Journal of Geophysical Research: Atmospheres最新文献

{"title":"Photocatalytic Chlorine Production From Iron Chlorides in Atmospheric Aerosols: Strategies for Quantifying Methane and Tropospheric Ozone Control","authors":"Maarten van Herpen, Luisa Pennacchio, Chloe Brashear, Marie K. Mikkelsen, Alfonzo Saiz-Lopez, Thomas Röckmann, Matthew S. Johnson","doi":"10.1029/2024JD041156","DOIUrl":"https://doi.org/10.1029/2024JD041156","url":null,"abstract":"<p>It was recently discovered that chlorine is produced photocatalytically from mineral dust-sea spray aerosols, impacting methane and tropospheric ozone, and an evaluation was made of the climate and environmental impact of a chlorine-based intervention to draw down methane. The generation of chlorine by the iron chlorides Fe(III)<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mrow>\u0000 <mi>C</mi>\u0000 <mi>l</mi>\u0000 </mrow>\u0000 <mi>n</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mn>3</mn>\u0000 <mo>−</mo>\u0000 <mi>n</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation> ${mathrm{C}mathrm{l}}_{n}^{(3-n)}$</annotation>\u0000 </semantics></math> will also occur due to iron present in shipping plumes. To study efficiency and environmental implications, there is a need for additional information about the behavior of the process under a range of atmospheric conditions. Here, we use box modeling to evaluate whether it is possible to experimentally observe this mechanism in a ship's plume, or in a plume of pure iron dust, emitted for example, from a tower. Detection limits for Cl, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>Cl</mtext>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${text{Cl}}_{2}$</annotation>\u0000 </semantics></math>, HOCl, ClO, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>ClNO</mtext>\u0000 <mn>3</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${text{ClNO}}_{3}$</annotation>\u0000 </semantics></math>, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mtext>ClNO</mtext>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${text{ClNO}}_{2}$</annotation>\u0000 </semantics></math>, CO, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>C</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 <msub>\u0000 <mi>H</mi>\u0000 <mn>6</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{C}}_{2}{mathrm{H}}_{6}$</annotation>\u0000 ","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041156","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constrained Projections of Extreme Low Temperatures in Eastern China","authors":"B. J. Wang,&nbsp;Y. Sun,&nbsp;X. B. Zhang,&nbsp;T. Hu,&nbsp;T. Li","doi":"10.1029/2024JD042741","DOIUrl":"https://doi.org/10.1029/2024JD042741","url":null,"abstract":"<p>The latest two generations of climate models (CMIP5 and CMIP6, Coupled Model Intercomparison Projects Phase 5 and 6) show a clear discrepancy in the projected future changes in mean temperature. Different methods have been proposed to reduce this difference, however, very limited studies are focused on extreme low temperatures (ELT). Here we propose a new method to constrain the projection of ELT changes by establishing their quasi-linear relationships with mean temperature (Tmean) in Eastern China. The results show that the Tmean weighting coefficients considering model performance and independence can effectively reduce the uncertainty range of future ELT. Before constraint, there are substantial differences in the projected ranges of Tmean and ELT between CMIP5 and CMIP6 models. After constraint, the projected ranges of CMIP6 models are considerably reduced, particularly at the warmer end, thus showing better consistency with CMIP5. Under the SSP5-8.5 scenario, at the end of the 21st century (2081–2100), the original projected changes in Tmean are constrained from 5.1 (3.5–7.9)°C to 5.0 (3.5–6.5)°C, with the warmer end of the projected range decreased by 1.4°C. For the ELT, the decreases of the warmer ends are 1.9°C and 1.2°C for the annual minima of daily minimum (TNn) and maximum temperature (TXn), respectively. The reliability evaluation shows that the differences between pseudo-observations represented by two large ensemble models and constrained projections are smaller than those for unconstrained projections, thereby confirming the reliability of the weighted method employed in this study.