scholarly journals SO<sub>2</sub> and BrO observation in the plume of the Eyjafjallajökull volcano 2010: CARIBIC and GOME-2 retrievals

2011 ◽  
Vol 11 (6) ◽  
pp. 2973-2989 ◽  
Author(s):  
K.-P. Heue ◽  
C. A. M. Brenninkmeijer ◽  
A. K. Baker ◽  
A. Rauthe-Schöch ◽  
D. Walter ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Satellite Observations ◽  
Optical Absorption Spectroscopy ◽  
Volcanic Plume ◽  
Local Distribution ◽  
Additional Information ◽  
Mixing Ratios ◽  
Civil Aircraft ◽  
Forecast Models ◽  
Ash Cloud

Abstract. The ash cloud of the Eyjafjallajökull (also referred to as: Eyjafjalla (e.g. Schumann et al., 2011), Eyjafjöll or Eyjafjoll (e.g. Ansmann et al., 2010)) volcano on Iceland caused closure of large parts of European airspace in April and May 2010. For the validation and improvement of the European volcanic ash forecast models several research flights were performed. Also the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) flying laboratory, which routinely measures at cruise altitude (≈11 km) performed three dedicated measurements flights through sections of the ash plume. Although the focus of these flights was on the detection and quantification of the volcanic ash, we report here on sulphur dioxide (SO2) and bromine monoxide (BrO) measurements with the CARIBIC DOAS (Differential Optical Absorption Spectroscopy) instrument during the second of these special flights on 16 May 2010. As the BrO and the SO2 observations coincide, we assume the BrO to have been formed inside the volcanic plume. Average SO2 and BrO mixing ratios of ≈40 ppb and ≈5 ppt respectively are retrieved inside the plume. The BrO to SO2 ratio retrieved from the CARIBIC observation is ≈1.3×10−4. Both SO2 and BrO observations agree well with simultaneous satellite (GOME-2) observations. SO2 column densities retrieved from satellite observations are often used as an indicator for volcanic ash. As the CARIBIC O4 column densities changed rapidly during the plume observation, we conclude that the aerosol and the SO2 plume are collocated. For SO2 some additional information on the local distribution can be derived from a comparison of forward and back scan GOME-2 data. More details on the local plume size and position are retrieved by combining CARIBIC and GOME-2 data.

scholarly journals SO<sub>2</sub> and BrO observation in the plume of the Eyjafjallajökull volcano 2010: CARIBIC and GOME-2 retrievals

2010 ◽  
Vol 10 (12) ◽  
pp. 29631-29682 ◽  
Author(s):  
K.-P. Heue ◽  
C. A. M. Brenninkmeijer ◽  
A. K. Baker ◽  
A. Rauthe-Schöch ◽  
D. Walter ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Satellite Observations ◽  
Optical Absorption Spectroscopy ◽  
Volcanic Plume ◽  
Local Distribution ◽  
Additional Information ◽  
Civil Aircraft ◽  
Forecast Models ◽  
Ash Cloud ◽  
Detection And Quantification

Abstract. The ash cloud of the Eyjafjallajökull1 volcano on Iceland caused closure of large parts of European airspace in April and May 2010. For the validation and improvement of the European volcanic ash forecast models several research flights were performed. Also the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) flying laboratory, which routinely measures at cruise altitude (≈11 km) performed three dedicated measurements flights through sections of the ash plume. Although the focus of these flights was on the detection and quantification of the volcanic ash, we report here on sulphur dioxide (SO2) and bromine monoxide (BrO) measurements with the CARIBIC DOAS (Differential Optical Absorption Spectroscopy) instrument during the second of these special flights on 16 May 2010. As the BrO and the SO2 observations coincide, we assume the BrO to have been formed inside the volcanic plume. Both SO2 and BrO observations agree well with simultaneous satellite (GOME-2) observations. SO2 column densities retrieved from satellite observations are often used as an indicator for volcanic ash. For SO2 some additional information on the local distribution can be derived from a~comparison of forward and back scan GOME-2 data. More details on the local plume size and position are retrieved by combining CARIBIC and GOME-2 data. 1Also referred to as: Eyjafjalla (e.g. Schumann et al., 2010), Eyjafjöll or Eyjafjoll (e.g. Ansmann et al., 2010).

