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Abstract
A mid-season test of a synoptic model for typhoon development (Sadler, 1976a) was conducted for July 1972 during an outbreak of four simultaneous typhoons. In agreement with the model, the rapid deepening phase of typhoons Rita, Phyllis and Tess was associated with multi-directional outflow channels to the large-scale flows of the upper troposphere. The depressions were positioned beneath the subequatorial ridge with normal outflow to the south into the equatorial easterlies. Vigorous outflow to the north was initiated by the proper positioning, through relative motion, of intense cells in the tropical upper tropospheric trough. Each storm, filled to minimal typhoon strength when either of these efficient outflow channels was denied to it. Susan was a study in contrasts. She spent most of her lifetime under large-scale unidirectional northeast flow aloft and attained doubtful minimal typhoon intensity for a few hours. The upper flow became favorable for intensification just prior to landfall.
Abstract
A mid-season test of a synoptic model for typhoon development (Sadler, 1976a) was conducted for July 1972 during an outbreak of four simultaneous typhoons. In agreement with the model, the rapid deepening phase of typhoons Rita, Phyllis and Tess was associated with multi-directional outflow channels to the large-scale flows of the upper troposphere. The depressions were positioned beneath the subequatorial ridge with normal outflow to the south into the equatorial easterlies. Vigorous outflow to the north was initiated by the proper positioning, through relative motion, of intense cells in the tropical upper tropospheric trough. Each storm, filled to minimal typhoon strength when either of these efficient outflow channels was denied to it. Susan was a study in contrasts. She spent most of her lifetime under large-scale unidirectional northeast flow aloft and attained doubtful minimal typhoon intensity for a few hours. The upper flow became favorable for intensification just prior to landfall.
Abstract
Seven years of daily satellite observations, ten years of commercial aircraft observations, a space–altitude meteorological cross section during EQUALANT II, and data from other investigations including analyses of 50 years of ship observations by Florida State University are combined to determine the meteorological setting for the GARP Atlantic Tropical Experiment (GATE).
The GATE lies in the western edge of the African monsoon. 1) A low-level monsoon trough lies across the GATE A–B scale ship array; 2) the trough is semianchored with little seasonal and interannual latitudinal variation in the monthly mean positions; 3) the trough is a strong gradient zone for most atmospheric parameters; 4) the major convective cloudiness is of the monsoon scale, zonally oriented, semianchored in the southern portion of the GATE area, and embedded in the westerly flow south of the trough line; and 5) the synoptic scale variability increases from June to September and is due mostly to vortices traveling vestward in the monsoon trough across the northern portion of the GATE area.
Abstract
Seven years of daily satellite observations, ten years of commercial aircraft observations, a space–altitude meteorological cross section during EQUALANT II, and data from other investigations including analyses of 50 years of ship observations by Florida State University are combined to determine the meteorological setting for the GARP Atlantic Tropical Experiment (GATE).
The GATE lies in the western edge of the African monsoon. 1) A low-level monsoon trough lies across the GATE A–B scale ship array; 2) the trough is semianchored with little seasonal and interannual latitudinal variation in the monthly mean positions; 3) the trough is a strong gradient zone for most atmospheric parameters; 4) the major convective cloudiness is of the monsoon scale, zonally oriented, semianchored in the southern portion of the GATE area, and embedded in the westerly flow south of the trough line; and 5) the synoptic scale variability increases from June to September and is due mostly to vortices traveling vestward in the monsoon trough across the northern portion of the GATE area.
Abstract
A synoptic model is developed to describe a role of the tropical upper tropospheric trough (TUTT) in early season typhoon development in the western Pacific low-level near-equatorial monsoon trough. The role is threefold: 1) The accompanying sub-equatorial ridge on the south side of the TUTT lies over the low-level trough and decreases the vertical shear; 2) the divergent Row on the south and cast side of a cyclonic cell in the TUTT increases the evacuation aloft to aid in depression development in a low-level trough; 3) a channel to large-scale westerlies is established for efficient outflow of the heat released by increased convection in the developing depression.
Abstract
A synoptic model is developed to describe a role of the tropical upper tropospheric trough (TUTT) in early season typhoon development in the western Pacific low-level near-equatorial monsoon trough. The role is threefold: 1) The accompanying sub-equatorial ridge on the south side of the TUTT lies over the low-level trough and decreases the vertical shear; 2) the divergent Row on the south and cast side of a cyclonic cell in the TUTT increases the evacuation aloft to aid in depression development in a low-level trough; 3) a channel to large-scale westerlies is established for efficient outflow of the heat released by increased convection in the developing depression.
Abstract
Photographic data from TIROS satellites indicate the frequency of tropical cyclones, of tropical storm and hurricane intensity, to be some three times greater than the frequency determined by conventional meteorological data in the eastern North Pacific. The sea surface temperatures exert an influence on the size, intensity, and track of the cyclones, but another influence, which prevents a large number of cyclones from being exported into the central Pacific with hurricane force winds, appears to be the “killing” effect of extreme vertical shear as the cyclones pass through the upper tropospheric ridge line. TIROS data are presented to illustrate the effects of these influences, separately and in combination, on the life history of eastern Pacific tropical cyclones.
Some clues are proposed for estimating the intensities of tropical cyclones.
