Continental Polar Air Masses Research Articles

The Seasonal Snowfall Contributions of Different Snowstorm Types in Central New York State

Located at the eastern extent of the Great Lakes snowbelt, Central New York averages some of the highest annual snowfall totals east of the Rocky Mountains. This is in large part due to the variety of snowstorms that affect the region including lake-effect storms, coastal storms, and overrunning storms. Previous estimates suggest that lake-effect snowstorms account for approximately half of the seasonal snow in the Great Lakes basin, but ignore the spatial variability that exists within the region. Therefore, this study examines the seasonal snowfall contributions of the different snowstorm types to affect Central New York. Results suggest that although lake-effect snowstorms are the dominant snowstorm type in the region, their seasonal snowfall contributions vary between 13 and 48%. Although lake-effect snowstorms produce more snow during the peak and mid-seasons, their relative contribution is greatest during the early and mid-winter seasons. Generally, higher contributions occur near the Tug Hill Plateau, with lower contributions in southern Central New York. Instead, snowfall in southern Central New York is mostly dominated by Nor'easters (16–35%), with lesser contributions from Rocky lows (14–29%). Overrunning storms that originate in Canada (e.g., Alberta clippers) and non-cyclonic storms contribute the least to seasonal snowfall totals across Central New York; however, they are often the catalyst for lake-effect snowstorms in the region, as they advect continental polar air masses that destabilize across the lake. Understanding the actual snowfall contribution from different snowstorm types is needed for future climate predictions. Since the potential trajectory of future snowfall varies according to the type of storm, climate models must accurately predict the type of storm that is producing the snow.

Flood risk analysis in the Taihu Basin during flood periods based on Copula function

太湖流域位于长江入海口，地处中国沿海经济带和长江沿线内陆经济带的交汇处，是中国高度城镇化地区之一.流域汛期降水受到多重天气系统的影响，不同的天气系统带来时空分布各异的降水，给该地区城镇防洪排涝工作造成了巨大的挑战.本文基于Copula理论对太湖流域汛期洪涝风险进行研究，考虑了因降水主导因素不同所造成的流域洪涝风险的时空差异性.在时间角度，采用降水主导因素发生时间的概率分布，将汛期划分为梅汛期和台汛期；在空间角度，通过Copula函数，对研究区进行聚类划分；在此基础上，根据太湖流域防洪规划，对流域梅汛期和台汛期的洪涝风险进行分析.研究结果表明：①太湖流域的汛期划分为：6月24日-7月21日为梅汛期，7月22日-9月22日为台汛期；②根据各分区降水和太湖水位的联合分布函数拟合效果的优劣，在梅汛期，太湖流域被划分为P-Ⅰ区、P-Ⅱ区和P-Ⅲ区；在台汛期，整个流域的降水作为一个整体，不分区；③到2025年，太湖流域在梅汛期和台汛期出现排涝不利情境的风险概率分别为2.4%和1.1%.本文的研究方法可以为太湖流域设计暴雨的调整、洪水资源的利用以及防洪排涝实时调度的决策提供科学参考.;The Taihu Basin is located at the estuary of the Yangtze River, belonging to the intersection of China coastal economic belt and the inland economic belt along the Yangtze River. It is one of China's highly urbanized areas. Under the influence of continental polar air masses, maritime tropical air masses and tropical cyclones, the types of precipitation in the Taihu Basin are divided into plum rain and typhoon rain. Different weather systems lead to the different heterogeneous precipitation, which brings great challenges to flood management in the basin. Taking the spatial and temporal differences of flood risk caused by different weather systems into consideration, this paper analyzed the flood risk based on Copula theory. In terms of time, the probability distribution of the precipitation dominant factors was used to divide the flood period into the plum rain period and the typhoon period. In terms of space, we clustered the study areas in the plum rain period and the typhoon period respectively by the Archimedean copula function. Finally, the flood disaster risk during the plum rain period and the typhoon period was analyzed. The results indicate that the flood period of the Taihu Basin is divided into the plum rain period (June 24 to July 21) and the typhoon period (July 22 to September 22). According to the joint distribution of sub-region precipitation and the Taihu Lake water level, the Taihu Basin is divided into three sub-regions (P-Ⅰ sub-region, P-Ⅱ sub-region and P-Ⅲ sub-region) in the plum rain period, while the Taihu Basin as a whole for flood risk analysis in the typhoon period. In the future, the probability of the drainage adverse in the Taihu Basin during the plum rain periods and the typhoon period is 2.4% and 1.1%, respectively. It is of great significance for the Taihu Basin to adjust the schemes of design storm and utilize flood resource and make the decision of real-time scheduling for flood control and drainage.