The Airyx 2D SkySpec instrument: MAX-DOAS measurements of tropospheric NO2 and HCHO in Munich and the comparison to satellite observations

2020 ◽  
Author(s):  
Johannes Lampel ◽  
Ka Lok Chan ◽  
Denis Pöhler ◽  
Matthias Wiegner ◽  
Carlos Alberti ◽  
...  
Keyword(s):  
Pearson Correlation ◽  
Satellite Observations ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Extinction ◽  
Aerosol Formation ◽  
Mixing Ratios ◽  
Monitor Data ◽  
Sun Light ◽  
Good Agreement

&lt;p&gt;We present the Airyx 2D SkySpec Instrument: A commercially available two-dimensionally scanning Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) setup for the observations of trace gases using spectral measurements of scattered sun light and optionally also direct sun light. The waterproof design of the scanner unit is designed for long-term outdoor deployment. Temperature stabilisation of the spectrometers and automatic calibration spectra measurement are used to ensure high-quality measurement data over months and years of observations.&lt;/p&gt;&lt;p&gt;We show 2.5 years of measurements in Munich. Vertical columns and vertical distribution profiles of aerosol extinction coefficient, NO&lt;sub&gt;2&lt;/sub&gt; and HCHO are retrieved from the 2D MAX-DOAS observations. The measured surface aerosol extinction coefficients and NO&lt;sub&gt;2&lt;/sub&gt; mixing ratios are compared to in-situ monitor data. The retrieved surface NO&lt;sub&gt;2&lt;/sub&gt; mixing ratios show good agreement with in-situ monitor data with a Pearson correlation coefficient (R) of 0.91. Good agreement (R= 0.80) is also found for AOD when compared to sun-photometer measurements. Tropospheric vertical column densities (VCDs) of NO2 and HCHO derived from the MAX-DOAS measurements are also used to validate OMI and TROPOMI satellite observations. Monthly averaged data show good correlation, however, satellite observations are on average 30% lower than the MAX-DOAS measurements. Furthermore, the 2D MAX-DOAS observations are used to investigate the spatio-temporal characteristic of NO2 and HCHO in Munich. Analysis of the relations among aerosol, NO&lt;sub&gt;2&lt;/sub&gt; and HCHO show higher aerosol to HCHO ratios in winter indicating a longer atmospheric lifetime of aerosol and HCHO. The analysis also suggests that secondary aerosol formation is the major source of aerosols in Munich.&lt;/p&gt;

scholarly journals Analysis of properties of the 19 February 2018 volcanic eruption of Mount Sinabung in S5P/TROPOMI and Himawari-8 satellite data

2020 ◽  
Vol 20 (5) ◽  
pp. 1203-1217 ◽  
Author(s):  
Adrianus de Laat ◽  
Margarita Vazquez-Navarro ◽  
Nicolas Theys ◽  
Piet Stammes
Keyword(s):  
Satellite Data ◽  
Volcanic Ash ◽  
Geostationary Satellite ◽  
Oxygen Absorption ◽  
Volcanic Plume ◽  
Accurate Information ◽  
Ice Crystal ◽  
Volcanic Ash Cloud ◽  
Absorbing Aerosols ◽  
Ash Cloud

