scholarly journals AirCore-HR: A high resolution column sampling to enhance the vertical description of CH<sub>4</sub> and CO<sub>2</sub>

2016 ◽  
Author(s):  
Olivier Membrive ◽  
Cyril Crevoisier ◽  
Colm Sweeney ◽  
François Danis ◽  
Albert Hertzog ◽  
...  
Keyword(s):  
High Resolution ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Vertical Profiles ◽  
Vertical Resolution ◽  
Low Resolution ◽  
Sampling System ◽  
Air Sample ◽  
First Time ◽  
The Vertical Distribution

Abstract. An original and innovative sampling system called AirCore was presented by NOAA in 2010 (Karion et al., 2010). It consists of a long (> 100 m) and narrow (< 1 cm) stainless steel tube that can retain a profile of atmospheric air. The captured air sample has then to be analyzed with a gas analyzer for trace mole fraction. In this study, we introduce a new AirCore aiming at improved resolution along the vertical with the objectives to: (i) better capture the vertical distribution of CO2 and CH4, (ii) provide a tool to compare AirCores and validate the estimated vertical resolution achieved by AirCores. This AirCore-HR (high resolution) consists of a 300 m tube, combining 200 m of 1/8 in. (3.175 mm) tube and a 100 m of 1/4 in. (6.35 mm) tube. This new configuration allows to achieve a vertical resolution of 300 m up to 15 km and better than 500 m up to 22 km (if analysis of the retained sample is performed within 3 hours). The AirCore-HR was flown for the first time during the annual StratoScience campaign from CNES in August 2014 from Timmins (Ontario, Canada). High-resolution vertical profiles of CO2 and CH4 up to 25 km were successfully retrieved. These profiles revealed well defined transport structures in the troposphere (also seen in CAMS-ECMWF high resolution forecasts of CO2 and CH4 profiles) and captured the decrease of CO2 and CH4 in the stratosphere. The multi-instruments gondola from the flight carried two other low-resolution AirCore-GUF that allowed to perform direct comparisons and study the underlying processing method used to convert the sample of air to greenhouse gases vertical profiles. In particular, degrading the AirCore-HR derived profiles to the low resolution of AirCore-GUF yields an excellent match between both sets of CH4 profiles, and shows a good consistency between vertical structures of CO2 and CH4. These results fully validate the theoretical vertical resolution achievable by AirCores. Finally, the uncertainties associated with the measurements are assessed, yielding an average uncertainty below 3 ppb for CH4 and 0.25 ppm for CO2 with the major source of uncertainty coming from the potential loss of air sample on the ground and the choice of the starting and ending point of the collected air sample inside the tube. In an ideal case where the sample would be fully retained, it would be possible to know precisely the pressure at which air was sampled last and thus to improve the overall uncertainty to about 0.1 ppm for CO2 and 2 ppb for CH4.

scholarly journals AirCore-HR: a high-resolution column sampling to enhance the vertical description of CH<sub>4</sub> and CO<sub>2</sub>

2017 ◽  
Vol 10 (6) ◽  
pp. 2163-2181 ◽  
Author(s):  
Olivier Membrive ◽  
Cyril Crevoisier ◽  
Colm Sweeney ◽  
François Danis ◽  
Albert Hertzog ◽  
...  
Keyword(s):  
High Resolution ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Vertical Profiles ◽  
Vertical Resolution ◽  
Low Resolution ◽  
Sampling System ◽  
Air Sample ◽  
Variable Bias ◽  
First Time

