scholarly journals Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

2020 ◽  
Author(s):  
Miguel Ricardo A. Hilario ◽  
Ewan Crosbie ◽  
Michael Shook ◽  
Jeffrey S. Reid ◽  
Maria Obiminda L. Cambaliza ◽  
...  
Keyword(s):  
Long Range ◽  
Southwest Monsoon ◽  
Long Range Transport ◽  
Northwest Pacific ◽  
Back Trajectories ◽  
Air Masses ◽  
China Sea ◽  
Range Transport ◽  
Transport Patterns ◽  
The Impact

Abstract. The tropical Western North Pacific (TWNP) is a receptor for pollution sources throughout Asia and is highly susceptible to climate change, making it imperative to understand long-range transport in this complex aerosol-meteorological environment. Measurements from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex; 24 Aug to 5 Oct 2019) and back trajectories from the National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) were used to examine transport into the TWNP from the Maritime Continent (MC), Peninsular Southeast Asia (PSEA), East Asia (EA), and West Pacific (WP). A mid-campaign monsoon shift on 20 Sep 2019 led to distinct transport patterns between the southwest monsoon (before 20 Sep) and monsoon transition (after 20 Sep). During the southwest monsoon, long-range transport was a function of southwesterly winds and cyclones over the South China Sea. Low (high) altitude air generally came from MC (PSEA), implying distinct aerosol processing related to convection and perhaps wind shear. The monsoon transition saw transport from EA and WP, driven by Pacific northeasterly winds, continental anticyclones, and cyclones over the East China Sea. Composition of transported air differed by emission source and accumulated precipitation along trajectories (APT) as an indicator of convection. MC air was characterized by biomass burning tracers while major components of EA air pointed to Asian outflow and secondary formation. Convective scavenging of PSEA air was evidenced by considerable vertical differences between aerosol species but not trace gases, as well as notably higher APT and smaller particles than other regions. Finally, we observed a possible wet scavenging mechanism acting on MC air aloft that was not strictly linked to precipitation. These results are important for understanding the transport and processing of air masses with further implications for modeling aerosol lifecycles and guiding international policymaking on public health and climate.

scholarly journals Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

2021 ◽  
Vol 21 (5) ◽  
pp. 3777-3802
Author(s):  
Miguel Ricardo A. Hilario ◽  
Ewan Crosbie ◽  
Michael Shook ◽  
Jeffrey S. Reid ◽  
Maria Obiminda L. Cambaliza ◽  
...  
Keyword(s):  
Long Range ◽  
Southwest Monsoon ◽  
Long Range Transport ◽  
Northwest Pacific ◽  
Back Trajectories ◽  
Air Masses ◽  
China Sea ◽  
Range Transport ◽  
Transport Patterns ◽  
The Impact

Abstract. The tropical Northwest Pacific (TNWP) is a receptor for pollution sources throughout Asia and is highly susceptible to climate change, making it imperative to understand long-range transport in this complex aerosol-meteorological environment. Measurements from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex; 24 August to 5 October 2019) and back trajectories from the National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) were used to examine transport into the TNWP from the Maritime Continent (MC), peninsular Southeast Asia (PSEA), East Asia (EA), and the West Pacific (WP). A mid-campaign monsoon shift on 20 September 2019 led to distinct transport patterns between the southwest monsoon (SWM; before 20 September) and monsoon transition (MT; after 20 September). During the SWM, long-range transport was a function of southwesterly winds and cyclones over the South China Sea. Low- (high-) altitude air generally came from MC (PSEA), implying distinct aerosol processing related to convection and perhaps wind shear. The MT saw transport from EA and WP, driven by Pacific northeasterly winds, continental anticyclones, and cyclones over the East China Sea. Composition of transported air differed by emission source and accumulated precipitation along trajectories (APT). MC air was characterized by biomass burning tracers while major components of EA air pointed to Asian outflow and secondary formation. Convective scavenging of PSEA air was evidenced by considerable vertical differences between aerosol species but not trace gases, as well as notably higher APT and smaller particles than other regions. Finally, we observed a possible wet scavenging mechanism acting on MC air aloft that was not strictly linked to precipitation. These results are important for understanding the transport and processing of air masses with further implications for modeling aerosol lifecycles and guiding international policymaking to public health and climate, particularly during the SWM and MT.

scholarly journals A decadal time series of water vapor and D / H isotope ratios above Zugspitze: transport patterns to central Europe

