Research

6211 KiB

Open AccessArticle

The Niger River Basin Moisture Sources: A Lagrangian Analysis

by Rogert Sorí, Raquel Nieto, Anita Drumond and Luis Gimeno

Atmosphere 2017, 8(2), 38; https://doi.org/10.3390/atmos8020038 - 14 Feb 2017

Cited by 10 | Viewed by 5745

The Niger River basin (NRB) is located in the important climatic region of the African Sahel. In this study we use the Lagrangian tridimensional model FLEXPART v9.0 to identify and characterise the moisture sources for the NRB. This method allows the integration of [...] Read more.

The Niger River basin (NRB) is located in the important climatic region of the African Sahel. In this study we use the Lagrangian tridimensional model FLEXPART v9.0 to identify and characterise the moisture sources for the NRB. This method allows the integration of the budget of evaporation minus precipitation over 10-day backward trajectories, thereby identifying the origins of the air masses residing over the NRB. The analysis was performed for the 35-year period from 1980 to 2014, which allowed us to identify the main semi-annual climatological moisture sources of the NRB, for November–April (NDJFMA) (dry season) and May–October (MJJASO) (wet season), and to quantify the respective moisture uptakes. Throughout the year, the NRB main moisture sources are located on the tropical eastern North Atlantic Ocean near Africa, the tropical eastern South Atlantic Ocean in the Gulf of Guinea, in the regions surrounding the Sahel and in the Mediterranean Sea. The extents of these sources vary between dry and wet seasons. In NDJFMA two regions appear in the east of the basin, which then join up, forming a larger source to the northeast of the basin in MJJASO, when three other less important moisture sources can be seen in central-equatorial Africa, the tropical western Indian Ocean and the Persian Gulf. In NDJFMA the majority of the moisture uptake comes from the NRB itself but then, later in MJJASO, when the precipitation increases over the basin the greatest uptake of moisture occurs over the tropical eastern South Atlantic Ocean, northeast Africa and the NRB, which suggests that these are the effective sources of precipitation in the basin in overall terms. The seasonal moisture uptake quantification over the moisture sources of the NRB, reveals that largest fraction of moisture income to the basin from outside its boundaries. Despite providing moisture to the NRB the source located in the tropical eastern North Atlantic Ocean does not contribute that much to precipitation in the basin. A daily (ten-day) backward analysis shows the importance of the moisture uptake within the NRB and from near moisture sources during the first few (backward) days, while the Atlantic Ocean sources and the Mediterranean became more important during the last five (backward) days of the analysis. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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8781 KiB

Open AccessArticle

Extreme Sea Ice Loss over the Arctic: An Analysis Based on Anomalous Moisture Transport

by Marta Vázquez, Raquel Nieto, Anita Drumond and Luis Gimeno

Atmosphere 2017, 8(2), 32; https://doi.org/10.3390/atmos8020032 - 07 Feb 2017

Cited by 10 | Viewed by 5279

Abstract

The Arctic system has experienced in recent times an extreme reduction in the extent of its sea ice. The years 2007 and 2012 in particular showed maxima in the loss of sea ice. It has been suggested that such a rapid decrease has [...] Read more.

The Arctic system has experienced in recent times an extreme reduction in the extent of its sea ice. The years 2007 and 2012 in particular showed maxima in the loss of sea ice. It has been suggested that such a rapid decrease has important implications for climate not only over the system itself but also globally. Understanding the causes of this sea ice loss is key to analysing how future changes related to climate change can affect the Arctic system. For this purpose, we applied the Lagrangian FLEXible PARTicle dispersion (FLEXPART) model to study the anomalous transport of moisture for 2006/2007 and 2011/2012 in order to assess the implications for the sea ice. We used the model results to analyse the variation in the sources of moisture for the system (backward analysis), as well as how the moisture supply from these sources differs (forward analysis) during these years. The results indicate an anomalous transport of moisture for both years. However, the pattern differs between events, and the anomalous moisture supply varies both in intensity and spatial distribution for all sources. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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5713 KiB