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atmosphere to Surface Profiles of Water-Vapor Isotopes and Meteorological Conditions Over the Northeast Greenland Ice Sheet","authors":"Kevin S. Rozmiarek,&nbsp;Laura J. Dietrich,&nbsp;Bruce H. Vaughn,&nbsp;Michael S. Town,&nbsp;Bradley R. Markle,&nbsp;Valerie Morris,&nbsp;Hans Christian Steen-Larsen,&nbsp;Xavier Fettweis,&nbsp;Chloe A. Brashear,&nbsp;Hayley Bennett,&nbsp;Tyler R. Jones","doi":"10.1029/2024JD042719","DOIUrl":"https://doi.org/10.1029/2024JD042719","url":null,"abstract":"<p>On polar ice sheets, water vapor interacts with surface snow, and through the exchange of water molecules, imprints an isotopic climate signal into the ice sheet. This exchange is not well understood due to sparse observations in the atmosphere. There are currently no published vertical profiles of water isotopes above ice sheets that span the planetary boundary layer and portions of the free troposphere. Here, we present a novel data set of water-vapor isotopes (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>δ</mi>\u0000 <mn>18</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${delta }^{18}$</annotation>\u0000 </semantics></math>O, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>δ</mi>\u0000 </mrow>\u0000 <annotation> $delta $</annotation>\u0000 </semantics></math>D, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>d</mi>\u0000 <mi>x</mi>\u0000 <mi>s</mi>\u0000 </mrow>\u0000 <annotation> $dxs$</annotation>\u0000 </semantics></math>) and meteorological variables taken by fixed-wing uncrewed aircraft on the northeast Greenland Ice Sheet (GIS). During June–July (2022), we collected 104 profiles of water-vapor isotopes and meteorological variables up to 1,500 m above ground level. Concurrently, surface snow samples were collected at 12-hr intervals, allowing connection to surface-snow processes. We pair observations with modeling output from a regional climate model as well as an atmospheric transport and water-isotope distillation model. Climate model output of mean temperature and specific humidity agrees well with observations, with a mean difference of +0.095°C and −0.043 g/kg (−2.91%), respectively. We find evidence that along an air parcel pathway, the distillation model is not removing enough water prior to onsite arrival. Below the mean temperature inversion (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>200 m), water-isotope observations indicate a kinetic fractionating process, likely the result of mixing sublimated vapor from the ice sheet surface along with an unknown fraction of katabatic wind vapor. Modeled <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>d</mi>\u0000 <mi>x</mi>\u0000 <mi>s</mi>\u0000 </mrow>\u0000 <annotation> $dxs$</annotation>\u0000 </semantics></math> does not agree well with observations, a result that requires substantial future analysis of kinetic fractionation processes along the entire moisture pathway.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of Pandemic-Associated Plastic Waste on Microplastics in Ambient PM2.5","authors":"Fobang Liu,&nbsp;Mengting Guo,&nbsp;Yanan Wang,&nbsp;Shuqi Yang,&nbsp;Xu Yang,&nbsp;Kai Wang,&nbsp;Junxian Hou,&nbsp;Guibin Wang,&nbsp;Chi He,&nbsp;Pengfei Wu","doi":"10.1029/2024JD043035","DOIUrl":"https://doi.org/10.1029/2024JD043035","url":null,"abstract":"<p>Microplastics (MPs) are a rising environmental and health concern, and the COVID-19 pandemic has increased plastic waste, particularly single-use plastics. While the impacts of pandemic-associated plastic waste on multiple environmental matrices (e.g., water and soil) have been well documented, its effects on MPs in atmospheric fine particles (PM_2.5) remain unclear. In this study, we analyzed the MPs in ambient PM_2.5 collected from urban Xi'an before, during, and after the COVID-19 pandemic in both summer and winter. Mean MP concentrations during and after the pandemic were three times higher than prepandemic levels, irrespective of the season. Transparent and white polypropylene and polyethylene terephthalate fibers dominated during and after the pandemic, while prepandemic MPs were more diverse in polymer types and colors. These results indicate a strong impact of pandemic-associated waste, especially discarded face masks, on the abundance and characteristics of MPs in ambient PM_2.5. Additionally, a positive correlation was found between MPs and ambient ozone, suggesting the potential for ozone to degrade plastics and release MPs into the air. Multiple-path particle dosimetry calculations revealed that MPs primarily deposit in the extrathoracic region of people across all age groups. However, teenagers and younger individuals showed increased susceptibility to deposition in tracheobronchial and pulmonary regions. Based on the estimated daily dose, inhalation of MPs from ambient PM_2.5 is proposed to be a significant exposure pathway for humans. Overall, our study highlights the substantial impacts of pandemic-associated plastic waste on MPs in ambient PM_2.5 and their potential implications for human exposure.