2017 ◽  
Vol 17 (12) ◽  
pp. 7635-7651 ◽  
Author(s):  
Petra Hausmann ◽  
Ralf Sussmann ◽  
Thomas Trickl ◽  
Matthias Schneider
Keyword(s):  
Time Series ◽  
Water Vapor ◽  
Long Range ◽  
Source Region ◽  
Long Range Transport ◽  
Air Masses ◽  
Range Transport ◽  
Intercontinental Transport ◽  
Transport Patterns

Abstract. We present vertical soundings (2005–2015) of tropospheric water vapor (H2O) and its D ∕ H isotope ratio (δD) derived from ground-based solar Fourier transform infrared (FTIR) measurements at Zugspitze (47° N, 11° E, 2964 m a.s.l.). Beside water vapor profiles with optimized vertical resolution (degrees of freedom for signal, DOFS,  =  2.8), {H2O, δD} pairs with consistent vertical resolution (DOFS  =  1.6 for H2O and δD) applied in this study. The integrated water vapor (IWV) trend of 2.4 [−5.8, 10.6] % decade−1 is statistically insignificant (95 % confidence interval). Under this caveat, the IWV trend estimate is conditionally consistent with the 2005–2015 temperature increase at Zugspitze (1.3 [0.5, 2.1] K decade−1), assuming constant relative humidity. Seasonal variations in free-tropospheric H2O and δD exhibit amplitudes of 140 and 50 % of the respective overall means. The minima (maxima) in January (July) are in agreement with changing sea surface temperature of the Atlantic Ocean. Using extensive backward-trajectory analysis, distinct moisture pathways are identified depending on observed δD levels: low column-based δD values (δDcol < 5th percentile) are associated with air masses originating at higher latitudes (62° N on average) and altitudes (6.5 km)than high δD values (δDcol > 95th percentile: 46° N, 4.6 km). Backward-trajectory classification indicates that {H2O, δD} observations are influenced by three long-range-transport patterns towards Zugspitze assessed in previous studies: (i) intercontinental transport from North America (TUS; source region: 25–45° N, 70–110° W, 0–2 km altitude), (ii) intercontinental transport from northern Africa (TNA; source region: 15–30° N, 15° W–35° E, 0–2 km altitude), and (iii) stratospheric air intrusions (STIs; source region: > 20° N, above zonal mean tropopause). The FTIR data exhibit significantly differing signatures in free-tropospheric {H2O, δD} pairs (5 km a.s.l.) – given as the mean with uncertainty of ±2 standard error (SE) – for TUS (VMRH2O  =  2.4 [2.3, 2.6]  ×  103 ppmv, δD  =  −315 [−326, −303] ‰), TNA (2.8 [2.6, 2.9]  ×  103 ppmv, −251 [−257, −246] ‰), and STIs (1.2 [1.1, 1.3]  ×  103 ppmv, −384 [−397, −372] ‰). For TUS events, {H2O, δD} observations depend on surface temperature in the source region and the degree of dehydration having occurred during updraft in warm conveyor belts. During TNA events (dry convection of boundary layer air) relatively moist and weakly HDO-depleted air masses are imported. In contrast, STI events are associated with import of predominantly dry and HDO-depleted air masses. These long-range-transport patterns potentially involve the import of various trace constituents to the central European free troposphere, i.e., import of pollution from North America (e.g., aerosol, ozone, carbon monoxide), Saharan mineral dust, stratospheric ozone, and other airborne species such as pollen. Our results provide evidence that {H2O, δD} observations are a valuable proxy for the transport of such tracers. To validate this finding, we consult a database of transport events (TNA and STI) covering 2013–2015 deduced by data filtering from in situ measurements at Zugspitze and lidar profiles at nearby Garmisch. Indeed, the FTIR data related to these verified TNA events (27 days) exhibit characteristic fingerprints in IWV (5.5 [4.9, 6.1] mm) and δDcol (−266 [−284, −247] ‰), which are significantly distinguishable from the rest of the time series (4.3 [4.1, 4.5] mm, −316 [−324, −308] ‰). This holds true for 136 STI days considering uncertainties of ±1 SE (4.2 [4.0, 4.3] mm, −322 [−327, −316] ‰) with respect to the remainder (4.6 [4.5, 4.8] mm, −302 [−307, −297] ‰). Furthermore, deep stratospheric intrusions to the Zugspitze summit (in situ humidity and beryllium-7 data filtering) show a significantly lower mean value (−334 [−337, −330] ‰) of lower-tropospheric δD (3–5 km a.s.l.) than the rest of the 2005–2015 time series (−284 [−286, −282] ‰) considering uncertainty of ±2 SE. Our results show that consistent {H2O, δD} observations at Zugspitze can serve as an operational indicator for long-range-transport events potentially affecting regional climate and air quality, as well as human health in central Europe.

