A Simulation and Diagnostic Study of Water Vapor Image Dry Bands

Muller, Bradley M.; Fuelberg, Henry E.

doi:10.1175/1520-0493(1990)118<0705:asadso>2.0.co;2

Cited by 18 publications

(7 citation statements)

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“…Midlatitude synoptic systems affect moisture transport and cloud distribution, and hence water vapor distribution (e.g., Muller and Fuelberg 1990;Price and Vaughan 1993). The evolution of storm systems is closely related to jet stream and baroclinic instability.…”

Section: B Variability Of Tropical Sst and Extratropical Circulationmentioning

confidence: 99%

Influences of ENSO SST Anomalies and Winter Storm Tracks on the Interannual Variability of Upper-Troposphere Water Vapor over the Northern Hemisphere Extratropics

Wang

2000

J. Climate

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This study examines the interannual variability of winter upper-troposphere water vapor over the Northern Hemisphere using the National Aeronautics and Space Administration Water Vapor Project, the International Satellite Cloud Climatology Project data, and the European Centre for Medium-Range Weather Forecasting reanalysis. The El Niño-Southern Oscillation related tropical sea surface temperature (SST) anomalies dominate the upper-troposphere water vapor anomalies south of the climatological jet. The anomalies of baroclinic instability in the storm track regions, which relate to the Pacific-North American and the North Atlantic oscillation patterns, dominate those north of the climatological jet. The upper-troposphere water vapor increases in the eastern tropical Pacific, the Gulf of Mexico, and some areas of the North Atlantic with warmer tropical SST. It decreases in the subtropical and extratropical northeastern Pacific. Deep convection and vertical moisture fluxes dominate these changes. To the north of the climatological jet, stronger upper-level cyclonic flow dries the upper troposphere when the baroclinicity of the storm tracks is enhanced. Both vertical and meridional moisture transport contribute to these water vapor anomalies in the midlatitudes. High clouds, as a possible source/sink of water vapor, respond to the tropical SST anomalies and extratropical circulation in a pattern similar to the uppertroposphere water vapor, and they consequently positively correlate to the latter. In the Tropics and extratropics where high clouds are relatively abundant, water vapor concentration increases with temperature. Thus, the increase of evaporation or sublimation of high clouds probably contributes to the observed moistening of the upper troposphere, in addition to enhanced vapor transport. Conversely, in the subtropics where high clouds appear infrequently, water vapor concentration decreases with temperature, suggesting that the downward advection of drier air associated with subsidence dominates the drying of the upper troposphere.

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Section: B Variability Of Tropical Sst and Extratropical Circulationmentioning

confidence: 99%

Influences of ENSO SST Anomalies and Winter Storm Tracks on the Interannual Variability of Upper-Troposphere Water Vapor over the Northern Hemisphere Extratropics

Wang

2000

J. Climate

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“…Thus, care should be taken in trying to relate fluid trapping to the location of the vorticity maximum, as sometimes happens when viewing water-vapor satellite imagery of a drier region commonly attributed to previously descended air associated with a short-wave trough. For an example of such a dry region associated with a short-wave trough, see Muller and Fuelberg (1990).…”

Section: A Evolution Of Parcel Pairsmentioning

confidence: 99%

Contraction Rate and Its Relationship to Frontogenesis, the Lyapunov Exponent, Fluid Trapping, and Airstream Boundaries

Cohen

Schultz

2005

Monthly Weather Review

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Although a kinematic framework for diagnosing frontogenesis exists in the form of the Petterssen frontogenesis function and its vector generalization, a similar framework for diagnosing airstream boundaries (e.g., drylines, lee troughs) has not been constructed. This paper presents such a framework, beginning with a kinematic expression for the rate of change of the separation vector between two adjacent air parcels. The maximum growth rate of the separation vector is called the instantaneous dilatation rate and its orientation is called the axis of dilatation. Similarly, a maximum decay rate is called the instantaneous contraction rate and its orientation is called the axis of contraction. These expressions are related to the vector frontogenesis function, in that the growth rate of the separation vector corresponds with the scalar frontogenesis function, and the rotation rate of the separation vector corresponds with the rotational component of the vector frontogenesis function.Because vorticity can rotate air-parcel pairs out of regions of deformation, the instantaneous dilatation and contraction rates and axes may not be appropriate diagnostics of airstream boundaries for fluid flows in general. Rather, the growth rate and orientation of an airstream boundary may correspond better to the so-called asymptotic contraction rate and the asymptotic axis of dilatation, respectively. Expressions for the asymptotic dilatation and contraction rates, as well as their orientations, the asymptotic dilatation and contraction axes, are derived. The asymptotic dilatation rate is related to the Lyapunov exponent for the flow. In addition, a fluid-trapping diagnostic is derived to distinguish among adjacent parcels being pulled apart, being pushed together, or trapped in an eddy. Finally, these diagnostics are applied to simple, idealized, steady-state flows and a nonsteady idealized vortex in nondivergent, diffluent flow to show their utility for determining the character of air-parcel trajectories and airstream boundaries.

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“…Ambient temperature variability does have an impact on T6.7 [Muller and Fuelberg, 1990] but this is often overlooked in the interpretation of channel 3 imagery.…”

Section: -8276/99/1998gl90022250500mentioning

confidence: 99%

Remotely sensed specific humidity: Development of a derived product from the GOES Imager channel 3

Moody

Wimmers

Devenport

1999

Geophysical Research Letters

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Abstract. The analytic expression relating GOES-E/W channel 3 water-vapor radiance to relative humidity is used along with upper-troposphere temperature observations to derive a high horizontal resolution brightness temperature product that correlates well with measured specific humidity. Moisture information in raw water-vapor images'is obscured by strong horizontal temperature gradients in the upper troposphere. This information is exposed in the derived product. Our results illustrate that the ability to remotely sense and resolve differences in water-vapor content increases with atmospheric dryness.

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A Simulation and Diagnostic Study of Water Vapor Image Dry Bands

Cited by 18 publications

References 0 publications

Influences of ENSO SST Anomalies and Winter Storm Tracks on the Interannual Variability of Upper-Troposphere Water Vapor over the Northern Hemisphere Extratropics

Influences of ENSO SST Anomalies and Winter Storm Tracks on the Interannual Variability of Upper-Troposphere Water Vapor over the Northern Hemisphere Extratropics

Contraction Rate and Its Relationship to Frontogenesis, the Lyapunov Exponent, Fluid Trapping, and Airstream Boundaries

Remotely sensed specific humidity: Development of a derived product from the GOES Imager channel 3

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