Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1464871
K. Budhavant, S. Bikkina, A. Andersson, E. Asmi, J. Backman, Jutta Kesti, H. Zahid, S. Satheesh, Ö. Gustafsson
Abstract This study presents and evaluates the most comprehensive set to date of chemical, physical and optical properties of aerosols in the outflow from South Asia covering a full winter (Nov. 2014 – March 2015), here intercepted at the Indian Ocean receptor site of the Maldives Climate Observatory in Hanimaadhoo (MCOH). Cluster analysis of air-mass back trajectories for MCOH, combined with AOD and meteorological data, demonstrate that the wintertime northern Indian Ocean is strongly influenced by aerosols transported from source regions with three major wind regimes, originating from the Indo-Gangetic Plain (IGP), the Bay of Bengal (BoB) and the Arabian Sea (AS). As much as 97 ± 3% of elemental carbon (EC) in the PM10 was also found in the fine mode (PM2.5). Other mainly anthropogenic constituents such as organic carbon (OC), non-sea-salt (nss) -K+, nss-SO42− and NH4+ were also predominantly in the fine mode (70–95%), particularly in the air masses from IGP. The combination at this large-footprint receptor observatory of consistently low OC/EC ratio (2.0 ± 0.5), strong linear relationships between EC and OC as well as between nss-K+ and both OC and EC, suggest a predominance of primary sources, with a large biomass burning contribution. The particle number-size distributions for the air masses from IGP and BoB exhibited clear bimodal shapes within the fine fraction with distinct accumulation (0.1 μm < d < 1 μm) and Aitken (0.025 μm < d < 0.10 μm) modes. This study also supports that IGP is a key source region for the wider South Asia and nearby oceans, as defined by the criteria that anthropogenic AODs exceed 0.3 and absorption AOD > 0.03. Taken together, the aerosol pollution over the northern Indian Ocean in the dry season is dominated by a well-mixed long-range transported regime of the fine-mode aerosols largely from primary combustion origin.
本研究介绍并评估了迄今为止最全面的一组南亚外流气溶胶的化学、物理和光学特性，涵盖了整个冬季(2014年11月- 2015年3月)，这些气溶胶在马尔代夫气候观测站位于哈尼马杜(MCOH)的印度洋受体站点拦截。结合AOD和气象数据，对MCOH气团反轨迹的聚类分析表明，冬季北印度洋受到来自印度-恒河平原(IGP)、孟加拉湾(BoB)和阿拉伯海(AS)三种主要风源区域输送的气溶胶的强烈影响。在细颗粒物(PM2.5)中，PM10中元素碳(EC)的含量也高达97±3%。其他主要人为成分如有机碳(OC)、非海盐(nss) -K+、nss- so42−和NH4+也以细态为主(70-95%)，特别是来自IGP的气团。在这个大足迹受体观测站，持续的低OC/EC比率(2.0±0.5)，EC和OC之间以及nss-K+与OC和EC之间的强线性关系，表明主要来源占主导地位，其中生物质燃烧贡献很大。IGP和BoB气团的颗粒数-尺寸分布在细段内呈现明显的双峰型，具有明显的累积模式(0.1 μm < d < 1 μm)和艾特肯模式(0.025 μm < d < 0.10 μm)。根据人为AOD超过0.3和吸收AOD > 0.03的标准，本研究还支持IGP是更广泛的南亚和附近海洋的关键源区。综上所述，旱季北印度洋上空的气溶胶污染主要是由主要来自一次燃烧的细态气溶胶的混合良好的远程输送状态所主导。
{"title":"Anthropogenic fine aerosols dominate the wintertime regime over the northern Indian Ocean","authors":"K. Budhavant, S. Bikkina, A. Andersson, E. Asmi, J. Backman, Jutta Kesti, H. Zahid, S. Satheesh, Ö. Gustafsson","doi":"10.1080/16000889.2018.1464871","DOIUrl":"https://doi.org/10.1080/16000889.2018.1464871","url":null,"abstract":"Abstract This study presents and evaluates the most comprehensive set to date of chemical, physical and optical properties of aerosols in the outflow from South Asia covering a full winter (Nov. 2014 – March 2015), here intercepted at the Indian Ocean receptor site of the Maldives Climate Observatory in Hanimaadhoo (MCOH). Cluster analysis of air-mass back trajectories for MCOH, combined with AOD and meteorological data, demonstrate that the wintertime northern Indian Ocean is strongly influenced by aerosols transported from source regions with three major wind regimes, originating from the Indo-Gangetic Plain (IGP), the Bay of Bengal (BoB) and the Arabian Sea (AS). As much as 97 ± 3% of elemental carbon (EC) in the PM10 was also found in the fine mode (PM2.5). Other mainly anthropogenic constituents such as organic carbon (OC), non-sea-salt (nss) -K+, nss-SO42− and NH4+ were also predominantly in the fine mode (70–95%), particularly in the air masses from IGP. The combination at this large-footprint receptor observatory of consistently low OC/EC ratio (2.0 ± 0.5), strong linear relationships between EC and OC as well as between nss-K+ and both OC and EC, suggest a predominance of primary sources, with a large biomass burning contribution. The particle number-size distributions for the air masses from IGP and BoB exhibited clear bimodal shapes within the fine fraction with distinct accumulation (0.1 μm < d < 1 μm) and Aitken (0.025 μm < d < 0.10 μm) modes. This study also supports that IGP is a key source region for the wider South Asia and nearby oceans, as defined by the criteria that anthropogenic AODs exceed 0.3 and absorption AOD > 0.03. Taken together, the aerosol pollution over the northern Indian Ocean in the dry season is dominated by a well-mixed long-range transported regime of the fine-mode aerosols largely from primary combustion origin.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"5 1","pages":"1 - 15"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87009569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1539618
C. Ritter, M. Burgos, M. Burgos, C. Böckmann, D. Mateos, J. Lisok, K. Markowicz, B. Moroni, D. Cappelletti, R. Udisti, M. Maturilli, R. Neuber
