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ISSN 1026-2237 BULLETIN OF HIGHER EDUCATIONAL INSTITUTIONS. NORTH CAUCASUS REGION. NATURAL SCIENCE. 2023. No. 1
Original article
UDC 551.576.4(479.25)
doi: 10.18522/1026-2237-2023-1-129-136
STATISTICAL ANALYSIS OF CONVECTIVE PROCESSES OVER THE ABSHERON PENINSULA
Aygun A. Bashirova
National Aviation Academy of the Republic ofAzerbaijan, Baku, Republic of Azerbaijan aygun. agayeva@bk. ru
Abstract. This paper is focuses on to determine the air masses observed during convective processes in Baku and the Absheron Peninsula in 2011-2020. As well as to identify the frequency of air masses and atmospheric phenomena by seasons and years. The purpose of this study is to determine weather phenomena that is significantly influence the safety and the operational activity of air traffic, particularly, in the areas of the aerodrome and route.
The formation of thunderstorms is a particularly important meteorological event that has major relevance to aviation safety. Despite all the safety improvements, the weather is still today a major cause of aviation accidents and incidents. According to the International Civil Aviation Organization (ICAO) statistics, 15-20 % of plane crashes are caused by severe weather conditions. Hazards associated with convective weather include thunderstorms with severe turbulence, intense up- and downdrafts, lightning, hail, heavy precipitation, icing, wind shear, microbursts and strong low-level winds. As a source of the information regular observations of Heydar Aliyev International Airport, also soundings, satellite images, surface and upper air maps were used.
Key words: thunderstorm, Absheron Peninsula, air masses, Heydar Aliyev International Airport, convective processes, lightning, regular observations, sounding, satellite images
For citation: Bashirova A.A. Statistical Analysis of Convective Processes Over the Absheron Peninsula. Bulletin of Higher Educational Institutions. North Caucasus Region. Natural Science. 2023;(1):129-136.
This is an open access article distributed under the terms of Creative Commons Attribution 4.0 International License (CC-BY4.0).
Научная статья
СТАТИСТИЧЕСКИЙ АНАЛИЗ КОНВЕКТИВНЫХ ПРОЦЕССОВ НАД АПШЕРОНСКИМ ПОЛУОСТРОВОМ
Айгюн Агабала Баширова
Национальная академия авиации Азербайджана, Баку, Республика Азербайджан aygun. agayeva@bk. ги
© Bashirova A.A., 2023
ISSN 1026-2237 BULLETINOFHIGHEREDUCATIONAL INSTITUTIONS. NORTHCAUCASUSREGION. NATURAL SCIENCE. 2023. No. 1
Аннотация. Данная работа посвящена определению воздушных масс, наблюдаемых при конвективных процессах в Баку и на Апшеронском полуострове в 2011-2020 гг., а также выявлению повторяемости воздушных масс и атмосферных явлений по сезонам и годам. Целью данного исследования является определение явлений погоды, оказывающих существенное влияние на безопасность и эксплуатационную деятельность воздушного движения, в частности в районах аэродрома и маршрута.
Формирование гроз является важным метеорологическим явлением, которое имеет большое значение для безопасности полетов. Несмотря на все улучшения безопасности, погода по-прежнему остается основной причиной авиационных происшествий и инцидентов. По статистике Международной организации гражданской авиации, 15-20 % авиакатастроф происходят из-за сложных погодных условий. Опасности, связанные с конвективной погодой, включают грозы с сильной турбулентностью, интенсивные восходящие и нисходящие потоки воздуха, молнии, град, сильные осадки, обледенение, сдвиг ветра, микропорывы и сильный ветер на малых высотах. В качестве источника информации использовались регулярные наблюдения в Международном аэропорту им. Гейдара Алиева, а также зондирование, спутниковые снимки, карты поверхности и верхних слоев атмосферы.