Abstract. This study presents an analysis of TROPOMI cloud heights as a proxy for volcanic plume heights in the presence of absorbing aerosols and sulfur dioxide for the 19 February 2018 eruption plume of the Sinabung volcano on Sumatra, Indonesia. Comparison with CALIPSO satellite data shows that all three TROPOMI cloud height data products based on oxygen absorption which are considered here (FRESCO, ROCINN, O22CLD) provide volcanic ash cloud heights comparable to heights measured by CALIPSO for optically thick volcanic ash clouds. FRESCO and ROCINN heights are very similar, with the only differences for FRESCO cloud top heights above 14 km altitude. O22CLD cloud top heights unsurprisingly fall below those of FRESCO and ROCINN, as the O22CLD retrieval is less sensitive to cloud top heights above 10 km altitude. For optically thin volcanic ash clouds, i.e., when Earth's surface or clouds at lower altitudes shine through the volcanic ash cloud, retrieved heights fall below the volcanic ash cloud heights derived from CALIPSO data. Evaluation of corresponding Himawari-8 geostationary infrared (IR) brightness temperature differences (ΔBTs) – a signature for detection of volcanic ash clouds in geostationary satellite data and widely used as input for quantitative volcanic ash cloud retrievals – reveals that for this particular eruption the ΔBT volcanic ash signature changes to a ΔBT ice crystal signature for the part of the ash plume reaching the upper troposphere beyond 10 km altitude several hours after the start of the eruption and which TROPOMI clearly characterizes as volcanic (SO2 > 1 DU – Dobson units – and AAI > 4 – absorbing aerosol index – or, more conservatively, SO2 > 10). The presence of ice in volcanic ash clouds is known to prevent the detection of volcanic ash clouds based on broadband geostationary satellite data. TROPOMI does not suffer from this effect and can provide valuable and accurate information about volcanic ash clouds and ash top heights in cases where commonly used geostationary IR measurements of volcanic ash clouds fail.

scholarly journals Interpretation of observed microwave signatures from ground dual polarization radar and space multi frequency radiometer for the 2011 Grímsvötn volcanic eruption

2013 ◽  
Vol 6 (4) ◽  
pp. 6215-6248 ◽  
Author(s):  
M. Montopoli ◽  
G. Vulpiani ◽  
D. Cimini ◽  
E. Picciotti ◽  
F. S. Marzano
Keyword(s):  
Spatial Resolution ◽  
Volcanic Ash ◽  
Volcanic Eruptions ◽  
Radar Data ◽  
Radar Signal ◽  
Volcanic Plume ◽  
Dual Polarization ◽  
X Band ◽  
Volcanic Vent ◽  
Ash Cloud

Abstract. The important role played by ground-based microwave weather radars for the monitoring of volcanic ash clouds has been recently demonstrated. The potential of microwaves from satellite passive and ground-based active sensors to estimate near-source volcanic ash cloud parameters has been also proposed, though with little investigation of their synergy and the role of the radar polarimetry. The goal of this work is to show the potentiality and drawbacks of the X-band Dual Polarization radar measurements (DPX) through the data acquired during the latest Grímsvötn volcanic eruptions that took place on May 2011 in Iceland. The analysis is enriched by the comparison between DPX data and the observations from the satellite Special Sensor Microwave Imager/Sounder (SSMIS) and a C-band Single Polarization (SPC) radar. SPC, DPX, and SSMIS instruments cover a large range of the microwaves spectrum, operating respectively at 5.4, 3.2, and 0.16–1.6 cm wavelengths. The multi-source comparison is made in terms of Total Columnar Concentration (TCC). The latter is estimated from radar observables using the "Volcanic Ash Radar Retrieval for dual-Polarization X band systems" (VARR-PX) algorithm and from SSMIS brightness temperature (BT) using a linear BT–TCC relationship. The BT–TCC relationship has been compared with the analogous relation derived from SSMIS and SPC radar data for the same case study. Differences between these two linear regression curves are mainly attributed to an incomplete observation of the vertical extension of the ash cloud, a coarser spatial resolution and a more pronounced non-uniform beam filling effect of SPC measurements (260 km far from the volcanic vent) with respect to the DPX (70 km from the volcanic vent). Results show that high-spatial-resolution DPX radar data identify an evident volcanic plume signature, even though the interpretation of the polarimetric variables and the related retrievals is not always straightforward, likely due to the possible formation of ash and ice particle aggregates and the radar signal depolarization induced by turbulence effects. The correlation of the estimated TCCs derived from DPX and SSMIS BTs reaches −0.73.

scholarly journals OClO and BrO observations in the volcanic plume of Mt. Etna – implications on the chemistry of chlorine and bromine species in volcanic plumes

