Frequency and Characteristics of Inland Advecting Sea Breezes in the Southeast United States

Sea breezes have been observed to move inland over 100 km. These airmasses can be markedly different from regional airmasses, creating a shallow layer with differences in humidity, wind, temperature and aerosol characteristics. To understand their influence on boundary layer and cloud development on subsequent days, we identify their frequency and characteristics. We visually identified sea breeze fronts on radar passing over the Savannah River Site (SRS) between March and October during 2015–2019. The SRS is ~150 km from the nearest coastal location; therefore, our detection suggests further inland penetration. We also identified periods when sea breeze fronts may have passed but were not visually observed on radar due to the shallow sea breeze airmass remaining below the radar beam elevation that ranges between approximately 1–8 km depending on the beam angle and radar source (Columbia, SC or Charleston, SC). Near-surface atmospheric measurements indicate that the dew point temperature increases, the air temperature decreases, the variation in wind direction decreases and the aerosol size increases after sea breeze frontal passage. A synoptic classification procedure also identified that inland moving sea breezes are more commonly observed when the synoptic conditions include weak to moderate offshore winds with an average of 35 inland sea breezes occurring each year, focused primarily in the months of April, May and June.

Synoptic classification of atmospheric circulation over the south Eastern Siberia and its relationship with glacier dynamics

<p>The energy balance of a glacial surface and its melting is strongly controlled by altering synoptic processes in the lower troposphere. Therefore, classification of the processes of atmospheric circulation over the glaciarized regions is very important for better understanding of long-term trends in glacier changes. The glaciers of the Kodar Ridge (south Eastern Siberia) have shrunk in area by about 60% since the mid-19th century, with the largest decline taking place at the end of the 20th century. We have compiled the daily catalog of the weather types (WTs) from 1970 to 2020 based on the Jenkinson and Collison objective classification applied for the area (47.5–67.5° N, 102.5–132.5° E) centered over the Kodar Ridge. The gridded sea level pressure (SLP) and isobaric 700 hPa data was obtained from the National Center for Environmental Prediction / National Center for Atmospheric Research (NCEP/NCAR) reanalysis. In total, 26 WTs were identified and the frequency of different synoptic types was statistically analyzed. The most frequent group of WTs is advective (40%), followed by anticyclonic (34%) and cyclonic (14%). The unclassified type totally accounts for 13%. We revealed the differences between the frequency of synoptic processes in seasonal cycle and at different atmospheric levels (SLP and 700 hPa). Cyclonic weather types usually prevail in summer, while anticyclonic ones in autumn and winter. At 700 hPa level, the frequency of anticyclonic WTs increases in summer, while the frequency of advective types increases in all seasons. Over the past 50 years, the frequency of anticyclonic types demonstrates decreasing trend, while that of cyclonic and advective weather types increased (SLP data). In the 1980s and early 1990s the frequency of cyclonic WTs decreased, which could lead to a decrease in cloud cover over the Kodar region and an increase in net radiation of glacier surfaces. This study was supported by the Russian Foundation for Basic Research (project No. 19-05-00668).</p>

Spatial–temporal distribution of heavy precipitation over Ukraine during 1979-2019 according to the ERA5 reanalysis

The paper presents the results of research of heavy and extreme precipitation in the form of rain (> 50 mm / 12 h) and snow (> 20 mm / 12 h) using the data from the atmospheric reanalysis ERA5 for the period of 1979-2019. According to the data of the European Centre for Medium-Range Weather Forecasts obtained through the numerical modeling and resulting from the data assimilation at the nodes of a regular grid with a spatial resolution of 0,25°×0,25°, there are 131 and 136 days with rain and snow during which precipitation intensity reached the criteria of meteorological phenomena of the 2nd and 3rd levels of danger. It was discovered that the last 40 years in Ukraine proved to have a tendency of an increased number of cases of heavy snowfall, and a slightly decreased number of heavy rains. The research pays considerable attention to the spatial-temporal analysis of the frequency and intensity of heavy rainfall with consideration of geographical factors. It determines the seasonal course of heavy and extreme precipitation, the maximum and minimum values of which did not differ from the climatic standard values observed during meteorological observations. Rainfalls with precipitation rates of more than 50 mm over 12 hours were observed almost over the entire territory of Ukraine and the maximum frequency zones were detected over the Carpathian Mountains, Donetsk Ridge, Podolsk Upland, and the south-western part of the country. Heavy snowfalls with more than 20 mm precipitation over 12 hours mostly occurred in the Carpathian region. The analysis of the geographical distribution revealed a center with maximum values of rain intensity (120-133 mm over 12 h) off the coast of the Sea of Azov, and the heaviest snowfalls (34-38 mm over 12 h) mainly formed in the Carpathian region. The paper established the types of elementary circulation mechanisms of Dzerdzeevsky’s synoptic classification of Northern Hemisphere atmospheric circulation. These types, when continuous in nature, resulted in a significantly increased precipitation in the form of rain and snow. According to the reanalysis data, cases with the maximum rain intensity were found over the period of 23 to 27 July 2008 when a catastrophic flood was observed in the Ukrainian Carpathians. This fact indicates that the structure of the field of heavy precipitation over the territory of Ukraine was adequately reproduced by the respective model of the European Centre for Medium-Range Weather Forecasts.

