The impact of tropical convection and cirrus on upper tropospheric humidity: A Lagrangian analysis of satellite measurements

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Abstract

Geostationary satellite observations are used in ion with an objective pattern-tracking algorithm to describe the Lagrangian evolution of convection, clouds and water vapor in the tropical upper troposphere. This analysis reveals that larger convective events within a Lagrangian air mass are associated with larger and longer-lived cirrus anvil shields. Convective systems which generate larger cirrus shields are, in turn, associated with higher downstream humidity levels following the anvil's dissipation. In the absence of cirrus, the clear-sky upper troposphere is shown to dry at a rate consistent with radiatively-driven subsidence. The presence of cirrus anvils following a convective event is shown to reduce the rate of drying and for large anvils can even change its sign. Analysis of the Lagrangian tendencies Suggests that this moistening effect is not attributable to the evaporation of cirrus condensate, but instead results from the same dynamical mechanisms responsible for the formation and maintenance of the cirrus anvil.

Original languageEnglish (US)
JournalGeophysical Research Letters
Volume31
Issue number20
DOIs
StatePublished - Oct 28 2004
Externally publishedYes

Fingerprint

Lagrangian analysis
cirrus
anvils
humidity
convection
troposphere
shield
vapors
synchronous satellites
satellite observation
air masses
subsidence
geostationary satellite
convective system
drying
maintenance
condensates
water vapor
sky
clear sky

Keywords

  • 3309 Meteorology and atmospheric dynamics: Climatology (1620)
  • 3314 Meteorology and atmospheric dynamics: Convective processes
  • 3360 Meteorology and atmospheric dynamics: Remote sensing

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

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title = "The impact of tropical convection and cirrus on upper tropospheric humidity: A Lagrangian analysis of satellite measurements",
abstract = "Geostationary satellite observations are used in ion with an objective pattern-tracking algorithm to describe the Lagrangian evolution of convection, clouds and water vapor in the tropical upper troposphere. This analysis reveals that larger convective events within a Lagrangian air mass are associated with larger and longer-lived cirrus anvil shields. Convective systems which generate larger cirrus shields are, in turn, associated with higher downstream humidity levels following the anvil's dissipation. In the absence of cirrus, the clear-sky upper troposphere is shown to dry at a rate consistent with radiatively-driven subsidence. The presence of cirrus anvils following a convective event is shown to reduce the rate of drying and for large anvils can even change its sign. Analysis of the Lagrangian tendencies Suggests that this moistening effect is not attributable to the evaporation of cirrus condensate, but instead results from the same dynamical mechanisms responsible for the formation and maintenance of the cirrus anvil.",
keywords = "3309 Meteorology and atmospheric dynamics: Climatology (1620), 3314 Meteorology and atmospheric dynamics: Convective processes, 3360 Meteorology and atmospheric dynamics: Remote sensing",
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T2 - A Lagrangian analysis of satellite measurements

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PY - 2004/10/28

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N2 - Geostationary satellite observations are used in ion with an objective pattern-tracking algorithm to describe the Lagrangian evolution of convection, clouds and water vapor in the tropical upper troposphere. This analysis reveals that larger convective events within a Lagrangian air mass are associated with larger and longer-lived cirrus anvil shields. Convective systems which generate larger cirrus shields are, in turn, associated with higher downstream humidity levels following the anvil's dissipation. In the absence of cirrus, the clear-sky upper troposphere is shown to dry at a rate consistent with radiatively-driven subsidence. The presence of cirrus anvils following a convective event is shown to reduce the rate of drying and for large anvils can even change its sign. Analysis of the Lagrangian tendencies Suggests that this moistening effect is not attributable to the evaporation of cirrus condensate, but instead results from the same dynamical mechanisms responsible for the formation and maintenance of the cirrus anvil.

AB - Geostationary satellite observations are used in ion with an objective pattern-tracking algorithm to describe the Lagrangian evolution of convection, clouds and water vapor in the tropical upper troposphere. This analysis reveals that larger convective events within a Lagrangian air mass are associated with larger and longer-lived cirrus anvil shields. Convective systems which generate larger cirrus shields are, in turn, associated with higher downstream humidity levels following the anvil's dissipation. In the absence of cirrus, the clear-sky upper troposphere is shown to dry at a rate consistent with radiatively-driven subsidence. The presence of cirrus anvils following a convective event is shown to reduce the rate of drying and for large anvils can even change its sign. Analysis of the Lagrangian tendencies Suggests that this moistening effect is not attributable to the evaporation of cirrus condensate, but instead results from the same dynamical mechanisms responsible for the formation and maintenance of the cirrus anvil.

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KW - 3360 Meteorology and atmospheric dynamics: Remote sensing

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