scholarly journals Triple Water Vapour–Isotopologues Record from Chhota Shigri, Western Himalaya, India: A Unified Interpretation based on δ17O, δ18O, δD and Comparison to Meteorological Parameters

2021 ◽  
Vol 8 ◽  
Author(s):  
S. Ranjan ◽  
AL. Ramanathan ◽  
Tirumalesh Keesari ◽  
Virendra B. Singh ◽  
Naveen Kumar ◽  
...  
Keyword(s):  
Water Vapour ◽  
Meteorological Parameters ◽  
Sampling Period ◽  
Western Himalaya ◽  
Temporal Variations ◽  
Moisture Loss ◽  
Specific Humidity ◽  
Air Mass ◽  
South Indian ◽  
Air Mass Trajectory

The objective of this study is to investigate and understand the source and transportation of water vapour in the western Himalayan region—that is still missing—using water vapour stable isotopologues and air mass trajectory diagnostics. We report the first-time triple oxygen isotopic compositions of water vapour from high altitude western Himalaya (Chhota Shigri, India) and compare them with meteorological conditions at the site of investigation as well as tracked backwards through the Lagrangian air mass trajectory diagnostics. A total of 21 water vapour samples were collected using a quantitative cryogenic method. δ17O and δ18O values show a significant correlation coefficient of 0.999 (p <0.01). The temporal variations of δ17O, δ18O, δD, D-excess and 17O-excess are 1.2, 2.3, 17.3, 11.6 and 39‰ permeg, respectively. δ17O and δ18O exhibit significant (p < 0.05) diurnal variations along with meteorological parameters. Chhota Shigri vapour isotopic results show a clear difference in the 17O-excess value compared to near the south Indian Ocean and the Southern Ocean regions, reflecting the influence of local moisture recycling at the continental site. NCEP/NCAR reanalyses show lower Specific Humidity during the sampling period (September, ending month of the Indian summer monsoon) favouring evaporative conditions which are further corroborated through the Lagrangian moisture diagnostics suggesting frequent moisture uptake and moisture loss in specific regions.

scholarly journals Simultaneous Monitoring of Particle-Bound PAHs Inside a Low-Energy School Building and Outdoors over Two Weeks in France

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 108
Author(s):  
Céline Liaud ◽  
Sarah Chouvenc ◽  
Stéphane Le Calvé
Keyword(s):  
Particle Size ◽  
Air Quality ◽  
High Performance ◽  
Sampling Period ◽  
Temporal Variations ◽  
Ventilation Rate ◽  
Low Energy ◽  
Total Particle ◽  
Polycyclic Aromatic ◽  
Individual Pahs

The emergence of new super-insulated buildings to reduce energy consumption can lead to a degradation of the indoor air quality. While some studies were carried out to assess the air quality in these super-insulated buildings, they were usually focused on the measurement of gas phase pollutants such as carbon dioxide and volatile organic compounds. This work reports the first measurements of Polycyclic Aromatic Hydrocarbons (PAHs) associated with particles as a function of time and particle size in a low-energy building. The airborne particles were collected indoors and outdoors over three to four days of sampling using two three-stage cascade impactors allowing to sample simultaneously particles with aerodynamic diameter Dae > 10 µm, 2.5 µm < Dae < 10 µm, 1 µm < Dae < 2.5 µm, and Dae < 1 µm. The 16 US-EPA priority PAHs were then extracted and quantified by high-performance liquid chromatography (HPLC) coupled to fluorescence detection. The resulting total particle concentrations were low, in the ranges 3.73 to 9.66 and 0.60 to 8.83 µg m-3 for indoors and outdoors, respectively. Thirteen PAHs were always detected in all the samples. The total PAH concentrations varied between 290 and 415 pg m−3 depending on the particle size, the environment (indoors or outdoors) and the sampling period considered. More interestingly, the temporal variations of individual PAHs highlighted that high molecular weight PAHs were mainly associated to the finest particles and some of them exhibited similar temporal behaviors, suggesting a common emission source. The indoor-to-outdoor concentration ratios of individual PAH were usually found close to or less than 1, except during the event combining rainy conditions and limited indoor ventilation rate.

scholarly journals Associations between seasonal influenza and meteorological parameters in Costa Rica, Honduras and Nicaragua

