Climatology of Upper Stratospheric Lower Mesospheric Disturbances in the Polar Winter

Details Climatology of Upper Stratospheric Lower Mesospheric Disturbances in the Polar Winter Climatology of Upper Stratospheric Lower Mesospheric Disturbances in the Polar Winter

Dec 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufmsa31b1727g&link_type=abstract

American Geophysical Union, Fall Meeting 2010, abstract #SA31B-1727

Physics

[3309] Atmospheric Processes / Climatology, [3334] Atmospheric Processes / Middle Atmosphere Dynamics, [3349] Atmospheric Processes / Polar Meteorology, [3364] Atmospheric Processes / Synoptic-Scale Meteorology

Scientific paper

The polar stratosphere and mesosphere are dynamically altered throughout the winter months by planetary wave activity and its interaction with the mean flow. An extreme interaction leads to polar vortex breakdown and a complete alteration in temperature from the lower stratosphere through the upper atmosphere. However, there are more regular disturbances where the dynamical interactions can alter the upper stratosphere and mesosphere without modification to the lower stratosphere; here these disturbances will be designated as Upper Stratospheric Lower Mesospheric (USLM) disturbances. Several USLM case studies have been presented in the literature, focusing particularly on thermal features and dynamics. These studies established characteristics in USLM disturbances allowing these disturbances to be identified over the 20-year record of MetO assimilated stratospheric data and to develop a climatology of USLM disturbances. The typical thermal structure of USLM disturbances is dipolar in nature at 2.0 hPa with strong thermal gradients across the polar vortex. From the assimilated data, we find that the geographic preference of the anomalously warm temperatures at 2.0 hPa are located on the East side of the polar low, while there is a related cool pool of air located on the West side. These geographic preferences and observed amplification in temperature help to support the proposed dynamical process of baroclinic instability. Indirect circulations are induced, and to preserve continuity, cells of ageostrophic and vertical motions occur well into the mesosphere, and potentially into the thermosphere. We find that the average frequency of USLM events is 1.63 events per season in the Northern Hemisphere. In addition, the assimilated data indicates that all Sudden Stratospheric Warmings (SSWs) are preceded by USLM events; SSW events occur with a frequency of 0.84 events per season (Northern Hemisphere). USLM disturbances persist from three to ten days and tend to precede SSW events by several days, although there may be multiple USLM disturbances prior to an SSW event occurring. Lastly we exhibit how USLM disturbances differ between the Northern and Southern poles, including differences in frequency and intensity. An open question is whether these frequent USLM polar winter disturbances impact the thermosphere and ionosphere.

Affiliated with

Also associated with

No associations

Rating

Climatology of Upper Stratospheric Lower Mesospheric Disturbances in the Polar Winter does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Climatology of Upper Stratospheric Lower Mesospheric Disturbances in the Polar Winter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Climatology of Upper Stratospheric Lower Mesospheric Disturbances in the Polar Winter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1504373