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Finding the magnetopause location using soft X-ray observations and a statistical inverse method

Earth and Planetary Physics 2024年第1期8卷 184-203页

作者： Gonzalo Cucho-Padin Hyunju Connor Jaewoong Jung Brian Walsh David G.Sibeck Space Weather Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Department of Physics The Catholic University of AmericaWashingtonDCUSA Geospace Physics Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Astronomy Department University of Maryland College ParkCollege ParkMDUSA Center for Space Physics Department of Mechanical EngineeringBoston UniversityBostonMAUSA

Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the *** spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to *** wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial *** upcoming missions,ESA/CAS SMILE and nasa’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral ***-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field *** work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth *** do so,we simulate the magnetosheath structure using the MHD-based OpenGGCM model and generate synthetic soft X-ray images using LEXI’s orbit and attitude *** results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray ***,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation hi

关键词： magnetopause soft X-ray tomography

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Hybrid-Vlasov simulation of soft X-ray emissions at the Earth’s dayside magnetospheric boundaries

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Earth and Planetary Physics 2024年第1期8卷 70-88页

作者： M.Grandin H.K.Connor S.Hoilijoki M.Battarbee Y.Pfau-Kempf U.Ganse K.Papadakis M.Palmroth Department of Physics University of HelsinkiHelsinkiFinland nasa Goddard Space Flight Center GreenbeltMD20771USA Space and Earth Observation Centre Finnish Meteorological InstituteHelsinkiFinland

Solar wind charge exchange produces emissions in the soft X-ray energy range which can enable the study of near-Earth space regions such as the magnetopause,the magnetosheath and the polar cusps by remote sensing *** Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)and Lunar Environment heliospheric X-ray Imager(LEXI)missions aim to obtain soft Xray images of near-Earth space thanks to their Soft X-ray Imager(SXI)*** earlier modeling works have already simulated soft X-ray images as might be obtained by SMILE SXI during its mission,the numerical models used so far are all based on the magnetohydrodynamics description of the space *** investigate the possible signatures of ion-kinetic-scale processes in soft Xray images,we use for the first time a global hybrid-Vlasov simulation of the geospace from the Vlasiator *** simulation is driven by fast and tenuous solar wind conditions and purely southward interplanetary magnetic *** first produce global X-ray images of the dayside near-Earth space by placing a virtual imaging satellite at two different locations,providing meridional and equatorial *** then analyze regional features present in the images and show that they correspond to signatures in soft X-ray emissions of mirrormode wave structures in the magnetosheath and flux transfer events(FTEs)at the *** results suggest that,although the time scales associated with the motion of those transient phenomena will likely be significantly smaller than the integration time of the SMILE and LEXI imagers,mirror-mode structures and FTEs can cumulatively produce detectable signatures in the soft X-ray *** instance,a local increase by 30%in the proton density at the dayside magnetopause resulting from the transit of multiple FTEs leads to a 12%enhancement in the line-of-sight-and time-integrated soft X-ray emissivity originating from this ***,a proton density increase by 14%in the magnetosheath

关键词： magnetosphere magnetosheath numerical simulation SMILE LEXI soft X-ray emissions hybrid-Vlasov model polar cusp flux transfer events mirror-mode waves

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A Note on Reviving the Goddard Satellite-Based Surface Turbulent Fluxes (GSSTF) Dataset

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Advances in Atmospheric Sciences 2009年第6期26卷 1071-1080页

作者： Chung-Lin SHIE Long S. CHIU Robert ADLER Eric NELKIN I-I LIN Pingping XIE Feng-Chin WANG R. CHOKNGAMWONG William OLSON D. Allen CHU UMBC/GEST Baltimore Maryland USA Code 613.1 NASA/GSFC Greenbelt Maryland USA GMU/CEOSR Fairfax Virginia USA CUHK/ISEIS Shatin NT Hong Kong UMCP/ESSIC College Park Maryland USA ssai Lanham Maryland USA NTU Taipei Taiwan NOAA/CPC Camp Springs Maryland USA CWB Taipei Chinese Taiwan UMBC/JCET Baltimore Maryland USA Code 613.2 NASA/GSFC Greenbelt Maryland USA

Accurate sea surface flux measurements are crucial for understanding the global water and energy cycles. The oceanic evaporation, which is a major component of the global oceanic fresh water flux, is useful for predicting oceanic circulation and transport. The global Goddard Satellite-based Surface Turbulent Fluxes Version-2 （GSSTF2; July 1987–December 2000） dateset that was o？cially released in 2001 has been widely used by scientific community for global energy and water cycle research, and regional and short period data analyses. We have recently been funded by nasa to resume processing the GSSTF dataset with an objective of continually producing a uniform dataset of sea surface turbulent fluxes, derived from remote sensing data. The dataset is to be reprocessed and brought up-to-date （GSSTF2b） using improved input datasets such as a recently upgraded NCEP/DOE sea surface temperature reanalysis, and an upgraded surface wind and microwave brightness temperature V6 dataset （Version 6） from the Special Sensor Microwave Imager （SSM/I） produced by Remote Sensing Systems （RSS）. A second new product （GSSTF3） is further proposed with a finer temporal （12-h） and spatial （0.25° × 0.25°） resolution. GSSTF2b （July 1987–December 2008） and GSSTF3 （July 1999–December 2009） will be released for the research community to use by late 2009 and early 2011, respectively.