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Radina P. Soebiyanto ◽  
Wilfrido A. Clara ◽  
Jorge Jara ◽  
Angel Balmaseda ◽  
Jenny Lara ◽  
...  
Keyword(s):  
Costa Rica ◽  
Central America ◽  
Seasonal Influenza ◽  
Meteorological Parameters ◽  
Correlation Coefficients ◽  
Tropical Rainfall Measuring Mission ◽  
Specific Humidity ◽  
Considerable Proportion ◽  
Influenza Activity ◽  
Land Data Assimilation System

Seasonal influenza affects a considerable proportion of the global population each year. We assessed the association between subnational influenza activity and temperature, specific humidity and rainfall in three Central America countries, <em>i.e.</em> Costa Rica, Honduras and Nicaragua. Using virologic data from each country’s national influenza centre, rainfall from the Tropical Rainfall Measuring Mission and air temperature and specific humidity data from the Global Land Data Assimilation System, we applied logistic regression methods for each of the five sub-national locations studied. Influenza activity was represented by the weekly proportion of respiratory specimens that tested positive for influenza. The models were adjusted for the potentially confounding co-circulating respiratory viruses, seasonality and previous weeks’ influenza activity. We found that influenza activity was proportionally associated (P&lt;0.05) with specific humidity in all locations [odds ratio (OR) 1.21-1.56 per g/kg], while associations with temperature (OR 0.69-0.81 per °C) and rainfall (OR 1.01-1.06 per mm/day) were location-dependent. Among the meteorological parameters, specific humidity had the highest contribution (~3-15%) to the model in all but one location. As model validation, we estimated influenza activity for periods, in which the data was not used in training the models. The correlation coefficients between the estimates and the observed were ≤0.1 in 2 locations and between 0.6-0.86 in three others. In conclusion, our study revealed a proportional association between influenza activity and specific humidity in selected areas from the three Central America countries.

scholarly journals Diagnosis of processes controlling water vapour in the tropical tropopause layer by a Lagrangian cirrus model

2007 ◽  
Vol 7 (2) ◽  
pp. 5515-5552 ◽  
Author(s):  
C. Ren ◽  
A. R. MacKenzie ◽  
C. Schiller ◽  
G. Shur ◽  
V. Yushkov
Keyword(s):  
Water Vapour ◽  
Specific Humidity ◽  
Mixing Ratio ◽  
Total Water ◽  
Water Mixing ◽  
Tropical Tropopause Layer ◽  
Mixing Ratios ◽  
Aircraft Flight ◽  
Tropical Tropopause ◽  
Ecmwf Model

Abstract. We have developed a Lagrangian air-parcel cirrus model (LACM), to diagnose the processes controlling water in the tropical tropopause layer (TTL). LACM applies parameterised microphysics to air parcel trajectories. The parameterisation includes the homogeneous freezing of aerosol droplets, the growth/sublimation of ice particles, and sedimentation of ice particles, so capturing the main dehydration mechanism for air in the TTL. Rehydration is also considered by resetting the water vapour mixing ratio in an air parcel to the value at the point in the 4-D analysis/forecast data used to generate the trajectories, but only when certain conditions, indicative of convection, are satisfied. These conditions are imposed to confine what processes contribute to rehydration. The conditions act to restrict rehydration of the Lagrangian air parcels to regions where convective transport of water vapour from below is significant, at least to the extent that the analysis/forecast captures this process. The inclusion of hydration and dehydration mechanisms in LACM results in total water fields near tropical convection that have more of the "stripey" character of satellite observations of high cloud, than do either the ECMWF analysis or trajectories without microphysics. The mixing ratios of total water in the TTL, measured by a high-altitude aircraft over Brazil (during the TROCCINOX campaign), have been reconstructed by LACM using trajectories generated from ECMWF analysis. Two other Lagrangian reconstructions are also tested: linear interpolation of ECMWF analysed specific humidity onto the aircraft flight track, and instantaneous dehydration to the saturation vapour pressure over ice along trajectories. The reconstructed total water mixing ratios along aircraft flight tracks are compared with observations from the FISH total water hygrometer. Process-oriented analysis shows that modelled cirrus cloud events are responsible for dehydrating the air parcels coming from lower levels, resulting in total water mixing ratios as low as 2 μmol/mol. Without adding water back to some of the trajectories, the LACM and instantaneous-dehydration reconstructions have a dry bias. The interpolated-ECMWF reconstruction does not suffer this dry bias, because convection in the ECMWF model moistens air parcels dramatically, by pumping moist air upwards. This indicates that the ECMWF model captures the gross features of the rehydration of air in the TTL by convection. Overall, the ECMWF models captures well the exponential decrease in total water mixing ratio with height above 250 hPa, so that all the reconstruction techniques capture more than 75% of the variance in the measured total water mixing ratios over the depth of the TTL. We have therefore developed a simple method for re-setting the total water in LACM using the ECMWF-analysed specific humidity in regions where the model predicts convection. By picking up the main contributing processes to dehydration and rehydration in the TTL, LACM reconstructs total water mixing ratios along aircraft flight tracks at the top of the TTL, close to the cold point, that are always in substantially better agreement with observations than instantaneous-dehydration reconstructions, and better than the ECMWF analysis for regions of high relative humidity and cloud.