Abstract In this work, an evaluation of an intense biomass burning event observed over Ny-Ålesund (Spitsbergen, European Arctic) in July 2015 is presented. Data from the multi-wavelengths Raman-lidar KARL, a sun photometer and radiosonde measurements are used to derive some microphysical properties of the biomass burning aerosol as size distribution, refractive index and single scattering albedo at different relative humidities. Predominantly particles in the accumulation mode have been found with a bi-modal distribution and dominance of the smaller mode. Above 80% relative humidity, hygroscopic growth in terms of an increase of particle diameter and a slight decrease of the index of refraction (real and imaginary part) has been found. Values of the single scattering albedo around 0.9 both at 355 nm and 532 nm indicate some absorption by the aerosol. Values of the lidar ratio are around 26 sr for 355 nm and around 50 sr for 532 nm, almost independent of the relative humidity. Further, data from the photometer and surface radiation values from the local baseline surface radiation network (BSRN) have been applied to derive the radiative impact of the biomass burning event purely from observational data by comparison with a clear background day. We found a strong cooling for the visible radiation and a slight warming in the infra-red. The net aerosol forcing, derived by comparison with a clear background day purely from observational data, obtained a value of –95 W/m2 per unit AOD500.
{"title":"Microphysical properties and radiative impact of an intense biomass burning aerosol event measured over Ny-Ålesund, Spitsbergen in July 2015","authors":"C. Ritter, M. Burgos, M. Burgos, C. Böckmann, D. Mateos, J. Lisok, K. Markowicz, B. Moroni, D. Cappelletti, R. Udisti, M. Maturilli, R. Neuber","doi":"10.1080/16000889.2018.1539618","DOIUrl":"https://doi.org/10.1080/16000889.2018.1539618","url":null,"abstract":"Abstract In this work, an evaluation of an intense biomass burning event observed over Ny-Ålesund (Spitsbergen, European Arctic) in July 2015 is presented. Data from the multi-wavelengths Raman-lidar KARL, a sun photometer and radiosonde measurements are used to derive some microphysical properties of the biomass burning aerosol as size distribution, refractive index and single scattering albedo at different relative humidities. Predominantly particles in the accumulation mode have been found with a bi-modal distribution and dominance of the smaller mode. Above 80% relative humidity, hygroscopic growth in terms of an increase of particle diameter and a slight decrease of the index of refraction (real and imaginary part) has been found. Values of the single scattering albedo around 0.9 both at 355 nm and 532 nm indicate some absorption by the aerosol. Values of the lidar ratio are around 26 sr for 355 nm and around 50 sr for 532 nm, almost independent of the relative humidity. Further, data from the photometer and surface radiation values from the local baseline surface radiation network (BSRN) have been applied to derive the radiative impact of the biomass burning event purely from observational data by comparison with a clear background day. We found a strong cooling for the visible radiation and a slight warming in the infra-red. The net aerosol forcing, derived by comparison with a clear background day purely from observational data, obtained a value of –95 W/m2 per unit AOD500.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"16 1","pages":"1 - 23"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75709570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1478594
O. T. Bui, S. Kameyama, H. Yoshikawa‐Inoue, M. Ishii, D. Sasano, H. Uchida, U. Tsunogai
Abstract We used a new underway measurement system to investigate the partial pressure of methane (CH4) in surface seawater and overlying air in the Southern Ocean from late November 2012 to mid-February 2013. The underway system consisted of a cavity ring-down spectroscopy analyser and a shower-head type equilibrator. The monthly mean atmospheric CH4 mixing ratios obtained agreed well (within 5 ppb) with those recorded at onshore baseline stations. CH4 saturation ratios (SR, %), defined as CH4 concentration in seawater divided by CH4 concentration equilibrated with atmospheric CH4, varied between 85 and 185%; most of the ratios we calculated indicated supersaturation, except for those from south of the Southern limit of Upper Circumpolar Deep Water. SR was higher at the lower latitudes, including coastal areas north of the Sub-Antarctic Front, but decreased gradually and monotonously between the Sub-Antarctic Front and the Upper Circumpolar Deep Water. At high latitudes south of the Polar Front, SR decreased to below 100% due to the effects of upwelling and vertical mixing. We found a strong linear correlation between SR and apparent oxygen utilisation (AOU) south of the Polar Front. Observed SR decreased with increasing AOU and reached 85% at high AOU (41 µmol kg−1) and low temperature (–1.8 °C). On the basis of the linear relationship between SR and AOU, we evaluated the climatological sea–air flux of CH4 from December to February for the entire Southern Ocean south of 50°S: Sea–air CH4 emission was estimated to be 0.027 Tg yr−1 in December, 0.04 Tg yr−1 in January, and 0.019 Tg yr−1 in February.