Open AccessArticle

Tracking the Origin of Moisture over the Danube River Basin Using a Lagrangian Approach

by Danica Ciric, Milica Stojanovic, Anita Drumond, Raquel Nieto and Luis Gimeno

Atmosphere 2016, 7(12), 162; https://doi.org/10.3390/atmos7120162 - 14 Dec 2016

Cited by 24 | Viewed by 6404

Abstract

In this study, we investigate the sources of moisture (and moisture for precipitation) over the Danube River Basin (DRB) by means of a Lagrangian approach using the FLEXPART V9.0 particle dispersion model together with ERA-Interim reanalysis data to track changes in atmospheric moisture [...] Read more.

In this study, we investigate the sources of moisture (and moisture for precipitation) over the Danube River Basin (DRB) by means of a Lagrangian approach using the FLEXPART V9.0 particle dispersion model together with ERA-Interim reanalysis data to track changes in atmospheric moisture over 10-day trajectories. This approach computes the budget of evaporation-minus-precipitation by calculating changes in specific humidity along forward and backward trajectories. We considered a time period of 34 years, from 1980 to 2014, which allowed for the identification of climatological sources and moisture transport towards the basin. Results show that the DRB mainly receives moisture from seven different oceanic, maritime, and terrestrial moisture source regions: North Atlantic Ocean, North Africa, the Mediterranean Sea, Black Sea, Caspian Sea, the Danube River Basin, and Central and Eastern Europe. The contribution of these sources varies by season. During winter (October–March) the main moisture source for the DRB is the Mediterranean Sea, while during summer (April–September) the dominant source of moisture is the DRB itself. Moisture from each source has a different contribution to precipitation in the DRB. Among the sources studied, results show that the moisture from the Mediterranean Sea provides the greatest contribution to precipitation in the basin in both seasons, extending to the whole basin for the winter, but being more confined to the western side during the summer. Moisture from the Caspian and Black Seas contributes to precipitation rather less. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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4020 KiB

Open AccessArticle

Sensitive versus Rough Dependence under Initial Conditions in Atmospheric Flow Regimes

by Anthony R. Lupo, Y. Charles Li, Z. C. Feng, Neil I. Fox, Jordan L. Rabinowitz and Micheal J. Simpson

Atmosphere 2016, 7(12), 157; https://doi.org/10.3390/atmos7120157 - 05 Dec 2016

Cited by 5 | Viewed by 5487

Abstract

In this work, we will identify the existence of “rough dependence on initial conditions” in atmospheric phenomena, a concept which is a problem for weather analysis and forecasting. Typically, two initially similar atmospheric states will diverge slowly over time such that forecasting the [...] Read more.

In this work, we will identify the existence of “rough dependence on initial conditions” in atmospheric phenomena, a concept which is a problem for weather analysis and forecasting. Typically, two initially similar atmospheric states will diverge slowly over time such that forecasting the weather using the Navier-Stokes equations is useless after some characteristic time scale. With rough dependence, two initial states diverge very quickly, implying forecasting may be impossible. Using previous research in atmospheric science, rough dependence is characterized by using quantities that can be calculated using atmospheric data and quantities. Rough dependence will be tested for and identified in atmospheric phenomena at different time scales using case studies. Data were provided for this project by archives outside the University of Missouri (MU) and by using the MU RADAR at the South Farm experiment station. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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2651 KiB

Open AccessArticle

Inverse Modeling of Nitrogen Oxides Emissions from the 2010 Russian Wildfires by Using Satellite Measurements of Nitrogen Dioxide

by Evgeny V. Berezin, Igor B. Konovalov and Yulia Y. Romanova

Atmosphere 2016, 7(10), 132; https://doi.org/10.3390/atmos7100132 - 16 Oct 2016

Cited by 2 | Viewed by 5197

Abstract

Observational constraints to biomass burning (BB) NO_x emissions as provided by satellite measurements of nitrogen dioxide (NO₂) critically depend on quantitative assumptions regarding the atmospheric NO_x lifetime. In this study, we investigated NO_x emissions from the extreme wildfires [...] Read more.

