Journal of Geophysical Research: Atmospheres最新文献

{"title":"Light Absorbing Particles Deposited to Snow Cover Across the Upper Colorado River Basin, Colorado, 2013–2016: Interannual Variations From Multiple Natural and Anthropogenic Sources","authors":"Richard L. Reynolds,&nbsp;Harland L. Goldstein,&nbsp;Raymond Kokaly,&nbsp;Heather Lowers,&nbsp;George N. Breit,&nbsp;Bruce M. Moskowitz,&nbsp;Peat Solheid,&nbsp;Jeff Derry,&nbsp;Corey R. Lawrence","doi":"10.1029/2024JD041676","DOIUrl":"https://doi.org/10.1029/2024JD041676","url":null,"abstract":"<p>Atmospheric particulate matter (PM) as light-absorbing particles (LAPs) deposited to snow cover can result in early onset and rapid snow melting, challenging management of downstream water resources. We identified LAPs in 38 snow samples (water years 2013–2016) from the mountainous Upper Colorado River basin by comparing among laboratory-measured spectral reflectance, chemical, physical, and magnetic properties. Dust sample reflectance, averaged over the wavelength range of 0.35–2.50 μm, varied by a factor of 1.9 (range, 0.2300–0.4444) and was suppressed mainly by three components: (a) carbonaceous matter measured as total organic carbon (1.6–22.5 wt. %) including inferred black carbon, natural organic matter, and carbon-based synthetic, black road-tire-wear particles, (b) dark rock and mineral particles, indicated by amounts of magnetite (0.11–0.37 wt. %) as their proxy, and (c) ferric oxide minerals identified by reflectance spectroscopy and magnetic properties. Fundamental compositional differences were associated with different iron oxide groups defined by dominant hematite, goethite, or magnetite. These differences in iron oxide mineralogy are attributed to temporally varying source-area contributions implying strong interannual changes in regional source behavior, dust-storm frequency, and (or) transport tracks. Observations of dust-storm activity in the western U.S. and particle-size averages for all samples (median, 25 μm) indicated that regional dust from deserts dominated mineral-dust masses. Fugitive contaminants, nevertheless, contributed important amounts of LAPs from many types of anthropogenic sources.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041676","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143119020","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":"Contrasting the Intraseasonal Precipitation in the Western and Eastern North Pacific During Boreal Winter","authors":"Jing Huang,&nbsp;Yang Zhang,&nbsp;Xin Wang,&nbsp;Mengling Wang","doi":"10.1029/2024JD041953","DOIUrl":"https://doi.org/10.1029/2024JD041953","url":null,"abstract":"<p>The wintertime North Pacific exhibits two types of intraseasonal periodicity in daily precipitation, with a period of 10–20 and 30–90 days in the western and eastern North Pacific. This study aims to identify and compare characteristics and mechanisms of intraseasonal precipitation in these two regions using daily observational data. Our results indicate their notable differences in atmospheric circulations and dynamical processes, despite similarities in moisture sources. A wave train associated with the intraseasonal precipitation in the western North Pacific characterized by anomalous cyclones and anticyclones from West Siberia into the North Pacific is observed, accompanied by anomalous wave activity. By diagnosing local finite-amplitude wave activity (LWA) budget, we demonstrate that the baroclinic eddy generation initiates the upstream growth of wave activity, whereas its downstream development is primarily attributed to the zonal advection of wave train. The upstream wave train induces barotropic and baroclinic instabilities in Kuroshio-Oyashio extension (KOE). In contrast, the anomalous atmospheric circulations related to intraseasonal precipitation in the eastern North Pacific feature a tripolar structure, with downstream propagation of wave activity from the eastern North Pacific to the North American continent. Diabatic heating, along with local eddy generation, contributes to the upstream growth of wave activity. Residual term, possibly linked to the wave activity dissipation associated with wave breaking, extends the wave activity downstream. Thermal and baroclinic instabilities, associated with the diabatic heating and local eddy generation, create favorable conditions for the precipitation. This study may contribute to the improvement of intraseasonal precipitation prediction over the pan-North Pacific region.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118892","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":"ENSO and QBO Controls the Favorableness of the MJO Realization Cooperatively","authors":"Daisuke Takasuka,&nbsp;Tsubasa Kohyama,&nbsp;Tamaki Suematsu,&nbsp;Hiroaki Miura","doi":"10.1029/2024JD042116","DOIUrl":"https://doi.org/10.1029/2024JD042116","url":null,"abstract":"<p>We examine a mechanism of the interannual variability of the realization frequency of the Madden-Julian oscillation (MJO). The activity of boreal-winter MJO realization is quantified by the number of MJO active days during the tracking of the real-time multivariate MJO index. In active years of MJO realization (MJO-A), multiple MJOs are initiated in the Indian Ocean (IO) and they propagate into the western Pacific (WP), but not so in inactive years (MJO-IA). This contrast is explained by whether vertical