2012年11月下旬至2013年2月中旬，利用一种新型测量系统对南大洋表层海水和上覆空气中甲烷(CH4)的分压进行了研究。该系统由一个腔衰荡光谱分析仪和一个淋头式平衡器组成。所获得的月平均大气CH4混合比与陆上基线站记录的结果非常吻合(在5 ppb以内)。CH4饱和比(SR， %)，定义为海水中的CH4浓度除以与大气CH4平衡的CH4浓度，变化范围在85 - 185%之间;除上环极深水南缘以南的比率外，我们计算的大多数比率显示过饱和。低纬度地区(包括亚南极锋以北沿海地区)SR较高，但在亚南极锋与环极上深水区之间SR逐渐单调降低。在极锋以南的高纬度地区，由于上升流和垂直混合的影响，SR降低到100%以下。我们发现SR与极锋以南的表观氧利用(AOU)之间存在很强的线性相关性。观察到SR随着AOU的增加而降低，在高AOU(41µmol kg−1)和低温(-1.8°C)下达到85%。基于SR与AOU的线性关系，对50°S以南整个南大洋12 - 2月的CH4海气通量进行了估算:12月的海气CH4排放量为0.027 Tg yr - 1, 1月为0.04 Tg yr - 1, 2月为0.019 Tg yr - 1。
{"title":"Estimates of methane emissions from the Southern Ocean from quasi-continuous underway measurements of the partial pressure of methane in surface seawater during the 2012/13 austral summer","authors":"O. T. Bui, S. Kameyama, H. Yoshikawa‐Inoue, M. Ishii, D. Sasano, H. Uchida, U. Tsunogai","doi":"10.1080/16000889.2018.1478594","DOIUrl":"https://doi.org/10.1080/16000889.2018.1478594","url":null,"abstract":"Abstract We used a new underway measurement system to investigate the partial pressure of methane (CH4) in surface seawater and overlying air in the Southern Ocean from late November 2012 to mid-February 2013. The underway system consisted of a cavity ring-down spectroscopy analyser and a shower-head type equilibrator. The monthly mean atmospheric CH4 mixing ratios obtained agreed well (within 5 ppb) with those recorded at onshore baseline stations. CH4 saturation ratios (SR, %), defined as CH4 concentration in seawater divided by CH4 concentration equilibrated with atmospheric CH4, varied between 85 and 185%; most of the ratios we calculated indicated supersaturation, except for those from south of the Southern limit of Upper Circumpolar Deep Water. SR was higher at the lower latitudes, including coastal areas north of the Sub-Antarctic Front, but decreased gradually and monotonously between the Sub-Antarctic Front and the Upper Circumpolar Deep Water. At high latitudes south of the Polar Front, SR decreased to below 100% due to the effects of upwelling and vertical mixing. We found a strong linear correlation between SR and apparent oxygen utilisation (AOU) south of the Polar Front. Observed SR decreased with increasing AOU and reached 85% at high AOU (41 µmol kg−1) and low temperature (–1.8 °C). On the basis of the linear relationship between SR and AOU, we evaluated the climatological sea–air flux of CH4 from December to February for the entire Southern Ocean south of 50°S: Sea–air CH4 emission was estimated to be 0.027 Tg yr−1 in December, 0.04 Tg yr−1 in January, and 0.019 Tg yr−1 in February.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"8 1","pages":"1 - 15"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79907340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1426316
Shohei Nomura, H. Mukai, Y. Terao, K. Takagi, M. Mohamad, M. F. Jahaya
Abstract Evaluation of carbon dioxide (CO2) sinks in forest areas of East and Southeast Asia (especially tropical regions) is important for assessing CO2 budgets at the regional scale. To evaluate the CO2 flux of large forest areas, we collected vertical CO2 profiles over the forest using a CO2 sonde and measured surface CO2 concentrations around the forest using continuous CO2 measurement equipment. These observations were performed over a typical northern forest (Hokkaido) in Japan, a subtropical forest island (Iriomote Island) in Japan, and a tropical forest in Borneo Island. We detected the differences in CO2 vertical profiles between dawn and daytime, and at the upwind and downwind sites of the forests with the observational results from the CO2 sonde. We also clarified that CO2 concentrations during daytime at the downwind sites (affected by the forest) were systematically lower than those at the upwind sites (not affected by the forest). In contrast, CO2 concentrations during dawn at the downwind sites were larger than those at the upwind site. We estimated the CO2 fluxes (μmol m−2 s−1) at dawn and daytime of the forests from these observational results. The CO2 fluxes of Borneo’s forest were very large (16.5 and −37.7 at dawn and daytime, respectively), whereas the CO2 fluxes of the forests in Hokkaido and Iriomote were lower (3.9 to 11.8 at dawn and −11.8 to −15.0 at daytime). These evaluated values were consistent with fluxes measured by the eddy-covariance method in the same region. Thus, use of the CO2 sonde to collect observations of CO2 vertical profiles was considered to be an effective method to verify CO2 absorption and emission in large forest areas. This method can also be used to evaluate dynamic CO2 absorption and emission processes in tropical forests.
