Polar Air Research Articles

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.

Spatial and temporal characteristics of stable isotopes in the Tarim River Basin

By using 233 isotope samples, we investigated the spatial and temporal variations of δ18O and δ2H in precipitation and surface water, and the contribution of different water sources in the rivers within the Tarim River Basin (TRB), which receives snow/glacier meltwater, groundwater, and rainfall. Our study revealed a similar seasonal pattern of precipitation δ18O and δ2H at both the north and south edges of the basin, indicating the dominant effect of westerly air masses in the summer and the combined influence of westerly and polar air masses during the winter, although the southern part showed more complex precipitation processes in the summer. River water in the basin has relatively large temporal variations in both δ18O and δ2H showing a distinct seasonal pattern with lower isotope values in May than in September. Higher d-excess values throughout the year in the Aksu river and the Tizinafu river suggest that water may be intensively recycled in the mountains of the TRB. Based on isotopic hydrograph separation, we found that groundwater is the main water source that discharges the entire basin although individual rivers vary.

ANÁLISE ATMOSFÉRICA DOS EVENTOS DE EFEITO SECUNDÁRIO DO BURACO DE OZÔNIO ANTÁRTICO SOBRE O SUL DO BRASIL EM 2012. PARTE 1: IDENTIFICAÇÃO DOS EVENTOS E ANÁLISE DA DINÂMICA DA ESTRATOSFERA

In this study were identified events of Influence of the Antarctic ozone hole over southern Brazil in the year 2012. For this, we analyzed the daily average data of total ozone column obtained through Brewer Spectrophotometer, installed in the southern Space Observatory-OESCRSINPE-MCTI (29.4° S; 53.8°; 488 m) and by satellite instruments Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI), seeking days of falls in the ozone content. For these days, we analyzed potential vorticity maps made using Reanalysis data provided by NCEPNCAR and retroactive trajectories made through the Hysplit model of NOAA, in order to verify the origin of the polar air mass poor in ozone. In addition, it was also conducted a complementary analysis through the images of the ozone content of the OMI satellite, verifying the performance of the Antarctic Ozone Hole in polar regions and its connection with the Southern Brazil. The methodology used was shown to be effective in the identification of 2 events of side effect of the Antarctic ozone hole over the South of Brazil, which showed a fall of 12.1 ± 2.3 average in the ozone content.

Estimating geometric anisotropy in spatial point patterns

Anisotropy in stationary spatial point patterns is investigated. We develop a two-stage non-parametric method for quantifying geometric anisotropy arising for example when the pattern is compressed or stretched. First, we fit ellipsoids to the pattern of pairwise difference vectors to estimate the direction of anisotropy. Then, we estimate the scale of anisotropy by identifying the back-transformation resulting in the most isotropic pattern. We demonstrate the applicability of the method mainly for regular patterns by numerical examples, and use it to improve the estimation of compression in 3D polar ice air bubble patterns.

Circulation patterns governing October snowfalls in southern Siberia

This study is focused on early fall season in southern Siberia (50–60 N) and is purposed as a contribution to the discussion on the climatic relevance of October Eurasian snow cover. Analysis is based on the daily snow depth data from 43 stations from years 1980–2012, available in the database of All-Russian Research Institute of Hydrometeorological Information—World Data Centre. The snow cover season in southern Siberia starts in early autumn and the number of days with snowfall varies from less than 5 days in the southernmost zone along the parallel 50 N to more than 25 days in the northeastern part of the analyzed area. October snowfall in southern Siberia is associated with occurrence of negative anomalies of sea level pressure (SLP), usually spreading right over the place of recorded intense snowfall or extending eastward from it. Negative anomalies of air temperature at the 850 hPa geopotential level (T850) occurring with increased cyclonic activity are also observed. Negative T850 anomalies are located west or northwest of the SLP depressions. Counterclockwise circulation around low-pressure systems transports cold Arctic air from the north or even colder Siberian polar air from the east, to the west, and northwest parts of cyclones, and induces negative anomalies of temperature. The pattern of T850 anomalies during heavy snowfalls in the eastern part of the southern Siberia is shifted counterclockwise in regard to SLP anomalies: the strongest negative T850 anomalies are located west or northwest of the SLP depressions.