2014 ◽  
Vol 14 (18) ◽  
pp. 25213-25280
Author(s):  
J. Gliß ◽  
N. Bobrowski ◽  
L. Vogel ◽  
U. Platt
Keyword(s):  
Early Morning ◽  
Optical Absorption Spectroscopy ◽  
Volcanic Plume ◽  
Plume Dispersion ◽  
Strong Indication ◽  
Volcanic Plumes ◽  
Mixing Ratios ◽  
Rate Of Increase ◽  
Mt Etna ◽  
The Impact

Abstract. Spatial and temporal profiles of chlorine dioxide (OClO), bromine monoxide (BrO) and sulphur dioxide (SO2) were measured in the plume of Mt. Etna, Italy, in September 2012 using Multi-Axis-Differential-Optical-Absorption-Spectroscopy (MAX-DOAS). OClO (BrO) was detected in 119 (452) individual measurements covering plume ages up to 6 (23) minutes. The retrieved slant column densities (SCDs) reached values up to 2.0 × 1014 molecules cm−2 (OClO) and 1.1 × 1015 molecules cm−2 (BrO). In addition, the spectra were analysed for signatures of IO, OIO and OBrO, none of these species could be detected. The corresponding detection limits for IO / SO2, OIO / SO2 and OBrO / SO2 were 1.8 × 10−6, 2.0 × 10−5 and 1.1 × 10−5 respectively. The measurements were performed at plume ages (τ) from zero to 23 min downwind the emission source. The chemical variability of BrO and OClO in the plume was studied analysing the OClO / SO2 and BrO / SO2-ratio. A marked increase of both ratios was observed in the young plume (τ < 3 min) and a levelling off at larger plume ages (τ > 3 min) with mean abundances of 3.17 × 10−5 (OClO / SO2), 1.55 × 10−4 (BrO / SO2) and 0.16 (OClO / BrO). Furthermore, enhanced BrO/SO2-ratios were found at the plume edges (by ~30–37%) and a strong indication of enhanced OClO / SO2-ratios as well (~10–250%). A measurement performed in the early morning (05:20–06:20 UTC, sunrise: 04:40 UTC) showed an BrO / SO2-ratio increasing with time until 05:35 UTC and a constant ratio afterwards. Observing this increase was only possible due to a correction for stratospheric BrO signals in the plume spectra. The corresponding OClO / SO2-ratio showed a similar trend stabilising around 06:13 UTC, approximately 40 min later than BrO. This is another strong indication for the photochemical nature of the reactions involved in the formation of oxidised halogens in volcanic plumes. In particular, these findings support the current understanding of the underlying chemistry, namely, that BrO is formed in an autocatalytic reaction mechanism in literature often referred to as "bromine explosion" and that OClO is formed in the "BrO + ClO"-reaction. BrO and OClO concentrations were estimated from the measured SCDs assuming a circular plume shape. In addition, mixing ratios of ClO were determined from the retrieved OClO and BrO-SCDs assuming chemical equilibrium between formation of OClO (BrO + ClO) and its destruction (photolysis). Mean abundances in the young plume (τ<4 min) were BrO = 1.35 ppb, OClO = 300 ppt and ClO = 139 ppt with peak values of 600 ppt (OClO), 2.7 ppb (BrO) and 235 ppt (ClO) respectively. The prevailing Cl-atom concentrations in the plume could be estimated from the rate of increase of OClO and BrO in the young plume and the determined ClO and OClO concentrations. Values between 5.1 × 106 cm−3 (at 40 ppb O3) and 2.1 × 108 cm−3 (at 1 ppb O3) were found. Based on that, a potential – chlorine induced – depletion of tropospheric methane (CH4) in the plume was investigated. CH4-lifetimes between 13 h (at 1 ppb O3) and 23 days (at 40 ppb O3) were found. These are considerably small compared to the atmospheric lifetime of CH4. However, the impact of gaseous chlorine on the CH4-budget in the plume environment was assessed to be relatively small, mainly due to plume dispersion (decrease of Cl number densities) and permanent mixing of the plume with the surrounding atmosphere (net supply of O3 and CH4).

