dc.contributor.author
Dolores Tesillos, Edgar
dc.date.accessioned
2022-11-09T13:19:50Z
dc.date.available
2022-11-09T13:19:50Z
dc.identifier.uri
https://refubium.fu-berlin.de/handle/fub188/36690
dc.identifier.uri
http://dx.doi.org/10.17169/refubium-36403
dc.description.abstract
Extratropical cyclones are a major control of weather and climate in the midlatitudes.
Climate model simulations have been used to analyze the influence of
global warming on extratropical cyclone dynamics. This study addresses the still
open questions of whether cyclones will become more intense, what dynamic processes
are responsible for these changes, and how this could impact the North Atlantic
region.
This study investigates extratropical cyclone dynamics over the two periods
1990-2000 and 2091-2100 using the Community Earth System Model Large Ensemble
(CESM-LE) dataset. We analyze the storm response in the extended winter and
summer seasons in the North Atlantic (NA) region. A Lagrangian cyclone detection
is used to analyze the occurrence and spatial distribution of storm tracks. The evolution
of cyclonic structures in a warming climate is studied with cyclone-centered
composites. Likewise, a potential vorticity (PV) perspective is adopted to study the
changes in the cyclone wind field near the surface. A trajectory analysis illuminates
the contribution of diabatic processes to future changes of cyclone-associated PV
anomalies.
Firstly, through comparison with ERA-Interim reanalysis data, we find that the
CESM-LE captures the current spatial distribution of intense cyclones adequately.
Robust changes in cyclone occurrence and properties are found in the NA region
for the end of the century. For instance, cyclone frequency decrease in a warming
climate, whereas precipitation intensity increases. Projected intensity changes are
generally small.
Secondly, the structure of those cyclones whose intensities fall within the 90th
percentile is studied via a composite analysis. Winter storm tracks of these most
intense cyclones respond to climate warming with an eastward shift. This shift increases
the risk of strong winds and extreme precipitation in western Europe. In
winter, extratropical cyclones also exhibit structural changes that amplify precipitation
intensity downstream and low-level wind flow to the southeast of the cyclone
center.
In present-day climate, PV inversion reveals the relevance of upper-level PV
anomalies for contributing to the poleward wind flow to the east of the cyclone
center. The simulated future intensification of this poleward flow is related to a
strengthening of the low-level PV anomaly associated with amplified diabatic heating
in combination with a dipole change in the upper-level PV anomaly pattern.
Furthermore, a Lagrangian trajectory analysis is adopted to explicitly identify
changes in air mass advection that result in the PV anomalies at lower and upper
levels. At upper levels, the decreased PV anomaly to the south of the cyclone
center results from a combined effect of a decreased climatological PV in the NA
region and a shift in the origin of the air masses. Increased diabatic heating along
backward trajectories leads to an amplification of positive PV anomalies near the
cyclone center at both lower and upper levels.
Finally, a scaling method is used to analyze the dynamic and thermodynamic
contributions to cyclone-related precipitation changes on a storm-scale for the 10%
most intense cyclones. Thermodynamic contributions dominate the precipitation
increase over the coma-shaped main area of precipitation, while changes in the vertical
wind (dynamic) contribute to enhanced frontal precipitation and a weakening
of the precipitation to the west of the cyclone center.
In conclusion, diabatic processes, specifically enhanced latent heat release, will
primarily shape the anatomy of intense extratropical cyclones in the North Atlantic
region in a warming climate. Therefore, a better representation of the diabatic
process in climate simulations can help to constrain better the future dynamics of
intense cyclones and their social impacts.
en
dc.format.extent
VII, 104, xxiii Seiten
dc.rights.uri
http://www.fu-berlin.de/sites/refubium/rechtliches/Nutzungsbedingungen
dc.subject
Extratropical cyclones
en
dc.subject
Potential vorticity
en
dc.subject
Warming climate
en
dc.subject.ddc
500 Natural sciences and mathematics::550 Earth sciences::551 Geology, hydrology, meteorology
dc.title
Changes in Extratropical Cyclone Dynamics in the North Atlantic in a Warming Climate
dc.contributor.gender
male
dc.contributor.firstReferee
Pfahl, Stephan
dc.contributor.furtherReferee
Pinto, Joaquim
dc.date.accepted
2022-10-12
dc.identifier.urn
urn:nbn:de:kobv:188-refubium-36690-7
refubium.affiliation
Geowissenschaften
dcterms.accessRights.dnb
free
dcterms.accessRights.openaire
open access
dcterms.accessRights.proquest
accept