Observational constraints to biomass burning (BB) NO_x emissions as provided by satellite measurements of nitrogen dioxide (NO₂) critically depend on quantitative assumptions regarding the atmospheric NO_x lifetime. In this study, we investigated NO_x emissions from the extreme wildfires that occurred in the European part of Russia in summer 2010 by using an original inverse modeling method that allowed us to avoid any a priori assumptions regarding the NO_x lifetime. The method was applied to the tropospheric NO₂ columns retrieved from the measurements performed by the OMI satellite instrument, while the relationship between BB NO_x emissions and tropospheric NO₂ columns was simulated with the CHIMERE mesoscale chemistry transport model. Our analysis indicated that this relationship depends strongly on BB emissions of volatile organic compounds and that a dependence of the effective NO_x lifetime on the NO_x fluxes can be essentially nonlinear. Our estimates of the total NO_x emissions in the study region are found to be at least 40% larger compared to the respective data from the GFASv1.0 and GFED4.1s global fire emission inventories. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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2222 KiB

Open AccessArticle

Measurements and Analysis of Polycyclic Aromatic Hydrocarbons near a Major Interstate

by Dennis K. Mikel and Viney P. Aneja

Atmosphere 2016, 7(10), 131; https://doi.org/10.3390/atmos7100131 - 16 Oct 2016

Cited by 1 | Viewed by 4287

Abstract

Polycyclic aromatic hydrocarbons (PAHs) were measured near Interstate 40, just east of Research Triangle Park, North Carolina, USA. The goals of this project were to ascertain whether a sufficient quantity of PAHs could be collected using low flow (16.7 L/minute) over 8-h periods [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) were measured near Interstate 40, just east of Research Triangle Park, North Carolina, USA. The goals of this project were to ascertain whether a sufficient quantity of PAHs could be collected using low flow (16.7 L/minute) over 8-h periods and if so, do investigate how the PAHs correlate to local sources, atmospheric pollutants and meteorology. The 8-h integrated samples were collected on 20 sampling days over a two month period during fall 2014. The samples were collected using low flow (BGI Incorporated PQ200) fine particulate samplers analyzed using gas chromatography-mass spectrometry (GC-MS). Temporal distributions of the PAHs (average mean 9.2 nanogram/cubic meter ±9.0 std) were compared to traffic count, and meteorological and pollutant data collected at the near roadway station. Using the meteorological data (i.e., wind speed and direction vector data), wind roses were created illustrating the local sources of the PAHs. In terms of correlation to atmospheric oxidants, (i.e., ozone, nitrogen dioxide and nitric oxide) wind rose analysis illustrated the morning hours which were predominantly southern winds, while the afternoon hours illustrated southerly and easterly winds, which suggests that the automobile traffic is the main source of PAHs. The nighttime hours wind rose shows winds from the northerly and easterly direction, which are predominantly from the RDU International Airport. Since the wind direction vectors illustrated that the afternoon hours (i.e., 12 p.m. to 8 p.m.) were from the interstate, comparisons were performed on the samples collected in this time period for both the traffic and pollutant data. The comparison of the traffic data showed a correlation with the number of vehicles (>60 feet i.e., heavy duty diesel engine vehicles). In addition, with the ozone, nitrogen dioxide and nitric oxide) there is a significant linear correlation between the sum of the measured PAHs with nitric oxide (NO), nitrogen dioxide (NO₂) and ozone (O₃) with the R² values being 0.1, 0.04 and 0.07 respectively. An analysis of variance (ANOVA) statistical regression was performed on the pollutant data versus the measured sum of the PAHs. With the alpha set at 0.05, (α = 0.05) the p-values for O₃, NO₂ and NO were 0.00613, 0.000496 and 0.000264, respectively, which are significant. In addition, the PAH concentration found in this study compare favorably to other published studies (0.1 to 193.6 ng/m³) both nationally and internationally. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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5020 KiB