Variability and trends in record air temperature events of Turkey and their associations with atmospheric oscillations and anomalous circulation patterns

The study investigated temporal variations of record and absolute maximum and minimum air temperatures (Tmax and Tmin, respectively), and surface and upper atmospheric conditions in years, in which the highest number of events were observed at 90 stations of Turkey during period of 1950–2015. The results have shown that annual frequency of record Tmin events revealed an evident decreasing since mid‐1980s while frequency of Tmax events increased particularly starting from the year of 2000. Half of record Tmax events were recorded during 2000–2015 period. On the other hand, daily absolute Tmax occurred mostly in 2000, whereas daily absolute Tmin events were mostly recorded in 1953.With respect to linkages to atmospheric teleconnection patterns, statistically significant negative relationships were detected between numbers of Turkey's record Tmax events and the North Atlantic Oscillation Index (NAOI) in July, December, and annually, and between the Arctic Oscillation Index (AOI) and the record Tmax events in winter months. The North Sea–Caspian Pattern Index (NCPI) had a significantly strong negative relationship with record‐breaking Tmax events in February, March, August, October, and annually. However, statistically significant relationships found between the NCPI and record Tmin events in November, January, and annually are different from other atmospheric oscillations.Well‐defined synoptic‐scale surface and upper atmospheric circulation anomalies closely controlled occurrence and nature/magnitude of highest number of record‐breaking Tmax events in Turkey by carrying frequently the tropical origin weather systems and continental tropical warm/hot air masses towards Turkey and her surroundings. On the other hands, record‐breaking Tmin events detected were related closely with the patterns of surface and upper atmospheric circulation anomalies carrying frequently polar and subpolar or mid‐latitudinal weather systems with the continental polar air masses mostly cold and stable to Turkey and her surrounding regions.

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.

The Great 2008 Chinese Ice Storm: Its Socioeconomic–Ecological Impact and Sustainability Lessons Learned

Abstract Extreme events often expose vulnerabilities of socioeconomic infrastructures and point to directions of much-needed policy change. Integrated impact assessment of such events can lead to finding of sustainability principles. Southern and central China has for decades been undergoing a breakneck pace of socioeconomic development. In early 2008, a massive ice storm struck this region, immobilizing millions of people. The storm was a consequence of sustained convergence between tropical maritime and continental polar air masses, caused by an anomalously stable atmospheric general circulation pattern in both low and high latitudes. Successive waves of freezing rain occurred during a month period, coating southern and central China with a layer of ice 50–160 mm in thickness. We conducted an integrated impact assessment of this event to determine whether and how the context of socioeconomic and human-disturbed natural systems may affect the transition of natural events into human disasters. We found th...

Snowstorm over the southwestern coast of the Korean Peninsula associated with the development of mesocyclone over the Yellow Sea

This study investigates the characteristics of a heavy snowfall event over the southwestern part of the Korean Peninsula on 4 December 2005. The snowstorm was a type of mesoscale maritime cyclone which resulted from barotropic instability, and diabatic heating from the warm ocean in continental polar air masses.

