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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2025-08-21 0:30 |
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Conference: Bucharest University Faculty of Physics 2025 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Research on the atmospheric phenomenon of icing in the Romanian airspace, in freezing rain conditions
Authors:
Laura NECUTA (1), Mihaela CAIAN (1, 2)
*
Affiliation:
1) University of Bucharest, Faculty of Physics, Romania
2) National Administration of Meteorology, Romania
E-mail
necutalaura@yahoo.com
Keywords:
freezing precipitation, FZRA, AIREP, forecast models, atmospheric survey
Abstract:
Aircraft icing is caused by freezing precipitation and can occur on the ground, during take-off, landing, or in flight at the base of a cloud. Frozen precipitation (FZRA, FZDZ, FZFG) represents severe phenomena that can impact air traffic. Their occurrence in Romania was analyzed using climatological observations from the period 2005–2025, based on METAR/TAF messages during the winter and early spring months (December, January, February, March). The winter months are the most critical in terms of flight safety, especially January and February, when freezing phenomena occur frequently. February shows occasional but intense peaks, while March events are rarer.
This study analyzes a freezing rain event that impacted aviation in southern and southeastern Romania on three consecutive days: December 27, 28, and 29, 2021, and another freezing rain event that disrupted air traffic for two hours near Ghimbav-Brașov Airport on December 22, 2023.
In both cases, thermal inversions were identified, with warmer air layers between 850 hPa and 950 hPa overlying cold air with negative temperatures near the ground. Pilot reports (AIREPs) recorded by ROMATSA in December 2021 indicated moderate and severe icing at altitudes between 3000 m and 4500 m, and also at low altitudes (600 m – 700 m), during takeoff and landing. At Ghimbav, the METAR/TAF warning for ground-level FZRA made takeoff and landing difficult.
In the first case, good correlation was found between data from the Wyoming soundings, INMH Băneasa synoptic maps, METAR messages at Otopeni Airport, and pilot reports on icing severity according to the FZRA profile. In the second case, forecast model validation using METAR and ERA5 reanalysis confirmed the presence of a thermal inversion specific to FZRA.
Furthermore, event predictability was analyzed using model simulations from ALARO, ECMWF, ICON, and ARPEGE, compared with observed data. The ALARO model best captured the cold layer near the ground at 950 hPa, while METAR data confirmed surface-level phenomena, supporting model validation.
In the Romanian airspace, the presence of severe frost phenomena is most often confirmed during winter, involving moderate to severe icing conditions in freezing precipitation, which endanger air traffic. Therefore, predicting such events is essential to ensure flight safety through measures such as de-icing and avoidance of low-level layers.
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