Water vapor, atmospheric electricity, and radon transfer to the near-surface soil layers and the atmosphere

Water vapor is able to transfer radon to the near-surface atmosphere. The ionizer concentration changes insignificantly because of the small thickness of the soil layer, from which evaporation occurs. The injection of water vapor into the near-surface air increases the density of neutral condensation nuclei and the atmospheric electric field. Evaporation clears the pore space, which facilitates the discharge of radon to the atmosphere and the enhancement of polar air conductivity.

GÊNESE E EVOLUÇÃO DAS TEMPERATURAS MÍNIMAS ABSOLUTAS NA REGIÃO CENTRO-SUL DO PARANÁ: A INFLUÊNCIA DA DINÂMICA ATMOSFÉRICA E DO RELEVO LOCAL

This study analyzed the frequency and intensity of absolute minimum temperatures associated with atmospheric systems in the Central Southern Paraná State. It was selected the municipalities of Guarapuava, Palmas, and Irati to represent the area, both considering the location and the available database. Daily temperature data provided by Agronomic Institute of Paraná (IAPAR) and National Meteorological Institute (INMET) and satellite imagery provided by Technological Institute of Paraná (SIMEPAR) were analyzed in the winter seasons from 2004 to 2012. Data of temperature were tabulated in Microsoft Excel and satellite imagery was analyzed through videos produced in Windows Live™ Movie Maker®. The highest influence of polar air masses (mPa and mPp) was prevalent, but the continental tropical mass frequently affected the study period, by reducing the surface cooling for several days.Keywords: air masses, negative temperatures, geographical climatology.

Daily global mapping of Mars ozone column abundances with MARCI UV band imaging

Since November of 2006, The Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) has obtained multiple-filter daily global images of Mars centered upon a local time (LT) of 3pm. Ultraviolet imaging bands placed within (260nm) and longward (320nm) of Hartley band (240–300nm) ozone (O3) absorption support retrievals of atmospheric ozone columns, with detection limits (∼1μm-atm) appropriate to mapping elevated O3 abundances at low latitudes around Mars aphelion, and over mid-to-high latitudes during fall/winter/spring seasons. MARCI O3 maps for these regions reveal the detailed spatial (∼1°lat/long, for 8×8pixel binned resolution) and temporal (daily, with substantial LT coverage at pole) behaviors of water vapor saturation conditions that force large variations in water vapor photolysis products (HOx-OH, HO2, and H) responsible for the catalytic destruction of O3 in the Mars atmosphere. A detailed description of the MARCI O3 data set, including measurement and retrieval characteristics, is provided in conjunction with comparisons to Mars Express SPICAM ozone measurements (Perrier, S. et al. [2006]. J. Geophys. Res. (Planets) 111) and LMD GCM simulated O3 abundances (Lefèvre, F. [2004]. J. Geophys. Res. (Planets) 109). Presented aspects of the MARCI ozone mapping data set include aphelion increases in low latitude O3, dynamically evolving high latitude O3 maxima associated with planetary waves and weather fronts during northern early spring, and distinctive winter/spring O3 and CO increases within the Hellas Basin associated with transport of condensation-enhanced south polar air mass. Comparisons of coincident MARCI measurements and LMD simulations for ice cloud and O3 columns are considered in the context of potential heterogeneous photochemical processes (Lefèvre, F. [2008]. Nature 454, 971–975), which are not strongly evidenced in the MARCI observations. Modest interannual variations are exhibited, most notably a 20% reduction in aphelion low latitude O3 columns following the 2007 perihelic global dust storm.

Charge and discharge of polar cold air mass in northern hemispheric winter

AbstractThis study shows the variability of polar cold air mass amount below potential temperature of 280 K, and north of 45°N can be understood with a concept of charge and discharge, where anomalously large daily discharge indicates an intermittent occurrence of cold air outbreak. The polar cold air mass amount north of 45°N gradually charges up due to diabatic cooling but dramatically discharges due to cold air outbreak with a pulse width of about 5 days. Cold air outbreaks tend to bring colder winter in East Asia and the east coast of North America, while warmer winter prevails on the northern side of these regions. The cold air mass amount south of 45°N increases just after a cold air outbreak but returns to the normal level soon because of its life time of about 3 days. Therefore, monthly mean of total cold air mass amount in the Northern Hemisphere is negatively correlated with the monthly mean discharge.