scholarly journals Airborne observations of the Eyjafjalla volcano ash cloud over Europe during air space closure in April and May 2010

2010 ◽  
Vol 10 (9) ◽  
pp. 22131-22218 ◽  
Author(s):  
U. Schumann ◽  
B. Weinzierl ◽  
O. Reitebuch ◽  
H. Schlager ◽  
A. Minikin ◽  
...  
Keyword(s):  
Mass Flux ◽  
Mass Concentration ◽  
Volcanic Ash ◽  
Mixing Ratio ◽  
Airborne Measurements ◽  
Particle Properties ◽  
Mixing Ratios ◽  
Coarse Mode ◽  
Space Closure ◽  
Ash Cloud

Abstract. Airborne measurements of Lidar backscatter, aerosol concentrations (particle diameters of 4 nm to 50 μm), trace gas mixing ratios (SO2, CO, O3, H2O), single particle properties, and meteorological parameters have been performed in volcanic ash plumes with the Falcon aircraft operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). A series of 17 flights was performed over Europe between Southern Germany and Iceland during the eruption period of the Eyjafjalla1 volcano between 19 April and 18 May 2010. Flight planning and measurement analyses were supported by a refined Meteosat ash product and trajectory model analysis. The volcanic ash plume was observed with Lidar directly over the volcano and up to a distance of 2700 km downwind. Lidar and in-situ measurements covered plume ages of 7 h to 120 h. Aged ash layers were between a few 100 m to 3 km deep, occurred between 1 and 7 km altitude, and were typically 100 to 300 km wide. Particles collected by impactors had diameters up to 20 μm diameter, with size and age dependent composition. Ash mass concentration was evaluated for a material density of 2.6 g cm−3 and for either weakly or moderately absorbing coarse mode particles (refractive index 1.59+0i or 1.59+0.004i). In the absorbing case, the ash concentration is about a factor of four larger than in the non-absorbing limit. Because of sedimentation constraints, the smaller results are the more realistic ones for aged plumes. The Falcon flew in ash clouds up to about 1 mg m−3 for a few minutes and in an ash cloud with more than 0.2 mg m−3 mean-concentration for about one hour without engine damages. In fresh plumes, the SO2 concentration was correlated with the ash mass concentration. Typically, 0.5 mg m−3 ash concentration was related to about 100 nmol mol−31 SO2 mixing ratio and 70 nmol mol−1 CO mixing ratio increases for this volcano period. In aged plumes, layers with enhanced coarse mode particle concentration but without SO2 enhancements occurred. To first order, ash concentration and SO2 mixing ratio in the plumes decreased by a factor of two within less than a day. The ash plumes were often visible as faint dark layers even for concentrations below 0.1 mg m−3. The ozone concentrations and the humidity inside the plumes were often reduced compared to ambient values. The large abundance of volatile Aitken mode particles suggests nucleation of sulfuric acid droplets. Ammonium sulfate particles were also found on the impactors. The effective diameters decreased from about 5 μm in the fresh plume to about 1 μm for plume ages of up to 6 days. The distal ash mass flux on 2 May was of the order 1800 kg s−1; the SO2 mass flux was about a factor of 3–4 smaller. The volcano ejected about 40 Tg of ash mass and 10 Tg of SO2 during the whole eruption period. The results of the Falcon flights were used to support the responsible agencies in their decisions concerning air traffic in the presence of volcanic ash. The data described may be used for further studies, including comparisons to satellite and ground or space based Lidar observations, and for model improvements. 1 Also known as Eyjafjallajökull or Eyjafjöll volcano, http://www.britannica.com/EBchecked/topic/1683937/Eyjafjallajokull-volcano

scholarly journals OClO and BrO observations in the volcanic plume of Mt. Etna – implications on the chemistry of chlorine and bromine species in volcanic plumes