Ключевые слова: гроза, Апшеронский полуостров, воздушные массы, Международный аэропорт им. Гейдара Алиева, конвективные процессы, молнии, регулярные наблюдения, зондирование, спутниковые снимки
Для цитирования: Bashirova A.A. Statistical Analysis of Convective Processes Over the Absheron Peninsula // Известия вузов. Северо-Кавказский регион. Естественные науки. 2023. № 1. С. 129-136.
Статья опубликована на условиях лицензии Creative Commons Attribution 4.0 International (CC-BY4.0).
Introduction
The study of thunderstorms is one of the most important areas of research in the field of atmospheric electricity, since lightning discharges pose the greatest threat to humans, technical devices, engineering structures, energy facilities, aviation and agriculture [1, 2].
The formation of thunderstorms is associated with the passage of cold fronts, convection processes and powerful updrafts in the atmosphere. The occurrence of thunderstorms is closely dependent on orography [3]. The formation of thunderstorms is also significantly affected by the orientation and height of the slopes, orographic protection. The relief of Azerbaijan is very diverse. Along with the high ridges rising above the snow line, there are extensive plains and lowlands, partially located below sea level. The distance from the Caspian Sea also affects thunderstorm activity. The lowest number of thunderstorm days (5-7 days) is observed offshore and coastal locations. Here, sea breezes affect the decrease in thunderstorm activity. Among the factors influencing the processes of atmospheric circulation over the Absheron Peninsula, the dominant role is played by the high mountain ranges of the Main Caucasus. The mountains of the Main Caucasus are a natural barrier that prevents the direct impact of cold air masses from the northwest. Air masses reaching the Absheron Peninsula meet with small hills in the northwestern and western parts. These small obstacles cause a slight deceleration of the air masses and thus change the thermodynamics of local processes. As a result, there is a convergence of air masses over Absheron, which provides additional energy reserves to the total flow. As a result, the air moves southward and causes Strong (22-27 knots) to Gale (34-40 knots) force N'ly winds over Absheron Peninsula. The plains in the south-west of Absheron also affect its weather. In summer, because of overheating during the day, a thermal minimum (a zone of low pressure) forms over the plain. It usually moves eastward from the southern part of the peninsula and forms short-term northerly winds in the lower part of the air over Absheron [4-7].
The proximity of the sea has a great influence on the atmospheric circulation and transformation of air masses over Absheron. In summer, the sea softens the warm air coming from the plains of Central Asia and the Caspian Sea. In winter, it increases the low temperature of cold air masses from the north. This increases cyclonic activity over the Caucasus and the Caspian Sea. In the cold season, the sea surface is warmer than the air, so the sea warms the air a little. As the cold air masses move from north to south, they warm up slightly as they cover long distances on the water [8].
Methods
As a result of the research, it was found that convective processes occurred when the following air masses entered the territory of the republic: Azores High; Arctic Maritime air masses; Continental Arctic air masses; Continental air of mid-latitudes; Southern cyclones and Central Asian anticyclone.
Continental Arctic air masses enter the Caspian Sea and Azerbaijan from northwestern Siberia, the Kara and Barents seas. Continental Arctic air masses, retaining some of their original features, rarely enter the Caspian Sea and Azerbaijan, especially the Absheron Peninsula. They usually undergo a strong transformation into cold continental air of mid-latitudes. In some cases, Continental Arctic air masses reaching the Absheron Peninsula in winter cause a sudden deterioration of the weather [9, 10].
Arctic Maritime air masses entering the Caspian Sea and the Caucasus from Spitsbergen and Greenland move southward, turning them into cold continental air of mid-latitudes. In the warm season, Arctic Maritime air masses usually enter the territory of Azerbaijan in a modified form. This condition is most pronounced during the summer months. At the same time, lightning, thunder and showers are observed over Absheron.
The climate of the Absheron Peninsula highly depends on the influence of the Azores High. Also known as the Azores anticyclone is a semi-permanent anticyclonic region with relatively consistent high pressure and subsiding air over the Atlantic Ocean. This phenomenon is especially common in the warm half of the year. Depending on the season, the directions of the maximum species of the Azores change: in winter they move to the north, and in summer to the south.
