Vertical distribution, seasonality and troposphericity of ice-supersaturated air masses in the northern mid-latitudes from regular in-situ observations by passenger aircraft

2020 ◽  
Author(s):  
Andreas Petzold ◽  
Susanne Rohs ◽  
Mihal Rütimann ◽  
Patrick Neis ◽  
Berkes Florian ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Vertical Distribution ◽  
North Atlantic ◽  
Observation Data ◽  
European Research ◽  
Air Masses ◽  
The North ◽  
The North Atlantic ◽  
Passenger Aircraft ◽  
The Vertical Distribution

<p>The vertical distribution and seasonal variation of water vapour volume mixing ratio (H<sub>2</sub>O VMR), relative humidity with respect to ice (RH<sub>ice</sub>) and particularly of regions with ice-supersaturated air masses (ISSR) in the extratropical upper troposphere and lowermost stratosphere are investigated at northern mid-latitudes over the regions Eastern North America, the North Atlantic and Europe for the period 1995 to 2010.</p><p>Observation data originate from regular and continuous long-term measurements of H<sub>2</sub>O VMR, temperature and RH<sub>ice</sub> by instrumented passenger aircraft in the framework of the European research program MOZAIC which is continued as European research infrastructure IAGOS (from 2011; see www.iagos.org). The observation data are analysed with respect to the thermal and dynamical tropopauses, as provided by ERA-Interim. Additionally, collocated O<sub>3</sub> observations from MOZAIC are used as tracer for stratospheric air masses.</p><p>Our key results provide in-depth insight into seasonal and regional variability and tropospheric nature of ice-supersaturated air masses at various distances from the tropopause layer. For the vertical distribution and seasonal variation of ISSR occurrence we show a comparison of our results to radio soundings and to satellite observations of cirrus cloud occurrence from AIRS and TOVs Path B instruments. Finally, for all three regions, we investigate the trends and the dependencies of ISSR occurrence on the North Atlantic Oscillation (NAO) index.</p>

scholarly journals Ice-supersaturated air masses in the northern mid-latitudes from regular in-situ observations by passenger aircraft: vertical distribution, seasonality and tropospheric fingerprint

2019 ◽  
Author(s):  
Andreas Petzold ◽  
Patrick Neis ◽  
Mihal Rütimann ◽  
Susanne Rohs ◽  
Florian Berkes ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Observation Data ◽  
European Research ◽  
Air Masses ◽  
The North ◽  
Upper Tropospheric Humidity ◽  
In Situ Observations ◽  
Passenger Aircraft ◽  
The Vertical Distribution

Abstract. The vertical distribution and seasonal variation of upper tropospheric humidity (UTH) and particularly of ice-supersaturated air masses in the extratropical upper troposphere and lowermost stratosphere (Ex-UTLS) is investigated at northern mid-latitudes over the regions Eastern North America, the North Atlantic and Europe for the period 1995 to 2010. Observation data originate from regular and continuous long-term measurements of water vapour volume mixing ratio (H2O VMR), temperature and relative humidity with respect to ice (RHice) by instrumented passenger aircraft in the framework of the European research program MOZAIC (1994–2010) which is continued as European research infrastructure IAGOS (from 2011). The in-situ observations of UTH with a vertical resolution of 30 hPa (

Vertical distribution of cephalopods at 40°N, 53°N and 60°N at 20°W in the North Atlantic

1975 ◽  
Vol 55 (1) ◽  
pp. 143-163 ◽  
Author(s):  
C. C. Lu ◽  
M. R. Clarke
Keyword(s):  
Vertical Distribution ◽  
North Atlantic ◽  
The North ◽  
The North Atlantic ◽  
The Mediterranean ◽  
The 1960S ◽  
The Vertical Distribution

Little work on vertical distribution of cephalopods was possible before the development, in the 1960s, of sophisticated opening-closing devices usable on midwater trawls such as the 10 ft Isaacs Kidd trawl (IKMT; Foxton, 1963; Aron et al. 1964) and the series of rectangular midwater trawls developed by the Institute of Oceanographic Sciences (previously the National Institute of Oceanography) (Clarke, 1969 a; Baker et al. 1973). These developments have resulted in three papers on vertical distribution of cephalopods in the North Atlantic (Clarke, 1969 ft; Gibbs & Roper, 1970; Clarke & Lu, 1974) and one for the Mediterranean (Roper, 1972). The present paper describes the vertical distribution of cephalopods caught at 40° N 20° W, 53° N 20° W and 60° N 20° W in the North Atlantic based upon day and night series of horizontal hauls between the surface and 2000 m using the RMT combination net (Baker et al. 1973).

