scholarly journals A chemical ionization technique for measurement of pernitric acid in the upper troposphere and the polar boundary layer

2001 ◽  
Vol 28 (20) ◽  
pp. 3875-3878 ◽  
Author(s):  
D. L. Slusher ◽  
S. J. Pitteri ◽  
B. J. Haman ◽  
D. J. Tanner ◽  
L. G. Huey
Keyword(s):  
Boundary Layer ◽  
Chemical Ionization ◽  
Ionization Technique ◽  
Upper Troposphere ◽  
Pernitric Acid

scholarly journals An aircraft-borne chemical ionization – ion trap mass spectrometer (CI-ITMS) for fast PAN and PPN measurements

2010 ◽  
Vol 3 (5) ◽  
pp. 4313-4354
Author(s):  
A. Roiger ◽  
H. Aufmhoff ◽  
P. Stock ◽  
F. Arnold ◽  
H. Schlager
Keyword(s):  
Boundary Layer ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Ion Trap ◽  
The Arctic ◽  
Arctic Boundary Layer ◽  
Online Calibration ◽  
Mixing Ratios ◽  
Ion Trap Mass Spectrometer ◽  
Research Aircraft

Abstract. An airborne chemical ionization ion trap mass spectrometer instrument (CI-ITMS) has been developed for tropospheric and stratospheric fast in-situ measurements of PAN (peroxyacetyl nitrate) and PPN (peroxypropionyl nitrate). The first scientific deployment of the FASTPEX instrument (FASTPEX = Fast Measurement of Peroxyacyl nitrates) took place in the Arctic during 18 missions aboard the DLR research aircraft Falcon, within the framework of the POLARCAT-GRACE campaign in the summer of 2008. The FASTPEX instrument is described and characteristic properties of the employed ion trap mass spectrometer are discussed. Atmospheric data obtained at altitudes of up to ~12 km are presented, from the boundary layer to the lowermost stratosphere. Data were sampled with a time resolution of 2 s and a 2σ detection limit of 25 pmol mol−1. An isotopically labelled standard was used for a permanent online calibration. For this reason the accuracy of the PAN measurements is better than ±10% for mixing ratios greater than 200 pmol mol−1. PAN mixing ratios in the summer Arctic troposphere were in the order of a few hundred pmol mol−1 and generally correlated well with CO. In the Arctic boundary layer and lowermost stratosphere smaller PAN mixing ratios were observed due to a combination of missing local sources of PAN precursor gases and efficient removal processes (thermolysis/photolysis). PPN, the second most abundant PAN homologue, was measured simultanously. Observed PPN/PAN ratios range between ~0.03 and 0.3.

scholarly journals Transport of short-lived halocarbons to the stratosphere over the Pacific Ocean

2020 ◽  
Vol 20 (2) ◽  
pp. 1163-1181
Author(s):  
Michal T. Filus ◽  
Elliot L. Atlas ◽  
Maria A. Navarro ◽  
Elena Meneguz ◽  
David Thomson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Lower Stratosphere ◽  
Atmospheric Transport ◽  
Convective Transport ◽  
Transport Processes ◽  
Lagrangian Model ◽  
Convection Scheme ◽  
Model Calculations ◽  
Upper Troposphere ◽  
Tropical Troposphere

Abstract. The effectiveness of transport of short-lived halocarbons to the upper troposphere and lower stratosphere remains an important uncertainty in quantifying the supply of ozone-depleting substances to the stratosphere. In early 2014, a major field campaign in Guam in the western Pacific, involving UK and US research aircraft, sampled the tropical troposphere and lower stratosphere. The resulting measurements of CH3I, CHBr3 and CH2Br2 are compared here with calculations from a Lagrangian model. This methodology benefits from an updated convection scheme that improves simulation of the effect of deep convective motions on particle distribution within the tropical troposphere. We find that the observed CH3I, CHBr3 and CH2Br2 mixing ratios in the tropical tropopause layer (TTL) are consistent with those in the boundary layer when the new convection scheme is used to account for convective transport. More specifically, comparisons between modelled estimates and observations of short-lived CH3I indicate that the updated convection scheme is realistic up to the lower TTL but is less good at reproducing the small number of extreme convective events in the upper TTL. This study consolidates our understanding of the transport of short-lived halocarbons to the upper troposphere and lower stratosphere by using improved model calculations to confirm consistency between observations in the boundary layer, observations in the TTL and atmospheric transport processes. Our results support recent estimates of the contribution of short-lived bromocarbons to the stratospheric bromine budget.