The first subtype of the anticyclone - Azores High center or its swirl moves over the northern part of the Atlantic Ocean through Eastern Great Britain towards Central Europe, Ukraine, then takes northern trajectory starting from North Caucasus to the Caspian Sea and Central Asia. These air masses got cool before reaching Absheron peninsula. Sometimes Azores High gets intensified due to moving Arctic air while following high trajectory. In the situation like that, very cold air masses move over Absheron Peninsula. When the region shows exposure to Azores High, the northern area of the Caspian Sea has North East convergence zone, North West convergence zone is observed in the central parts of the Sea with North convergence zone recorded in the South; in contrast, the South Caspian region hosts divergence zone.
The second subtype of the anticyclone - Azores High center or the swirl follows the south trajectory of move covering the Bay of Biscay, southern European areas, the South of Ukraine, the Northern Caucasus, the Caspian Sea and Central Asia. Exposure of our territory to Azores High is frequently recorded in warm season.
Continental air of mid-latitudes is divided into two subtypes. In the first half, air masses come to the Absheron Peninsula from Western Siberia and Kazakhstan, and in the second half - from the central and southern parts of Eastern Europe. The first subspecies is observed in the cold half of the year, when an anticyclone develops over Western Siberia and Kazakhstan.
The passage of the Southern cyclones, both individually and in series, is accompanied by the inflow of cold air masses from the northern regions into the Caspian Sea, including Absheron. This causes long-term changeable weather over Absheron Peninsula.
The influx of continental air masses from Central Asia to the Absheron Peninsula occurs under conditions of a strong anticyclone and strong cyclonic activity in the eastern regions of the Mediterranean and Black Seas. As the cyclone moves northeast, it interacts with the Central Asian anticyclone, causing the air masses of Central Asia to spread to the Caspian Sea and Absheron [5, 9].
Results and Discussion
Along with the analysis of the physical and synoptic conditions of the formation of cumulonimbus clouds during the meteorological support of civil aviation flights, the statistical study of the probability of their recurrence is also very important from a practical point of view. Thus, the factors that have the greatest impact on meteorological phenomena during aviation flights are associated with convective processes occurring in the atmosphere.
The presented above a bar chart illustrates the frequency of air masses entering to Baku and the Absheron Peninsula in 2011 -2020 (Fig. 1). As seen from the bar chart convective processes in Baku and on the Absheron Peninsula occurred mainly as a result of the entering of air masses from Azores islands, Arctic Maritime and Continental Arctic masses into our territory. Convective processes were minimal during Continental air of mid-latitudes, Central Asian anticyclone and Southern cyclones.
ISSN 1026-2237 BULLETIN OF HIGHER EDUCATIONAL INSTITUTIONS. NORTH CAUCASUS REGION. NATURAL SCIENCE. 2023. No. 1
Fig. 1. Frequency of air masses over Absheron Peninsula for 2011-2020 years. a - Azores High; b - Arctic Maritime air masses; c - Continental Arctic air masses; d - Continental air of mid-latitudes; e - Southern cyclones; f - Central Asian anticyclone / Рис. 1. Повторяемость воздушных масс над Апшеронским полуостровом в 2011-2020 гг. а - воздушные массы с Азорских островов; б - арктические морские воздушные массы; в - континентальные арктические воздушные массы; г - континентальный воздух средних широт; д - южные циклоны; е - среднеазиатский антициклон.
Cumulonimbus clouds are born through convection, often growing from small cumulus clouds over a hot surface. They can also form along cold fronts because of forced convection, where milder air is forced to rise over the incoming cold air. Given below bar chart and graph (Fig. 2) represents the frequency of occurrence of cumulonimbus clouds, monthly and yearly, for a specified period of time. As shown below bar chart cumulonimbus clouds were observed almost for the whole year. According to the graph, the sharp rise has been recorded in 2016. As a result of the study, it was found that during the study period, 2016 was the year of the most active convective processes for Baku and the Absheron Peninsula. The strong lightning process and rain showers that took place on 28.09.16 and 17.10.16 on the Absheron Peninsula are also explained by the inflow of Arctic Maritime air masses [10-13].
