07 Sept 201515th EMS / 12th ECAM

07-11 Sept 2015, Sofia, BulgariaPage 1

A persistent fog in Sofia in January 2014: Analysis by equivalent potential temperature

Anastasiya Stoychevaa, Stilian Evtimovb

aNational Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences, 66 Tsarigradsko shose Blvd., 1784 Sofia

bFaculty of Physics, Sofia University ”St. Kliment Ohridski”, 5 James Bourchier Blvd., 1164 Sofia

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Data:

• SYNOP 00, 03, 06, 09, 12, 15, 18, 21 UTC for Sofia:� temperature; � relative humidity; � pressure;� wind;� horizontal visibility; � fog phase and type;

• SOUNDINGS 12 UTC:� altitude;� pressure;� temperature; � relative humidity;

• Synoptic charts.

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Methodology:

• statistical modelling (by the multiple linear regression with structural changes (Bai and Perron, 1998; 2003)) of time series of:�equivalent potential temperature

�pressure

• synoptic analysis:�SLP analysis

�G 850, G700, G500

Breakpoint

Slope 1 ≠ Slope 2 and/or Intercept 1≠ Intercept 2

Regression line 1 Regression line 2

Confidence interval

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Results:

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Conclusions:

equivalent potential temperature

pressure

synoptic analysis

+

+

an

EFFECTIVE

TOOL

the analysis of the prolonged fog life cycle

in Sofia during the period 03-10 Jan 2014

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Thank you for the attention!