An air-mass trajectory study of the transport of radioactivity from Fukushima to Thessaloniki, Greece and Milan, Italy

2013 ◽  
Vol 75 ◽  
pp. 163-170 ◽  
Author(s):  
A. Ioannidou ◽  
E. Giannakaki ◽  
M. Manolopoulou ◽  
S. Stoulos ◽  
E. Vagena ◽  
...  
Keyword(s):  
Air Mass ◽  
Air Mass Trajectory

Changes of air pollutants’ concentrations in selected Romanian cities during the pandemic year 2020

2021 ◽  
Author(s):  
Gabriela Iorga ◽  
George-Bogdan Burghelea
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
European Commission ◽  
Air Pollutants ◽  
Meteorological Parameters ◽  
Dust Particles ◽  
Spatial And Temporal Variation ◽  
Pollution Level ◽  
Data Set ◽  
Air Mass

&lt;p&gt;Present research contributes to scientific knowledge concerning spatial and temporal variation of major air pollutants with high resolution at the country scale bringing statistical information on concentrations of NOx, O&lt;sub&gt;3&lt;/sub&gt;, CO, SO&lt;sub&gt;2&lt;/sub&gt; and particulate matter with an aerodynamic diameter below 10&amp;#160;&amp;#956;m (PM&lt;sub&gt;10&lt;/sub&gt;) and below 2.5&amp;#160;&amp;#956;m (PM&lt;sub&gt;2.5&lt;/sub&gt;) during the pandemic year 2020 using an observational data set from the Romanian National Air Quality Network in seven selected cities spread out over the country. These cities have different level of development, play regional roles, might have potential influence at European scale and they are expected to be impacted by different pollution sources. Among them, three cities (Bucharest, Bra&amp;#537;ov, Ia&amp;#537;i) appear frequently on the list of the European Commission with reference to the infringement procedure that the European Commission launched against Romania in the period 2007-2020 regarding air quality.&lt;/p&gt;&lt;p&gt;Air pollutant data was complemented with local meteorological parameters at each site (atmospheric pressure, relative humidity, temperature, global solar radiation, wind speed and direction). Statistics of air pollutants provide us with an overview of air pollution in main Romanian cities.&amp;#160; Correlations between meteorological parameters and ambient pollutant levels were analyzed. Lowest air pollution levels were measured during the lockdown period in spring, as main traffic and non-essential activities were severely restricted. Among exceptions were the construction activities that were not interrupted. During 2020, some of selected cities experienced few pollution episodes which were due to dust transport from Sahara desert. However, in Bucharest metropolitan area, some cases with high pollution level were found correlated with local anthropogenic activity namely, waste incinerations. Air mass origins were investigated for 72 hours back by computing the air mass backward trajectories using the HYSPLIT model. Dust load and spatial distribution of the aerosol optical depth with BSC-DREAM8b v2.0 and NMBM/BSC-Dust models showed the area with dust particles transport during the dust events.&lt;/p&gt;&lt;p&gt;The obtained results are important for investigations of sources of air pollution and for modeling of air quality.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgment:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;The research leading to these results has received funding from the NO Grants 2014-2021, under Project contract no. 31/2020, EEA-RO-NO-2019-0423 project. NOAA Air Resources Laboratory for HYSPLIT transport model, available at READY website https://www.ready.noaa.gov &amp;#160;and the Barcelona dust forecast center for BSC-DREAM8b and NMBM/BSC-Dust models, available at: &amp;#160;https://ess.bsc.es/bsc-dust-daily-forecast are also acknowledged. The data regarding ground-based air pollution and meteorology by site was extracted from the public available Romanian National Air Quality Database, www.calitateaer.ro.&lt;/p&gt;

scholarly journals The Mass of the Atmosphere: A Constraint on Global Analyses

2005 ◽  
Vol 18 (6) ◽  
pp. 864-875 ◽  
Author(s):  
Kevin E. Trenberth ◽  
Lesley Smith
Keyword(s):  
Water Vapor ◽  
Surface Pressure ◽  
Total Mass ◽  
Precipitable Water ◽  
Atmospheric Composition ◽  
Specific Humidity ◽  
Air Mass ◽  
Dry Air ◽  
Annual Range ◽  
Global Mean