{"title":"Evaluation of forest CO2 fluxes from sonde measurements in three different climatological areas including Borneo, Malaysia, and Iriomote and Hokkaido, Japan","authors":"Shohei Nomura, H. Mukai, Y. Terao, K. Takagi, M. Mohamad, M. F. Jahaya","doi":"10.1080/16000889.2018.1426316","DOIUrl":"https://doi.org/10.1080/16000889.2018.1426316","url":null,"abstract":"Abstract Evaluation of carbon dioxide (CO2) sinks in forest areas of East and Southeast Asia (especially tropical regions) is important for assessing CO2 budgets at the regional scale. To evaluate the CO2 flux of large forest areas, we collected vertical CO2 profiles over the forest using a CO2 sonde and measured surface CO2 concentrations around the forest using continuous CO2 measurement equipment. These observations were performed over a typical northern forest (Hokkaido) in Japan, a subtropical forest island (Iriomote Island) in Japan, and a tropical forest in Borneo Island. We detected the differences in CO2 vertical profiles between dawn and daytime, and at the upwind and downwind sites of the forests with the observational results from the CO2 sonde. We also clarified that CO2 concentrations during daytime at the downwind sites (affected by the forest) were systematically lower than those at the upwind sites (not affected by the forest). In contrast, CO2 concentrations during dawn at the downwind sites were larger than those at the upwind site. We estimated the CO2 fluxes (μmol m−2 s−1) at dawn and daytime of the forests from these observational results. The CO2 fluxes of Borneo’s forest were very large (16.5 and −37.7 at dawn and daytime, respectively), whereas the CO2 fluxes of the forests in Hokkaido and Iriomote were lower (3.9 to 11.8 at dawn and −11.8 to −15.0 at daytime). These evaluated values were consistent with fluxes measured by the eddy-covariance method in the same region. Thus, use of the CO2 sonde to collect observations of CO2 vertical profiles was considered to be an effective method to verify CO2 absorption and emission in large forest areas. This method can also be used to evaluate dynamic CO2 absorption and emission processes in tropical forests.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"40 1","pages":"1 - 19"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79964007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1450589
H. Yeo, Sang‐Jong Park, Baek‐Min Kim, M. Shiobara, Sang-Woo Kim, H. Kwon, Joo‐Hong Kim, Jee-Hoon Jeong, S. Park, T. Choi
Abstract Ten-year (2004–2013) observations of cloud and surface shortwave (SW) and longwave (LW) fluxes at Ny-Ålesund were analysed to investigate monthly variations in cloudiness and their impacts on the surface LW radiation budget and near-surface temperature (Ts). The cloud fraction (CF) showed distinct monthly variations, high in summer (0.90) and lower in winter (0.79). The downward SW flux increased from March and showed a peak (~200 W m−2) in June. In contrast, the downward LW (LWD) flux increased from ~200 W m−2 in February to ~300 W m−2 in July. Both LWD and upward LW (LWU) fluxes and their difference increased during winter as lowest cloud base height (LCBH) decreased and CF increased. Ts difference and both LW fluxes difference (ΔLWD and ΔLWU), calculated as the difference in monthly mean Ts and LW between all-sky and cloud-free conditions, were highly correlated (R2 = 0.68 for LWD and R2 = 0.92 for LWU). Dramatic changes in Ts, CF and LW fluxes at Ny-Ålesund were closely associated with cold and warm air mass advection on a multi-day time scale. The average Ts under low-level clouds (LCBH ≤ 2 km) was estimated as −7.4 ± 6.1 °C due to warm air masses advected from the North Atlantic Ocean and Barents Sea, whereas the average Ts on cloud-free days was −14.5 ± 5.7 °C because of cold air mass advection from the pole. However, the duration of low-level clouds may not be long enough to drive such large Ts variations. 75-percentile of low-level cloud conditions at Ny-Ålesund persisted up to 2.3 days, whereas cloud-free and high-altitude cloud (LCBH > 2 km) conditions lasted for approximately 0.8 and 0.5 days, respectively. This implies that cloud LW effects on several warm days may be larger than the monthly average, but may not be accumulated enough to induce surface warming due to abrupt Ts drop associated with cold air mass advection.