scholarly journals A decadal time series of water vapor and D/H isotope ratios above Mt. Zugspitze: transport patterns to Central Europe

2017 ◽  
Author(s):  
Petra Hausmann ◽  
Ralf Sussmann ◽  
Thomas Trickl ◽  
Matthias Schneider
Keyword(s):  
Time Series ◽  
Water Vapor ◽  
Long Range ◽  
Source Region ◽  
Long Range Transport ◽  
Air Masses ◽  
Range Transport ◽  
Intercontinental Transport ◽  
Transport Patterns

Abstract. We present vertical soundings (2005–2015) of tropospheric water vapor (H2O) and its D/H isotope ratio (δD) at Mt. Zugspitze (47° N, 11° E, 2964 m a.s.l.) derived from ground-based solar Fourier transform infrared (FTIR) measurements. Beside water vapor profiles with optimized vertical resolution (degrees of freedom for signal DOFS = 2.8), the retrieval provides {H2O, δD} pairs with consistent vertical resolution (DOFS = 1.6 for H2O and δD) applied in this study. The integrated water vapor (IWV) trend of 2.4 [−5.8, 10.6] % per decade (statistically insignificant, 95 % confidence interval) can be reconciled with the 2005–2015 temperature increase at Mt. Zugspitze (1.3 [0.5, 2.1] K per decade) assuming constant relative humidity. Seasonal variations in free-tropospheric H2O and δD exhibit amplitudes of 140 % and 50 % of the respective overall means. The minima (maxima) in January (July) are in agreement with changing sea surface temperature of the Atlantic Ocean. Using extensive backward trajectory analysis, distinct moisture pathways are identified depending on observed δD levels: low column-based δD values (δDcol < 5th percentile) are associated with air masses originating in higher latitudes (62° N on average) and altitudes (6.5 km) compared to high δD values (δDcol > 95th percentile: 46° N, 4.6 km). Backward trajectory classification indicates that {H2O, δD} observations are influenced by three long-range transport patterns towards Mt. Zugspitze assessed in previous studies: (i) intercontinental transport from North America (TUS; source region: 25–45° N, 70–110° W, 0–2 km altitude), (ii) intercontinental transport from Northern Africa (TNA; source region: 15–30° N, 15° W–35° E, 0–2 km altitude), and (iii) stratospheric air intrusions (STI; source region: > 20° N, above zonal mean tropopause). The FTIR data exhibit significantly differing signatures in free-tropospheric {H2O, δD} pairs (given as mean with uncertainty of ±2 standard errors) for TUS (VMRH2O = 2.4 [2.3, 2.6] × 103 ppmv, δD = −315 [−326, −303] ‰), TNA (2.8 [2.6, 2.9] × 103 ppmv, −251 [−257, −246] ‰), and STI (1.2 [1.1, 1.3] × 103 ppmv, −384 [−397, −372] ‰). For TUS events, {H2O, δD} observations depend on surface temperature in the source region and the degree of dehydration having occurred during updraft in warm conveyor belts. During TNA events (dry convection of boundary layer air) relatively moist and weakly HDO-depleted air masses are imported. In contrast, STI events are associated to import of predominantly dry and HDO-depleted air masses. These long-range transport patterns potentially involve the import of various trace constituents to the Central European free troposphere, i.e., import of pollution from North America (e.g., aerosol, ozone, carbon monoxide), Saharan mineral dust, stratospheric ozone and other airborne species such as pollen. Our above results provide evidence that {H2O, δD} observations are a valuable proxy for the potential transport of such tracers. To validate this finding, we consult a data base of transport events (TNA and STI) covering 2013–2015 deduced by data filtering from in situ measurements at Mt. Zugspitze and lidar profiles at near-by Garmisch. Indeed, the FTIR data related to these verified TNA events (27 days) exhibit characteristic fingerprints in IWV (5.5 [4.9, 6.1] mm) and δDcol (−266 [−284, −247] ‰), which are significantly distinguishable from the rest of the time series (4.3 [4.1, 4.5] mm, −316 [−324, −308] ‰). This holds true on 1-σ level for 136 STI days (mean ± 1 standard error: 4.2 [4.0, 4.3] mm, −322 [−327, −316] ‰) with respect to the remainder (4.6 [4.5, 4.8] mm, −302 [−307, −297] ‰). Furthermore, deep stratospheric intrusions to the Zugspitze summit (in situ humidity and beryllium-7 data filtering) show a significantly lower mean value (−334 [−337, −330] ‰) of lower-tropospheric δD (3–5 km a.s.l.) on 2-σ level than the rest of the 2005–2015 time series (−284 [−286, −282] ‰). Our results show that consistent {H2O, δD} observations at Mt. Zugspitze can serve as an operational indicator for long-range transport events potentially affecting regional climate, air quality, as well as human health in Central Europe.

