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National Science Review 2024年第3期11卷 150-158页

作者： Kun Li Jun Zhang David M.Bell Tiantian Wang Houssni Lamkaddam Tianqu Cui Lu Qi Mihnea Surdu Dongyu Wang Lin Du Imad El Haddad Jay G.Slowik Andre S.H.Prevot Environment Research institute Shandong University Laboratory of atmospheric Chemistry Paul Scherrer Institute

Organic vapors from biomass burning are a major source of secondary organic aerosols(SOAs). Previous smog chamber studies found that the SOA contributors in biomass-burning emissions are mainly volatile organic compounds(VOCs). While intermediate volatility organic compounds(IVOCs) are efficient SOA precursors and contribute a considerable fraction of biomass-burning emissions, their contribution to SOA formation has not been directly observed. Here, by deploying a newly-developed oxidation flow reactor to study SOA formation from wood burning, we find that IVOCs can contribute ～70% of the formed SOA, i.e.>2 times more than VOCs. This previously missing SOA fraction is interpreted to be due to the high wall losses of semi-volatile oxidation products of IVOCs in smog chambers. The finding in this study reveals that SOA production from biomass burning is much higher than previously thought, and highlights the urgent need for more research on the IVOCs from biomass burning and potentially other emission sources.

关键词： atmospheric chemistry biomass burning secondary organic aerosol intermediate volatility organic compounds

Comparison of the Minimum Bounding Rectangle and Minimum Circumscribed Ellipse of Rain Cells from TRMM

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Advances in atmospheric Sciences 2024年第3期41卷 391-406页

作者： Hongke CAI Yaqin MAO Xuanhao ZHU Yunfei FU Renjun ZHOU Plateau atmospheric and Environment Laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225China School of Earth and space Sciences University of Science and Technology of ChinaHefei 230026China Center for atmospheric Optics Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China

Based on the TRMM dataset, this paper compares the applicability of the improved MCE(minimum circumscribed ellipse), MBR(minimum bounding rectangle), and DIA(direct indexing area) methods for rain cell fitting. These three methods can reflect the geometric characteristics of clouds and apply geometric parameters to estimate the real dimensions of rain cells. The MCE method shows a major advantage in identifying the circumference of rain cells. The circumference of rain cells identified by MCE in most samples is smaller than that identified by DIA and MBR, and more similar to the observed rain cells. The area of rain cells identified by MBR is relatively robust. For rain cells composed of many pixels(N> 20), the overall performance is better than that of MCE, but the contribution of MBR to the best identification results,which have the shortest circumference and the smallest area, is less than that of MCE. The DIA method is best suited to small rain cells with a circumference of less than 100 km and an area of less than 120 km^(2), but the overall performance is mediocre. The MCE method tends to achieve the highest success at any angle, whereas there are fewer “best identification”results from DIA or MBR and more of the worst ones in the along-track direction and cross-track direction. Through this comprehensive comparison, we conclude that MCE can obtain the best fitting results with the shortest circumference and the smallest area on behalf of the high filling effect for all sizes of rain cells.

关键词： TRMM minimum bounding rectangle minimum circumscribed ellipse

Assessing the performance of magnetopause models based on THEMIS data

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Earth and Planetary Physics 2024年第5期8卷 776-786页

作者： Yang Lin JianYong Lu BaoHang Qu Xi Wang institute of space Weather School of Atmospheric PhysicsNanjing University of Information Science & Technology

The magnetopause is the boundary between the Earth's magnetic field and the interplanetary magnetic field（IMF）,located where the supersonic solar wind and magnetospheric pressure are in *** empirical models and global magnetohydrodynamic simulations have been used to define the magnetopause,each of these has *** this work,we use15 years of magnetopause crossing data from the THEMIS（Time History of Events and Macroscale Interactions during Substorms）spacecraft and their corresponding solar wind parameters to investigate under which solar wind conditions these models predict more *** analyze the pattern of large errors in the extensively used magnetopause model and show the specific solar wind parameters,such as components of the IMF,density,velocity,temperature,and others that produce these *** is shown that（1） the model error increases notably with increasing solar wind velocity,decreasing proton density,and increasing temperature;（2） when the cone angle becomes smaller or|Bx|is larger,the Shue98 model errors increase,which might be caused by the magnetic reconnection on the dayside magnetopause;（3） when|By|is large,the error of the model is large,which may be caused by the east–west asymmetry of the magnetopause due to magnetic reconnection;（4） when Bzis southward,the error of the model is larger;and（5） the error is larger for positive dipole tilt than for negative dipole tilt and increases with an increasing dipole tilt ***,the global simulation model b Liu ZQ et al.（2015） shows a substantial improvement in prediction accuracy when IMF Bx,By,or the dipole tilt cannot be *** result can help us choose a more accurate model for forecasting the magnetopause under different solar wind conditions.