摘要:分析了2004-2013年10年Ny-Ålesund云和地表短波(SW)和长波(LW)通量的观测资料，探讨了云量的月变化及其对地表短波辐射收支和近地表温度的影响。云分数(CF)呈明显的月变化，夏季高(0.90)，冬季低(0.79)。从3月开始，西南偏南向下的通量增加，6月达到峰值(~200 W m−2)。而向下的LWD通量从2月的~200 W m−2增加到7月的~300 W m−2。随著冬季最低云底高度(LCBH)的降低和CF的增加，LWD和LWU上升通量及其差值均增大。Ts差值与LW通量差值(ΔLWD和ΔLWU)高度相关(LWD的R2 = 0.68, LWU的R2 = 0.92)。Ny-Ålesund的Ts、CF和LW通量的剧烈变化与冷暖气团平流在多天尺度上密切相关。由于来自北大西洋和巴伦支海的暖气团平流，低空云层(LCBH≤2 km)下的平均Ts为- 7.4±6.1°C，而无云日的平均Ts为- 14.5±5.7°C，这是由于来自极地的冷空气平流。然而，低空云层的持续时间可能不够长，不足以驱动如此大的Ts变化。Ny-Ålesund 75%的低云状况持续了2.3 d，而无云和高空云(LCBH > 2 km)状况分别持续了约0.8 d和0.5 d。这意味着在几个温暖的日子里，云低气压的影响可能大于月平均水平，但由于与冷气团平流相关的Ts突然下降，云低气压的积累可能不足以引起地面变暖。
{"title":"The observed relationship of cloud to surface longwave radiation and air temperature at Ny-Ålesund, Svalbard","authors":"H. Yeo, Sang‐Jong Park, Baek‐Min Kim, M. Shiobara, Sang-Woo Kim, H. Kwon, Joo‐Hong Kim, Jee-Hoon Jeong, S. Park, T. Choi","doi":"10.1080/16000889.2018.1450589","DOIUrl":"https://doi.org/10.1080/16000889.2018.1450589","url":null,"abstract":"Abstract Ten-year (2004–2013) observations of cloud and surface shortwave (SW) and longwave (LW) fluxes at Ny-Ålesund were analysed to investigate monthly variations in cloudiness and their impacts on the surface LW radiation budget and near-surface temperature (Ts). The cloud fraction (CF) showed distinct monthly variations, high in summer (0.90) and lower in winter (0.79). The downward SW flux increased from March and showed a peak (~200 W m−2) in June. In contrast, the downward LW (LWD) flux increased from ~200 W m−2 in February to ~300 W m−2 in July. Both LWD and upward LW (LWU) fluxes and their difference increased during winter as lowest cloud base height (LCBH) decreased and CF increased. Ts difference and both LW fluxes difference (ΔLWD and ΔLWU), calculated as the difference in monthly mean Ts and LW between all-sky and cloud-free conditions, were highly correlated (R2 = 0.68 for LWD and R2 = 0.92 for LWU). Dramatic changes in Ts, CF and LW fluxes at Ny-Ålesund were closely associated with cold and warm air mass advection on a multi-day time scale. The average Ts under low-level clouds (LCBH ≤ 2 km) was estimated as −7.4 ± 6.1 °C due to warm air masses advected from the North Atlantic Ocean and Barents Sea, whereas the average Ts on cloud-free days was −14.5 ± 5.7 °C because of cold air mass advection from the pole. However, the duration of low-level clouds may not be long enough to drive such large Ts variations. 75-percentile of low-level cloud conditions at Ny-Ålesund persisted up to 2.3 days, whereas cloud-free and high-altitude cloud (LCBH > 2 km) conditions lasted for approximately 0.8 and 0.5 days, respectively. This implies that cloud LW effects on several warm days may be larger than the monthly average, but may not be accumulated enough to induce surface warming due to abrupt Ts drop associated with cold air mass advection.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"18 1","pages":"1 - 10"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74394429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1463806
Xiangrui Kong, M. Wolf, M. Roesch, E. Thomson, T. Bartels-Rausch, P. Alpert, M. Ammann, N. Prisle, D. Cziczo
Abstract Phase changes of sea salt particles alter their physical and chemical properties, which is significant for Earth’s chemistry and energy budget. In this study, a continuous flow diffusion chamber is used to investigate deliquescence, homogeneous and heterogeneous ice nucleation between 242 K and 215 K, of four salts: pure NaCl, pure MgCl2, synthetic sea water salt, and salt distilled from sampled sea water. Anhydrous particles, aqueous droplets and ice particles were discriminated using a polarisation-sensitive optical particle counter coupled with a machine learning analysis technique. The measured onset deliquescence relative humidities agree with previous studies, where sea water salts deliquescence at lower humidities than pure NaCl. Deliquesced salt droplets homogenously freeze when the relative humidity reaches a sufficiently high value at temperatures below 233 K. From 224 K and below, deposition nucleation freezing on a fraction of NaCl particles was observed at humidities lower than the deliquescence relative humidity. At these low temperatures, otherwise unactivated salt particles deliquesced at the expected deliquescence point, followed by homogeneous freezing at temperatures as low as 215 K. Thus, the observed sea salt particles exhibit a triad of temperature-dependent behaviours. First, they act as cloud condensation particles (CCNs) > 233 K, second they can be homogeneous freezing nuclei (HFNs) < 233 K and finally they act as ice nucleating particles (INPs) for heterogeneous nucleation <224 K.