关键词： surface turbulent fluxes global oceanic satellite-based

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A Study of Air/Space-borne Dual-Wavelength Radar for Estimation of Rain Profiles

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Advances in Atmospheric Sciences 2005年第6期22卷 841-851页

作者： Liang LIAO Robert MENEGHINI Goddard Earth Sciences ＆ Technology Center/Caelum Greenbelt MD 20771 Code 614.6 NASA/GSFC Greenbelt MD 20771

In this study, a framework is given by which air/space-borne dual-wavelength radar data can be used to estimate the characteristic parameters of hydrometeors. The focus of the study is on the Global Precipitation Measurement （GPM） precipitation radar, a dual-wavelength radar that will operate in the Ku （13.6 GHz） and Ka （35 GHz） bands. A key aspect of the retrievals is the relationship between the differential frequency ratio （DFR） and the median volume diameter, Do, and its dependence on the phase state of the hydrometeors. It is shown that parametric plots of Do and particle concentration in the plane of the DFR and the radar reflectivity factor in the Ku band can be used to reduce the ambiguities in deriving Do from DFR. A self-consistent iterative algorithm, which does not require the use of an independent pathattenuation constraint, is examined by applying it to the apparent radar reflectivity profiles simulated from a drop size distribution （DSD） model. For light to moderate rain, the self-consistent rain profiling approach converges to the correct solution only if the same shape factor of the Gamma distributions is used both to generate and retrieve the rain profiles. On the other hand, if the shape factors differ, the iteration generally converges but not to the correct solution. To further examine the dual-wavelength techniques, the selfconsistent iterative algorithm, along with forward and backward rain profiling algorithms, are applied to measurements taken from the 2nd generation Precipitation Radar （PR-2） built by the Jet Propulsion Laboratory. Consistent with the model results, it is found that the estimated rain profiles are sensitive to the shape factor of the size distribution when the iterative, self-consistent approach is used but relatively insensitive to this parameter when the forward- and backward-constrained approaches are used.

关键词： rain rate dual-wavelength radar raindrop size distribution and GPM

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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

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Development of an operational land water mask for MODIS Collection 6,and influence on downstream data products

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International Journal of Digital Earth 2017年第2期10卷 207-218页

作者： M.L.Carroll C.M.DiMiceli J.R.G.Townshend R.A.Sohlberg A.I.Elders S.Devadiga A.M.Sayer R.C.Levy nasa/gsfc Biospheric Sciences Laboratory GreenbeltMDUSA Science Systems and Applications Inc. LanhamMDUSA Department of Geographical Sciences University of MarylandCollege ParkMDUSA Atmospheric Oceanic and Earth SciencesGeorge Mason UniversityFairfaxVAUSA nasa/gsfc Terrestrial Information Systems Laboratory GreenbeltMDUSA fGoddard Earth Sciences Technology and Research Universities Space Research AssociationGreenbeltMDUSA nasa/gsfc Climate and Radiation Laboratory GreenbeltMDUSA

Data from the Moderate Resolution Imaging Spectro-radiometer(MODIS)on-board the Earth Observing System Terra and Aqua satellites are processed using a land water mask to determine when an algorithm no longer needs to be run or when an algorithm needs to follow a different *** the fourth reprocessing(Collection 6(C6))the MODIS team replaced the 1 km water mask with a 500 m water mask for improved representation of the continental *** new water mask represents more small water bodies for an overall increase in water surface from 1%to 2%of the continental *** this is still a small fraction of the overall global surface area the increase is more dramatic in certain areas such as the Arctic and Boreal regions where there are dramatic increases in water surface area in the new *** products generated by the on-going C6 reprocessing using the new land water mask show significant impact in areas with high concentrations of change in the land water *** differences between the Collection 5(C5)and C6 water masks and the impact of these differences on the MOD04 aerosol product and the MOD11 land surface temperature product are shown.

关键词： Earth observation image processing land cover remote sensing water resources

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Coniferous Canopy BRF Simulation Based on 3-D Realistic Scene

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光谱学与光谱分析 2011年第9期31卷 2495-2498页

作者： WANG Xin-yun GUO Zhi-feng QIN Wen-han SUN Guo-qing Key Lab for Restoration and Reconstruction of Degraded Ecosystem in North-Western China ofMinistry of Education Ningxia University Yinchuan 750021 China Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China ssai/nasa gsfc Greenbelt MD 20771 USA Department of Geography University of Maryland MD 20742 USA

It is difficulties for the computer simulation method to study radiation regime at *** coniferous model was investigated in the present *** makes the computer simulation methods such as L-systems and radiosity-graphics combined method(RGM) more powerful in remote sensing of heterogeneous coniferous forests over a large-scale region.L-systems is applied to render 3-D coniferous forest scenarios,and RGM model was used to calculate BRF(bidirectional reflectance factor) in visible and near-infrared *** in this study show that in most cases both agreed *** at a tree and forest level,the results are also good.