2015 ◽  
Vol 15 (10) ◽  
pp. 5659-5681 ◽  
Author(s):  
J. Gliß ◽  
N. Bobrowski ◽  
L. Vogel ◽  
D. Pöhler ◽  
U. Platt
Keyword(s):  
Heterogeneous Reaction ◽  
Early Morning ◽  
Optical Absorption Spectroscopy ◽  
Volcanic Plume ◽  
Plume Dispersion ◽  
Volcanic Plumes ◽  
Mixing Ratios ◽  
New Findings ◽  
Mt Etna ◽  
The Impact

Abstract. Spatial and temporal profiles of chlorine dioxide (OClO), bromine monoxide (BrO) and sulfur dioxide (SO2) of the volcanic plume at Mt. Etna, Italy, were investigated in September 2012 using Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). OClO was detected in 119 individual measurements covering plume ages up to 6 min. BrO could be detected in 452 spectra up to 23 min downwind. The retrieved slant column densities (SCDs) reached maximum values of 2.0 × 1014 molecules cm-2 (OClO) and 1.1 × 1015 molecules cm-2 (BrO). Mean mixing ratios of BrO and OClO were estimated assuming a circular plume cross section. Furthermore, ClO mixing ratios were derived directly from the BrO and OClO-SCDs. Average abundances of BrO = 1.35 ppb, OClO = 300 ppt and ClO = 139 ppt were found in the young plume (plume age τ < 4 min) with peak values of 2.7 ppb (BrO), 600 ppt (OClO) and 235 ppt (ClO) respectively. The chemical evolution of BrO and OClO in the plume was investigated in great detail by analysing the OClO/SO2 and BrO/SO2 ratios as a function of plume age τ. A marked increase of both ratios was observed in the young plume (τ < 142 s) and a levelling off at larger plume ages showing mean SO2 ratios of 3.17 × 10-5 (OClO/SO2) and 1.65 × 10-4 (BrO/SO2). OClO was less abundant in the plume compared to BrO with a mean OClO/BrO ratio of 0.16 at plume ages exceeding 3 min. A measurement performed in the early morning at low solar radiances revealed BrO/SO2 and OClO/SO2 ratios increasing with time. This observation substantiates the importance of photochemistry regarding the formation of BrO and OClO in volcanic plumes. These findings support the current understanding of the underlying chemistry, namely, that BrO is formed in an autocatalytic, heterogeneous reaction mechanism (in literature often referred to as "bromine explosion") and that OClO is formed in the reaction of OClO with BrO. These new findings, especially the very detailed observation of the BrO and OClO formation in the young plume, were used to infer the prevailing Cl-atom concentrations in the plume. Relatively small values ranging from [Cl] = 2.5 × 106 cm-3 (assuming 80 ppb background O3) to [Cl] = 2.0 × 108 cm-3 (at 1 ppb O3) were calculated at plume ages of about 2 min. Based on these Cl abundances, a potential – chlorine-induced – depletion of tropospheric methane (CH4) in the plume was investigated. CH4 lifetimes between 14 h (at 1 ppb O3) and 47 days (at 80 ppb O3) were derived. While these lifetimes are considerably shorter than the atmospheric lifetime of CH4, the impact of gaseous chlorine on the CH4 budget in the plume environment should nevertheless be relatively small due to plume dispersion (decreasing Cl concentrations) and ongoing mixing of the plume with the surrounding atmosphere (replenishing O3 and CH4). In addition, all spectra were analysed for signatures of IO, OIO and BrO. None of these species could be detected. Upper limits for IO/SO2, OIO/SO2 and OBrO/SO2 are 1.8 × 10-6, 2.0 × 10-5 and 1.1 × 10-5 respectively.

scholarly journals MAX-DOAS measurements of tropospheric NO<sub>2</sub> and HCHO in Munich and the comparison to OMI and TROPOMI satellite observations

2020 ◽  
Author(s):  
Ka Lok Chan ◽  
Matthias Wiegner ◽  
Carlos Alberti ◽  
Mark Wenig
Keyword(s):  
Pearson Correlation ◽  
Satellite Observations ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Extinction ◽  
Aerosol Formation ◽  
Vertical Column ◽  
Mixing Ratios ◽  
Monitor Data ◽  
Good Agreement