Abstract The total mass of the atmosphere varies mainly from changes in water vapor loading; the former is proportional to global mean surface pressure and the water vapor component is computed directly from specific humidity and precipitable water using the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analyses (ERA-40). Their difference, the mass of the dry atmosphere, is estimated to be constant for the equivalent surface pressure to within 0.01 hPa based on changes in atmospheric composition. Global reanalyses satisfy this constraint for monthly means for 1979–2001 with a standard deviation of 0.065 hPa. New estimates of the total mass of the atmosphere and its dry component, and their corresponding surface pressures, are larger than previous estimates owing to new topography of the earth’s surface that is 5.5 m lower for the global mean. Global mean total surface pressure is 985.50 hPa, 0.9 hPa higher than previous best estimates. The total mean mass of the atmosphere is 5.1480 × 1018 kg with an annual range due to water vapor of 1.2 or 1.5 × 1015 kg depending on whether surface pressure or water vapor data are used; this is somewhat smaller than the previous estimate. The mean mass of water vapor is estimated as 1.27 × 1016 kg and the dry air mass as 5.1352 ± 0.0003 × 1018 kg. The water vapor contribution varies with an annual cycle of 0.29-hPa, a maximum in July of 2.62 hPa, and a minimum in December of 2.33 hPa, although the total global surface pressure has a slightly smaller range. During the 1982/83 and 1997/98 El Niño events, water vapor amounts and thus total mass increased by about 0.1 hPa in surface pressure or 0.5 × 1015 kg for several months. Some evidence exists for slight decreases following the Mount Pinatubo eruption in 1991 and also for upward trends associated with increasing global mean temperatures, but uncertainties due to the changing observing system compromise the evidence. The physical constraint of conservation of dry air mass is violated in the reanalyses with increasing magnitude prior to the assimilation of satellite data in both ERA-40 and the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalyses. The problem areas are shown to occur especially over the Southern Oceans. Substantial spurious changes are also found in surface pressures due to water vapor, especially in the Tropics and subtropics prior to 1979.

scholarly journals Simultaneous monitoring of stable oxygen isotope composition in water vapour and precipitation over the central Tibetan Plateau

2015 ◽  
Vol 15 (18) ◽  
pp. 10251-10262 ◽  
Author(s):  
W. Yu ◽  
L. Tian ◽  
Y. Ma ◽  
B. Xu ◽  
D. Qu
Keyword(s):  
Tibetan Plateau ◽  
Water Vapour ◽  
Indian Monsoon ◽  
Isotope Composition ◽  
Precipitation Amount ◽  
Sampling Period ◽  
Time Data ◽  
Moisture Sources ◽  
Northern Tibetan Plateau ◽  
Central Tibetan Plateau

Abstract. This study investigated daily δ18O variations of water vapour (δ18Ov) and precipitation (δ18Op) simultaneously at Nagqu on the central Tibetan Plateau for the first time. Data show that the δ18O tendencies of water vapour coincide strongly with those of associated precipitation. The δ18O values of precipitation affect those of water vapour not only on the same day, but also for the following several days. In comparison, the δ18O values of local water vapour may only partly contribute to those of precipitation. During the entire sampling period, the variations of δ18Ov and δ18Op at Nagqu did not appear dependent on temperature, but did seem significantly dependent on the joint contributions of relative humidity, pressure, and precipitation amount. In addition, the δ18O changes in water vapour and precipitation can be used to diagnose different moisture sources, especially the influences of the Indian monsoon and convection. Moreover, intense activities of the Indian monsoon and convection may cause the relative enrichment of δ18Op relative to δ18Ov at Nagqu (on the central Tibetan Plateau) to differ from that at other stations on the northern Tibetan Plateau. These results indicate that the effects of different moisture sources, including the Indian monsoon and convection currents, need be considered when attempting to interpret paleoclimatic records on the central Tibetan Plateau.

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