Abstract
Photographic data from TIROS satellites indicate the frequency of tropical cyclones, of tropical storm and hurricane intensity, to be some three times greater than the frequency determined by conventional meteorological data in the eastern North Pacific. The sea surface temperatures exert an influence on the size, intensity, and track of the cyclones, but another influence, which prevents a large number of cyclones from being exported into the central Pacific with hurricane force winds, appears to be the “killing” effect of extreme vertical shear as the cyclones pass through the upper tropospheric ridge line. TIROS data are presented to illustrate the effects of these influences, separately and in combination, on the life history of eastern Pacific tropical cyclones.
Some clues are proposed for estimating the intensities of tropical cyclones.
Abstract
Western North Pacific tropical cyclone data were evaluated for the period 1970–79 to determine characteristics of recurving typhoons near and after recurvature. Case studies revealed a good relationship between typhoon movement speed after recurvature and the upper tropospheric winds at and before recurvature observed along the future typhoon track. This relationship was then determined for a sample of 71 recurving typhoons from 1962 through 1978 and compared with operational forecasts for a subsample of 29 typhoons in 1972–78. The derived simple aid could have reduced the average forecast speed errors by more than 50% in the subsample.
Abstract
Western North Pacific tropical cyclone data were evaluated for the period 1970–79 to determine characteristics of recurving typhoons near and after recurvature. Case studies revealed a good relationship between typhoon movement speed after recurvature and the upper tropospheric winds at and before recurvature observed along the future typhoon track. This relationship was then determined for a sample of 71 recurving typhoons from 1962 through 1978 and compared with operational forecasts for a subsample of 29 typhoons in 1972–78. The derived simple aid could have reduced the average forecast speed errors by more than 50% in the subsample.
Abstract
Climatological shears between ship winds and satellite-observed, low-level cloud motions are used to derive monthly mean surface winds from satellite observations of low-level cloud drift. The derived surface winds compare well with observed surface winds from ships, moored buoys and the Seasat altimeter.
Abstract
Climatological shears between ship winds and satellite-observed, low-level cloud motions are used to derive monthly mean surface winds from satellite observations of low-level cloud drift. The derived surface winds compare well with observed surface winds from ships, moored buoys and the Seasat altimeter.
Time-lapse films of the earth from high-flying ballistic missiles have provided the meteorologist with the first synoptic detailed coverage of cloud patterns over large areas. Analysis of the film obtained on 24 August 1959 shows the cloud patterns over an area corresponding to one-twentieth of the earth's total surface.
Comparison of the rectified cloud positions with, the high- and low-level synoptic charts shows large-scale cloud patterns directly associated with high-level vortices and troughs as well as patterns associated with a quasi-stationary front and the intertropical convergence zone. Details suggesting low-level vortices, frontal waves, and a squall line appear, but they cannot be verified due to sparse surface observations. Other details, such as the effects of large and small islands, coastlines and rivers upon the pattern of vertical motion are indicated by the clouds.
Time-lapse films of the earth from high-flying ballistic missiles have provided the meteorologist with the first synoptic detailed coverage of cloud patterns over large areas. Analysis of the film obtained on 24 August 1959 shows the cloud patterns over an area corresponding to one-twentieth of the earth's total surface.
Comparison of the rectified cloud positions with, the high- and low-level synoptic charts shows large-scale cloud patterns directly associated with high-level vortices and troughs as well as patterns associated with a quasi-stationary front and the intertropical convergence zone. Details suggesting low-level vortices, frontal waves, and a squall line appear, but they cannot be verified due to sparse surface observations. Other details, such as the effects of large and small islands, coastlines and rivers upon the pattern of vertical motion are indicated by the clouds.
Abstract
Oceanwide direct measurement of the surface wind stress is impracticable; instead, the wind stress must be parameterized in terms of individual shipboard wind reports. The number of ship observations, however, are insufficient over the tropical oceans for an adequate analysis of the wind stress. A method is developed to take advantage of the monthly mean wind field which can be determined by meshing several sources of data with the ship observations. It is shown that a single empirical correction factor can be used to estimate the surface pseudostress from monthly mean winds for all months throughout the oceanic tropics.
Abstract
Oceanwide direct measurement of the surface wind stress is impracticable; instead, the wind stress must be parameterized in terms of individual shipboard wind reports. The number of ship observations, however, are insufficient over the tropical oceans for an adequate analysis of the wind stress. A method is developed to take advantage of the monthly mean wind field which can be determined by meshing several sources of data with the ship observations. It is shown that a single empirical correction factor can be used to estimate the surface pseudostress from monthly mean winds for all months throughout the oceanic tropics.
Abstract
Hourly values of the concentration of atmospheric carbon dioxide at Mauna Loa Observatory (MLO) formed the basis for an investigation of concentration fluctuations on daily to monthly time scales. In agreement with earlier studies we found no evidence linking the fluctuations with large-scale variations in the atmospheric circulation. Neither did local cane fires produce any measurable effects. A diurnal variation that comprises daytime forest depletion and nighttime enhancement by outgassing from the summit caldera need not affect overall data quality. We conclude that MLO is an excellent site for monitoring atmospheric carbon dioxide.
Abstract
Hourly values of the concentration of atmospheric carbon dioxide at Mauna Loa Observatory (MLO) formed the basis for an investigation of concentration fluctuations on daily to monthly time scales. In agreement with earlier studies we found no evidence linking the fluctuations with large-scale variations in the atmospheric circulation. Neither did local cane fires produce any measurable effects. A diurnal variation that comprises daytime forest depletion and nighttime enhancement by outgassing from the summit caldera need not affect overall data quality. We conclude that MLO is an excellent site for monitoring atmospheric carbon dioxide.