关键词： magnetopause empirical model global magnetohydrodynamic simulation THEMIS solar wind parameters

Mshpy23:a user-friendly,parameterized model of magnetosheath conditions

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Earth and Planetary Physics 2024年第1期8卷 89-104页

作者： Jaewoong Jung Hyunju Connor Andrew Dimmock Steve Sembay Andrew Read Jan Soucek NASA Goddard space Flight Center GreenbeltMDUSA Department of Astronomy University of MarylandCollege ParkMDUSA Swedish Institude of space Physics UppsalaSweden University of Leicester LeicesterUK institute of atmospheric Physics Academy of Sciences of the Czech Republic

Lunar Environment heliospheric X-ray Imager(LEXI)and Solar wind−Magnetosphere−Ionosphere Link Explorer(SMILE)will observe magnetosheath and its boundary motion in soft X-rays for understanding magnetopause reconnection modes under various solar wind conditions after their respective launches in 2024 and *** conditions,namely,plasma density,velocity,and temperature,are key parameters for predicting and analyzing soft X-ray images from the LEXI and SMILE *** developed a userfriendly model of magnetosheath that parameterizes number density,velocity,temperature,and magnetic field by utilizing the global Magnetohydrodynamics(MHD)model as well as the pre-existing gas-dynamic and analytic *** this parameterized magnetosheath model,scientists can easily reconstruct expected soft X-ray images and utilize them for analysis of observed images of LEXI and SMILE without simulating the complicated global magnetosphere ***,we created an MHD-based magnetosheath model by running a total of 14 OpenGGCM global MHD simulations under 7 solar wind densities(1,5,10,15,20,25,and 30 cm)and 2 interplanetary magnetic field Bz components(±4 nT),and then parameterizing the results in new magnetosheath *** compared the magnetosheath model result with THEMIS statistical data and it showed good agreement with a weighted Pearson correlation coefficient greater than 0.77,especially for plasma density and plasma ***,we compiled a suite of magnetosheath models incorporating previous magnetosheath models(gas-dynamic,analytic),and did two case studies to test the *** MHD-based model was comparable to or better than the previous models while providing self-consistency among the magnetosheath ***,we constructed a tool to calculate a soft X-ray image from any given vantage point,which can support the planning and data analysis of the aforementioned LEXI and SMILE missions.A release of the code has been uploaded to a Git

关键词： magnetosheath python modeling

The Observed Near-Surface Energy Exchange Processes over Arctic Glacier in Summer

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Journal of Meteorological Research 2024年第3期38卷 600-607页

作者： Libo ZHOU Jinhuan ZHU Linlin KONG Peng LI Shupo MA Fei LI Han ZOU Meigen ZHANG Irina REPINA Department of Lower atmospheric Observation and Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of atmospheric Boundary Layer Physics and atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Department of Weather Forecast Aviation Meteorological Centre of Air Traffic Management BureauCivil Aviation Administration of ChinaBeijing100015China A.M.Obukhov institute of atmospheric Physics Russian Academy of Sciences(RAS)Moscow119017Russian Federation

Under Arctic warming,near-surface energy transfers have significantly changed,but few studies have focused on energy exchange over Arctic glacier due to limitations in available *** this study,the atmospheric energy exchange processes over the Arctic glacier surface were analyzed by using observational data obtained in summer 2019 in comparison with those over the Arctic tundra *** energy budget over the glacier greatly differed from that over the tundra,characterized by less net shortwave radiation and downward sensible heat flux,due to the high albedo and icy *** of the incoming solar radiation was injected into the glacier in summer,leading to snow ice *** the observation period,strong daily variations in near-surface heat transfer occurred over the Arctic glacier,with the maximum downward and upward heat fluxes occurring on 2 and 6 July 2019,*** analyses suggested that the maximum downward heat flux is mainly caused by the strong local thermal contrast above the glacier surface,while the maximum upward heat transfer cannot be explained by the classical turbulent heat transfer theory,possibly caused by countergradient heat *** results indicated that the near-surface energy exchange processes over Arctic glacier may be strongly related to local forcings,but a more in-depth investigation will be needed in the future when more observational data become available.