Observations on the Vertical Distribution of the Genus Acanthephyra (Crustacea: Decapoda) in the eastern North Atlantic, with particular reference to Species of the ‘purpurea’ Group.

1972 ◽  
Vol 73 ◽  
pp. 301-313 ◽  
Author(s):  
P. Foxton
Keyword(s):  
Vertical Distribution ◽  
North Atlantic ◽  
South Atlantic ◽  
The North ◽  
Mesopelagic Zone ◽  
Vertical Distributions ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
The Vertical Distribution ◽  
Mesopelagic Species

SynopsisThe vertical distribution of pelagic decapods has been investigated at six positions, each located approximately at 10° interval of latitude between 11°N and 60°N in the eastern North Atlantic. An account of the day and night depth distribution of four mesopelagic species, Acanthephyra purpurea, A. pelagica, A. sexspinosa and A. acanthitelsonis, and four bathypelagic species, A. prionota, A. curtirostris, A. acutifrons and A. stylorostratis, is presented. The four mesopelagic species have vertical distributions which vary latitudinally in association with geographical gradients in temperature, the mesopelagic zone from about the latitude of 28°N cooling both polewards and equatorwards. It is concluded that environmental temperature is a major factor in controlling the vertical ranges of these species although other physical variables, principally light, must also be involved.A faunal boundary exists in the region of 18°N, where the North Atlantic species A. purpurea and A.pelagica are replaced by the Central and South Atlantic species A. sexspinosa and A. acanthitelsonis. The nature of the physical boundary is not clear, but it is tentatively proposed that it represents a relatively broad area where the North Atlantic Central Water and South Atlantic Central Water meet.

scholarly journals Ice-supersaturated air masses in the northern mid-latitudes from regular in situ observations by passenger aircraft: vertical distribution, seasonality and tropospheric fingerprint

2020 ◽  
Vol 20 (13) ◽  
pp. 8157-8179 ◽  
Author(s):  
Andreas Petzold ◽  
Patrick Neis ◽  
Mihal Rütimann ◽  
Susanne Rohs ◽  
Florian Berkes ◽  
...  
Keyword(s):  
North Atlantic ◽  
Occurrence Probability ◽  
European Regions ◽  
Air Masses ◽  
The North ◽  
In Situ Observations ◽  
The North Atlantic ◽  
Passenger Aircraft

