Maritime Polar Air Research Articles

PSCF and CWT methods as a tool to identify potential sources of 7Be and 210Pb aerosols in Granada, Spain

This research is focused on studying the preferred source regions and the pathways of the air masses with high particulate concentrations impacting on the activity concentrations of 7Be and 210Pb aerosols in Granada atmosphere. For this purpose, three different source-receptor methods have been used: Cluster Analysis, Potential Source Contribution Function (PSCF), and Concentration Weighted Trajectory (CWT). Air filter samples were weekly collected and analysed in Granada university (Spain 37.177N, 3.598 W, 687m a.s.l.) during 12 years (2006–2017) for the activity concentration of 7Be, and during 5 years (2010–2014) for the one of 210Pb. The time series of the collected data indicate that the concentration of both radiotracers present a cyclical and seasonal pattern, in association with their origins and atmospheric conditions. Clustering analysis showed that the air masses arriving to Granada can be classified as: (1) tropical continental air masses coming from the Mediterranean Sea, (2) tropical and warm polar maritime air masses produced over the Atlantic Ocean, and (3) continental air masses originated over Europe and Northern Africa. The PSCF and CWT methods confirmed that the main source areas of 7Be are located in the Atlantic coast of southern Morocco, and Northern Africa. On the other hand, southern France and the Algerian desert were found to be the main region sources of 210Pb. In addition, the Mediterranean Basin has been postulated as a strong source region for 7Be and 210Pb. Furthermore, the PSCF and CWT models show that the regions with larger 7Be/210Pb ratios are located in the Atlantic Ocean, due to frequent stratospheric intrusions specially during the winter months.

Weather events and respiratory diseases in children: case studies in the metropolitan region of São Paulo, Brazil

This paper presents a preliminary analysis of meteorological variables and their relationship with respiratory morbidity in children under two years old of São Paulo city, taking into account the synoptical systems and their constructive structures of residences. Measurements of indoor air temperature and relative humidity were collected using a thermohygrographic across of 378 residences, between years 2003 to 2006. Outdoor meteorological variables have been obtained from meteorological station. A summary with four case studies is shown relating the thermal behavior in each residence and the onset of respiratory illness in children (wheezing). The results show associations of children respiratory crises and air temperature fall and increase of relative humidity, associated with maritime polar air masses and frontal systems (cold front). Specific residences have higher indoor humidity values than others, due to their constructive types and it is an important factor to bring out wheezing problems. Considering such results, acknowledging periods favorable to occurrences of wheezing in children, as well as the constructive type of residences, it is feasible to predict respiratory morbidity and to establish public policy in order to alert the population, minimizing weather/climate impacts on children's health

The gust that never was: a meteorological instrumentation mystery

During the early hours of Easter Monday, 28 March 2016, the passage of a very rapidly-deepening depression across central England resulted in a rare inland gale, followed by a succession of squally showers during the afternoon in the polar maritime air behind the cold front. During one of these showers, two anemometers (at 2 m and 10 m above ground level) located in the Atmospheric Observatory at the University of Reading recorded gusts exceeding 30 m/s (60 kn), the highest recorded at the site for almost 20 years. Although these were well in excess of other local gust speeds, the meteorological situation was favourable for very high squally gusts, and this taken together with records from a well-maintained site with impeccable site and instrument metadata initially suggested the observations were beyond reproach. However, it soon became clear that wind speeds from other anemometers on the site (one on the same mast) did not support these extreme gusts. A careful investigation into the circumstances concluded that both anemometer outputs were temporarily incremented by rapid pulses resulting from coronal discharge (St Elmo’s fire), even though observed electric fields were not sufficiently large to result in lightning. Other instances of observed high wind gusts from similar instruments, apparently genuinely recorded but lacking supportive evidence in terms of substantive infrastructure damage or confirmation from a second instrument, may now warrant retrospective re-examination.