moisture advection over the WP is disrupted or not. It is related to differences in boreal-winter mean convection and circulations: MJO-A (MJO-IA) years are characterized by enhanced and suppressed (suppressed and enhanced) convection over the WP/IO and Maritime Continent (MC), respectively. This modulation results from combined effects of the El Niño-Southern oscillation (ENSO) and quasi-biennial oscillation (QBO). During moderate-to-strong El Niño, MJO is realized actively irrespective of QBO, if no additional convective suppression over the eastern IO and/or MC due to other forcing such as a positive Indian Ocean Dipole mode. During other ENSO phases, stronger QBO-easterly phases favor MJO realization irrespective of ENSO. This QBO–MJO connection except for El Niño conditions is due to zonally heterogeneous QBO impacts that the seasonal mean static stability change near the tropopause over the WP alters the mean convective activity there. This zonal heterogeneity and ENSO phase-dependency of QBO impacts is interpreted with a focus on vertical propagation of Kelvin wave structure over the MC, affected by both QBO winds and background Walker circulations.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042116","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118891","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":"Do Microplastics Contribute to the Total Number Concentration of Ice Nucleating Particles?","authors":"Daria Tatsii,&nbsp;Blaž Gasparini,&nbsp;Ioanna Evangelou,&nbsp;Silvia Bucci,&nbsp;Andreas Stohl","doi":"10.1029/2024JD042827","DOIUrl":"https://doi.org/10.1029/2024JD042827","url":null,"abstract":"<p>Microplastics (MPs) can be transported into clouds, where they may act as ice nucleating particles (INPs). However, MPs have not been considered as contributors to INP concentrations. Here, we quantify road traffic-related MP number concentrations, and estimate their contribution to total INP concentrations using the atmospheric transport model FLEXPART. We find that under a high emission scenario ice-active MPs can account from about 0.1% to more than 40% of the total INP number in immersion freezing conditions in the tropics, whereas for cirrus conditions, their contribution can be up to about 7% over the tropical Pacific and up to about 20% over East Antarctica. Thus, in regions where other effective INPs are rare, ice-active MP concentrations may be sufficient to trigger heterogeneous nucleation of ice crystals in mixed-phase clouds or cirrus. This suggests that MP may affect cloud formation and highlights the need to reduce uncertainty in MP emissions and their fate in the atmosphere as plastic use continues to grow.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042827","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118350","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":"Contrasting Responses of Ion Concentration Variations to Atmospheric Patterns in Central Himalayan Ice Cores","authors":"Akane Tsushima,&nbsp;Nao Esashi,&nbsp;Sumito Matoba,&nbsp;Yoshinori Iizuka,&nbsp;Ryu Uemura,&nbsp;Kouji Adachi,&nbsp;Takeshi Kinase,&nbsp;Motohiro Hirabayashi,&nbsp;Kaoru Kawakami,&nbsp;Rijan B. Kayastha,&nbsp;Koji Fujita","doi":"10.1029/2024JD042392","DOIUrl":"https://doi.org/10.1029/2024JD042392","url":null,"abstract":"<p>We analyzed the water-soluble chemical composition of an 81.2-m-long ice core collected in 2019 from <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>6,000 m elevation on a south-facing glacier in the Nepal Himalaya. The ice core chronology is based on variability in nitrate and calcium ions, which reveal an apparently seasonal periodicity (with winter maxima) throughout the core's length. Two annual boundaries are consistent with the tritium peak representing nuclear tests conducted in 1963 CE and with the spike in sulfate ions due to the eruption of Krakatau in 1883 CE. The ice core spans 145 years from 1875 to 2019 CE. Dating uncertainties due to the layer counting methodology were estimated as <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 <annotation> $pm 1$</annotation>\u0000 </semantics></math> year for 1963–2019 CE and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> $pm 2$</annotation>\u0000 </semantics></math> years for 1875–1963 CE. Comparison with earlier ice cores drilled on the northern side of the Himalayas revealed that the ion components exhibit inverse correlations with two key climatic indices: the North Atlantic Oscillation and Southern Oscillation Index. Composite analysis of reanalysis climate data suggests that these inverse relationships reflect springtime pressure patterns, which show regional differences between the northern and southern sides of the Himalayan range.