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mountain-Facilitated Lee-Slope Transport and Daytime Boundary Layer Mixing of Volcano Plumes Exacerbates Air Pollution Over Arequipa, Peru","authors":"Xiao-Ming Hu,&nbsp;Ming Xue,&nbsp;Tingting Qian,&nbsp;Xingliang Li,&nbsp;Hector Mayol Novoa,&nbsp;Jose Luis Ticona Jara,&nbsp;Lan Gao,&nbsp;Elinor Martin,&nbsp;Yongjie Huang,&nbsp;Adriana E. Larrea Valdivia","doi":"10.1029/2024JD042905","DOIUrl":"https://doi.org/10.1029/2024JD042905","url":null,"abstract":"<p>Severe air pollution plagues Arequipa, Peru, due to anthropogenic and natural emissions. Persistent volcano emission in the vicinity of Arequipa makes it among the largest SO₂ sources in the world. Because volcano plumes mostly exist in the free troposphere and stratosphere where horizontal transport acts rather quickly, previous studies mostly focused on their global-scale impacts. Whether these plumes can affect near-surface air quality has not attracted much research attention. This study uses WRF-Chem simulations to reveal that in the presence of northerly/northwesterly winds and favorable mountain meteorology, the plume from volcano Sabancaya (elevation 5,960 m, ∼80 km north of Arequipa) can be brought down to near the surface of Arequipa through two steps of transport and dispersion processes: (a) With northerly/northwesterly winds, the free troposphere plume from Sabancaya is transported southward and intercepted by Mountain Chachani located between Sabancaya and Arequipa and subsequently transported downward to Arequipa by nighttime downslope winds linked to large-amplitude lee-side mountain gravity waves. Often the plume reaches down to be close to the boundary layer over Arequipa. (b) In the following day, convective boundary layer growth brings the above boundary-layer plume to near the surface through vertical mixing processes, thus exacerbating ambient air pollution in Arequipa. A mechanism on how volcano plumes above 6-km height cause air pollution over the lower-lying Arequipa city is therefore revealed for the first time. The mountain dynamic effect in inducing the large-amplitude mountain lee waves is further illustrated by an idealized simulation excluding mountain's thermal effect.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoupling of Temperature and Water Vapor in Terrestrial Monsoon Regions Due To Decreasing Ocean Evaporation At Low Latitudes","authors":"Jing Peng,&nbsp;Wenxiu Zhong,&nbsp;Junbin Wang,&nbsp;Li Dan,&nbsp;Wenfang Xu,&nbsp;Song Yang,&nbsp;Wenping Yuan","doi":"10.1029/2024JD042675","DOIUrl":"https://doi.org/10.1029/2024JD042675","url":null,"abstract":"<p>The relationship between air temperature and atmospheric water vapor is important for understanding the changes in the climate system as well as water, energy, and carbon cycles at the global scale. We investigated the changes in atmospheric actual water vapor (AVP) at seasonal and spatial scales from 1979 to 2018 and their sensitivity to air temperature (<i>S</i>_avp). Comparing two different periods, 1979–1998 and 1999–2018, large differences in <i>S</i>_avp were found over land during summer. The west coasts of low-latitude regions gained enhanced water vapor for each 1°C increase in temperature, while the east coasts showed a deceleration in additional water vapor for each 1°C increase in temperature in the latter period compared to the former one. Although there is spatial heterogeneity in changes in Savp after the 1990s compared to before the 1990s, overall summer Savp has decreased by 33% over land and 27% in the monsoon region. These shifts were well reproduced by the Community Earth System Model and are closely related to a shift in low-latitude ocean evaporation (<i>E</i>_ocean) from an upward trend before the late 1990s to a downward trend after the late 1990s (<i>p</i> &lt; 0.05). Furthermore, we found that the significant decrease (<i>p</i> &lt; 0.05) in <i>S</i>_avp over land in summer was due to (a) weaker increase in actual atmospheric water vapor and (b) reduced zonal winds from oceans to the land, rather than through the direct effects of global warming on the atmospheric water