Observations on changes in Korean Changma rain associated with climate warming in 2017 and 2018

The period of prolonged summer rain in Korea called Changma was studied. Changma, also known as Meiyu in China and Baiu in Japan, is an integral part of the East Asian Summer Monsoon System. Until the 1980s, the Changma rainy season in Korea occurred from late June and July for 30 to 40 days or approximately 4 to 5 weeks. This study investigated whether changes have been observed in the timing and amounts of precipitation associated with Changma. From the analysis of meteorological data obtained in 2017 and 2018, it is observed that the length of the rainy season has shortened to 2 to 3 weeks in agreement with the earlier studies. Furthermore, during the rainy season, there were many days of no rain and partly cloudy days. Although an active elongated-linear Changma front was common in the past, it was found that an inactive Changma front with a large meridional amplitude has caused intermittent rain showers for several hours from linear convective cloud streaks. In recent years, this has produced large variations in rainfall amounts among regional measuring stations in Korea. Climate warming in the north side of the Changma front has resulted in less contrast with the warm-moist air in the south side of it from the Pacific Ocean. This has resulted in a weaker and inactive quasi-stationary front which has caused a discontinuous broken Changma front and sporadic showery days. It is also observed that maritime polar air mass, mP, over the Okhotsk Sea of far eastern Russia has not affected the Changma front over the Korean Peninsula. Overall, this study found that the characteristics of past Changma fronts have changed significantly in recent years. The present observations imply the need of further studies on climate change and summer rainfall including water management.

Thermal Conditions Relative to Atmospheric Circulation in the Christmas Period in Poland

Abstract The main objective of this article was to determine thermal conditions in the Christmas period and the impact of atmospheric circulation on their formation. The article is based on data on the mean daily air temperature for 16 stations in Poland for the 1966-2014 multiannual period. In this period, no statistically significant changes of air temperature were observed, neither in December, nor the Christmas period. The occurrence of averagely warmer holidays was associated with the inflow of maritime polar air masses from the western sector, while colder holidays occurred with the inflow of continental polar air masses from the eastern sector.

Variability of Air Masses Over Podlasie (Ne Poland) in the Years 2001–2010

Abstract This paper concerns the frequency and duration of air masses over Podlasie (NE Poland) in the years 2001-2010. The synoptic maps in the Daily Meteorological Bulletin of the Institute of Meteorology and Water Management (IMGW 2001-2010) were the basis for the designation of six air masses observed over the area of Podlasie every day for 12.00 UTC. They were: arctic air (A), continental polar air (cP) partly transformed from old arctic air (oA), maritime polar air (mP), maritime warm polar air (mwP), old maritime polar air (omP), tropical air (T). The analysis shows that the most frequent air mass in the whole period was cP partly transformed from oA (approx. 33%) followed by omP (approx. 24%) and mP (19%). Tropical air occurred over Podlasie with the lowest frequency, with a value of only 3.6%. The frequencies of their occurrence varied from year to year. Less than 12% of cases (approx. 210) occurred for 4-20 days. The minimum values occurred for periods of more than 9 days (cP and omP masses, only). Slightly higher values occurred in the case of 7- to 9-day periods (6-14 cases 1.5%).

A provisional climatology of cool-season convective lines in the UK

A 7-year climatology of cool-season convective lines in the UK has been constructed using archived radar rainfall data. 103 lines meeting basic size, duration and intensity criteria were identified over the period September 2003 to February 2010. Of these, 87% occurred in association with frontal systems (mostly cold fronts). The remaining 13% occurred within polar-maritime air masses to the rear of frontal systems. Annual frequencies were highest over inland areas of southern and central England (5.0–7.5 events per 10,000km2, per year) and decreased markedly to the north (<1.0 events per 10,000km2, per year over north and west Scotland). Tornado and Storm Research Organisation (TORRO) tornado data revealed that 27.2% of lines produced at least one tornado. The environment of tornadic and non-tornadic lines was investigated by analysis of available observations, from which representative values of various environmental parameters were obtained. Tornadic lines were found to be associated with significantly larger pre-line surface-based CAPE, line-normal forward motion, cross-line horizontal wind veer, and cross-line temperature decrease. Furthermore, a tendency for tornadic lines to occur near the core, or under the left exit region, of mid-level jets was apparent.