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042392","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118351","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":"Energetic Particles Produced by Thunderstorm Electric Fields","authors":"Joseph R. Dwyer","doi":"10.1029/2024JD042193","DOIUrl":"https://doi.org/10.1029/2024JD042193","url":null,"abstract":"<p>In this work, detailed Monte Carlo simulations were performed to test whether terrestrial gamma-ray flashes (TGFs) may be produced by thunderstorm electrification alone, without the presence of lightning, by the relativistic feedback mechanism. TGFs are powerful bursts of gamma rays produced by thunderstorms, often in association with lightning. They are produced by bremsstrahlung interactions of relativistic runaway electrons with air, typically requiring &gt;10¹⁷ energetic electrons to account for the gamma-ray emissions. These energetic electrons may be produced in the high-field regions near lightning leaders, or they may be produced by the self-sustained production of runaway electrons by relativistic feedback involving backward propagating runaway positrons and backscattered x-rays. It has been challenging to tell which mechanism is correct when lightning is present, since both may occur in the fields generated by the propagating leaders. Prior to 2023, the gamma-ray emissions from thunderstorms were broadly classified as either long-lasting gamma-ray glows or TGFs. However, recent aircraft observations by ALOFT are upending this distinction, showing that gamma-ray glows are highly dynamic and often morph into intense pulses that resemble TGFs observed from space. It is shown here that rapid thunderstorm charging produces strong gamma-ray glows with oscillating gamma-ray rates. These oscillations develop into intense pulse trains that closely resemble the multi-pulsed TGFs observed by CGRO/BATSE and ALOFT. Furthermore, the ionization produced by the high-energy particles partially discharges the electric field in some regions while strongly amplifying it in other regions, potentially leading to the initiation of narrow bipolar events and/or lightning.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD042193","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117801","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":"Two Decades of Fire-Induced Albedo Change and Associated Short-Wave Radiative Effect Over Sub-Saharan Africa","authors":"Michaela Flegrová,&nbsp;Helen Brindley","doi":"10.1029/2024JD041491","DOIUrl":"https://doi.org/10.1029/2024JD041491","url":null,"abstract":"&lt;p&gt;We present an analysis of 20 years of fire and albedo data in Africa. We show that, in the mean, the sub-Saharan Africa post-fire surface albedo anomaly can be parameterized using an exponential recovery function, recovering from a decrease of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.019&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.001&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $0.019pm 0.001$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; immediately after a fire with a time constant of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;34.0&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.4&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $34.0pm 0.4$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; days. Although the magnitude of albedo changes shows large spatial and temporal variations and a strong land cover type (LCT) dependency, exponential recovery is observed in the majority of LCTs. We show that fires cause long-term surface brightening, with an Africa-wide albedo increase of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;9.5&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;4&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $(9.5pm 0.2)times 1{0}^{-4}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 10 months after a fire, but we find this is driven almost exclusively by slow vegetation recovery in the Kalahari region, confirming previous findings. Using downward surface shortwave flux (DSSF) estimates, we calculate the fire-induced surface radiative forcing (RF), peaking at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;5&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $5pm 2$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; Wm&lt;sup&gt;−2&lt;/sup&gt; in the burn areas, albeit with a significantly smaller effect when averaged temporally and spatially. We find that the long-term RF in months 5–10 after a burn averaged over the continent is negative because of the brightening observed. Despite a well-documented reduction in burning in Africa in the recent decades, our temporal analysis does not indicate a decrease in the overall fire-induced RF likely due to large interannual variability in albedo anomaly and DSSF data. However, we observe a decline in the sho","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041491","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117819","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":"Dynamics and Mechanisms of South Indian Ocean Teleconnection on the West Antarctic Sea Ice in the Cold Season","authors":"Hongyi Hou,&nbsp;Li Zhang,&nbsp;Wenju Cai,&nbsp;Lixin Wu","doi":"10.1029/2024JD042176","DOIUrl":"https://doi.org/10.1029/2024JD042176","url":null,"abstract":"<p>Tropical-polar teleconnections are believed to play a key role in the observed changes in Antarctica and the Southern Ocean, which have been widely studied. Here we identify a fingerprint of the South Indian Ocean (SIO) in Antarctic sea ice concentration (SIC) in the cold season, detectable as early as May. Specifically, sea surface temperature (SST) warming in the central SIO excites a downstream wave train, inducing an anomalous cyclonic circulation over the Amundsen Sea. This, in turn, leads to increased SIC in the Amundsen Sea and decreased SIC in the eastern Bellingshausen Sea and the northern Weddell Sea via anomalous wind-driven forcing and air advection. We further reveal the dynamical processes that establish the atmospheric bridge between the SIO and polar regions. On the one hand, anomalous Rossby wave sources appear over the SIO, attributed to anomalous divergent flows induced by convective and diabatic heating anomalies. On the other hand, the equivalent barotropic response of atmospheric circulation is reinforced by the feedback of storm activities, dominated by eddy vorticity forcing. In a warming climate, climate models project SST warming in the SIO, accompanied by an increasing meridional SST gradient, suggesting that the strengthened impact of the SIO on Antarctic sea ice is likely to continue.