{"title":"A continuous flow diffusion chamber study of sea salt particles acting as cloud nuclei: deliquescence and ice nucleation","authors":"Xiangrui Kong, M. Wolf, M. Roesch, E. Thomson, T. Bartels-Rausch, P. Alpert, M. Ammann, N. Prisle, D. Cziczo","doi":"10.1080/16000889.2018.1463806","DOIUrl":"https://doi.org/10.1080/16000889.2018.1463806","url":null,"abstract":"Abstract Phase changes of sea salt particles alter their physical and chemical properties, which is significant for Earth’s chemistry and energy budget. In this study, a continuous flow diffusion chamber is used to investigate deliquescence, homogeneous and heterogeneous ice nucleation between 242 K and 215 K, of four salts: pure NaCl, pure MgCl2, synthetic sea water salt, and salt distilled from sampled sea water. Anhydrous particles, aqueous droplets and ice particles were discriminated using a polarisation-sensitive optical particle counter coupled with a machine learning analysis technique. The measured onset deliquescence relative humidities agree with previous studies, where sea water salts deliquescence at lower humidities than pure NaCl. Deliquesced salt droplets homogenously freeze when the relative humidity reaches a sufficiently high value at temperatures below 233 K. From 224 K and below, deposition nucleation freezing on a fraction of NaCl particles was observed at humidities lower than the deliquescence relative humidity. At these low temperatures, otherwise unactivated salt particles deliquesced at the expected deliquescence point, followed by homogeneous freezing at temperatures as low as 215 K. Thus, the observed sea salt particles exhibit a triad of temperature-dependent behaviours. First, they act as cloud condensation particles (CCNs) > 233 K, second they can be homogeneous freezing nuclei (HFNs) < 233 K and finally they act as ice nucleating particles (INPs) for heterogeneous nucleation <224 K.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"30 1","pages":"1 - 11"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88093967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1498688
I. Chandra, T. Seto, Y. Otani, Y. Inomata, Naoya Hama, A. Yoshino, A. Takami, N. Takegawa
Abstract Emissions of polluted air in East Asia have gradually decreased over the last decade. Those air pollutants have been transported over long distances and influenced new particle formation (NPF) in the downstream region. We obtained 5-year data of the mobility size distribution and SO2 and particulate (PM2.5) emissions on Fukue Island (32.75°N, 128.68°E), Japan. Frequent NPF events in the 2013 campaign were observed around 60% under the transboundary transport of polluted air by northwesterly wind. In contrast to the data obtained in the last 2-year campaign (2016–2017), these NPF events (<25%) may reflect a relatively clean environment. The daily average SO2 and PM2.5 concentrations over the campaign periods are 2.3 ± 2.2 ppb and 17.6 ± 8.5 µg·m−3 (February 23 to March 7, 2013), 1.3 ± 0.9 ppb and 13.8 ± 4.7 µg·m−3 (February 27 to March 18, 2015), 0.8 ± 0.5 ppb and 14.7 ± 5.3 µg·m−3 (February 27 to March 25, 2016), and 0.5 ± 0.5 ppb and 12.1 ± 4.6 µg·m−3 (January 28 to April 19, 2017), respectively. These reductions of emissions may be due to the measures implemented by the local government in the source region to handle the adverse impacts of environmental pollution. The latest condition of atmospheric nanoparticles on Fukue Island can be used as an indicator to determine the concentration levels of regional air pollutants in East Asia.
