Multiple tropopauses are structures that regularly recur in the midlatitudes. Recent studies have relied on the notion of the excursion of tropical air from the upper troposphere into higher latitudes, thereby overlaying the tropopause of the midlatitudes. We herein analyse the origin and characteristics of the air at the Boulder radiosonde station, between the first and second tropopauses combining an analysis of radiosonde data with a Lagrangian approach based on the FlexPart model and ERA-40 analysis data. Our results show that the air between both tropopauses has its origin in midlatitudes.
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http://dx.doi.org/10.1100/2012/191028 | DOI Listing |
Atmos Chem Phys
September 2017
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
The representation of upper tropospheric/lower stratospheric (UTLS) jet and tropopause characteristics is compared in five modern high-resolution reanalyses for 1980 through 2014. Climatologies of upper tropospheric jet, subvortex jet (the lowermost part of the stratospheric vortex), and multiple tropopause frequency distributions in MERRA (Modern Era Retrospective Analysis for Research and Applications), ERA-I (the ECMWF interim reanalysis), JRA-55 (the Japanese 55-year Reanalysis), and CFSR (the Climate Forecast System Reanalysis) are compared with those in MERRA-2. Differences between alternate products from individual reanalysis systems are assessed; in particular, a comparison of CFSR data on model and pressure levels highlights the importance of vertical grid spacing.
View Article and Find Full Text PDFScientificWorldJournal
October 2012
Smith School of Enterprise and Environment, University of Oxford, Oxford OX1 2BQ, UK.
Multiple tropopauses are structures that regularly recur in the midlatitudes. Recent studies have relied on the notion of the excursion of tropical air from the upper troposphere into higher latitudes, thereby overlaying the tropopause of the midlatitudes. We herein analyse the origin and characteristics of the air at the Boulder radiosonde station, between the first and second tropopauses combining an analysis of radiosonde data with a Lagrangian approach based on the FlexPart model and ERA-40 analysis data.
View Article and Find Full Text PDFPolarization lidar data are used to demonstrate that clouds composed of hexagonal ice crystals can generate multiple-ringed colored coronas. Although relatively uncommon in our mid-latitude cirrus sample (derived from Project FIRE extended time observations), the coronas are associated with unusual cloud conditions that appear to be effective in generating the displays. Invariably, the cirrus cloud tops are located at or slightly above elevated tropopauses (12.
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