Dynamic Linkage between Cold Air Outbreaks and Intensity Variations of the Meridional Mass Circulation

Abstract This study investigates the dynamical linkage between the meridional mass circulation and cold air outbreaks using the ERA-Interim data covering the period 1979–2011. It is found that the onset date of continental-scale cold air outbreaks coincides well with the peak time of stronger meridional mass circulation events, when the net mass transport across 60°N in the warm or cold air branch exceeds ~88 × 109 kg s−1. During weaker mass circulation events when the net mass transport across 60°N is below ~71.6 × 109 kg s−1, most areas of the midlatitudes are generally in mild conditions except the northern part of western Europe. Composite patterns of circulation anomalies during stronger mass circulation events greatly resemble that of the winter mean, with the two main routes of anomalous cold air outbreaks being along the climatological routes of polar cold air: namely, via East Asia and North America. The Siberian high shifts westward during stronger mass circulation events, opening up a third route of cold air outbreaks through eastern Europe, where lies the poleward warm air route in the winter-mean condition. The strengthening of the Icelandic low and Azores high during stronger mass circulation events acts to close off the climatological-mean cold air route via western Europe; this is responsible for the comparatively normal temperature there. The composite pattern for weaker mass circulation events is generally reversed, where the weakening of the Icelandic low and Azores high, corresponding to the negative phase of the North Atlantic Oscillation (NAO), leads to the reopening and strengthening of the equatorward cold air route through western Europe, which is responsible for the cold anomalies there.

Air mass distribution and the heterogeneity of the climate change signal in the Hudson Bay/Foxe Basin region, Canada

The linkage between changes in air mass distribution and temperature trends from 1971 to 2010 is explored in the Hudson Bay/Foxe Basin region. Statistically significant temperature increases were found of varying spatial and temporal magnitude. Concurrent statistically significant changes in air mass frequency at the same locations were also detected, particularly in the declining frequency of dry polar (DP) air. These two sets of changes were found to be linked, and we thus conclude that the heterogeneity of the climatic warming signal in the region is at least partially the result of a fundamental shift in the concurrent air mass frequency in addition to global and regional changes in radiative forcing due to increases in long-lived greenhouse gases.

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5μm (H-band) were performed during the same night using instruments with adaptive optics at both the W.M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate resolving power, R=λ/Δλ≈1500, while the Keck observations were performed with NIRSPAO near 1.5525μm at higher resolution, R≈25,000. The moderate resolution observations are used for flux calibration and for the determination of model parameters that can be degenerate in the interpretation of high resolution spectra. Line-by-line calculations of CH4 and CH3D correlated k distributions from the HITRAN 2012 database were used, which incorporate revised line assignments near 1.5μm. We fit the surface albedo and aerosol distributions in the VLT SINFONI observations that cover the entire H-band window and used these quantities to constrain the models of the high-resolution Keck NIRSPAO spectra when retrieving the methane abundances. Cassini VIMS images of the polar regions, acquired on 20 July 2014 UT, are used to validate the assumption that the opacity of tropospheric aerosol is relatively uniform below 10km. We retrieved methane abundances at latitudes between 42°S and 80°N. The tropospheric methane in the Southern mid-latitudes was enhanced by a factor of ∼10–40% over the nominal profile that was measured using the GCMS on Huygens. The northern hemisphere had ∼90% of the nominal methane abundance up to polar latitudes (80°N). These measurements suggest that a source of saturated polar air is equilibrating with dryer conditions at lower latitudes.

Characteristics of atmospheric precipitation isotopes and isotopic evidence for the moisture origin in Yushugou River basin, Eastern Tianshan Mountains, China

Based on the variations in stable hydrogen and oxygen isotope ratios (δD and δ18O) of precipitation and NCEP/NCAR (National Centers of Environmental Prediction/National Center for Atmospheric Research) re-analysis data, we investigated the characteristics of the precipitation isotopes and the moisture origin during spring and summer seasons (from May to August) in the Yushugou River basin, East Tianshan Mountains. The more negative δ18O and higher d-excess values in spring and more positive δ18O and lower d-excess values in summer indicated the different moisture sources and temperature effects on isotope variations. By studying the meteoric water line, we found that the slope and intercept of local meteoric water line (LMWL) were lower than the global meteoric water line (GMWL) and China LMWL, which indicated arid climate. The temperature effect of δD and δ18O in precipitation was obvious with correlation coefficients of 0.41 and 0.48, respectively, and there was no rainfall effect. The research of water vapor transfer showed that the moisture origin was predominantly from westerly air masses during the observation period. δ18O and d-excess values variations in precipitation and the HYSPLIT4.0 air mass trajectory model suggested that there were accidental events, and sometimes the moisture was from drier polar air masses during the spring.