scholarly journals Origin of aerosol particles in the mid-latitude and subtropical upper troposphere and lowermost stratosphere from cluster analysis of CARIBIC data

2009 ◽  
Vol 9 (21) ◽  
pp. 8413-8430 ◽  
Author(s):  
M. Köppe ◽  
M. Hermann ◽  
C. A. M. Brenninkmeijer ◽  
J. Heintzenberg ◽  
H. Schlager ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cluster Analysis ◽  
Particle Number ◽  
Aerosol Particles ◽  
Free Troposphere ◽  
Data Set ◽  
Upper Troposphere ◽  
Eurasian Continent ◽  
Aitken Mode ◽  
Seasonal Data

Abstract. The origin of aerosol particles in the upper troposphere and lowermost stratosphere over the Eurasian continent was investigated by applying cluster analysis methods to in situ measured data. Number concentrations of submicrometer aerosol particles and trace gas mixing ratios derived by the CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container) measurement system on flights between Germany and South-East Asia were used for this analysis. Four cluster analysis methods were applied to a test data set and their capability of separating the data points into scientifically reasonable clusters was assessed. The best method was applied to seasonal data subsets for summer and winter resulting in five cluster or air mass types: stratosphere, tropopause, free troposphere, high clouds, and boundary layer influenced. Other source clusters, like aircraft emissions could not be resolved in the present data set with the used methods. While the cluster separation works satisfactory well for the summer data, in winter interpretation is more difficult, which is attributed to either different vertical transport pathways or different chemical lifetimes in both seasons. The geographical distribution of the clusters together with histograms for nucleation and Aitken mode particles within each cluster are presented. Aitken mode particle number concentrations show a clear vertical gradient with the lowest values in the lowermost stratosphere (750–2820 particles/cm3 STP, minimum of the two 25% – and maximum of the two 75%-percentiles of both seasons) and the highest values for the boundary-layer-influenced air (4290–22 760 particles/cm3 STP). Nucleation mode particles are also highest in the boundary-layer-influenced air (1260–29 500 particles/cm3 STP), but are lowest in the free troposphere (0–450 particles/cm3 STP). The given submicrometer particle number concentrations represent the first large-scale seasonal data sets for the upper troposphere and lowermost stratosphere over the Eurasian continent.

scholarly journals Continental outflow from the US to the upper troposphere over the North Atlantic during the NASA INTEX-NA Airborne Campaign

2008 ◽  
Vol 8 (7) ◽  
pp. 1989-2005 ◽  
Author(s):  
S. Y. Kim ◽  
R. Talbot ◽  
H. Mao ◽  
D. Blake ◽  
S. Vay ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
The United States ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
The North ◽  
Southeastern Us ◽  
The Us ◽  
The North Atlantic ◽  
Continental Outflow

Abstract. A case of continental outflow from the United States (US) was examined using airborne measurements from NASA DC-8 flight 13 during the Intercontinental Chemical Transport Experiment – North America (INTEX-NA). Mixing ratios of methane (CH4) and carbon monoxide (CO) at 8–11 km altitude over the North Atlantic were elevated to 1843 ppbv and 134 ppbv respectively, while those of carbon dioxide (CO2) and carbonyl sulfide (COS) were reduced to 372.4 ppmv and 411 pptv respectively. In this region, urban and industrial influences were evidenced by elevated mixing ratios and good linear relationships between urban and industrial tracers compared to North Atlantic background air. Moreover, low mixing ratios and a good correlation between COS and CO2 showed a fingerprint of terrestrial uptake and minimal dilution during rapid transport over a 1–2 day time period. Analysis of synoptic conditions, backward trajectories, and photochemical aging estimates based on C3H8/C2H6 strongly suggested that elevated anthropogenic tracers in the upper troposphere of the flight region were the result of transport via convection and warm conveyor belt (WCB) uplifting of boundary layer air over the southeastern US. This mechanism is supported by the similar slope values of linear correlations between long-lived (months) anthropogenic tracers (e.g., C2Cl4 and CHCl3) from the flight region and the planetary boundary layer in the southeastern US. In addition, the aircraft measurements suggest that outflow from the US augmented the entire tropospheric column at mid-latitudes over the North Atlantic. Overall, the flight 13 data demonstrate a pervasive impact of US anthropogenic emissions on the troposphere over the North Atlantic.