关键词： Arctic glacier tundra energy exchange processes

The dawn−dusk asymmetry in mesosphere and lower thermosphere temperature disturbances during geomagnetic storms at high latitude

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Earth and Planetary Physics 2024年第2期8卷 356-367页

作者： GuanChun Wei JianYong Lu Fen Tang JingYuan Li Meng Sun institute of space Weather School of Atmospheric PhysicsNanjing University of Information Science&TechnologyNanjing 210044China College of Information and Communication National University of Defense TechnologyWuhan 430019China

Utilizing observations by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument,we quantitatively assessed the dawn-dusk asymmetry in temperature disturbances within the high-latitude mesosphere and lower thermosphere(MLT)during the main phase of geomagnetic storms in this *** analysis of five geomagnetic superstorm events indicated that during the main phase,negative temperature disturbances were more prevalent on the dawn side than on the dusk side in the high-latitude MLT *** of a statistical analysis of 54 geomagnetic storm events also revealed a notable disparity in temperature disturbances between the dawn and dusk *** high latitudes,38.2%of the observational points on the dawn side exhibited negative temperature disturbances(less than−5 K),whereas on the dusk side,this percentage was only 29.5%.In contrast,at mid-latitudes,these proportions were 34.1%and 36.5%,respectively,showing no significant *** also conducted a statistical analysis of temperature disturbances at different altitudes,which revealed an increase in the proportion of warming disturbances with ***,the proportion of cooling disturbances initially rose with altitude,reaching a peak around 105 km,and subsequently *** temperature disturbance differences could be explained by the day-night asymmetry in vertical wind disturbances during storm conditions.

关键词： dawn dusk asymmetry SABER(Sounding of the Atmosphere using Broadband Emission Radiometry) geomagnetic storms mesosphere and lower thermosphere

Are Solar Active Regions Born with Neutralized Currents?

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Research in Astronomy and Astrophysics 2024年第7期24卷 82-91页

作者： Aiying Duan Yaoyu Xing Chaowei Jiang Planetary Environmental and Astrobiological Research Laboratory (PEARL) School of Atmospheric SciencesSun Yat-sen University Yunnan Key Laboratory of the Solar Physics and space Science Key Laboratory of Tropical Atmosphere-Ocean System Sun Yat-sen UniversityMinistry of Education institute of space Science and Applied Technology Harbin Institute of Technology

Solar active regions(ARs) are formed by the emergence of current-carrying magnetic flux tubes from below the photosphere. Although for an isolated flux tube the direct and return currents flowing along the tube should balance with each other, it remains controversial whether such a neutralization of currents is also maintained during the emergence process. Here we present a systematic survey of the degrees of the current neutralization in a large sample of flux-emerging ARs which appeared on the solar disk around the central meridian from 2010 to *** vector magnetograms taken by Helioseismic and Magnetic Imager onboard Solar Dynamic Observatory are employed to calculate the distributions of the vertical current density at the photosphere. Focusing on the main phase of flux emergence, i.e., the phase in which the total unsigned magnetic flux is continuously increased, we statistically examined the ratios of direct to return currents in all the ARs. Such a large-sample statistical study suggests that most of the ARs were born with currents close to neutralization. The degree of current neutralization seems to be not affected by the active-region size, the active-region growing rate, and the total unsigned *** only correlation of significance as found is that the stronger the magnetic field nonpotentiality is, the further the AR deviates from current neutrality, which supports previous event studies that eruption-productive ARs often have non-neutralized currents.