Abstract. The vertical distribution and seasonal variation of water vapour volume mixing ratio (H2O VMR), of relative humidity with respect to ice (RHice) and particularly of regions with ice-supersaturated air masses (ISSRs) in the extratropical upper troposphere and lowermost stratosphere are investigated at northern mid-latitudes over the eastern North American, North Atlantic and European regions for the period 1995 to 2010. Observation data originate from regular and continuous long-term measurements on board instrumented passenger aircraft in the framework of the European research programme MOZAIC (1994–2010), which continues as the European research infrastructure IAGOS (from 2011). Data used in our study result from collocated observations of O3 VMR, RHice and temperature, as well as H2O VMR deduced from RHice and temperature data. The in situ observations of H2O VMR and RHice with a vertical resolution of 30 hPa (< 750 m at the extratropical tropopause level) and a horizontal resolution of 1 km resolve detailed features of the distribution of water vapour and ice-supersaturated air relative to the thermal tropopause, including their seasonal and regional variability and chemical signatures at various distances from the tropopause layer. Annual cycles of the investigated properties document the highest H2O VMR and temperatures above the thermal tropopause in the summer months, whereas RHice above the thermal tropopause remains almost constant in the course of the year. Over all investigated regions, upper tropospheric air masses close to the tropopause level are nearly saturated with respect to ice and contain a significant fraction of ISSRs with a distinct seasonal cycle of minimum values in summer (30 % over the ocean, 20 %–25 % over land) and maximum values in late winter (35 %–40 % over both land and ocean). Above the thermal tropopause, ISSRs are occasionally observed with an occurrence probability of 1.5 ± 1.1 %, whereas above the dynamical tropopause at 2 PVU (PVU: potential vorticity unit), the occurrence probability increases 4-fold to 8.4 ± 4.4 %. In both coordinate systems related to tropopause height (TPH), the ISSR occurrence probabilities drop to values below 1 % for the next higher air mass layer with pressure levels p < pTPH−15 hPa. For both tropopause definitions, the tropospheric nature or fingerprint, based on O3 VMR, indicates the continuing tropospheric influence on ISSRs inside and above the respective tropopause layer. For the non-ISSRs, however, the stratospheric nature is clearly visible above the thermal tropopause, whereas above the dynamical tropopause the air masses show a still substantial tropospheric influence. For all three regions, seasonal deviations from the long-term annual cycle of ISSR occurrence show no significant trends over the observation period of 15 years, whereas a statistically significant correlation between the North Atlantic Oscillation (NAO) index and the deviation of ISSR occurrence from the long-term average is observed for the North Atlantic region but not for the eastern North American and European regions.

scholarly journals Composite analysis of the tropopause inversion layer in extratropical baroclinic waves

2019 ◽  
Vol 19 (10) ◽  
pp. 6621-6636 ◽  
Author(s):  
Thorsten Kaluza ◽  
Daniel Kunkel ◽  
Peter Hoor
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Inversion Layer ◽  
Static Stability ◽  
Composite Analysis ◽  
Sea Level Pressure ◽  
Air Masses ◽  
Upper Troposphere ◽  
The North ◽  
The North Atlantic

Abstract. The evolution of the tropopause inversion layer (TIL) during cyclogenesis in the North Atlantic storm track is investigated using operational meteorological analysis data (Integrated Forecast System from the European Centre for Medium-Range Weather Forecasts). For this a total of 130 cyclones have been analysed during the months August through October between 2010 and 2014 over the North Atlantic. Their paths of migration along with associated flow features in the upper troposphere and lower stratosphere (UTLS) have been tracked based on the mean sea level pressure field. Subsets of the 130 cyclones have been used for composite analysis using minimum sea level pressure to filter the cyclones based on their strength. The composite structure of the TIL strength distribution in connection with the overall UTLS flow strongly resembles the structure of the individual cyclones. Key results are that a strong dipole in TIL strength forms in regions of cyclonic wrap-up of UTLS air masses of different origin and isentropic potential vorticity. These air masses are associated with the cyclonic rotation of the underlying cyclones. The maximum values of enhanced static stability above the tropopause occur north and northeast of the cyclone centre, vertically aligned with outflow regions of strong updraft and cloud formation up to the tropopause, which are situated in anticyclonic flow patterns in the upper troposphere. These regions are co-located with a maximum of vertical shear of the horizontal wind. The strong wind shear within the TIL results in a local minimum of Richardson numbers, representing the possibility for turbulent instability and potential mixing (or air mass exchange) within regions of enhanced static stability in the lowermost stratosphere.

scholarly journals Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment – Part 1: Distributions and variability

2016 ◽  
Vol 16 (13) ◽  
pp. 8643-8666 ◽  
Author(s):  
Eunsil Jung ◽  
Bruce A. Albrecht ◽  
Graham Feingold ◽  
Haflidi H. Jonsson ◽  
Patrick Chuang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Cloud Base ◽  
Cumulus Clouds ◽  
Air Masses ◽  
Shallow Marine ◽  
Cloud Radar ◽  
Aerosol Cloud ◽  
The North ◽  
The North Atlantic