demand. These results highlight the urgent need for <i>E</i>_ocean monitoring and forecasting to accurately assess land <i>S</i>_avp. Significance statements understanding how water vapor responds to changes in temperature is crucial for understanding global climate dynamics and the movement of water, energy, and carbon throughout the Earth system. We investigated the variations in water vapor temperature sensitivity across different seasons and regions from 1979 to 2018. By comparing two time periods, we found great differences in water vapor temperature sensitivity over land during summer. Overall, there was a weakening of water vapor temperature sensitivity over land and in monsoon regions. These changes were predicted by a climate model and correlated closely with changes in ocean evaporation patterns. This highlights the importance of closely monitoring ocean evaporation to predict the response of water vapor to warming over land.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploration of Predictors for Statistical-Dynamical Subseasonal Prediction of Western North-Pacific Tropical Cyclone Activity in Earth System Models","authors":"Kurt A. Hansen,&nbsp;Matthew A. Janiga","doi":"10.1029/2024JD042341","DOIUrl":"https://doi.org/10.1029/2024JD042341","url":null,"abstract":"<p>Subseasonal prediction of tropical cyclones (TCs) has many potential applications but remains a challenge due to biases in both model-based large-scale conditions and TCs in coupled global models. Model forecasts of environmental parameters can be linked to TC activity and then be used to extend the horizon of useful skill through statistical-dynamical models. The aim of this work is to assess the utility of incorporating model forecasted environmental fields in a statistical model compared with skill coming from model forecasted Madden Julian Oscillation (MJO) state in predicting TC activity over the Western North Pacific (WNP). In this study, we evaluate the European Center for Medium-Range Weather Forecasts (ECMWF) from the Subseasonal-to-Seasonal (S2S) database and the Navy Earth System Prediction Capability (ESPC) as part of the Subseasonal Experiment on their ability to predict WNP TC activity using environmental fields. To isolate the environmental signals associated with subseasonal variability of TC activity, we examine events of anomalous accumulated cyclone energy, genesis, and TC days. These events are used to create composites of ERA5 reanalysis fields of environmental conditions related to WNP TC activity, which are used to select predictors for statistical dynamical hybrid models. The ECMWF statistical-dynamical scheme exhibits an improvement in skill by using a tailored outgoing longwave radiation (OLR) predictor compared with the MJO predictors. The Navy-ESPC generally performs worse than the ECMWF and has OLR biases that impede it from improving skill in the statistical-dynamical schemes. Using shear and humidity fields as predictors did not improve predictability in either model.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042341","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ice Crystal Habit Effects on the Resilience of Arctic Mixed-Phase Stratus Clouds in a One-Dimensional Model","authors":"Abhisek Das,&nbsp;Eugene E. Clothiaux,&nbsp;Jerry Y. Harrington","doi":"10.1029/2024JD041305","DOIUrl":"https://doi.org/10.1029/2024JD041305","url":null,"abstract":"<p>Arctic single-layer mixed-phase clouds were studied using a one-dimensional model that incorporated the adaptive habit growth model for ice microphysics. The base case was from the Indirect and Semidirect Aerosol Campaign, and it was perturbed over a range of cloud-average temperatures, maximum (per model run) ice nuclei (IN) concentrations, and large-scale subsidence velocities. For each parameter combination, the model was iterated out to 48 hr, and the time, called the glaciation time, to complete disappearance of liquid recorded if this occurred within the 48 hr. Dependence of glaciation times on cloud-average temperatures from −30°C to −5°C, maximum IN concentrations from 0.10 to 30 L⁻¹, and strong–no subsidence, with both isometric and habit-dependent ice crystal growth, were investigated. For isometric crystal growth, the relationship between the critical maximum IN concentration (IN_crit), the maximum (per model run) IN concentration above which a mixed-phase cloud glaciated within a fixed model runtime, and cloud-average temperature was monotonic. IN_crit decreased with decreasing cloud-average