scholarly journals Measurements of CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> in the upper troposphere

2014 ◽  
Vol 7 (9) ◽  
pp. 9453-9479
Author(s):  
B. A. Nault ◽  
C. Garland ◽  
S. E. Pusede ◽  
P. J. Wooldridge ◽  
K. Ullmann ◽  
...  
Keyword(s):  
Detection Limit ◽  
Low Temperatures ◽  
Theoretical Calculations ◽  
Thermal Dissociation ◽  
Atmospheric Composition ◽  
Upper Troposphere ◽  
Convective Clouds ◽  
Peroxy Nitrates ◽  
Deep Convective Clouds ◽  
Pernitric Acid

Abstract. The non-acyl peroxy nitrates, HO2NO2 and CH3O2NO2, are predicted to be important for photochemistry at low temperatures characteristic of the upper troposphere. We report the first measurements of methyl peroxy nitrate (CH3O2NO2). During the Deep Convective Clouds and Chemistry (DC-3) and the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) experiments, different inlet configurations for the UC Berkeley Thermal Dissociation-Laser Induced Instrument were tested to optimize measurements of CH3O2NO2 from the NASA DC-8. In addition, the inlet modifications were optimized for measurements of NO2 without CH3O2NO2 interferences. The CH3O2NO2 measurements we report have a detection limit (S/N = 2) of 15 pptv (parts per trillion by volume) at 1 min averaging on a background of 200 pptv NO2 and an accuracy of ±40%. Both observations and theoretical calculations were used to constrain the interference of pernitric acid (HO2NO2), which partially decomposes (~ 11%) along with CH3O2NO2 in our heated CH3O2NO2 channel. Evaluation of the accuracy of the CH3O2NO2 measurements is presented.

scholarly journals Evaluating a 3-D transport model of atmospheric CO<sub>2</sub> using ground-based, aircraft, and space-borne data

2010 ◽  
Vol 10 (7) ◽  
pp. 18025-18061 ◽  
Author(s):  
L. Feng ◽  
P. I. Palmer ◽  
Y. Yang ◽  
R. M. Yantosca ◽  
S. R. Kawa ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North America ◽  
Seasonal Cycle ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Co2 Fluxes ◽  
A Posteriori ◽  
Upper Troposphere ◽  
Co2 Concentrations ◽  
Geographical Regions

Abstract. We evaluate the GEOS-Chem atmospheric transport model (v8-02-01) of CO2 over 2003–2006, driven by GEOS-4 and GEOS-5 meteorology from the NASA Goddard Global Modelling and Assimilation Office, using surface, aircraft and space-borne concentration measurements of CO2. We use an established ensemble Kalman filter to estimate a posteriori biospheric+biomass burning (BS+BB) and oceanic (OC) CO2 fluxes from 22 geographical regions, following the TransCom 3 protocol, using boundary layer CO2 data from a subset of GLOBALVIEW surface sites. Global annual net BS+BB+OC CO2 fluxes over 2004–2006 for GEOS-4 (GEOS-5) meteorology are −4.4±0.9 (−4.2±0.9), −3.9±0.9 (−4.5±0.9), and −5.2±0.9 (−4.9±0.9) Pg C yr−1 , respectively. The regional a posteriori fluxes are broadly consistent in the sign and magnitude of the TransCom-3 study for 1992–1996, but we find larger net sinks over northern and southern continents. We find large departures from our a priori over Europe during summer 2003, over temperate Eurasia during 2004, and over North America during 2005, reflecting an incomplete description of terrestrial carbon dynamics. We find GEOS-4 (GEOS-5) a posteriori CO2 concentrations reproduce the observed surface trend of 1.91–2.43 ppm yr−1, depending on latitude, within 0.15 ppm yr−1 (0.2 ppm yr−1) and the seasonal cycle within 0.2 ppm (0.2 ppm) at all latitudes. We find the a posteriori model reproduces the aircraft vertical profile measurements of CO2 over North America and Siberia generally within 1.5 ppm in the free and upper troposphere but can be biased by up to 4–5 ppm in the boundary layer at the start and end of the growing season. The model has a small negative bias in the free troposphere CO2 trend (1.95–2.19 ppm yr−1) compared to AIRS data which has a trend of 2.21–2.63 ppm yr−1 during 2004–2006, consistent with surface data. Model CO2 concentrations in the upper troposphere, evaluated using CONTRAIL (Comprehensive Observation Network for TRace gases by AIrLiner) aircraft measurements, reproduce the magnitude and phase of the seasonal cycle of CO2 in both hemispheres. We generally find that the GEOS meteorology reproduces much of the observed tropospheric CO2 variability, suggesting that these meteorological fields will help make significant progress in understanding carbon fluxes as more data become available.