An assessment of air quality variations in the south‐western USA using an upper air synoptic climatology

AbstractDaily particulate concentrations in the Desert South‐west from 1984 to 1988 are analysed using a synoptic climatology based upon tropospheric thermal, moisture, and flow conditions. Using a combination of principal components analysis and cluster analysis, 13 distinct synoptic types (clusters) are identified that correspond to seasonal variations in the atmosphere's general circulation. These include summer clusters, which reflect monsoonal and non‐monsoonal conditions, winter clusters defined by the positions of the polar and subtropical jets and shortwave ridges and troughs, and clusters that predominate in the transition seasons.Particulate concentrations vary significantly by synoptic type. Three clusters have poor air quality. ‘Summer monsoon’ days have high humidity and cloud cover, conditions that encourage aerosol growth. ‘Continental high’ days have a slow‐moving anticyclone centred over the Great Basin that traps particulates within the boundary layer. ‘Rockies ridge’ days are associated with strong south‐westerly flow and the advection of regional haze from southern California into the Desert South‐west. In all of these clusters, high humidity or cloud cover enhance particulate growth. Good air quality in the summer occurs on monsoonal ‘break’ days when relative humidity and cloud cover decrease. In the winter, good air quality occurs when Arctic or continental polar air masses are present, or when either the polar or subtropical jets are strong and positioned over the South‐west. In some of these latter situations, widespread precipitation removes particulates through wet deposition.These results suggest that the Navajo Generating Station (NGS), a large coal‐fired power plant on the Arizona‐Utah border, does not contribute significantly to air quality degradation in the Grand Canyon National Park, Arizona. Most of the days with high particulate levels are associated with transport from southern California or unstable summer days with high humidity and contributions from many point and regional sources. There may be some contribution from the NGS on ‘continental high’ days, but when this cluster occurs on consecutive days, air quality improves rather than declines. This research provides a useful framework for future mesoscale modelling studies of air quality in south‐western USA.

Large‐scale variability of ozone and aerosols in the summertime Arctic and sub‐Arctic troposphere

Measurements of ozone (O3) and aerosol distributions were made with an airborne lidar system in the Arctic and sub‐Arctic during July–August 1988 as part of the NASA Global Tropospheric Experiment/Arctic Boundary Layer Expedition (ABLE 3A). Aerosol and O3 profiles were measured simultaneously above and below the Electra aircraft from near the surface to above the tropopause. In situ measurements of O3 mixing ratios and aerosol size distributions and number densities were also made on the aircraft. Many different atmospheric conditions were investigated on long‐range survey flights in the Arctic and on intensive flights over the tundra, ice, and marine regions near Barrow and Bethel, Alaska. The tropospheric composition at high latitudes was found to be strongly influenced by stratospheric intrusions. Regions of low‐aerosol scattering and enhanced O3 mixing ratios were correlated with descending air from the lower stratosphere. Over 37% of the troposphere along our flight track at latitudes >57°N had significantly enhanced O3 levels due to stratospheric intrusions, and in the 4‐ to 6‐km altitude range the tropospheric extent of the enhanced O3 exceeded 56%. Ozone mixing ratios of 80 ppbv at 6 km were common, with vertical O3 gradients of over 11 ppbv km−1 observed across the base of strong intrusions. In the mixed layer over the tundra, O3 was in the 25–35 ppbv range with a gradient of 5.5 ppbv km−1, while in continental polar air masses, the average gradient in the lower troposphere was 7.4 ppbv km−1, indicating more downward transport of O3 at higher latitudes. Due to the many forest fires that year, plumes from biomass burning sources were observed on several flights over Alaska. Plumes influenced about 10% of the air below 4 km, and in some photochemically active plumes, O3 was enhanced by 10–20 ppbv over ambient levels. Pollution plumes from industrial sources were infrequently observed; however, a few large plumes were found over the North Pacific with greatly enhanced aerosol scattering and with O3 levels exceeding 75 ppbv.

