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1. Introduction In a recent paper, Martin (2006) examined the distributions of the quasigeostrophic (QG) vertical motions associated with the transverse and shearwise components of the Q vector (oriented perpendicular to, and along, the geostrophic vertical shear, respectively) throughout the life cycle of two extratropical cyclones. He presented evidence that these two components of the QG vertical motion play different roles in the typical midlatitude cyclone life cycle. Specifically, it
1. Introduction In a recent paper, Martin (2006) examined the distributions of the quasigeostrophic (QG) vertical motions associated with the transverse and shearwise components of the Q vector (oriented perpendicular to, and along, the geostrophic vertical shear, respectively) throughout the life cycle of two extratropical cyclones. He presented evidence that these two components of the QG vertical motion play different roles in the typical midlatitude cyclone life cycle. Specifically, it
1. Background Tropical large-scale vertical motion profiles are important for a wide variety of dynamics problems. However, they are difficult to measure, simulate, and estimate, and basic science questions about what controls profile shape, or “top heaviness,” remain to be determined. The term top-heaviness in this work is used to refer to the extent to which vertical motion peaks in the upper troposphere compared to lower in the troposphere. In this work, we compare climatological vertical
1. Background Tropical large-scale vertical motion profiles are important for a wide variety of dynamics problems. However, they are difficult to measure, simulate, and estimate, and basic science questions about what controls profile shape, or “top heaviness,” remain to be determined. The term top-heaviness in this work is used to refer to the extent to which vertical motion peaks in the upper troposphere compared to lower in the troposphere. In this work, we compare climatological vertical
shown by F03 , quite similar analysis increments resulted from this new analysis procedure as compared with the previous operational use of linear regressions mentioned above. A noticeable distinction, however, was obtained for the divergent part of the wind increments and, consequently, vertical motion increments. As one would expect from balanced considerations at synoptic scales treated by ECMWF analysis, the QG omega equation enforced coherent extratropical divergent flow structures depending
shown by F03 , quite similar analysis increments resulted from this new analysis procedure as compared with the previous operational use of linear regressions mentioned above. A noticeable distinction, however, was obtained for the divergent part of the wind increments and, consequently, vertical motion increments. As one would expect from balanced considerations at synoptic scales treated by ECMWF analysis, the QG omega equation enforced coherent extratropical divergent flow structures depending
reflectivity data for validation of a numerical simulation of Hurricane Bonnie (1998) and showed that the model significantly overproduced precipitation, in part because of water conservation errors associated with the model numerics. Key to understanding the precipitation distribution in hurricanes is an understanding of factors determining the distribution of vertical motion. While the tangential wind field is dominated by its azimuthal mean component ( Fig. 1a shows an example from the simulation of
reflectivity data for validation of a numerical simulation of Hurricane Bonnie (1998) and showed that the model significantly overproduced precipitation, in part because of water conservation errors associated with the model numerics. Key to understanding the precipitation distribution in hurricanes is an understanding of factors determining the distribution of vertical motion. While the tangential wind field is dominated by its azimuthal mean component ( Fig. 1a shows an example from the simulation of
simple theory of the large-scale tropical circulation. Simple models can also give valuable intuitive understanding of what may be occurring in more complex simulations and parameterizations that are less easily understood from first principles. In this work, using a combination of physical reasoning and empiricism, we develop a simple model that predicts monthly rainfall and vertical motion profiles from SST and surface convergence with skill comparable to current atmospheric general circulation
simple theory of the large-scale tropical circulation. Simple models can also give valuable intuitive understanding of what may be occurring in more complex simulations and parameterizations that are less easily understood from first principles. In this work, using a combination of physical reasoning and empiricism, we develop a simple model that predicts monthly rainfall and vertical motion profiles from SST and surface convergence with skill comparable to current atmospheric general circulation
