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A 4D feature tracking algorithm: a multidimensional view of cyclone systems
An objective 4D algorithm developed to track extratropical relative vorticity anomaly 3D structure over time
is introduced and validated. The STACKER algorithm, structured with the TRACKER single level tracking
algorithm as source of the single-level raw tracks, objectively combines tracks from various levels to
determine the 3D structure of the cyclone (or anticyclone) events throughout their life cycle. Stacker works
progressively, beginning with two initial levels and then adding additional levels to the stack in a bottom-up
and/or top-down approach. This allows an iterative stacking approach, adding one level at a time, resulting in
an optimized 4D determination of relative vorticity anomaly events.
A two-stage validation process is carried out with the ERA-Interim dataset for the 2015 austral winter. First
the overall tracking capability during an austral winter, taking into account a set of climate indicators and
their impacts on Southern Hemisphere circulation, was compared to previous climatologies, in order to
verify the density and distribution of the cyclone events detected by STACKER. Results show the cyclone
density distribution is in very good agreement with previous climatologies, after taking into account potential
differences due to climate variability and different tracking methodologies. The second stage focuses on
three different long-lived events over the Southern Hemisphere, during the winter of 2015 spanning seven
different pressure levels. Both GOES satellite imagery, infrared and water vapour channels, and ERAInterim
cloud cover products are used in order to validate the tracks obtained as well as the algorithm’s
capability and reliability. The observed 3D cyclone structures and their time evolution are consistent with
current understanding of cyclone system development. Thus, the two-stage validation confirms that the
algorithm is suitable to track multilevel events, and can follow and analyse their 3-D life cycle and develop
full 3D climatologies and climate variability studie
REGIONAL CLIMATE MODELING STUDY FOR THE CARPATHIAN REGION USING REGCM4 EXPERIMENTS
The newest model version of RegCM is adapted with the ultimate aim of providing climate projection for the Carpathian region with 10 km horizontal resolution. For this purpose, first, coarse resolution reanalysis data and global climate model outputs are used to drive 50 km resolution model experiments, from which the outputs are used to provide necessary boundary conditions for the fine scale model runs. Besides the historical runs (for the period 1981-2010), RCP4.5 scenario is also analyzed in this paper for the 21st century. These experiments are essential since they form the basis of national climate and adaptation strategies by providing detailed regional scale climatic projections and enabling specific impact studies for various sectors