Abstract. An original and innovative sampling system called AirCore was presented by NOAA in 2010 Karion et al.(2010). It consists of a long ( >  100 m) and narrow ( <  1 cm) stainless steel tube that can retain a profile of atmospheric air. The captured air sample has then to be analyzed with a gas analyzer for trace mole fraction. In this study, we introduce a new AirCore aiming to improve resolution along the vertical with the objectives to (i) better capture the vertical distribution of CO2 and CH4, (ii) provide a tool to compare AirCores and validate the estimated vertical resolution achieved by AirCores. This (high-resolution) AirCore-HR consists of a 300 m tube, combining 200 m of 0.125 in. (3.175 mm) tube and a 100 m of 0.25 in. (6.35 mm) tube. This new configuration allows us to achieve a vertical resolution of 300 m up to 15 km and better than 500 m up to 22 km (if analysis of the retained sample is performed within 3 h). The AirCore-HR was flown for the first time during the annual StratoScience campaign from CNES in August 2014 from Timmins (Ontario, Canada). High-resolution vertical profiles of CO2 and CH4 up to 25 km were successfully retrieved. These profiles revealed well-defined transport structures in the troposphere (also seen in CAMS-ECMWF high-resolution forecasts of CO2 and CH4 profiles) and captured the decrease of CO2 and CH4 in the stratosphere. The multi-instrument gondola also carried two other low-resolution AirCore-GUF that allowed us to perform direct comparisons and study the underlying processing method used to convert the sample of air to greenhouse gases vertical profiles. In particular, degrading the AirCore-HR derived profiles to the low resolution of AirCore-GUF yields an excellent match between both sets of CH4 profiles and shows a good consistency in terms of vertical structures. This fully validates the theoretical vertical resolution achievable by AirCores. Concerning CO2 although a good agreement is found in terms of vertical structure, the comparison between the various AirCores yields a large and variable bias (up to almost 3 ppm in some parts of the profiles). The reasons of this bias, possibly related to the drying agent used to dry the air, are still being investigated. Finally, the uncertainties associated with the measurements are assessed, yielding an average uncertainty below 3 ppb for CH4 and 0.25 ppm for CO2 with the major source of uncertainty coming from the potential loss of air sample on the ground and the choice of the starting and ending point of the collected air sample inside the tube. In an ideal case where the sample would be fully retained, it would be possible to know precisely the pressure at which air was sampled last and thus to improve the overall uncertainty to about 0.1 ppm for CO2 and 2 ppb for CH4.

scholarly journals Technical Note: Regularization performances with the error consistency method in the case of retrieved atmospheric profiles

2006 ◽  
Vol 6 (6) ◽  
pp. 13307-13321
Author(s):  
S. Ceccherini ◽  
C. Belotti ◽  
B. Carli ◽  
P. Raspollini ◽  
M. Ridolfi
Keyword(s):  
Regularization Parameter ◽  
Technical Note ◽  
Field Of View ◽  
Regularization Methods ◽  
Vertical Profiles ◽  
Vertical Resolution ◽  
Vertical Field ◽  
The Stability ◽  
First Time ◽  
Consistency Method

Abstract. The retrieval of concentration vertical profiles of atmospheric constituents from spectroscopic measurements is often an ill-conditioned problem and regularization methods are frequently used to improve its stability. Recently a new method, that provides a good compromise between precision and vertical resolution, was proposed to determine analytically the value of the regularization parameter. This method is applied for the first time to real measurements with its implementation in the operational retrieval code of the satellite limb-emission measurements of the MIPAS instrument and its performances are quantitatively analyzed. The adopted regularization improves the stability of the retrieval providing smooth profiles without major degradation of the vertical resolution. In the analyzed measurements the retrieval procedure provides a vertical resolution that, in the troposphere and low stratosphere, is smaller than the vertical field of view of the instrument.

scholarly journals Estimate of the D/H ratio in the Martian upper atmosphere from the low spectral resolution mode of MAVEN/IUVS

2020 ◽  
Author(s):  
Jean-Yves Chaufray ◽  
Majd Mayyasi ◽  
Michael Chaffin ◽  
Justin Deighan ◽  
Dolon Bhattacharyya ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Quantitative Information ◽  
Upper Atmosphere ◽  
Vertical Profiles ◽  
Low Resolution ◽  
Mars Atmosphere