Traces of fission products in southeast Spain after the Fukushima nuclear accident

Traces of 131I, 134Cs and 137Cs were measured after the Fukushima nuclear accident between 23 March and 13 April 2011 in southeast Spain. The movement of the radioactive cloud toward southeast Spain was reconstructed based on the backward and forward trajectory cluster analyses. Polar maritime air masses which had originated over North America transported the radioactive plume toward the southeast Spain. Aerosols, rainwater, vegetables and cheese were analyzed to determine the radioactive risk. The highest concentrations of 131I, 134Cs and 137Cs in air samples were 2.63 ± 0.12 mBq/m3; 0.10 ± 0.03 mBq/m3; 0.09 ± 0.02 mBq/m3, respectively. After precipitation on April 3rd, the maximum concentrations of 131I, 134Cs and 137Cs were detected in rainwater samples, 1.10 ± 0.16 mBq/L; 0.022 ± 0.003 mBq/L; 0.05 ± 0.03 mBq/L, respectively. As a consequence, 131I was transferred to the human food chain, and found in chard and goat cheese, 0.97 ± 0.20 Bq/kg and 0.52 ± 0.08 Bq/kg, respectively. The traces of 131I, 134Cs and 137Cs detected in the different samples were so low, that there is no impact on human health or the environment in Spain after the Fukushima nuclear accident.

Air mass origin and its influence on radionuclide activities ( 7Be and 210Pb) in aerosol particles at a coastal site in the western Mediterranean

Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of 7Be and 210Pb in aerosols at Málaga (36° 43′ 40″ N; 4° 28′ 8″ W) for the period 2000–2006 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory clusters. The average concentration values of 7Be and 210Pb over the 7 year period have been found to be 4.6 and 0.58 mBq m −3, respectively, with mean aerosol mass concentration of 53.6 μg m −3. The identified air flow types arriving at Málaga reflect the transitional location of the Iberian Peninsula and show significant differences in radionuclide activities. Air concentrations of both nuclides and the aerosol mass concentration are controlled predominantly by the synoptic scenarios leading to the entrance of dust-laden continental flows from northern Africa and the arrival of polar maritime air masses, as implied by the strong correlations found between the monthly frequencies of the different air masses and the specific activities of both radionuclides. Correlations between activity concentrations and precipitation are significant though lower than with air masses.

A synoptic analysis of the diurnal cycle of thunderstorm precipitation in Kraków (Southern Poland)

AbstractA study was made of the relationships between the diurnal pattern of thunderstorm precipitation in Kraków and the types of air masses and atmospheric fronts prevailing over southern Poland during the period 1951–2006. The results of these investigations contribute to a better understanding of the physical processes taking place in the atmosphere that are associated with convective rainfall and may be used to improve the forecasting of the temporal distribution of convective precipitation. The elementary parameters of the daily precipitation cycle were identified, such as the amplitude and phase of the frequency and total thunderstorm precipitation. A separate analysis was performed of air mass and frontal precipitation. The 24‐h thunderstorm precipitation cycle depends on the synoptic situation that determines the thermal and humidity properties of air masses. There is an afternoon peak in Kraków's general diurnal pattern of thunderstorm precipitation that is primarily linked to cold fronts and to air mass precipitation occurring in polar maritime air. Thunderstorm precipitation linked to warm fronts is less frequent and is concentrated in the evening. Copyright © 2009 Royal Meteorological Society

Air Mass Transformation along Trajectories of Airflow and Its Relation to Vertical Structures of the Maritime Atmosphere and Clouds in Yamase Events

