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T. N. Krishnamurti

symmetric monsoon in a generalcirculation model. The model included oceans to thesouth, and land areas with mountains to the north.Other features were air-sea interaction, convective adjustment, detailed radiative processes and large scalecondensation. With the inclusion of mountains and amean July solar insolation input the model simulateda realistic monsoon including such features as: themonsoon trough, monsoon rainfall, warm troposphere,tropical easterly jet, strong Hadley circulation andlower

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David M. Schultz and Philip N. Schumacher

and Aktary 1993 , 1995 ). Although we do not deny the likely existence of slantwise convection or the possible involvement of MSI in some precipitating systems in the atmosphere, it is our contention that CSI is frequently misused and overused as a diagnostic tool, a point also noted by Wiesmueller and Zubrick (1998 , p. 86). We believe the following four reasons are responsible, in part, for the present situation. 1) The theory of CSI has certain limitations and caveats that are discussed

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Robert A. Houze Jr.

large-scale wind. Figure 1b shows how the tracks are generally westward at lower latitudes, where easterlies dominate the large-scale flow. The storms often “recurve” toward the east, when they move poleward into the midlatitude westerlies. When they encounter land or colder water, they die out or (more rarely) transition into extratropical cyclones ( Jones et al. 2003 ). Although tropical cyclones form at low latitudes, generally between 5° and 20° ( Fig. 1a ), they rarely form within ±5° of the

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Zhiyong Meng and Fuqing Zhang

harder to define because of the complicated multiscale interactions. A successive covariance localization (SCL) technique was proposed by Zhang et al. (2009a) to assimilate dense radar observations that contain information about the state of the atmosphere at a wide range of scales. SCL assumes that both large- and small-scale errors are simultaneously present and was designed to reduce computational cost and sampling errors. This technique uses the Gaspari and Cohn (1999) fifth-order correlation

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P. L. Houtekamer and Fuqing Zhang

section 2e , we discuss why it is too early to favor one EnKF algorithm over another. a. General description Any EnKF implementation updates a prior estimate of the atmosphere valid at some time t with the information in new observations to arrive at an updated estimate of the atmosphere as in Eq. (1) . To this end, a Kalman gain matrix can be used to give an appropriate weight to the observations, which have error covariance , and the background, which has error covariance , as in Eq

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Bogdan Antonescu, David M. Schultz, Fiona Lomas, and Thilo Kühne

tornado is a vortex between a cloud and the land or water surface, in which the connection between the cloud and surface is often visible . According to this definition, all waterspouts would be included as tornadoes, which is consistent with the Glossary definitions. However, the inclusion of the waterspouts inflates the inventory of tornadoes in Europe. This inflation is due to two reasons. First, there are two types of waterspouts: (i) tornadic waterspouts associated with supercells or quasi

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