&lt;p&gt;The recent observations performed with the high-resolution &amp;#8220;echelle mode&amp;#8221; by the Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission indicated large deuterium brightness near Ls=270&amp;#176;. The deuterium brightness observed at the beginning of the mission, when Mars was close to its perihelion show brightness ~ 1 kR much larger than the first deuterium detection from Earth ~ 20-50R in 20-21 January 1997 (Ls = 67&amp;#176;). This low brightness of the deuterium emission is consistent with the lack of deuterium observation with the echelle mode of IUVS at solar longitudes around aphelion (Ls = 71&amp;#176;). During southern summer (Ls = 270&amp;#176;), especially near the terminator, the Lyman-&amp;#945; emission observed at 121.6 nm with the &amp;#8220;low resolution mode&amp;#8221; presents some vertical profiles that were not reproducible with models including only the emission from the thermal hydrogen population. In this study, we investigate the possibility to derive quantitative information on the D/H ratio at Mars from the vertical Lyman-&amp;#945; profiles observed with the &amp;#8220;low resolution mode&amp;#8221;, and the main limits of the method.&lt;/p&gt;

scholarly journals A longslit spectroscopic survey of bulges in disc galaxies

2012 ◽  
Vol 10 (H16) ◽  
pp. 345-345
Author(s):  
Maximilian Fabricius ◽  
Roberto Saglia ◽  
David Fisher ◽  
Niv Drory ◽  
Ralf Bender ◽  
...  
Keyword(s):  
High Resolution ◽  
Velocity Dispersion ◽  
Low Resolution ◽  
Present Evidence ◽  
Counter Rotation ◽  
Two Systems ◽  
Velocity Dispersions ◽  
First Time ◽  
Disc Galaxies

AbstractWe use the Marcario Low Resolution Spectrograph (LRS) at the Hobby-Eberly-Telescope (HET) to study the kinematics of pseudobulges and classical bulges in 45 S0-Sc type galaxies in the nearby universe. Our high-resolution (instrumental σ ≈ 39 km s−1) spectra allo only to resolve the typical velocity dispersions of our targets but also to derive the h3 and h4 Gauss-Hermite moments. We demonstrate for the first time that purely kinematic diagnostics of the bulge dichotomy agree systematically with those based on Sérsic index. Low Sérsic index bulges have both increased rotational support (higher v/σ values) and on average lower central velocity dispersions. Pseudobulges have systematically shallower velocity dispersion profiles. The same correlation also holds when visual morphologies are used to diagnose bulge type. Finally, we present evidence for formerly undetected counter rotation in the two systems NGC 3945 and NGC 4736. With these, a total of 16% of the systems in or sample show signs for stellar counter rotation.

scholarly journals High-resolution vertical distribution and sources of HONO and NO<sub>2</sub> in the nocturnal boundary layer in urban Beijing, China

2020 ◽  
Vol 20 (8) ◽  
pp. 5071-5092 ◽  
Author(s):  
Fanhao Meng ◽  
Min Qin ◽  
Ke Tang ◽  
Jun Duan ◽  
Wu Fang ◽  
...  
Keyword(s):  
High Resolution ◽  
Vertical Distribution ◽  
Inversion Layer ◽  
Ground Surface ◽  
Residual Layer ◽  
Urban Atmosphere ◽  
Vertical Profiles ◽  
Haze Episode ◽  
Beijing China ◽  
The Vertical Distribution