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117869","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":"Constraining the Uncertainty Associated With Sea Salt Aerosol Parameterizations in Global Models Using Nudged UKESM1-AMIP Simulations","authors":"Abhijith U. Venugopal,&nbsp;Yusuf A. Bhatti,&nbsp;Olaf Morgenstern,&nbsp;Jonny Williams,&nbsp;Nick Edkins,&nbsp;Catherine Hardacre,&nbsp;Anthony Jones,&nbsp;Laura E. Revell","doi":"10.1029/2024JD041643","DOIUrl":"https://doi.org/10.1029/2024JD041643","url":null,"abstract":"<p>Sea salt is the largest source of natural aerosol in the atmosphere by mass. Formed when ocean waves break and bubbles burst, sea salt aerosols (SSA) influence Earth's climate via direct and indirect processes. Models participating in the sixth Coupled Model Intercomparison project (CMIP6) demonstrate a negative effective radiative forcing (ERF) when SSA emissions are doubled. However, the magnitude of the ERF ranges widely from −0.35 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math> 0.04 W <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{m}}^{-2}$</annotation>\u0000 </semantics></math> to −2.28 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math> 0.07 W <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{m}}^{-2}$</annotation>\u0000 </semantics></math>, with the largest difference over the Southern Ocean. Differences in the response to doubled SSA emissions arise from model uncertainty (e.g., individual model physics, aerosol size distribution) and parameterization uncertainty (e.g., how SSA is produced in the model). Here, we perform single-model experiments with UKESM1-AMIP incorporating all of the SSA parameterizations used by the current generation of CMIP6 Earth system models (ESMs). Using a fixed SSA size distribution, our experiments show that the parameterization uncertainty causes large inter-model diversity in SSA emissions in the models, particularly over the tropics and the Southern Ocean. The choice of parameterization influences the ambient aerosol size distribution, cloud condensation nuclei and cloud droplet number concentrations, and therefore direct and indirect radiative forcing. We recommend that modeling groups evaluate their SSA parameterizations and update them where necessary in preparation for future model intercomparison activities.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041643","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117235","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":"Evaluating Cloud Properties at Scott Base: Comparing Ceilometer Observations With ERA5, JRA55, and MERRA2 Reanalyses Using an Instrument Simulator","authors":"A. J. McDonald,&nbsp;P. Kuma,&nbsp;M. Panell,&nbsp;O. K. L. Petterson,&nbsp;G. E. Plank,&nbsp;M. A. H. Rozliaiani,&nbsp;L. E. Whitehead","doi":"10.1029/2024JD041754","DOIUrl":"https://doi.org/10.1029/2024JD041754","url":null,"abstract":"<p>This study compares CL51 ceilometer observations made at Scott Base, Antarctica, with statistics from the ERA5, JRA55, and MERRA2 reanalyses. To enhance the comparison we use a lidar instrument simulator to derive cloud statistics from the reanalyses which account for instrumental factors. The cloud occurrence in the three reanalyses is slightly overestimated above 3 km, but displays a larger underestimation below 3 km relative to observations. Unlike previous studies, we see no relationship between relative humidity and cloud occurrence biases, suggesting that the cloud biases do not result from the representation of moisture. We also show that the seasonal variation of cloud occurrence and cloud fraction, defined as the vertically integrated cloud occurrence, are small in both the observations and the reanalyses. We also examine the quality of the cloud representation for a set of weather states derived from ERA5 surface winds. The variability associated with grouping cloud occurrence based on weather state is much larger than the seasonal variation, highlighting weather state is a strong control of cloud occurrence. All the reanalyses continue to display underestimates below 3 km and overestimates above 3 km for each weather state. But the variability in ERA5 statistics matches the changes in the observations better than the other reanalyses. We also use a machine learning scheme to estimate the quantity of supercooled liquid water cloud from the ceilometer observations. Ceilometer low-level supercooled liquid water cloud occurrences are considerably larger than values derived from the reanalyses, further highlighting the poor representation of low-level clouds in the reanalyses.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD041754","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117289","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}