Abstract. We present two dimensionally scanning Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of nitrogen dioxide (NO2) and formaldehyde (HCHO) in Munich. Vertical columns and vertical distribution profiles of aerosol extinction coefficient, NO2 and HCHO are retrieved from the 2D MAX-DOAS observations. The measured surface aerosol extinction coefficients and NO2 mixing ratios derived from the retrieved profiles are compared to in-situ monitor data, and the surface NO2 mixing ratios show good agreement with in-situ monitor data with a Pearson correlation coefficient (R) of 0.91. The aerosols optical depths (AODs) show good agreement as well (R = 0.80) when compared to sun-photometer measurements. Tropospheric vertical column densities (VCDs) of NO2 and HCHO derived from the MAX-DOAS measurements are also used to validate OMI and TROPOMI satellite observations. Monthly averaged data show good correlation, however, satellite observations are on average 30 % lower than the MAX-DOAS measurements. Furthermore, the MAX-DOAS observations are used to investigate the spatio-temporal characteristic of NO2 and HCHO in Munich. Analysis of the relations among aerosol, NO2 and HCHO shows higher aerosol to HCHO ratios in winter indicating a longer atmospheric lifetime of aerosol and HCHO. The analysis also suggests that secondary aerosol formation is the major source of aerosols in Munich.

scholarly journals Variation Characteristics and Transportation of Aerosol, NO2, SO2, and HCHO in Coastal Cities of Eastern China: Dalian, Qingdao, and Shanghai

2021 ◽  
Vol 13 (5) ◽  
pp. 892
Author(s):  
Xiaomei Li ◽  
Pinhua Xie ◽  
Ang Li ◽  
Jin Xu ◽  
Zhaokun Hu ◽  
...  
Keyword(s):  
Eastern China ◽  
Temporal Distribution ◽  
Correlation Coefficients ◽  
Optical Absorption Spectroscopy ◽  
Near Surface ◽  
Mixing Ratios ◽  
Variation Characteristics ◽  
Spatio Temporal ◽  
Gas Volume ◽  
Transport Flux

This paper studied the method for converting the aerosol extinction to the mass concentration of particulate matter (PM) and obtained the spatio-temporal distribution and transportation of aerosol, nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) based on multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations in Dalian (38.85°N, 121.36°E), Qingdao (36.35°N, 120.69°E), and Shanghai (31.60°N, 121.80°E) from 2019 to 2020. The PM2.5 measured by the in situ instrument and the PM2.5 simulated by the conversion formula showed a good correlation. The correlation coefficients R were 0.93 (Dalian), 0.90 (Qingdao), and 0.88 (Shanghai). A regular seasonality of the three trace gases is found, but not for aerosols. Considerable amplitudes in the weekly cycles were determined for NO2 and aerosols, but not for SO2 and HCHO. The aerosol profiles were nearly Gaussian, and the shapes of the trace gas profiles were nearly exponential, except for SO2 in Shanghai and HCHO in Qingdao. PM2.5 presented the largest transport flux, followed by NO2 and SO2. The main transport flux was the output flux from inland to sea in spring and winter. The MAX-DOAS and the Copernicus Atmosphere Monitoring Service (CAMS) models’ results were compared. The overestimation of NO2 and SO2 by CAMS is due to its overestimation of near-surface gas volume mixing ratios.

scholarly journals Volcanic ash cloud detection from space: a comparison between the RSTASHtechnique and the water vapour corrected BTD procedure

2011 ◽  
Vol 2 (3) ◽  
pp. 263-277 ◽  
Author(s):  
Alessandro Piscini ◽  
Stefano Corradini ◽  
Francesco Marchese ◽  
Luca Merucci ◽  
Nicola Pergola ◽  
...  
Keyword(s):  
Water Vapour ◽  
Volcanic Ash ◽  
Cloud Detection ◽  
Volcanic Ash Cloud ◽  
Ash Cloud
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