Abstract. Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), plays a key role in atmospheric chemistry, but its sources are still debated. The production of HONO on aerosol surfaces or on ground surfaces in nocturnal atmospheres remains controversial. The vertical profile provides vertical information on HONO and NO2 to understand the nocturnal HONO production and loss. In this study, we report the first high-resolution (<2.5 m) nocturnal vertical profiles of HONO and NO2 measured from in situ instruments on a movable container that was lifted on the side wiring of a 325 m meteorological tower in Beijing, China. High-resolution vertical profiles revealed the negative gradients of HONO and NO2 in nocturnal boundary layers, and a shallow inversion layer affected the vertical distribution of HONO. The vertical distribution of HONO was consistent with stratification and layering in the nocturnal urban atmosphere below 250 m. The increase in the HONO ∕ NO2 ratio was observed throughout the column from the clean episode to the haze episode, and relatively constant HONO∕NO2 ratios in the residual layer were observed during the haze episode. Direct HONO emissions from traffic contributed 29.3 % ± 12.4 % to the ambient HONO concentrations at night. The ground surface dominates HONO production by heterogeneous uptake of NO2 during clean episodes. In contrast, the HONO production on aerosol surfaces (30–300 ppt) explained the observed HONO increases (15–368 ppt) in the residual layer, suggesting that the aerosol surface dominates HONO production aloft during haze episodes, while the surface production of HONO and direct emissions into the overlying air are minor contributors. Average dry deposition rates of 0.74±0.31 and 1.55±0.32 ppb h−1 were estimated during the clean and haze episodes, respectively, implying that significant quantities of HONO could be deposited to the ground surface at night. Our results highlight the ever-changing contributions of aerosol and ground surfaces in nocturnal HONO production at different pollution levels and encourage more vertical gradient observations to evaluate the contributions from varied HONO sources.

scholarly journals Technical Note: Regularization performances with the error consistency method in the case of retrieved atmospheric profiles

2007 ◽  
Vol 7 (5) ◽  
pp. 1435-1440 ◽  
Author(s):  
S. Ceccherini ◽  
C. Belotti ◽  
B. Carli ◽  
P. Raspollini ◽  
M. Ridolfi
Keyword(s):  
Regularization Parameter ◽  
Technical Note ◽  
Field Of View ◽  
Regularization Methods ◽  
Vertical Profiles ◽  
Vertical Resolution ◽  
Vertical Field ◽  
The Stability ◽  
First Time ◽  
Consistency Method

Abstract. The retrieval of concentration vertical profiles of atmospheric constituents from spectroscopic measurements is often an ill-conditioned problem and regularization methods are frequently used to improve its stability. Recently a new method, that provides a good compromise between precision and vertical resolution, was proposed to determine analytically the value of the regularization parameter. This method is applied for the first time to real measurements with its implementation in the operational retrieval code of the satellite limb-emission measurements of the MIPAS instrument and its performances are quantitatively analyzed. The adopted regularization improves the stability of the retrieval providing smooth profiles without major degradation of the vertical resolution. In the analyzed measurements the retrieval procedure provides a vertical resolution that, in the troposphere and low stratosphere, is smaller than the vertical field of view of the instrument.

AirCore: An Innovative Atmospheric Sampling System

2010 ◽  
Vol 27 (11) ◽  
pp. 1839-1853 ◽  
Author(s):  
Anna Karion ◽  
Colm Sweeney ◽  
Pieter Tans ◽  
Timothy Newberger
Keyword(s):  
Ambient Pressure ◽  
Ambient Air ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Sampling System ◽  
Sampling Device ◽  
Measurement Resolution ◽  
Longitudinal Mixing ◽  
Atmospheric Sampling ◽  
Validation Tests

Abstract This work describes the AirCore, a simple and innovative atmospheric sampling system. The AirCore used in this study is a 150-m-long stainless steel tube, open at one end and closed at the other, that relies on positive changes in ambient pressure for passive sampling of the atmosphere. The AirCore evacuates while ascending to a high altitude and collects a sample of the ambient air as it descends. It is sealed upon recovery and measured with a continuous analyzer for trace gas mole fraction. The AirCore tubing can be shaped into a variety of configurations to accommodate any sampling platform; for the testing done in this work it was shaped into a 0.75-m-diameter coil. Measurements of CO2 and CH4 mole fractions in laboratory tests indicate a repeatability and lack of bias to better than 0.07 ppm (one sigma) for CO2 and 0.4 ppb for CH4 under various conditions. Comparisons of AirCore data with flask data from aircraft flights indicate a standard deviation of differences of 0.3 ppm and 5 ppb for CO2 and CH4, respectively, with no apparent bias. Accounting for longitudinal mixing, the expected measurement resolution for CO2 is 110 m at sea level, 260 m at 8000 m, and 1500 m at 20 000 m ASL after 3 h of storage, decreasing to 170, 390, and 2300 m, after 12 h. Validation tests confirm that the AirCore is a robust sampling device for many species on a variety of platforms, including balloons, unmanned aerial vehicles (UAVs), and aircraft.