scholarly journals What do we learn on bromoform transport and chemistry in deep convection from fine scale modelling?

2011 ◽  
Vol 11 (11) ◽  
pp. 29561-29600 ◽  
Author(s):  
V. Marécal ◽  
M. Pirre ◽  
G. Krysztofiak ◽  
B. Josse
Keyword(s):  
Boundary Layer ◽  
Transport Model ◽  
Deep Convection ◽  
Chemical Species ◽  
Convective Cloud ◽  
Initial Boundary ◽  
Mixing Ratio ◽  
Atmospheric Conditions ◽  
Upper Troposphere ◽  
Soluble Species

Abstract. Bromoform is one of the main sources of halogenated Very Short-Lived Species (VSLS) that possibly contributes when degradated to the inorganic halogen loading in the stratosphere. Because of its short lifetime of about four weeks, its pathway to the stratosphere is mainly the transport by convection up to the tropical tropopause layer (TTL) and then by radiative ascent in the low stratosphere. Some of its degradation product gases (PGs) that are soluble can be scavenged and not reach the TTL. In this paper we present a detailed modelling study of the transport and the degradation of bromoform and its PGs in convection. We use a 3-D-cloud resolving model coupled with a chemistry model including gaseous and aqueous chemistry. We run idealised simulations up to 10 days, initialised using a tropical radiosounding for atmospheric conditions and using outputs from a global chemistry-transport model for chemical species. Bromoform is initialised only in the low levels. The first simulation is run with stable atmospheric conditions. It shows that the sum of the bromoform and its PGs significantly decreases with time because of dry deposition and that PGs are mainly in the form of HBr after 2 days of simulation. The other simulation is similar to the first simulation but includes perturbations of temperature and of moisture leading to the development of a convective cloud reaching the TTL. Results of this simulation show an efficient vertical transport of the bromoform from the boundary layer in the upper troposphere and TTL (mixing ratio up to 45% of the initial boundary layer mixing ratio). The organic PGs, which are for the most abundant of them not very soluble, are also uplifted efficiently. For the inorganic PGs, which are more abundant than organic PGs, their mixing ratios in the upper troposphere and in the TTL depend on the partitioning between inorganic soluble and inorganic non soluble species in the convective cloud. Important soluble species such as HBr and HOBr are efficiently scavenged by rain. This removal is reduced by the production of Br2 (not soluble) in the gas phase from aqueous processes in the cloud droplets. This Br2 production process is therefore important for the PG budget in the upper troposphere and in the TTL. We also showed that this process is favoured by acidic conditions in the coud droplets, i.e. polluted conditions.

scholarly journals The impact of orbital sampling, monthly averaging and vertical resolution on climate chemistry model evaluation with satellite observations

2011 ◽  
Vol 11 (3) ◽  
pp. 9705-9742
Author(s):  
A. M. Aghedo ◽  
K. W. Bowman ◽  
D. T. Shindell ◽  
G. Faluvegi
Keyword(s):  
Climate Change ◽  
Boundary Layer ◽  
Carbon Monoxide ◽  
Water Vapour ◽  
Climate Models ◽  
Atmospheric Temperature ◽  
Satellite Observations ◽  
Vertical Resolution ◽  
Upper Troposphere ◽  
The Impact

