Maximum winter temperature over Romania in connection to atmospheric circulation

This study investigates the dominant large-scale air circulations that control the winter maximum temperature distributions over Romania. We focus on the winter frequency of circulation types determined from the Grosswetter-Types (GWT) classification methods. We applied an unmixing method based on n...

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Bibliographic Details
Published in:Theoretical and applied climatology 2024-05, Vol.155 (5), p.3861-3870
Main Authors: Necula, Cristian, Stefan, Sabina, Birsan, Marius-Victor, Barbu, Nicu, Nita, Ion-Andrei
Format: Article
Language:English
Subjects:
Absolute maximum
Air temperature
Aquatic Pollution
Atmospheric circulation
Atmospheric Protection/Air Quality Control/Air Pollution
Atmospheric Sciences
Circulation
Circulation types
Climatology
Earth and Environmental Science
Earth Sciences
Extreme value distribution
Extreme values
Maximum temperatures
Orography
Temperature
Temperature distribution
Temperature extremes
Waste Water Technology
Water Management
Water Pollution Control
Weather stations
Winter
Winter temperatures
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Summary:This study investigates the dominant large-scale air circulations that control the winter maximum temperature distributions over Romania. We focus on the winter frequency of circulation types determined from the Grosswetter-Types (GWT) classification methods. We applied an unmixing method based on non-negative matrix factorization (NMF) to cumulative distributions of monthly absolute maximum winter temperatures recorded at 163 Romanian weather stations between 1961 and 2013. This method can determine both the form of the end-members and their contributions using only the input maximum temperature distributions, giving access to extreme temperature distributions and providing further insight about the link between thermal extremes and large-scale atmospheric circulation. For comparison, we also fitted the generalized extreme value distribution (GEV) to the time series. Our findings show that the particular shape of the Romanian Carpathians divides the territory into two distinct climatological areas (the intra-Carpathian and the extra-Carpathian). The NMF method proved that all maximum winter temperature distributions from 163 Romanian meteorological stations could be entirely explained by only four end-members (EMs). Both the NMF and the GEV distributions can be explained by the interplay between circulations and orography. Hence, different circulation types combined with different orography could produce similar extreme temperature distributions.
ISSN:0177-798X
1434-4483
DOI:10.1007/s00704-024-04854-5