the subcloud layer moves toward sea surface virtual potential temperature. Lab. for Atmos., NASA/ Goddard Space Flight Center, Greenbelt, MD 20771, USA.

87:6192 Burlutskii, R.F., 1986. Mechanism of strengthening of

tropical cyclones. Soy. Met. Hydrol. (a translation of Meteorologiya Gidrol.), 9:22-28.

The discrepancy between actual supergradient wind predominance in a developing tropical cyclone and the theory that wind strengthening is due to conservation of angular momentum of centripetal air particles is examined. (jrb)

87:6193 Chong, Michel, Paul Amayenc, Georges Scialom

and Jacques Testud, 1987. A tropical squall line observed during the COPT 81 experiment in West Africa. Part 1. Kipematic structure inferred from dual-Doppler radar data. Mon. Weath. Rev., 115(3):670-694.

The general characteristics of this system allow it to be referred to as a typical squall line system; however, it is shown that the explicit internal structure reveals some unexpected features. This paper describes only the kinematic structure and the role of convective-scale and mesoscale motions in the mass transports, in connection with the observed thermodynamic changes. CNET, CNRS, Centre de Rech. en Phys. de l'Environ. Terr. et Planet., 92131 Issy-les-Moulineaux, France.

87:6194 Tsou, C.-H., P.J. Smith and P.M. Pauley, 1987. A

comparison of adiabatic and diabatic forcing in an intense extratropical cyclone system. Mon. Weath. Rev., 115(4):763-786.

The main goal of the study is to assess the relative importance of adiabatic and diabatic forcings which significantly influence cyclone development. Di- agnostic experiments were performed for an intense surface cyclone associated with a strong upper-air wave and jet stream observed over North America on 9-11 January 1975. Results indicated that vorticity advection has a primary influence on movement and propagation of the wave system; differential thermal advection plays a secondary role in wave development; the influence of latent heating is less than the other mechanisms; and vertical advection of static stability makes a significant contribution. Dept. of Earth and Atmos. Sci., Purdue Univ., West Lafayette, IN 47907, USA.

87:6195 Weng, H.Y. and A. Barcilon, 1987. Favorable

environments for explosive cyclogenesis in a modified two-layer Eady model. Tellus, 39A(3): 202-214.