scholarly journals First simultaneous measurements of peroxyacetyl nitrate (PAN) and ozone at Nam Co in the central Tibetan Plateau: impacts from the PBL evolution and transport processes

2017 ◽  
Author(s):  
Xiaobin Xu ◽  
Hualong Zhang ◽  
Weili Lin ◽  
Ying Wang ◽  
Shihui Jia
Keyword(s):  
Long Range ◽  
Early Morning ◽  
Diurnal Variations ◽  
Long Range Transport ◽  
Nam Co ◽  
Monsoon Period ◽  
Air Masses ◽  
Upper Troposphere ◽  
Central Tibetan Plateau ◽  
Range Transport

Abstract. Both peroxyacetyl nitrate (PAN) and ozone (O3) are key photochemical products in the atmosphere. Most of the previous in-situ observations of both gases have been made in polluted regions and at low altitude sites. Here we present first simultaneous measurements of PAN and O3 at Nam Co (NMC, 90°57′ E, 30°46′ N, 4745 m  a.s.l.), a remote site in the central Tibetan Plateau (TP). The observations were made during summer periods in 2011 and 2012. The PAN concentrations averaged 0.36 ppb (range: 0.11–0.76 ppb) and 0.44 ppb (range: 0.21–0.99 ppb) during 16–25 August 2011 and 15 May to 13 July 2012, respectively. The O3 concentration varied from 27.9 ppb to 96.4 ppb, with an average of 60.0 ppb. Profound diurnal cycles of PAN and O3 were observed, with minimum values around 05:00 LT, steep rises in the early morning, and broader platforms of high values during 09:00–20:00 LT. We find that the evolution of planetary boundary layer (PBL) played a key role in shaping the diurnal patterns of both gases, particularly the rapid increases of PAN and O3 in the early morning. Air entrainment from the free troposphere into the PBL seemed to cause the early morning increase and be a key factor of sustaining the daytime high concentrations of both gases. The days with higher daytime PBL (about 3 km) showed stronger diurnal variations of both gases and were mainly distributed in the drier pre-monsoon period, while those with shallower daytime PBL (about 2 km) showed minor diurnal variations of both gases and were mainly distributed in the humid monsoon period. Episodes of higher PAN levels were observed occasionally at NMC. These PAN episodes were caused either by rapid downward transport of air masses from the middle/upper troposphere or by long-range transport of PAN plumes from North India. The PAN level in the downward transport cases ranged from 0.5 ppb to 0.7 ppb and may indicate the PAN abundance in the middle/upper troposphere. In the long-range transport case, the PAN level varied in the range of 0.6–1.0 ppb. This long-range transport process influenced most of the western and central TP region for about a week in early June 2012. Our results suggest that polluted air masses from South Asia can significantly enhance the PAN level over the TP. As PAN act as a reservoir of NOx, the impacts of pollution transport from South Asia on tropospheric photochemistry over the TP region deserve further studies.

scholarly journals Long-range Transport Impacts on Surface Aerosol Concentrations and the Contributions to Haze Events in China: an HTAP2 Multi-Model Study

2018 ◽  
Author(s):  
Xinyi Dong ◽  
Joshua S. Fu ◽  
Qingzhao Zhu ◽  
Jian Sun ◽  
Jiani Tan ◽  
...  
Keyword(s):  
East Asia ◽  
Long Range ◽  
Source Region ◽  
Long Range Transport ◽  
Special Focus ◽  
Anthropogenic Emission ◽  
Multiple Model ◽  
Aerosol Mass Concentration ◽  
Range Transport ◽  
The Impact