The Yamase is a cool easterly wind that is observed in summer along the eastern coast of the northern part of the main island (Honshu) of Japan. It usually accompanies a boundary layer cloud, the “Yamase cloud.” The origin of the Yamase is the cool polar maritime air mass that develops over the North Pacific, including the Bering Sea and the Sea of Okhotsk. The characteristics of the Yamase are controlled by air mass transformation over the western North Pacific. Campaign observations of the Yamase were performed using the marine vessel Koufu-maru of the Japan Meteorological Agency over the sea east of northern Honshu in summer, from 2001 to 2007. We studied two Yamase events and examined the heat flux along back trajectories as well as the heat and moisture budget. The vertical structure of the Yamase was strongly dependent on the history of the air over the ocean, despite the many factors that influence boundary layer clouds. In the June 2003 event, the stepwise upward development of Yamase clouds observed at the Koufu-maru site was related to the influence of Hokkaido Island and an oceanic front on Yamase flow trajectories. For the July 2006 event, the temperature profiles observed from the Koufu-maru changed from stable layer type to mixed layer type. Changes in the visibility and oceanic heating along Yamase air trajectories were also observed. Ocean heating increased when the trajectories changed from westward to southward across an oceanic front located to the east of 144°E in the Kuroshio-Oyashio extension. The meridional SST gradient was smaller over water off northern Honshu, where the Oyashio current prevailed. A heat and moisture budget analysis using aerological data observed by the Koufu-maru and three weather stations in northern Japan showed weak sensible heating and weak moisture sink when the Yamase wind prevailed. We ascribed the weak sensible heating to the small air-sea temperature difference, which was caused by the weak meridional SST gradient and offset by radiative cooling at the cloud top.

Factors influencing new particle formation at the rural site, Harwell, United Kingdom

A study of large‐scale episodes of new particle formation observed at a rural site in southern England which is a receptor site for air masses with varying degrees of pollution is presented. Large‐scale episodes of new particle formation are infrequent at Harwell (26 episodes for 1999–2001; data capture of 55%), and it is shown that the most favorable situation for new particle formation in southern England is also infrequent. All episodes but three occurred when clean cool arctic or polar maritime air masses arrived in the UK bringing days of high solar radiation and thin cloud cover. The incursion of these cool air masses may be associated with passage of a cold front and leads to stronger winds and probably strong turbulent mixing; all favor new particle production. More exceptionally, nucleation occurred in warm polluted continental or tropical maritime air masses which shows that different conditions are also possible but much less probable. Higher concentrations of SO2 and higher relative humidity favor higher particle number in agreement with nucleation processes involving H2SO4 and H2O. Taken together, these parameters are insufficient to predict when a burst of particle formation due to nucleation will occur at Harwell, and other important variables must be influential.

Seasonal characteristics of diurnal precipitation variation in Kraków (South Poland)

AbstractThis paper describes the diurnal cycle of liquid precipitation using the amplitude and phase of two precipitation characteristics: frequency and totals. A uniquely long set of uniform hourly precipitation data from Kraków (South Poland) was used. This vast and reliable basic material was collected by the author using pluviographic data covering the period 1886–2002. The role of precipitation type in forming the general diurnal cycle of precipitation was discussed. Two precipitation types, frontal and air mass, were taken into consideration. The role of particular air masses (polar maritime and polar continental) and atmospheric fronts (warm and cold fronts) in the 24‐h precipitation cycle was determined. The frontal and air mass precipitation events were identified using a documentation of synoptic situations by Niedźwiedź over the area of southern Poland for the 1951–2002 period.Depending on the precipitation characteristic (frequency or totals), season of the year and precipitation type, the diurnal precipitation cycle may have one or two modes. The bimodality of the distribution occurs mainly for air mass precipitation. The morning maximum of precipitation frequency in all seasons of the year mimics the diurnal variation of precipitation in maritime polar air masses. Precipitation concentration in the afternoon hours is determined mainly by the intensity of processes in the cold front zone and in the homogeneous polar continental and maritime air masses. Significant differences in precipitation distribution in cold and warm fronts are connected with the time of precipitation concentration within the diurnal period. The type of atmospheric front determines the layout of precipitation clouds, intensity of precipitation formation and the velocity of front movement. Copyright © 2006 Royal Meteorological Society

On applicability of model aerosol distributions for urban region of Bratislava city