{"title":"Current situation of atmospheric nanoparticles in Fukue Island, Japan","authors":"I. Chandra, T. Seto, Y. Otani, Y. Inomata, Naoya Hama, A. Yoshino, A. Takami, N. Takegawa","doi":"10.1080/16000889.2018.1498688","DOIUrl":"https://doi.org/10.1080/16000889.2018.1498688","url":null,"abstract":"Abstract Emissions of polluted air in East Asia have gradually decreased over the last decade. Those air pollutants have been transported over long distances and influenced new particle formation (NPF) in the downstream region. We obtained 5-year data of the mobility size distribution and SO2 and particulate (PM2.5) emissions on Fukue Island (32.75°N, 128.68°E), Japan. Frequent NPF events in the 2013 campaign were observed around 60% under the transboundary transport of polluted air by northwesterly wind. In contrast to the data obtained in the last 2-year campaign (2016–2017), these NPF events (<25%) may reflect a relatively clean environment. The daily average SO2 and PM2.5 concentrations over the campaign periods are 2.3 ± 2.2 ppb and 17.6 ± 8.5 µg·m−3 (February 23 to March 7, 2013), 1.3 ± 0.9 ppb and 13.8 ± 4.7 µg·m−3 (February 27 to March 18, 2015), 0.8 ± 0.5 ppb and 14.7 ± 5.3 µg·m−3 (February 27 to March 25, 2016), and 0.5 ± 0.5 ppb and 12.1 ± 4.6 µg·m−3 (January 28 to April 19, 2017), respectively. These reductions of emissions may be due to the measures implemented by the local government in the source region to handle the adverse impacts of environmental pollution. The latest condition of atmospheric nanoparticles on Fukue Island can be used as an indicator to determine the concentration levels of regional air pollutants in East Asia.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"11 1","pages":"1 - 12"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91285121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1463807
Z. Z. Martin, I. S. Martinez, Ricky B. Nellas
Abstract The Classical Nucleation Theory (CNT) has been a dominant model in understanding the self-assembly of new thermodynamic phases. CNT provides significant explanations to processes such as aerosol formation and cloud condensation. In this work, we generated the nucleation free energy profiles of normal alkanes (n-propane, n-octane and n-dodecane) at five different temperatures using the grand-canonical version of the nucleation algorithm. From these free energy profiles, characteristic () values were obtained. Using the density, values from United-Atom Transferable Potentials for Phase Equilibria (TraPPE-UA) force field and the obtained values, we calculated the corresponding surface tension, values of these n-alkane systems at different temperatures. Values obtained are within reasonable agreement with experimental data.
{"title":"Surface tension data of n-propane, n-octane and n-dodecane from nucleation simulations","authors":"Z. Z. Martin, I. S. Martinez, Ricky B. Nellas","doi":"10.1080/16000889.2018.1463807","DOIUrl":"https://doi.org/10.1080/16000889.2018.1463807","url":null,"abstract":"Abstract The Classical Nucleation Theory (CNT) has been a dominant model in understanding the self-assembly of new thermodynamic phases. CNT provides significant explanations to processes such as aerosol formation and cloud condensation. In this work, we generated the nucleation free energy profiles of normal alkanes (n-propane, n-octane and n-dodecane) at five different temperatures using the grand-canonical version of the nucleation algorithm. From these free energy profiles, characteristic () values were obtained. Using the density, values from United-Atom Transferable Potentials for Phase Equilibria (TraPPE-UA) force field and the obtained values, we calculated the corresponding surface tension, values of these n-alkane systems at different temperatures. Values obtained are within reasonable agreement with experimental data.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"15 1","pages":"1 - 5"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85576473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2018.1507390
T. Sekiyama, T. Iwasaki
Abstract The flow vectors of radioactive cesium-137 (137Cs) plume emitted from the Fukushima Daiichi nuclear power plant in March 2011 were quantitatively depicted by a mass flux analysis in this study. 137Cs plumes were calculated by an Eulerian dispersion model with a 3-km horizontal resolution. The vertically column-integrated mass flux was consistent with the flow approximation based on ground surface 137Cs observations, even though there were some discrepancies that were caused by differences in the wind direction between the ground surface and the dominant plume layer. These discrepancies were explained by combining the use of the ground surface horizontal mass flux with the column-integrated mass flux. The mass flux analysis clearly provided an illustration of 137Cs dominant stream locations, directions, and depositions by reducing high-dimensional model outputs into a lower-dimensional plot. Mass flux (i.e. the product of the mass density and wind velocity) has often been used in dynamic meteorology but has not been used as frequently in atmospheric chemistry or pollutant dispersion studies. However, the concept of mass flux is a robust alternative for conventional validation approaches that only utilize a time series of pollutant concentrations. Mass flux analyses can be used further in atmospheric chemistry as a quantitative visualization tool to track the emission, advection, dispersion, and deposition of atmospheric constituents.