temperature. Strengthening of subsidence led to a further decrease in IN_crit for every cloud-average temperature. For habit-dependent ice crystal growth, the relationship between IN_crit and cloud-average temperature was nonmonotonic. Ice crystals develop dendritic and columnar habits near −15°C and −7°C, respectively, and at these two temperatures, ice crystals grew and depleted supercooled liquid water faster than the case when ice crystals grew isometrically. This led to deep local minima in IN_crit around these two temperatures in the model runs. Habit-dependent ice crystal growth, coupled with changes in cloud-average temperature, IN_crit, and subsidence strength, led to significant changes in Arctic single-layer mixed-phase cloud lifetimes.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041305","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source and Transport of Dust to the North Pacific: Observations and Analysis From a High Mountain","authors":"Fujung Tsai,&nbsp;Yu-Chen Chien,&nbsp;Wei-Nai Chen,&nbsp;Michael Notaro,&nbsp;Hung-Yu Chen,&nbsp;Neng-Huei Lin,&nbsp;Po-Chun Hsu,&nbsp;Yu-Chi Lin","doi":"10.1029/2024JD042415","DOIUrl":"https://doi.org/10.1029/2024JD042415","url":null,"abstract":"<p>Dust transported to the North Pacific originates not only from East Asian sources but also from non-East Asian sources, providing important marine nutrients to the open ocean. This study analyzes the sources, transport routes, and dust concentrations during 13 North Pacific events in 2010 observed at Mt. Lulin on the Northwest Pacific margin. In addition to aerosol measurements, surface weather data, space lidar observations, MERRA-2 reanalysis data, and trajectory simulations were used. The results show that, during transport to the Pacific, dust from North Africa and the Middle East first moves northeast to Central Asia (30–55°N) and ascends to 200–400 hPa before crossing East Asia. In contrast, dust from the Taklamakan Desert in East Asia rises to 300–400 hPa before being transported eastward. As these dust sources descend into East Asia, they often mix with dust from the Gobi Desert. Indian dust travels zonally eastward at altitudes of 600–800 hPa over Southeast Asia without mixing. In the northwest Pacific, reanalysis data show that while dust is concentrated near the surface, maximum outflow to the Pacific occurs at 400 hPa in the mid-latitudes due to strong westerlies. Trajectory analysis combined with observations suggests that this high-altitude transport includes dust from the Sahara, Arabia, and Taklamakan deserts. At Mt. Lulin along the subtropical coast of East Asia, measured dust concentrations during dust events range from 15 to 39 μg m⁻³, while the annual average is close to 5 μg m⁻³, accounting for 42% of the aerosol concentration over the high mountain.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid Surface Drying During the Black Summer Bushfires in Australia: Insights From High-Resolution Simulations","authors":"Hooman Ayat,&nbsp;Todd P. Lane,&nbsp;Scott Wales,&nbsp;Michael J. Reeder,&nbsp;Yi Huang","doi":"10.1029/2024JD041706","DOIUrl":"https://doi.org/10.1029/2024JD041706","url":null,"abstract":"<p>This study investigates the meteorological processes that contributed to rapid drying at the surface and extreme wildfire conditions (forest fire danger index &gt;100) in southeastern Australia between 29 December 2019 and 2 January 2020. This period was part of the so-called Black Summer 2019/2020. The underlying physical mechanisms and the origin of the near-surface dry air are explored with simulations from the Unified Model (UM) l with 2.2-km horizontal grid spacing and with back trajectories using winds from the UM and ERA5. We find that a near-surface dry region forms prior to the passage of a strong front. The near-surface dry air originates in the upper atmosphere over the Indian Ocean and Southern Ocean, before circulating around an anticyclone, descending as a dry slot onto a deep mixed layer, and finally rapidly reaching the surface through convective rolls. A second dry region forms after the front passes. Again, much of the dry air originates in the upper atmosphere near Antarctica, before descending to the top of the boundary layer and forming a postfrontal dry slot. The dry air then mixes rapidly to the surface. These findings have potential applications for fire weather forecasting and fire management.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 6","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}