GOES layer average specific humidity is a useful tool for identifying dry streamers in the upper troposphere that are dynamically associated with tropopause folding.
Key Features
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GLASH imagery shows strong moisture gradients. |
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Strong water vapor gradients correspond with sharp gradients in Isentropic Potential Vorticity (IPV) a dynamical tracer that is used to identify air with stratospheric signatures but is located in the troposphere. |
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Aircraft flights across these gradients clearly indicate folding, evident in thermodynamic fields (e.g., potential temperature) and chemical fields (ozone and water vapor); high in ozone as observed with aircraft DIAL lidar imaging. |
Evidence
- Observation 1
- There is a close relationship between GLASH brightness temperature gradients and and total ozone gradients (based on the GOES sounder Total Ozone product) that suggests both types of imagery are detecting the tropopause break.
- Observation 2
- Transects constructed from aircraft lidar and in situ observations of ozone illustrate the existence of tropopause folding along the AWV gradient. Ten out of ten available transects during the February to May study period of the 2000 Tropospheric Ozone about the Spring Equinox campaign (TOPSE) show tropopause folding where indicated by the satellite imagery.
- Observation 3
- This is strong evidence that folding is ubiquitous across the polar/stratospheric air mass boundary during the study period, and that the associated intrusions of stratospheric air into the troposphere can be located continuously using AWV imagery.