关键词： Sun: corona Sun: coronal mass ejections (CMEs) Sun: flares Sun: magnetic fields

Quantifying the Role of the Eddy Transfer Coefficient in Simulating the Response of the Southern Ocean Meridional Overturning Circulation to Enhanced Westerlies in a Coarse-resolution Model

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Advances in atmospheric Sciences 2024年第9期41卷 1853-1867页

作者： Yiwen LI Hailong LIU Pengfei LIN Eric PCHASSIGNET Zipeng YU Fanghua WU School of Ocean Sciences China University of GeosciencesBeijing 100083China Laoshan Laboratory Qingdao 266237China institute of atmospheric Physics Chinese Academy of SciencesBeijing 100029China Center for Ocean-atmospheric Prediction studies Florida State UniversityTallahassee 32306FloridaUSA China Meteorological Administration Beijing 100081China

This study assesses the capability of a coarse-resolution ocean model to replicate the response of the Southern Ocean Meridional Overturning Circulation(MOC) to intensified westerlies,focusing on the role of the eddy transfer coefficient(κ).κ is a parameter commonly used to represent the velocities induced by unresolved *** findings reveal that a stratification-dependent κ,incorporating spatiotemporal variability,leads to the most robust eddy-induced MOC response,capturing 82% of the reference eddy-resolving *** the eddy-induced velocity into its vertical variation(VV) and spatial structure(SS) components unveils that the enhanced eddy compensation response primarily stems from an augmented SS term,while the introduced VV term weakens the ***,the temporal variability of the stratification-dependent κ emerges as a key factor in enhancing the eddy compensation response to intensified *** experiment with stratification-dependent κ exhibits a more potent eddy compensation response compared to the constant κ,attributed to the structure of κ and the vertical variation of the density *** results underscore the critical role of accurately representing κ in capturing the response of the Southern Ocean MOC and emphasize the significance of the isopycnal slope in modulating the eddy compensation mechanism.

关键词： eddy transfer coefficient mesoscale eddy parameterization enhanced westerlies Southern Ocean Meridional Overturning Circulation ocean model

Understanding the Low Predictability of the 2015/16 El Niño Event Based on a Deep Learning Model

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Advances in atmospheric Sciences 2024年第7期41卷 1313-1325页

作者： Tingyu WANG Ping HUANG Xianke YANG Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China National space Science Center Chinese Academy of SciencesBeijing 100190China State Key Laboratory of space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China College of Plant Science and Technology Huazhong Agricultural UniversityWuhan 430070China

The 2015/16 El Niño event ranks among the top three of the last 100 years in terms of intensity,but most dynamical models had a relatively low prediction skill for this event before the summer ***,the attribution of this particular event can help us to understand the cause of super El Niño–Southern Oscillation events and how to forecast them *** present study applies attribute methods based on a deep learning model to study the key factors related to the formation of this event.A deep learning model is trained using historical simulations from 21 CMIP6 models to predict the Niño-3.4 *** integrated gradient method is then used to identify the key signals in the North Pacific that determine the evolution of the Niño-3.4 *** crucial signals are then masked in the initial conditions to verify their roles in the *** addition to confirming the key signals inducing the super El Niño event revealed in previous attribution studies,we identify the combined contribution of the tropical North Atlantic and the South Pacific oceans to the evolution and intensity of this event,emphasizing the crucial role of the interactions among them and the North *** approach is also applied to other El Niño events,revealing several new precursor *** study suggests that the deep learning method is useful in attributing the key factors inducing extreme tropical climate events.

关键词： ENSO attribution deep learning ENSO prediction extreme El Niño

Spatial continuous modeling of early Cenozoic carbon cycle and climate

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National Science Review 2024年第4期11卷 30-32页

作者： Yonggang Liu Jian Zhang Haoyue Zuo Zhilin He Jiaqi Guo Qifan Lin Haonan Yu Jiawenjing Lan Jing Han Zhihong Song Zihan Yin Liang Zhao Yongyun Hu Zhengtang Guo Laboratory for Climate and Ocean-Atmosphere studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

The partial pressure of atmospheric CO2（pCO2） is determined by the carbon cycle that involves climate, biogeochemistry, and plate tectonics. In this cycle,atmospheric CO2is converted into organic carbon and carbonates by biological activities and silicate weathering, and buried as sediments. The sediments on the ocean floor are subducted into the Earth’s interior, and subsequently converted back into CO2and outgassed into the atmosphere.

关键词： atmospheric CO2