关键词： BRF RGM model L-systems

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The　Influence　of　Changes　in　Vegetation　Type　on　the　Surface　Energy　Budget

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Advances in Atmospheric Sciences 1994年第2期11卷 139-161页

作者： Runhua Yang (1) J. Shukla (1) P. J. Sellers (2) 1. Center for Ocean-Land-Atmosphere Studies 4041 Powder Mill Road 20705 Calverton MD USA 2. nasa / gsfc 923 20771 Greenbelt MD USA

The influence of changes in vegetation type on the surface energy budget was studied using the Simple Biosphere Model (SiB) of Sellers et al. (1986). The modeled energy budget response to the conversion of forest to short vegetation or bare soil (deforestation) was investigated with SiB forced by three time--series of atmospheric boundary conditions collected at three different climatic sites: an Amazonian tropical forest, a U.S. Great Plains grassland, and a central Wales spruce forest. The results show that SiB can simulate realistic surface energy budgets and surface temperatures, and that deforestation may have a significant influellce on the local surface energy budget and surface weather. The influence is especially prominent at the Amazonian and U.S. Great Plains sites, and greater in summer than in other *** was found that atmospheric boundary conditions play a dominant role in determining the degree of changes in the surface fluxes and temperature induced by deforestation; the largest change in latent heat flux appeared at the Amazon site, the largest change in sensible heat flux appeared at the Spruce forest site, and the largest change in surface temperature appeared at the Great Plains site. The Bowen ratios of the SiB sensitivity integrations for each site are comparable with observations. The values of the Bowen ratio and the ratio of latent heat flux to net radiation vary distinctly from site to site, implying that local atmospheric conditions limit the range of changes caused by the vegetation change.

关键词： Biosphere model Vegetation effect Sensitivity test Land -atmosphere interaction

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A striking confluence between theory and observations of high-mass X-ray binary pulsars

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Research in Astronomy and Astrophysics 2018年第10期18卷 117-122页

作者： Dimitris M.Christodoulou Silas G.T.Laycock Demosthenes Kazanas Lowell Center for Space Science and Technology University of Massachusetts Lowell Dept.of Mathematical Sciences Univ.of Massachusetts Lowell Dept. of Physics & Applied Physics Univ. of Massachusetts Lowell nasa/gsfc Laboratory for High-Energy Astrophysics

We analyze the most powerful X-ray outbursts from neutron stars in eleven Magellanic high-mass X-ray binaries and three pulsating ultraluminous X-ray sources. Most of the outbursts rise to Lmax which is about the level of the Eddington luminosity, while the remaining more powerful outbursts also appear to recognize that limit when their emissions are assumed to be anisotropic and beamed toward our direction. We use the measurements of pulsar spin periods Ps and their derivatives Ps to calculate the X-ray luminosities Lp in their faintest accreting （＂propeller-line＂） states. In five cases with unknown Ps, we use the lowest observed X-ray luminosities, which only adds to the heterogeneity of the sample. Then we calculate the ratios Lp/Lmax and we obtain an outstanding confluence of theory and observations from which we conclude that work done on both fronts is accurate and the results are trustworthy： sources known to reside on the lowest Magellanic propeller line are all located on/near that line, whereas other sources jump higher and reach higher-lying propeller lines. These jumps can be interpreted in only one way, higher-lying pulsars have stronger surface magnetic fields in agreement with previous empirical results in which Ps and Lp values were not used.

关键词： accretion accretion disks - stars magnetic fields - stars neutron - X-rays binaries

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Metadata requirements analysis for the emerging Sensor Web

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International Journal of Digital Earth 2009年第S01期2卷 3-17页

作者： Liping Di Karen L.Moe Genong(Eugene)Yu Center for Spatial Information Science and Systems(CSISS) George Mason University6301 Ivy LnSuite 620GreenbeltMD 20770USA Earth System Technology Office NASA/GSFC MS Code 407GreenbeltMD 20771USA

The Sensor Web has emerged from Earth Science research with the development of Web technology,to achieve process automation,sensor interoperation,and service *** promises require the discovery of the right sensor at the right time and the right location with the right ***,for sensor,platform,and data,are crucial for achieving such ***,analysis and practical use of these metadata reveals that the metadata and their associations are not applicable or suitable for the Sensor *** shortfalls are(1)the nonstandard metadata expression language;(2)the missing link between sensor and domain knowledge;(3)the insufficiency in the information for geographic locating and sensor tasking;and(4)the enhanced requirements on the quality,security,and ownership of both sensors and their sensed *** paper reviews the current standards that have metadata components for the sensor and its platform,especially those from ISO TC211,Open Geospatial Consortium Inc.,and The National Aeronautics and Space Administration Global Change Master Directory.A recommendation on metadata that meets the requirement of crossmission sensor discovery in a pervasive Web environment is derived from *** recommendation addresses issues on language formalization,sensor geolocation,semantics,quality,and *** of the emerging semantic Web technology for enabling robust discovery of sensor are discussed.

关键词： Sensor Web geospatial standards metadata interoperation semantic web

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