1. Introduction The VHF Doppler radar installed in western Sumatra, Indonesia (0.2°S, 100.32°E) has enabled the observation of vertical motion W with fine time (3 min) and vertical (150 m) resolutions. This paper describes the fine structure of W within the stratiform precipitation region of tropical mesoscale cloud clusters. In a mesoscale cloud cluster, the stratiform precipitation region, mainly consisting of nimbostratus, occupies most of the area. Vertical motions are related closely
1. Introduction The VHF Doppler radar installed in western Sumatra, Indonesia (0.2°S, 100.32°E) has enabled the observation of vertical motion W with fine time (3 min) and vertical (150 m) resolutions. This paper describes the fine structure of W within the stratiform precipitation region of tropical mesoscale cloud clusters. In a mesoscale cloud cluster, the stratiform precipitation region, mainly consisting of nimbostratus, occupies most of the area. Vertical motions are related closely
,d,f ), and contributes to the formation of a steep, single-step tropopause structure during all event types via the downward advection of high-PV stratospheric air. Considered together, the influence of vertical motion during the production of each jet superposition event type motivates further investigation into the dynamical processes responsible for the production of vertical motion during jet superpositions. Fig . 2. (left) Composite 250-hPa geopotential height (black solid lines every 120 m), 250
,d,f ), and contributes to the formation of a steep, single-step tropopause structure during all event types via the downward advection of high-PV stratospheric air. Considered together, the influence of vertical motion during the production of each jet superposition event type motivates further investigation into the dynamical processes responsible for the production of vertical motion during jet superpositions. Fig . 2. (left) Composite 250-hPa geopotential height (black solid lines every 120 m), 250
examine vertical motion profiles in various tropical weather states. In the atmosphere, rising air parcels (theoretical packets of air) cool less rapidly with height than they would if they were dry because of the condensation of water vapor. These buoyant updrafts, making up only a small fraction of the area of a cloud field, induce subsidence around them, rapidly warming the environment near clouds ( Bretherton and Smolarkiewicz 1989 ). The combination of the condensational processes and the
examine vertical motion profiles in various tropical weather states. In the atmosphere, rising air parcels (theoretical packets of air) cool less rapidly with height than they would if they were dry because of the condensation of water vapor. These buoyant updrafts, making up only a small fraction of the area of a cloud field, induce subsidence around them, rapidly warming the environment near clouds ( Bretherton and Smolarkiewicz 1989 ). The combination of the condensational processes and the
Pacific ( Knutson and Weickmann 1987 ; Hsu 1996 ). In particular, distinct anomalous vertical motion, associated with the subtropical divergence–convergence as a counterpart of the MJO, is found near the entrance region of the jet stream in East Asia. A recent diagnostic study by Kim et al. (2006) has suggested that a strong vertical motion occurs to meet the quasigeostrophic balance as the subtropical Rossby gyres of the MJO pass the strong baroclinic zone near the Asia–Pacific jet. Despite the
Pacific ( Knutson and Weickmann 1987 ; Hsu 1996 ). In particular, distinct anomalous vertical motion, associated with the subtropical divergence–convergence as a counterpart of the MJO, is found near the entrance region of the jet stream in East Asia. A recent diagnostic study by Kim et al. (2006) has suggested that a strong vertical motion occurs to meet the quasigeostrophic balance as the subtropical Rossby gyres of the MJO pass the strong baroclinic zone near the Asia–Pacific jet. Despite the
mass flux. Vogel et al. (2020) show that mass flux is regulated by environmental factors, primarily the mesoscale atmospheric vertical motion at cloud base. This suggests that clouds depend directly on mesoscale circulation features, and that the connection between the two may need to be accounted for when predicting cloudiness. To study the influence of circulation on clouds, observational challenges have compelled previous investigations to use reanalysis data, and since these are more reliable
mass flux. Vogel et al. (2020) show that mass flux is regulated by environmental factors, primarily the mesoscale atmospheric vertical motion at cloud base. This suggests that clouds depend directly on mesoscale circulation features, and that the connection between the two may need to be accounted for when predicting cloudiness. To study the influence of circulation on clouds, observational challenges have compelled previous investigations to use reanalysis data, and since these are more reliable