Open AccessArticle

Satellite Assessments of Tropopause Dry Intrusions Correlated to Mid-Latitude Storms

by Yi-Xuan Shou, Feng Lu and Shaowen Shou

Atmosphere 2016, 7(10), 128; https://doi.org/10.3390/atmos7100128 - 11 Oct 2016

Cited by 1 | Viewed by 5047

Abstract

Dry intrusion is an important mid-latitude atmosphere phenomenon within the upper troposphere and lower stratosphere. It is often found to be related to the cyclogenesis, rainstorm, as well as convection generation and precipitation enhancement. Since the atmosphere environment for any of these above-mentioned [...] Read more.

Dry intrusion is an important mid-latitude atmosphere phenomenon within the upper troposphere and lower stratosphere. It is often found to be related to the cyclogenesis, rainstorm, as well as convection generation and precipitation enhancement. Since the atmosphere environment for any of these above-mentioned weather is terribly complicated, those preexisting popular schemes which takes no account of water vapor may not suitable for detecting the dry intrusion related to such weather events. With regard to the merits and demerits of the current preexisting schemes, a new scheme based on Fengyun-2E geo-stationary satellite data is presented in this study to detect the tropopause dry intrusion. The scheme is set up based on the statistical relationship between water vapor at high level troposphere, the general moist potential vorticity, ozone concentration and upper-level jets. Validations are made by using Fengyun-3B observed ozone profiles and NCEP FNL analysis data. Two mid-latitude storm episodes occurred in China in 2012 and 2014 are selected as demonstration to show the applicability of the method we developed in this study. Good application effects in both cases suggest that the new method for detecting dry intrusion is applicable and can be helpful in middle-latitude disastrous weather monitoring and forecasting. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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2431 KiB

Open AccessArticle

Phases of the Isobaric Surface Shapes in the Geostrophic State of the Atmosphere and Connection to the Polar Vortices

by Robert Zakinyan, Arthur Zakinyan and Roman Ryzhkov

Atmosphere 2016, 7(10), 126; https://doi.org/10.3390/atmos7100126 - 05 Oct 2016

Cited by 2 | Viewed by 4611

Abstract

This paper presents a theoretical study of the disturbed isobaric surface shape in the geostrophic state of the atmosphere. It has been shown that, depending on the overheat sign at the equator, the isobaric surface has the shape of an oblate or prolate [...] Read more.

This paper presents a theoretical study of the disturbed isobaric surface shape in the geostrophic state of the atmosphere. It has been shown that, depending on the overheat sign at the equator, the isobaric surface has the shape of an oblate or prolate geoid. If the geostrophic wind velocity is nonzero at the poles, the local pressure extrema (minima for oblate geoid and maxima for prolate geoid) appear at the poles in the geostrophic state. This result correlates with the well-known polar vortex phenomenon and possibly can refine our understanding and interpretation of the phenomenon. In other words, the existence of polar minima and maxima of the pressure field can be the peculiarity of the geostrophic state of the atmosphere. It has been found that air must be colder than the surrounding atmosphere for initiation of the zonal eastward transport. For warm air mass, only easterly winds will be observed. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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1445 KiB

Open AccessArticle

Sensitivity of the Reaction Mechanism of the Ozone Depletion Events during the Arctic Spring on the Initial Atmospheric Composition of the Troposphere

by Le Cao, Min He, Haimei Jiang, Holger Grosshans and Nianwen Cao

Atmosphere 2016, 7(10), 124; https://doi.org/10.3390/atmos7100124 - 30 Sep 2016

Cited by 4 | Viewed by 5620

Abstract

Ozone depletion events (ODEs) during the Arctic spring have been investigated since the 1980s. It was found that the depletion of ozone is highly associated with the release of halogens, especially bromine containing compounds. These compounds originate from various substrates such as the [...] Read more.