Mesozooplankton biomass in the Celtic Sea: a first approach to comparing and combining CPR and LHPR data

1999 ◽  
Vol 79 (1) ◽  
pp. 179-181 ◽  
Author(s):  
S.D. Batten ◽  
A.G. Hirst ◽  
J. Hunter ◽  
R.S. Lampitt
Keyword(s):  
High Resolution ◽  
Vertical Distribution ◽  
Zooplankton Biomass ◽  
Data Sets ◽  
Shelf Edge ◽  
Mesozooplankton Biomass ◽  
Celtic Sea ◽  
First Time ◽  
Vertical Scales ◽  
The Vertical Distribution

Zooplankton biomass varies on temporal, horizontal and vertical scales. However, data sets which incorporate all these dimensions at high resolution are very rare. Two devices which measure all these aspects have recently been simultaneously deployed in the Celtic Sea, the continuous plankton recorder (CPR) and the Longhurst–Hardy plankton recorder (LHPR). This demonstrates that integrated biomass derived from the LHPR are not significantly different from those derived using the CPR. Values have, therefore, been combined for the first time to describe the vertical distribution of mesozooplankton biomass at the Celtic Sea shelf edge through an annual cycle. This suggests that the surface biomass peak is broader at the shelf break than in the open ocean and in the autumn the main biomass peak may be below the depth sampled by the CPR.

High Resolution DNS of Shear-Convective Turbulence and Its Implications to Second-Order Parameterization

2003 ◽  
Author(s):  
K. L. Tse ◽  
A. Mahalov ◽  
B. Nicolaenko ◽  
B. Joseph
Keyword(s):  
High Resolution ◽  
Second Order ◽  
Heat Fluxes ◽  
Quasi Equilibrium ◽  
Vertical Profiles ◽  
Turbulence Statistics ◽  
Convective Turbulence ◽  
Unstable Layer ◽  
Momentum And Heat Fluxes ◽  
First Time

High resolution 3D direct numerical simulation (DNS) of a model tropopause jet, with an underlying convectively unstable layer, is performed. We obtain quasi-equilibrium turbulent dataset, in which the budgets are nearly balanced. Vertical profiles of turbulence statistics and budgets are presented. Using this DNS dataset, we evaluate the performance of some popular models used in second-order closure of turbulence. To our knowledge, this is first time that such a study is conducted for turbulence under the combined influence of shear and convection. From this quasi-equilibrium dataset, we unambigously identify layers of countergradient momentum and heat fluxes which occur near regions of penetrative convection. These are also regions where conventional second-order closure models fail.

Dipole matrix elements for vibration–rotation lines in the 2–0 band of the hydrogen bromide molecule

1968 ◽  
Vol 46 (24) ◽  
pp. 2739-2743 ◽  
Author(s):  
B. Sesh Rao ◽  
LuVerne H. Lindquist
Keyword(s):  
High Resolution ◽  
Hydrogen Bromide ◽  
Matrix Elements ◽  
Low Resolution ◽  
Rotation Band ◽  
Grating Spectrometer ◽  
Vibration Rotation ◽  
First Time ◽  
Resolution Spectrometer ◽  
Line Strengths

The equivalent widths, the line strengths, and the squares of the dipole matrix elements of the 2–0 vibration–rotation band lines of the H79Br molecule are measured. The measurements are made on a high-resolution infrared grating spectrometer which could completely resolve the two isotopic lines of H79Br and H81Br. This is the first time the high-resolution work on the intensities of the HBr molecule has ever been presented. The present data are compared with the earlier work obtained using a low-resolution spectrometer. It is found that the present values are considerably less than the earlier low-resolution values. The discrepancy between the two sets of results is attributed to the lack of resolution in the earlier investigations.

Sign in / Sign up

Export Citation Format

Share Document