†Camelosphecia gen. nov., lost ant-wasp intermediates from the mid-Cretaceous (Hymenoptera, Formicoidea)

Fossils provide primary material evidence for the pattern and timing of evolution. The newly discovered “beast ants” from mid-Cretaceous Burmite, †Camelospheciagen. nov., display an exceptional combination of plesiomorphies, including absence of the metapleural gland, and a series of unique apomorphies. Females and males, represented by †C. fossorsp. nov. and †C. venatorsp. nov., differ in a number of features which suggest distinct sexual biologies. Combined-evidence phylogenetic analysis recovers †Camelosphecia and †Camelomecia as a clade which forms the extinct sister group of the Formicidae. Notably, these genera are only known from alate males and females; workers, if present, have yet to be recovered. Based on ongoing study of the total Aculeata informed by the beast ant genera, we provide a brief diagnosis of the Formicoidea. We also provide the first comprehensive key to the major groupings of Mesozoic Formicoidea, alongside a synoptic classification in which †Zigrasimeciinaestat. nov. and †Myanmyrma marauderacomb. nov. are recognized. Finally, a brief diagnosis of the Formicoidea is outlined.

Changes in the characteristics of ‘wet’ and ‘dry’ Red Sea Trough over the Eastern Mediterranean in CMIP5 climate projections

The Eastern Mediterranean resides on the border between the temperate and semi-arid and arid climate zones, and is thus influenced by both mid-latitude and sub-tropical weather systems. Precipitation and extreme weather in this region are mainly associated with either Cyprus Lows or the “wet” Red Sea Troughs. Current regional climate projections indicate that the region may become warmer and drier in future decades. Here, we analyze the influence of enhanced greenhouse gas forcing on the climatological properties of the ‘wet’ and ‘dry’ Red Sea Trough (WRST & DRST, respectively). With this aim, a regional synoptic classification and a downscaling algorithm based on past analogs are applied to eighteen rain stations over the main ground water basins in Israel. The algorithms are applied to the NCEP/NCAR reanalysis data for 1986–2005 and to eight CMIP5 model simulations for the historical (1986–2005) and end of the century (2081–2100) climate conditions according to the RCP8.5 scenario. For the historical period, the CMIP5 models are largely able to represent the characteristics of the Red Sea Trough. Based on the multi-model mean, significant changes are found for WRST and DRST for the late XXI Century. First, an increase in the meridional pressure gradient is found for both the WRST and the DRST, implying stronger horizontal winds. Furthermore, a significant decrease in the occurrence of the WRST (− 20%) and a significant increase in the frequency of the DRST (+ 19%) are identified. Accordingly, the persistence of the WRST decreases (− 9%), while for DRST increases (+ 9%). The decline in the frequency of WRST occurs primarily in the transition seasons, while the increase for DRST is found throughout the wet season. In total, the daily rainfall associated with the WRST system is projected to significantly decline (− 37%) by the end of the XXI century. These results document the projected changes in a dominant synoptic system in this area, which can facilitate a better estimation of the arising challenges, e.g., related to shortage of water resources and associated political unrest, reduced agricultural potential, and increased air pollution and forest fires. Such a pathway can ultimately foster novel mitigation strategies for water resources management and regional climate change adaptation.

Synoptic causes of torrential rainfall in South-eastern Spain (1941–2017)

The weather types of 68 dates with torrential rainfall (≥200 mm/day) recorded at any weather station in the provinces of Alicante or Murcia during the period between 1941 and 2017 were determined using the Martín-Vide’s 1984 manual synoptic classification. Other relevant synoptic characteristics, as well as the surface pressure, and the value of the Western Mediterranean Oscillation index (WeMOi) on which those dates fell were also considered. The results show the high percentage of the Advection from the East with DANA (isolated high-altitude depression) or ‘gota fría’ type, which is present in more than 50% of the events, followed by the Trough type at 500 hPa and the Dynamic or Cold-core Low type, in the torrential rainfalls of South-eastern Spain. Except for the latter type, the average air pressure is close to or higher than normal. The WeMOi was negative for all events, which is consistent with the nature of this teleconnection pattern.

Climatological Large-Scale Circulation Patterns over The Middle Americas Region

In this study, twenty large-scale circulation patterns are identified to generate a synoptic classification of Weather Types (WT) over a region that comprises Mexico, the Intra-Americas Seas, Central America, and northern South America. This classification is performed using Self-Organizing Maps (SOMs) with mean sea-level pressure standardized anomalies from reanalysis. The influence of quasi-permanent pressure centers over the region, such as North Atlantic Subtropical High (NASH) and North Pacific High (NPH) are well captured. Seasonal variability of high-pressure centers for dry (November–April) and wet (May–October) periods over the entire region are also well represented in amplitude and pattern among the WTs. The NASH influence and intensification of the Caribbean low-level jet and the North American monsoon system is well captured. During the dry period, a strong trough wind advects cold air masses from mid-latitudes to the subtropics over the western Atlantic Ocean. High-frequency transitions among WTs tend to cluster around the nearest neighbors in SOM space, while low-frequency transitions occur along columns instead of rows in the SOM matrix. Low-frequency transitions are related to intraseasonal and seasonal scales. The constructed catalog can identify near-surface atmospheric circulation patterns from a unified perspective of synoptic climate variability, and it is in high agreement with previous studies for the region.