Ozone depletion events (ODEs) during the Arctic spring have been investigated since the 1980s. It was found that the depletion of ozone is highly associated with the release of halogens, especially bromine containing compounds. These compounds originate from various substrates such as the ice/snow-covered surfaces in Arctic. In the present study, the dependence of the mixing ratios of ozone and principal bromine species during ODEs on the initial composition of the Arctic atmospheric boundary layer was investigated by using a concentration sensitivity analysis. This analysis was performed by implementing a reaction mechanism representing the ozone depletion and halogen release in the box model KINAL (KInetic aNALysis of reaction mechanics). The ratios between the relative change of the mixing ratios of particular species such as ozone and the variation in the initial concentration of each atmospheric component were calculated, which indicate the relative importance of each initial species in the chemical kinetic system. The results of the computations show that the impact of various chemical species is different for ozone and bromine containing compounds during the depletion of ozone. It was found that CH₃CHO critically controls the time scale of the complete removal of ozone. However, the rate of the ozone loss and the maximum values of bromine species are only slightly influenced by the initial value of CH₃CHO. In addition, according to the concentration sensitivity analysis, the reduction of initial Br₂ was found to cause a significant retardant of the ODE while the initial mixing ratio of HBr exerts minor influence on both ozone and bromine species. In addition, it is also interesting to note that the increase of C₂H₂ would significantly raise the amount of HOBr and Br in the atmosphere while the ozone depletion is hardly changed. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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1759 KiB

Open AccessArticle

Molecular Dications in Planetary Atmospheric Escape

by Stefano Falcinelli, Fernando Pirani, Michele Alagia, Luca Schio, Robert Richter, Stefano Stranges, Nadia Balucani and Franco Vecchiocattivi

Atmosphere 2016, 7(9), 112; https://doi.org/10.3390/atmos7090112 - 26 Aug 2016

Cited by 25 | Viewed by 5511

Abstract

Fundamental properties of multiply charged molecular ions, such as energetics, structure, stability, lifetime and fragmentation dynamics, are relevant to understand and model the behavior of gaseous plasmas as well as ionosphere and astrophysical environments. Experimental determinations of the Kinetic Energy Released (KER) for [...] Read more.

Fundamental properties of multiply charged molecular ions, such as energetics, structure, stability, lifetime and fragmentation dynamics, are relevant to understand and model the behavior of gaseous plasmas as well as ionosphere and astrophysical environments. Experimental determinations of the Kinetic Energy Released (KER) for ions originating from dissociations reactions, induced by Coulomb explosion of doubly charged molecular ions (molecular dications) produced by double photoionization of CO₂, N₂O and C₂H₂ molecules of interest in planetary atmospheres, are reported. The KER measurement as a function of the ultraviolet (UV) photon energy in the range of 28–65 eV was extracted from the electron-ion-ion coincidence spectra obtained by using tunable synchrotron radiation coupled with ion imaging techniques at the ELETTRA Synchrotron Light Laboratory Trieste, Italy. These experiments, coupled with a computational analysis based on a Monte Carlo trajectory simulation, allow assessing the probability of escape for simple ionic species in the upper atmosphere of Mars, Venus and Titan. The measured KER in the case of H⁺, C⁺, CH⁺, CH₂⁺, N⁺, O⁺, CO⁺, N₂⁺ and NO⁺ fragment ions range between 1.0 and 5.5 eV, being large enough to allow these ionic species to participate in the atmospheric escape from such planets into space. In the case of Mars, we suggest a possible explanation for the observed behavior of the O⁺ and CO₂²⁺ ion density profiles. Full article

(This article belongs to the Special Issue Selected Papers from The 1st International Electronic Conference on Atmospheric Sciences)

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