Abstract. Haze has been severely affecting the densely populated areas in China during recent years. While many of the pilot studies have been devoted to investigate the contributions from local anthropogenic emission, limited attention has been paid to the influence from long-range transport. In this study, we use simulations from 6 participating models supplied through the Task Force on Hemispheric Transport of Air Pollution Phase 2 (HTAP2) exercise to investigate the long-range transport impact of Europe and Russia/Belarussia/Ukraine on the surface air quality in East Asia, with special focus on their contributions during the haze episodes over China. The impact of 20 % anthropogenic emission perturbation from the source region is extrapolated by a factor of 5 to estimate the full impact. We find that the full impacts from EUR and RBU are 0.99 µg/m3 (3.1 %) and 1.32 µg/m3 (4.1 %) respectively during haze episodes, while the annual averaged full impacts are only 0.35 µg m3 (1.7 %) and 0.53 µg/m3 (2.6 %) respectively. By estimating the aerosol response within and above the planetary boundary layer (PBL), we find that long-range transport within the PBL contributes to 22–38 % of the total column density of aerosol response. Comparison with the HTAP Phase 1 (HTAP1) assessment reveals that from 2000 to 2010, the long-range transport from Europe to East Asia has decreased significantly by a factor of 2–10 for surface aerosol mass concentration due to the simultaneous emission reduction in source region and emission increase in the receptor region. By investigating the visibility response, we find that the long-range transport from the Europe and RBU region increases the number of haze events in China by 0.15 % and 0.11 % respectively, and the North China Plain and southeast China receives 1–3 extra haze days. This study is the first investigation into the contribution of long-range transport to haze in China with multiple model experiments.

Radioactivity measurements in the atmosphere and water column of Rogoznica Lake (central Adriatic)

2021 ◽  
Author(s):  
Ivana Tucaković ◽  
Sarah Mateša ◽  
Ivana Coha ◽  
Marija Marguš ◽  
Milan Čanković ◽  
...  
Keyword(s):  
Water Column ◽  
Long Range ◽  
Lake Water ◽  
Dry Deposition ◽  
Long Range Transport ◽  
Atmospheric Input ◽  
Air Masses ◽  
Activity Concentrations ◽  
Range Transport ◽  
Radionuclide Activity

&lt;p&gt;Croatian Science Foundation MARRES project (MARine lake (Rogoznica) as a model for EcoSystem functioning in a changing environment) aims to investigate the unique environment (slow exchange of seawater with the sea; atmospheric input is the only source of freshwater) of the marine lake which is an example of highly stratified (permanent anoxia bellow 9 m depth), and by climate changes affected marine system in the middle of the eastern Adriatic coast (43.53&amp;#176; N, 15.95&amp;#176; E). The area of the lake is characterized by the extensive tourism and mariculture, and the low impact of local industrial activities. It is also affected by the combined influence of long-range transport of air masses and local emissions (open-fire events).&lt;/p&gt;&lt;p&gt;An important part of the project is focused on the exchange and interaction between atmosphere, water column and sediment by measuring the atmospheric input (wet and dry deposition) of sulphur compounds, organic carbon, trace metals and radionuclides (Be-7, Pb-210).&lt;/p&gt;&lt;p&gt;This work for the first time will present the current state of the measurements of radioactivity in the Rogoznica lake area, including samples of aerosol particulate matter, PM2.5 &lt; 2.5 um, rainwater and lake water column. Namely, the concentrations of Be-7 and Pb-210 in PM2.5 are measured to determine and correlate the dynamics of particle transport, meteorological information, especially origin of air masses and seasonal variation of PM2.5. While presence of Be-7 indicates the recent wet or dry deposition from the upper parts of the atmosphere, Pb-210 may be used as a tracer for continental air masses. Therefore, it can also indicate the influence of the pollution induced by human activity. Regarding that, special attention will be paid to compare results before and during the Covid-19 lockdown periods.&lt;/p&gt;&lt;p&gt;So far, preliminary results do not show significant difference in PM2.5 masses and measured radionuclide activity concentrations for the lockdown period. Be-7 and Pb-210 were regularly detected in aerosols collected on a glass fiber filters during a one-week sampling periods with the air flow rate of 2.3 m&lt;sup&gt;3&lt;/sup&gt;/h. Their activity concentrations are determined by gamma spectrometry using High Purity Germanium detectors. The results are found to be correlated with PM2.5 masses, ranging from 2.9 to 12.2 Bq/m&lt;sup&gt;3&lt;/sup&gt; for Be-7 and from 0.5 to 2.5 Bq/m&lt;sup&gt;3&lt;/sup&gt; for Pb-210. First analyses show that the highest values can be related to the long-range transport of air masses and to the recorded near open-fire event. As expected, Be-7 is also detected in almost every rainwater sample (event), with the activity concentration up to 5.6 Bq/L, while low activities of Pb-210 are detected only sporadically. Related to that, Be-7 is detected in lake water column as well, but only in the surface layer and in samples collected during, or immediately after the rain events.&amp;#160;&lt;/p&gt;&lt;p&gt;Dynamics and seasonal variation of radionuclide activity concentrations in here studied samples will be discussed, and the relationships with some meteorological parameters (temperature, wind speed, relative humidity, precipitation level) as well as local and long-range transport and physico-chemical conditions in the lake water column will be established.&lt;/p&gt;

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