Abstract. Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment- BACEX, March–April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter), particles that are large enough to be effective giant cloud condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer), Africa (Saharan air layer), and mid-latitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ∼ 3 km, while most clouds were less than 1 km deep. Clouds tend to precipitate when the cloud is thicker than 500–600 m. Distributions of cloud field characteristics (depth, radar reflectivity, Doppler velocity, precipitation) were well identified in the reflectivity–velocity diagram from the cloud radar observations. Two types of precipitation features were observed for shallow marine cumulus clouds that may impact boundary layer differently: first, a classic cloud-base precipitation where precipitation shafts were observed to emanate from the cloud base; second, cloud-top precipitation where precipitation shafts emanated mainly near the cloud tops, sometimes accompanied by precipitation near the cloud base. The second type of precipitation was more frequently observed during the experiment. Only 42–44 % of the clouds sampled were non-precipitating throughout the entire cloud layer and the rest of the clouds showed precipitation somewhere in the cloud, predominantly closer to the cloud top.

scholarly journals Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

2010 ◽  
Vol 10 (21) ◽  
pp. 10223-10236 ◽  
Author(s):  
J. B. Gilman ◽  
J. F. Burkhart ◽  
B. M. Lerner ◽  
E. J. Williams ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Transport Model ◽  
Arctic Basin ◽  
The Arctic ◽  
Arctic Boundary Layer ◽  
Air Masses ◽  
The North ◽  
The North Atlantic

Abstract. The influence of halogen oxidation on the variabilities of ozone (O3) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N) was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

Vertical distribution of cephalopods at 11°N, 20°W in the North Atlantic

1975 ◽  
Vol 55 (2) ◽  
pp. 369-389 ◽  
Author(s):  
C. C. Lu ◽  
M. R. Clarke
Keyword(s):  
Vertical Distribution ◽  
North Atlantic ◽  
The North ◽  
North Eastern ◽  
The North Atlantic

This is one of a series of four papers dealing with vertical distribution of cephalopods in the North Eastern Atlantic at six stations near 20° W and at about 10° intervals from 60°N to 11° N (Clarke & Lu, 1974, 1975 a; Lu & Clarke, 1975). The present study is based upon a series of hauls made at discrete horizons between o and 2000 m with opening-closing nets during both daylight and darkness. The collections were made for the ecological programme of the National Institute of Oceanography, Wormley, Surrey, England (now part of the Institute of Oceanographic Sciences).

scholarly journals Importance of the Saharan Heat Low on the control of the North Atlantic free tropospheric humidity deduced from IASI δD observations

2017 ◽  
Author(s):  
Jean-Lionel Lacour ◽  
Cyrille Flamant ◽  
Camille Risi ◽  
Cathy Clerbaux ◽  
Pierre-François Coheur
Keyword(s):  
North Atlantic ◽  
Turbulent Mixing ◽  
Added Value ◽  
Free Troposphere ◽  
Air Masses ◽  
Annual Variations ◽  
The North ◽  
The North Atlantic ◽  
Different Sources ◽  
Heat Low

Abstract. The isotopic composition of water vapour in the North Atlantic free troposphere is investigated with IASI measurements of the D/H ratio (δD) above the ocean. We show that in the vicinity of West Africa, the seasonality of δD is particularly strong (160 ‰), which is related with the installation of the Saharan Heat Low (SHL) during summertime. The SHL indeed largely influences the dynamic in that region by producing deep turbulent mixing layers, yielding a specific water vapor isotopic footprint. The influence of the SHL on the isotopic budget is analysed at various time and space scales and is shown to be large, highlighting the importance of the SHL dynamics on the moistening and the HDO-enrichment of the free troposphere over the North Atlantic. We also report important inter-annual variations of δD above Izana (Canary Islands) that we interpret, using backward trajectory analyses, in terms of the ratio of air-masses coming from the North Atlantic and air-masses coming from the African continent. Finally, we present spatial distributions of δD and humidity above the North Atlantic and we show that the different sources and dehydration pathways controlling the humidity can be disentangled thanks to the added value of δD observations.

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