On the atmospheric conditions affecting the variation of tritium concentration in rainfall

Atmospheric conditions affecting the variation of tritium concentration in rainfall were investigated by meteorological analysis during 1980 in Pusan, Korea. Tritium concentrations were high in winter, autumn and spring, in comparison with summer. If was found that there is generally a negative correlation between tritium concentration in rainfall and the mixing ratio, and atmospheric thicknesses. In winter, spring and autumn, high tritium concentrations occurred as the southward continental polar air masses from the north merged into the low pressure air mass in southern China; and relatively low concentrations of tritium appeared when the southward polar air masses combined with the northward low pressure air mass from the East China Sea. In the rainy season, extremely low concentrations of tritium were found when a stationary front was located to the south of Korea, allowing a warm and humid southwest airflow to travel toward the Korean peninsula, and here the potential instability and the existence of active convective clouds were major factors affecting the variation of tritium concentration.

Development of an automated spatial synoptic climatological classification

AbstractA spatial synoptic climatological index is developed that both characterizes the dynamic and thermodynamic surface weather regime and is capable of assessing and analysing the impact of synoptic‐scale variations on numerous environmental parameters. Based upon surface weather data for the contiguous USA for 1984, daily maps are produced that show those areas under the influence of similar weather conditions. The index is developed by applying principal components analysis to a daily matrix of 141 stations by 24 weather elements (chosen to represent the thermal‐moisture and surface flow characteristics). The resulting component scores are grouped using a two‐stage clustering technique. This yields a map showing lobes of air having relatively homogeneous weather characteristics. These lobes (clusters) are spatially coherent and correspond closely to surface weather map features.To allow for daily tracking of the clusters and identification days or weeks after disappearance, the means of each of the daily clusters are grouped across days. The resulting 90‐cluster categorization describes all of the major synoptic situations that occurred in 1984. Some of the common categories include maritime and continental polar air masses, frontal passages, and continental high dominance. These groups demonstrate seasonality, regionality, and high within‐category similarity. The resulting maps are useful since they are surface weather maps yet add clarity for environmental interpretation.

The Contribution of Radiative Cooling to the Formation of Cold-Core Anticyclones

Abstract Cold-core anticyclones are a dominant feature of the circulation in the high latitudes during the cold half of the year. This paper focuses on how the radiative cooling associated with the formation of continental polar air masses contributes to the anticyclogenesis. The processes occurring in cold-core anticyclones are investigated with a nonlinear axisymmetric numerical model. The model experiments employ three different types of radiative cooling parameterization: 1) externally specified radiative cooling rates; 2) internally determined radiative cooling rates with all condensed water assumed to fall out immediately, not affecting the radiative transfer (after Wexler); and 3) fully interactive calculation, whereby the radiative effects of the condensate that forms in the cooling air are included (Curry). The following physical processes are considered in the fully interactive calculation: 1) condensation of water vapor and freezing of liquid water; 2) radiative transfer from water vapor, CO2, ...

Ambient sulfate concentrations and windflow patterns at Whiteface Mountain, New York

Particulate sulfate in air was monitored daily from 15 June 1978 to 31 December 1979 at Whiteface Mountain, New York. The daily SO42− concentrations were related to surface‐air trajectory ensembles to assess the relative contribution from the U.S. and from Canada. During the study period the site was influenced approximately equally by continental polar and maritime tropical air masses. However the maritime air masses from the U.S. were the principal conveyors of high SO42− concentrations at this site and transported about 4 to 5 times more SO42− than did the continental polar air masses from Canada.

Atmospheric Turbidity over the United States, 1961–1966

Five years of turbidity measurements from a network of stations in the United States are analyzed. Measurements are made with the Volz sunphotometer; the instrumentits calibration, and its use are described. The relationship of these measurements to those of Linke and Ångström is briefly discussed. Analysis of the data indicates the following: 1) an annual mean pattern of low turbidity (near 0.05) over the western plains and Rocky Mountains and high turbidity (near 0.14) in the east; 2) observed minimum turbidity near 0.02; 3) an annual cycle of low turbidity in winter and high in summer; 4) lowest turbidity in continental polar air masses and highest in maritime tropical; and 5) no noticeable lowering of turbidity following precipitation.

RADAR STUDIES OF SONGBIRD MIGRATION IN COASTAL NEW ENGLAND*

RADAR STUDIES OF SONGBIRD MIGRATION IN COASTAL NEW ENGLAND*