Classification of Synoptic Circulation Patterns for Fog in the Urumqi Airport

According to the Glossary of Meteorology from the American Meteorological Society, fog is a collection of water droplets suspended in the atmosphere in the vicinity of the earth's surface that affects visibility. Specifically, fog reduces visibility below 1 kilometer (or 0.62 miles). It is the biggest cause of aviation accidents, severe fog can lead to poor visibility, affecting the aircraft’s normal taking-off and landing, increasing the aircraft’s ice, bumps, etc., in the clouds. A long-time continuing fog causes airport closures, flights canceled, resulting in a large number of passengers stranded, affecting the flight safety and normal operating order.

In this study, the authors aimed to investigate the Classification of Synoptic Circulation Patterns for Fog in the Urumqi Airport in Xinjiang, China. By using relevant climate statistical method, the hourly ground observation data and four times per day and NCEP/NCAR reanalysis data (1° × 1°) from 1985 to 2014 were analyzed. The results showed that: 1) The occurrence of fog significantly increased during 1985 and 2014; There were two stages of the airport fog in the 30 years: less-fog period (1985-2002) and more-fog period (2002-2014), the fog focused occurred in November to March of the following year, most in December and least in March; 2) Based on Lamb-Jenkinson method, the dominant types of fog in Urumqi Airport were C, E, SE, W, A types (Among them, A, C, E, W, SE are the circulation types. C is Cyclone, A is Anti-cyclone, E is East, W is West, SE is Southeast), and the international distribution of each type was also different; 3) The dominant types of persistence fog were A, C, E, SE types, A type appeared in the afternoon to the nighttime, in the morning less frequent, on the other hand, C type was just the opposite; 4) Atmospheric circulation characteristics for persistence fog profile can be divided into four series: A, C, E, SE series, and climatic characteristics in different series were different.

Article by Nan Wang, et al, from Urumqi, China.

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Image by Henrique Junior, from Flickr-cc.