Relationship between Warm Airmass Transport into the Upper Polar Atmosphere and Cold Air Outbreaks in Winter

Abstract This study investigates dominant patterns of daily surface air temperature anomalies in winter (November–February) and their relationship with the meridional mass circulation variability using the daily Interim ECMWF Re-Analysis in 1979–2011. Mass circulation indices are constructed to measure the day-to-day variability of mass transport into the polar region by the warm air branch aloft and out of the polar region by the cold air branch in the lower troposphere. It is shown that weaker warm airmass transport into the upper polar atmosphere is accompanied by weaker equatorward advancement of cold air in the lower troposphere. As a result, the cold air is largely imprisoned within the polar region, responsible for anomalous warmth in midlatitudes and anomalous cold in high latitudes. Conversely, stronger warm airmass transport into the upper polar atmosphere is synchronized with stronger equatorward discharge of cold polar air in the lower troposphere, resulting in massive cold air outbreaks in midlatitudes and anomalous warmth in high latitudes. There are two dominant geographical patterns of cold air outbreaks during the cold air discharge period (or 1–10 days after a stronger mass circulation across 60°N). One represents cold air outbreaks in midlatitudes of both North America and Eurasia, and the other is the dominance of cold air outbreaks only over one of the two continents with abnormal warmth over the other continent. The first pattern mainly corresponds to the first and fourth leading empirical orthogonal functions (EOFs) of daily surface air temperature anomalies in winter, whereas the second pattern is related to the second EOF mode.

Génesis de tormentas severas y su incidencia en la Región de Murcia

En el Sureste peninsular son constantes las situaciones de inestabilidad convectiva alimentadas en niveles altos atmosféricos por irrupciones de masas de aire ártica/polar. Bajo estas condiciones, debido al desplazamiento de los núcleos convectivos, las cuencas y valles fluviales intrabéticos son bastante proclives a los meteoros severos, tales como lluvias torrenciales, granizo o descargas eléctricas. Uno de los sistemas más perjudiciales, las supercélulas, suelen gestarse en los meses estivales o tardo-estivales, especialmente con la superficie terrestre muy calentada, acompañado además de altos índices de cizalla y helicidad. En este trabajo se analizan estos factores y las situaciones de inestabilidad convectiva más importantes registradas en la Región de Murcia (Sureste de España) en época reciente. La zona más afectada por las tormentas severas corresponde al norte de la Región, principalmente debido a vaguadas y vórtices fríos de origen ártico/polar marítimo de onda corta. Para ello se han utilizado: (i) los datos de estaciones meteorológicas en superficie y (ii) los sondeos aerológicos disponibles en el área, en particular los relativos a régimen de temperaturas, estratificación térmica vertical e indicadores de inestabilidad atmosférica. Se han obtenido correlaciones entre diferentes variables tormentosas, mostrando, por ejemplo, una buena relación la altitud con el número de días de tormenta, pero no así con las tormentas severas.

Physics of Climate Change: Harmonic and exponential processes from in situ ocean time series observations show rapid asymmetric warming.

Physics of Climate Change: Harmonic and exponential processes from in situ ocean time series observations show rapid asymmetric warming.

Global Hawk dropsonde observations of the Arctic atmosphere obtained during the Winter Storms and Pacific Atmospheric Rivers (WISPAR) field campaign