{"title":"Mass flux analysis of 137Cs plumes emitted from the Fukushima Daiichi nuclear power plant","authors":"T. Sekiyama, T. Iwasaki","doi":"10.1080/16000889.2018.1507390","DOIUrl":"https://doi.org/10.1080/16000889.2018.1507390","url":null,"abstract":"Abstract The flow vectors of radioactive cesium-137 (137Cs) plume emitted from the Fukushima Daiichi nuclear power plant in March 2011 were quantitatively depicted by a mass flux analysis in this study. 137Cs plumes were calculated by an Eulerian dispersion model with a 3-km horizontal resolution. The vertically column-integrated mass flux was consistent with the flow approximation based on ground surface 137Cs observations, even though there were some discrepancies that were caused by differences in the wind direction between the ground surface and the dominant plume layer. These discrepancies were explained by combining the use of the ground surface horizontal mass flux with the column-integrated mass flux. The mass flux analysis clearly provided an illustration of 137Cs dominant stream locations, directions, and depositions by reducing high-dimensional model outputs into a lower-dimensional plot. Mass flux (i.e. the product of the mass density and wind velocity) has often been used in dynamic meteorology but has not been used as frequently in atmospheric chemistry or pollutant dispersion studies. However, the concept of mass flux is a robust alternative for conventional validation approaches that only utilize a time series of pollutant concentrations. Mass flux analyses can be used further in atmospheric chemistry as a quantitative visualization tool to track the emission, advection, dispersion, and deposition of atmospheric constituents.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"1 1","pages":"1 - 11"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75623194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-01DOI: 10.1080/16000889.2017.1414571
E. Asmi, K. Neitola, K. Teinilä, E. Rodríguez, A. Virkkula, J. Backman, M. Bloss, J. Jokela, H. Lihavainen, G. de Leeuw, J. Paatero, V. Aaltonen, M. Mei, Gonzalo Gambarte, Gustavo E. Copes, M. Albertini, Germán Pérez Fogwill, Jonathan E. Ferrara, M. E. Barlasina, Ricardo Sánchez
Abstract Aerosol particle optical properties were measured continuously between years 2013–2015 at the Marambio station in the Antarctic Peninsula. Annual cycles of particle scattering and absorption were studied and explained using measured particle chemical composition and the analysis of air mass transport patterns. The particle scattering was found elevated during the winter but the absorption did not show any clear annual cycle. The aerosol single scattering albedo at nm was on average 0.96 0.10, with a median of 0.99. Aerosol scattering Ångström exponent increased during summer, indicating an increasing fraction of fine mode particles. The aerosol was mainly composed of sea salt, sulphate and crustal soil minerals, and most of the particle mass were in the coarse mode. Both the particle absorption and scattering were increased during high wind speeds. This was explained by the dominance of the primary marine sea-spray and wind-blown soil dust sources. In contrast, the back-trajectory analysis suggested that long-range transport has only a minor role as a source of absorbing aerosol at the peninsula.
{"title":"Primary sources control the variability of aerosol optical properties in the Antarctic Peninsula","authors":"E. Asmi, K. Neitola, K. Teinilä, E. Rodríguez, A. Virkkula, J. Backman, M. Bloss, J. Jokela, H. Lihavainen, G. de Leeuw, J. Paatero, V. Aaltonen, M. Mei, Gonzalo Gambarte, Gustavo E. Copes, M. Albertini, Germán Pérez Fogwill, Jonathan E. Ferrara, M. E. Barlasina, Ricardo Sánchez","doi":"10.1080/16000889.2017.1414571","DOIUrl":"https://doi.org/10.1080/16000889.2017.1414571","url":null,"abstract":"Abstract Aerosol particle optical properties were measured continuously between years 2013–2015 at the Marambio station in the Antarctic Peninsula. Annual cycles of particle scattering and absorption were studied and explained using measured particle chemical composition and the analysis of air mass transport patterns. The particle scattering was found elevated during the winter but the absorption did not show any clear annual cycle. The aerosol single scattering albedo at nm was on average 0.96 0.10, with a median of 0.99. Aerosol scattering Ångström exponent increased during summer, indicating an increasing fraction of fine mode particles. The aerosol was mainly composed of sea salt, sulphate and crustal soil minerals, and most of the particle mass were in the coarse mode. Both the particle absorption and scattering were increased during high wind speeds. This was explained by the dominance of the primary marine sea-spray and wind-blown soil dust sources. In contrast, the back-trajectory analysis suggested that long-range transport has only a minor role as a source of absorbing aerosol at the peninsula.","PeriodicalId":22320,"journal":{"name":"Tellus B: Chemical and Physical Meteorology","volume":"67 3 1","pages":"1 - 16"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86433746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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