Long-term measurements of spectral atmospheric transparency are analysed to describe the aerosol size distribution as well as the aerosol optical thickness in the urban region of Bratislava city, capital of Slovak Republic. Aerosol characteristics are related to the most frequent air masses, especially to the continental polar (cP—with a 54% occurrence) and maritime polar (mP—with 34% occurrence), to the wind direction and speed, as well as to the relative humidity. Including both random and systematic errors of the observations into the calculation procedures, the aerosol optical thickness is obtained with approximately 4% error at all wavelengths. Averaged values of the aerosol optical thickness τ a( λ) at reference wavelength λ=520 nm vary over a wide range, from 0.1 to 0.7. Besides, the aerosol optical thickness of the continental polar air mass is obviously higher than corresponding values in the maritime polar air mass. It is shown that the transformation inside the air mass reflects the changes of the optical characteristics of aerosols, especially during decay of air mass. The function τ a( λ) seems to be monomodal in the majority of cases, with the mode position about λ≈400 nm for cP, and λ≈500 nm for mP. A value of power parameter δ of the function τ a( λ)≈ λ − δ is about 0.8–1.6 for maritime polar and about 0.3–1.2 for continental polar. Two simple model functions (Junge and gamma) are examined to find a best fit of real distribution retrieved from the aerosol optical thickness data using the inverse techniques based on Mellin transform. The gamma function much better than Junge's function supply the real aerosol component of all studied air masses (mainly for cP and mP). The average modal radius of gamma distribution practically does not exceed the value of 0.06 μm. Real distributions retrieved using a Mellin transform give an averaged morning value of particle modal radius r m about 0.084 μm, and averaged daily value r m about 0.054 μm.

An early‐autumn polar low formation over the Norwegian Sea

Around October 15, 1993, an unusual polar low formation took place over the Norwegian Sea. The evolution is studied by means of the HIRLAM forecasting model at the Danish Meteorological Institute, satellite imagery and observations. The investigation, to some extent based on generalized forms of the equations for omega and geopotential tendency, reveals that the disturbance forms initially by baroclinic instability along a frontal zone within a maritime polar air mass and in close proximity of an intense extratropical cyclone. During its growth to a polar low, air‐sea interaction seems to work in conjunction with the baroclinic process. A parallel forecast with the latent heat set to zero shows that heating of the atmosphere, associated with precipitation, is necessary for the polar low formation.

Nonsphericity of aerosol particles and their contribution to radiative forcing

Observations of combined spectral aerosol optical thickness and sky brightness in the almucantar for clear sky conditions indicate a discrepancy between the measured and modeled radiation field in certain air mass situations [maritime polar air (mP) and particular continental subtropic air (cS)], which cannot be closed using the commonly made assumption of sphericity of the aerosol particles or explained by measurement uncertainties. In these cases, mostly associated with flat spectral slopes of the aerosol optical thickness (caused by large particles, e.g. at marine and desert aerosols as well as thin ice clouds) increased side scattering is observed in the sky brightness. A Coupled Inversion Radiation Transfer program (CIRATRA) is used for the determination of climate-relevant aerosol parameters assuming spherical as well as nonspherical particle shapes. The observed increased side scattering for the marine and desert aerosols only can be explained by the use of scattering phase functions produced by nonspherical particles and consequently smaller asymmetry parameters. In these cases the best fit to the measured sky brightnesses (within the observable range of scattering angles (3–150 deg)) could be obtained by the use of the semi-empirical scattering theory of Pollack and Cuzzi 1 with less asymmetric phase functions and smaller asymmetry parameters than Mie theory. Conclusions regarding radiative forcing by aerosols are made for different values of aerosol optical thickness. The cooling effect by aerosols in cases of nonsphericity reaches up to a factor of 2 compared with the cooling of spherical particles.

Variations of tropospheric HCl amounts over northern Sweden

Unexpectedly large variations of tropospheric HCl zenith column amounts were observed over Kiruna, Northern Sweden, in the arctic winters of 1991/92 and 1992/93. Trajectory calculations prove a strong dependence of tropospheric HCl variation on the origin of the air mass observed. This effect cannot be explained by different altitudes of the tropopause caused by dynamical processes. Polar maritime air contains 0.67 ± 0.11 × 1015 more HCl molecules cm−2, in terms of tropospheric zenith column amounts, than maritime midlatitudinal air. The latter contains 0.39 ± 0.16 × 1015 more HCl molecules cm−2 than continental air from midlatitudes. The HCl loading of arctic air is comparable to that of maritime polar air, except for one measurement on January 28, 1993, which showed significantly less tropospheric HCl. Tropospheric chlorine activation, along with ozone destruction in the troposphere, is considered a candidate for explanation. Furthermore, HCl strongly correlates with CH2O.