Abstract. In February and March of 2011, the Global Hawk unmanned aircraft system (UAS) was deployed over the Pacific Ocean and the Arctic during the Winter Storms and Pacific Atmospheric Rivers (WISPAR) field campaign. The WISPAR science missions were designed to (1) mprove our understanding of Pacific weather systems and the polar atmosphere; (2) evaluate operational use of unmanned aircraft for investigating these atmospheric events; and (3) demonstrate operational and research applications of a UAS dropsonde system at high latitudes. Dropsondes deployed from the Global Hawk successfully obtained high-resolution profiles of temperature, pressure, humidity, and wind information between the stratosphere and surface. The 35 m wingspan Global Hawk, which can soar for ~ 31 h at altitudes up to ~ 20 km, was remotely operated from NASA's Dryden Flight Research Center at Edwards Air Force Base (AFB) in California. During the 25 h polar flight on 9–10 March 2011, the Global Hawk released 35 sondes between the North Slope of Alaska and 85° N latitude, marking the first UAS Arctic dropsonde mission of its kind. The polar flight transected an unusually cold polar vortex, notable for an associated record-level Arctic ozone loss, and documented polar boundary layer variations over a sizable ocean–ice lead feature. Comparison of dropsonde observations with atmospheric reanalyses reveal that, for this day, large-scale structures such as the polar vortex and air masses are captured by the reanalyses, while smaller-scale features, including low-level jets and inversion depths, are mischaracterized. The successful Arctic dropsonde deployment demonstrates the capability of the Global Hawk to conduct operations in harsh, remote regions. The limited comparison with other measurements and reanalyses highlights the potential value of Arctic atmospheric dropsonde observations where routine in situ measurements are practically nonexistent.

Nitrate postdeposition processes in Svalbard surface snow

AbstractThe snowpack acts as a sink for atmospheric reactive nitrogen, but several postdeposition pathways have been reported to alter the concentration and isotopic composition of snow nitrate with implications for atmospheric boundary layer chemistry, ice core records, and terrestrial ecology following snow melt. Careful daily sampling of surface snow during winter (11–15 February 2010) and springtime (9 April to 5 May 2010) near Ny‐Ålesund, Svalbard reveals a complex pattern of processes within the snowpack. Dry deposition was found to dominate over postdeposition losses, with a net nitrate deposition rate of (0.6 ± 0.2) µmol m−2 d−1 to homogeneous surface snow. At Ny‐Ålesund, such surface dry deposition can either solely result from long‐range atmospheric transport of oxidized nitrogen or include the redeposition of photolytic/bacterial emission originating from deeper snow layers. Our data further confirm that polar basin air masses bring 15N‐depleted nitrate to Svalbard, while high nitrate δ(18O) values only occur in connection with ozone‐depleted air, and show that these signatures are reflected in the deposited nitrate. Such ozone‐depleted air is attributed to active halogen chemistry in the air masses advected to the site. However, here the Ny‐Ålesund surface snow was shown to have an active role in the halogen dynamics for this region, as indicated by declining bromide concentrations and increasing nitrate δ(18O), during high BrO (low‐ozone) events. The data also indicate that the snowpack BrO‐NOx cycling continued in postevent periods, when ambient ozone and BrO levels recovered.

Composition of 15–85 nm particles in marine air

Abstract. The chemical composition of 15–85 nm diameter particles was measured at Mace Head, Ireland, during May 2011 using the TDCIMS (thermal desorption chemical ionization mass spectrometer). Measurable levels of chloride, sodium, and sulfate were present in essentially all collected samples of these particles at this coastal Atlantic site. Acetaldehyde and benzoic acid were also frequently detected. Concomitant particle hygroscopicity observations usually showed a sea-salt mode and a lower hygroscopicity mode with growth factors near to that of ammonium sulfate. There were many periods lasting from hours to about 2 days during which the 10–60 nm particle number increased dramatically in polar oceanic air. These periods were correlated with the presence of benzoic acid in the particles and an increase in the number of lower hygroscopicity mode particles. Very small (< 10 nm) particles were also present, suggesting that new particle formation contributed to these nanoparticle enhancement events.

Tornadoes in the Central United States and the “Clash of Air Masses”

After tornado outbreaks or individual violent tornadoes occur in the central United States, media stories often attribute the location, number, or intensity of tornadoes to the “clash of air masses” between warm tropical air and cold polar air. This article argues that such a characterization of tornadogenesis is oversimplified, outdated, and incorrect. Airmass boundaries and associated temperature gradients can be important in tornadogenesis, but not in the ways envisioned on the synoptic scale with the clash-of-air-masses conceptual model. In fact, excessively strong horizontal temperature gradients (either on the synoptic scale or associated with a storm's own cool outflow) may be detrimental to tornadogenesis. Where adjacent air masses are relevant is through their vertical distribution that produces the requisite instability for the convective storm, but that instability is not directly related to the formation of tornadoes. Therefore, this article recommends that a greater effort be made to communic...