Abstract. Ensemble climate model simulations used for the Intergovernmental Panel on Climate Change (IPCC) assessments have become important tools for exploring the response of the Earth System to changes in anthropogenic and natural forcings. The systematic evaluation of these models through global satellite observations is a critical step in assessing the uncertainty of climate change projections. This paper presents the technical steps required for using nadir sun-synchronous infrared satellite observations for multi-model evaluation and the uncertainties associated with each step. This is motivated by need to use satellite observations to evaluate climate models. We quantified the implications of the effect of satellite orbit and spatial coverage, the effect of variations in vertical sensitivity as quantified by the observation operator and the impact of averaging the operators for use with monthly-mean model output. We calculated these biases in ozone, carbon monoxide, atmospheric temperature and water vapour by using the output from two global chemistry climate models (ECHAM5-MOZ and GISS-PUCCINI) and the observations from the Tropospheric Emission Spectrometer (TES) satellite from January 2005 to December 2008. The results show that sampling and monthly averaging of the observation operators produce biases of less than ±3% for ozone and carbon monoxide throughout the entire troposphere in both models. Water vapour sampling biases were also within the insignificant range of ±3% (that is ±0.14 g kg−1) in both models. Sampling led to a temperature bias of ±0.3 K over the tropical and mid-latitudes in both models, and up to −1.4 K over the boundary layer in the higher latitudes. Using the monthly average of temperature and water vapour operators lead to large biases over the boundary layer in the southern-hemispheric higher latitudes and in the upper troposphere, respectively. Up to 8% bias was calculated in the upper troposphere water vapour due to monthly-mean operators, which may impact the detection of water vapour feedback in response to global warming. Our results reveal the importance of using the averaging kernel and the a priori profiles to account for the limited vertical resolution of a nadir observation during model application. Neglecting the observation operators resulted in large biases, which are more than 60% for ozone, ±30% for carbon monoxide, and range between −1.5 K and 5 K for atmospheric temperature, and between −60% and 100% for water vapour.

scholarly journals Impact of nucleation on global CCN

2009 ◽  
Vol 9 (3) ◽  
pp. 12999-13037 ◽  
Author(s):  
J. Merikanto ◽  
D. V. Spracklen ◽  
G. W. Mann ◽  
S. J. Pickering ◽  
K. S. Carslaw
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Environmental Changes ◽  
Control Strategies ◽  
Cloud Condensation Nuclei ◽  
Free Troposphere ◽  
Carbonaceous Particles ◽  
Upper Troposphere ◽  
Low Level ◽  
Primary Emissions

Abstract. Cloud condensation nuclei (CCN) are derived from particles emitted directly into the atmosphere (primary emissions) or from the growth of nanometer-sized particles nucleated in the atmosphere. It is important to separate these two sources because they respond in different ways to gas and particle emission control strategies and environmental changes. Here, we use a global aerosol microphysics model to quantify the contribution of primary and nucleated particles to global CCN. The model considers primary emissions of sea spray, sulfate and carbonaceous particles, and nucleation processes appropriate for the free troposphere and boundary layer. We estimate that 45% of global low-level cloud CCN at 0.2% supersaturation are secondary aerosol derived from nucleation (ranging between 31–49% taking into account uncertainties primary emissions and nucleation rates), the remainder being directly emitted as primary aerosol. The model suggests that 35% of CCN (0.2%) in low-level clouds were created in the free and upper troposphere. In the marine boundary layer 55% of CCN (0.2%) are from nucleation, 45% being entrained from the free troposphere. Both in global and marine boundary layer 10% of CCN (0.2%) is nucleated in the boundary layer. Combinations of model runs show that primary and nucleated CCN are non-linearly coupled. In particular, boundary layer nucleated CCN are strongly suppressed by both primary emissions and entrainment of particles nucleated in the free troposphere. Elimination of all primary emissions reduces global CCN (0.2%) by only 20% and elimination of upper tropospheric nucleation reduces CCN (0.2%) by only 12% because of increased impact of boundary layer nucleation on CCN.

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