Fig. 2. Frequency of Cb clouds on the territory of Heydar Aliyev International Airport / Рис. 2. Повторяемость кучево-дождевых облаков на территории Международного аэропорта им. Гейдара Алиева
The presented below bar chart and graph (Fig. 3) shows the frequency of rain showers, monthly and yearly. The maximum amount of rain showers was observed in April and November with peak in October and the minimum was in July.
Fig. 3. Frequency of rain showers on the territory of Heydar Aliyev International Airport / Рис. 3. Повторяемость ливневого дождя на территории Международного аэропорта им. Гейдара Алиева
The bar chart and graph (Fig. 4) have been preferred to illustrate frequency of thundery shower monthly and yearly. The lowest frequency of thundery shower was recorded in winter. The maximum frequency of thundery shower was observed in September.
Fig. 4. Frequency of thundery showers on the territory of Heydar Aliyev International Airport / Рис. 4. Повторяемость грозовых ливней на территории Международного аэропорта им. Гейдара Алиева
As we know for the development of thunderstorm, we need a large depth of convection with a large amount of moisture. The temperature of the top of the cloud should be colder than -20 °C. The simple bar chart and graph (Fig. 5) represents average monthly and yearly thunderstorm from 2011 to 2020. The maximum frequency of thunderstorm was observed in May and June (4.7 and 5.0 respectively). During the winter period, thunderstorm was not observed.
Fig. 5. Frequency of thunderstorm (without shower) on the territory of Heydar Aliyev International Airport / Рис. 5. Повторяемость гроз (без ливня) на территории Международного аэропорта им. Гейдара Алиева
Sleet showers when surface air temperatures are below 0 °C and cumulonimbus clouds are observed. Sleet has no internationally agreed definition but is reported in meteorological observations as a combination or mix of rain and snow. Sleet may occur when a warm layer of air lies above a below-freezing layer of air at the Earth's surface.
During this period for Baku and Absheron Peninsula the maximum frequency of sleet was observed in November and January (1.0 and 3.4 respectively). The peak of snow shower was in December and February (7.9 and 9.3 respectively) (Fig. 6.).
Fig. 6. Frequency of sleet shower (a) and snow shower (b) on the territory of Heydar Aliyev International Airport / Рис. 6. Повторяемость ливня с мокрым снегом (а) и ливневого снега (б) на территории Международного аэропорта им. Гейдара Алиева
It should be noted that such a statistical analysis of hazardous atmospheric phenomena leads to an increase in operational weather forecasts and other qualitative indicators [14-16].
ISSN 1026-2237 BULLETIN OF HIGHER EDUCATIONAL INSTITUTIONS. NORTH CAUCASUS REGION. NATURAL SCIENCE. 2023. No. 1
Conclusion
Taking into account the importance of studying cumulonimbus clouds and related atmospheric phenomena, based on archived weather data for 2011-2020 at Heydar Aliyev International Airport, the statistical frequency of cumulonimbus clouds, thunderstorms and other atmospheric phenomena associated with these clouds by months and years have been analyzed. For this purpose Meteorological Aerodrome Reports for Heydar Aliyev international Airport (METAR), surface maps, upper air maps for 700 and 500 hPa levels, satellite images and soundings were analyzed. For statistical analyses of climatic characteristic at the airport of Heydar Aliyev, records from AWOS have been received and processed scrupulously. Initial data have been obtained from hourly and a half hourly recorded meteorological data at the range from 2011 to 2020.
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A.A. Bashirova - PhD Student, Lecturer, Department of Aviation Meteorology. Информация об авторе
А. А. Баширова - докторант, преподаватель, кафедра авиационной метеорологии.
Статья поступила в редакцию 01.07.2022; одобрена после рецензирования 17.08.2022; принята к публикации 02.03.2023. The article was submitted 01.07.2022; approved after reviewing 17.08.2022; accepted for publication 02.03.2023.