Spring-season climate variability in the central Canadian Arctic Islands

The Resolute Bay area in the central Canadian Arctic Islands is in a region of maximum variability in 50 kPa heights in spring. This is the northern part of an oscillation in large-scale atmospheric circulation called the Baffin Island West Atlantic Oscillation (BWA). The historical record of temperature at Resolute Bay, Northwest Territories, over the 1948–93 period is compared with circulation patterns for extremely warm and cold spring seasons, using a composite technique and a simple index of the intensity of the BWA. The extremely cold spring of 1992, the second coldest of the 46a record, was probably caused by reduced solar radiational forcing due to the increased dust veil caused by Mount Pinatubo.Within each spring season, large-scale synoptic conditions provided an important control on the timing of critical stages leading to full snow melt on the sea-ice surface. The first stage is the change from dominance of the region by wintertime continental polar air to the frequent invasion of maritime polar air masses, resulting in increased cloud cover and reduced frequency of Arctic inversions. The second stage is the transition to full melt on the ice with a sharp drop in surface albedo. During the spring on 1993, the first stage was triggered by a major storm which moved through the area on 9–10 May 1993. The second snow-melt stage was triggered by a stationary upper ridge which remained over the area for a 2 week period from 15 May to early June and produced clear to scattered-cloud conditions and high downward solar radiation.

Spring-season climate variability in the central Canadian Arctic Islands

The Resolute Bay area in the central Canadian Arctic Islands is in a region of maximum variability in 50 kPa heights in spring. This is the northern part of an oscillation in large-scale atmospheric circulation called the Baffin Island West Atlantic Oscillation (BWA). The historical record of temperature at Resolute Bay, Northwest Territories, over the 1948–93 period is compared with circulation patterns for extremely warm and cold spring seasons, using a composite technique and a simple index of the intensity of the BWA. The extremely cold spring of 1992, the second coldest of the 46a record, was probably caused by reduced solar radiational forcing due to the increased dust veil caused by Mount Pinatubo.Within each spring season, large-scale synoptic conditions provided an important control on the timing of critical stages leading to full snow melt on the sea-ice surface. The first stage is the change from dominance of the region by wintertime continental polar air to the frequent invasion of maritime polar air masses, resulting in increased cloud cover and reduced frequency of Arctic inversions. The second stage is the transition to full melt on the ice with a sharp drop in surface albedo. During the spring on 1993, the first stage was triggered by a major storm which moved through the area on 9–10 May 1993. The second snow-melt stage was triggered by a stationary upper ridge which remained over the area for a 2 week period from 15 May to early June and produced clear to scattered-cloud conditions and high downward solar radiation.

Pattern of glacial—interglacial vegetation in subtropical Chile

Pleistocene vegetation in the Mediterranean climate region of subtropical Chile during >40,000 yr of the last glaciation stands in contrast with vegetation of the past 10,000 yr of the present interglaciation. During the last ice age, open woodland of southern beech (Nothofagus dombeyi and N. obliqua types) and Andean podocarp (Prumnopitys andina) mixed with grasses and composites, was established on unglaciated, low‐lying terrain now occupied by broad sclerophyllous plant communities. This marked vegetation change during a glacial‐interglacial cycle, inferred from pollen contained in a core from Laguna de Tagua Tagua (34°30'S), suggests a pattern applicable to the vegetational setting during repeated cycles throughout the Quaternary. Ice‐age vegetation can be accounted for by year‐long domination of the polar maritime air mass at lower, middle latitudes, unlike modern interglacial type plant formations, which are regulated by seasonal interaction between subtropical and polar maritime air. Glacial‐interg...