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Journal articleCeppi P, Zelinka MD, Hartmann DL, 2014, , Geophysical 91桃色 Letters, Vol: 41, Pages: 3244-3250, ISSN: 0094-8276
A strong relationship is found between changes in the meridional gradient of absorbed shortwave radiation (ASR) and Southern Hemispheric jet shifts in 21st century climate simulations of CMIP5 (Coupled Model Intercomparison Project phase 5) coupled models. The relationship is such that models with increases in the meridional ASR gradient around the southern midlatitudes, and therefore increases in midlatitude baroclinicity, tend to produce a larger poleward jet shift. The ASR changes are shown to be dominated by changes in cloud properties, with sea ice declines playing a secondary role. We demonstrate that the ASR changes are the cause, and not the result, of the intermodel differences in jet response by comparing coupled simulations with experiments in which sea surface temperature increases are prescribed. Our results highlight the importance of reducing the uncertainty in cloud feedbacks in order to constrain future circulation changes.
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Book chapterGaland MIF, Coates A, Cravens T, et al., 2014,
Titan's Ionosphere
, Titan: Interior, Surface, Atmosphere, and Space Environment, Editors: Mueller-Wodarg, Griffith, Lellouch, Cravens, Publisher: Cambridge University Press, Pages: 376-418, ISBN: 9780521199926 -
Journal articleVigren E, Galand M, Shebanits O, et al., 2014, , ASTROPHYSICAL JOURNAL, Vol: 786, ISSN: 0004-637X
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- Citations: 10
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Journal articleSouthwood D, 2014, , NATURE, Vol: 509, Pages: 32-32, ISSN: 0028-0836
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Journal articleBunce EJ, Grodent DC, Jinks SL, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 3528-3543, ISSN: 2169-9380
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- Citations: 17
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Journal articleAnsell C, Brindley HE, Pradhan Y, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 119, Pages: 4070-4086, ISSN: 2169-897X
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- Citations: 15
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Journal articleGoldman MV, Newman DL, Lapenta G, et al., 2014, , PHYSICAL REVIEW LETTERS, Vol: 112, ISSN: 0031-9007
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- Citations: 56
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Journal articleBadman SV, Branduardi-Raymont G, Galand M, et al., 2014, , Space Science Reviews, Vol: 187, Pages: 99-179, ISSN: 1572-9672
The ionospheric response to auroral precipitation at the giant planets is reviewed,using models and observations. The emission processes for aurorae at radio, infrared, visible,ultraviolet, and X-ray wavelengths are described, and exemplified using ground- andspace-based observations. Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics oratmospheric conditions. Finally, the spatial distributions and dynamics of the various componentsof the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetosphericprocesses and boundaries, using theory, in situ, and remote observations, withthe aim of distinguishing between those related to internally-driven dynamics, and thoserelated to the solar wind interaction.
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Journal articleMessori G, Czaja A, 2014, , QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 140, Pages: 1377-1386, ISSN: 0035-9009
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- Citations: 8
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Journal articleShen C, Yang YY, Rong ZJ, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2458-2465, ISSN: 2169-9380
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- Citations: 36
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Journal articleFuselier SA, Frahm R, Lewis WS, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2563-2578, ISSN: 2169-9380
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- Citations: 55
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Journal articlePilkington NM, Achilleos N, Arridge CS, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2858-2875, ISSN: 2169-9380
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- Citations: 20
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Journal articleKriegel H, Simon S, Meier P, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2740-2774, ISSN: 2169-9380
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- Citations: 39
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Journal articleMeredith CJ, Alexeev II, Badman SV, et al., 2014, , Journal of Geophysical 91桃色: Space Physics, Vol: 119, Pages: 1994-2008, ISSN: 2169-9402
We examine a unique data set from seven Hubble Space Telescope (HST) “visits” that imagedSaturn’s northern dayside ultraviolet emissions exhibiting usual circumpolar “auroral oval” morphologies,during which Cassini measured the interplanetary magnetic field (IMF) upstream of Saturn’s bow shock overintervals of several hours. The auroras generally consist of a dawn arc extending toward noon centered near~15° colatitude, together with intermittent patchy forms at ~10° colatitude and poleward thereof, locatedbetween noon and dusk. The dawn arc is a persistent feature, but exhibits variations in position, width, andintensity, which have no clear relationship with the concurrent IMF. However, the patchy postnoon aurorasare found to relate to the (suitably lagged and averaged) IMF Bz, being present during all four visits withpositive Bz and absent during all three visits with negative Bz. The most continuous such forms occur in thecase of strongest positive Bz. These results suggest that the postnoon forms are associated with reconnectionand open flux production at Saturn’s magnetopause, related to the similarly interpreted bifurcated auroral arcstructures previously observed in this local time sector in Cassini Ultraviolet Imaging Spectrograph data,whose details remain unresolved in these HST images. One of the intervals with negative IMF Bz howeverexhibits a prenoon patch of very high latitude emission extending poleward of the dawn arc to the magnetic/spin pole, suggestive of the occurrence of lobe reconnection. Overall, these data provide evidence ofsignificant IMF dependence in the morphology of Saturn’s dayside auroras.
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Journal articleMasters A, Fujimoto M, Hasegawa H, et al., 2014, , GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 1862-1868, ISSN: 0094-8276
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- Citations: 23
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Journal articleCargill PJ, 2014, , ASTROPHYSICAL JOURNAL, Vol: 784, ISSN: 0004-637X
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- Citations: 73
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Journal articleJasinski JM, Arridge CS, Lamy L, et al., 2014, , Geophysical 91桃色 Letters, Vol: 41, Pages: 1382-1388, ISSN: 1944-8007
We report on the first analysis of magnetospheric cusp observations at Saturn by multiple insitu instruments onboard the Cassini spacecraft. Using this we infer the process of reconnection wasoccurring at Saturn’s magnetopause. This agrees with remote observations that showed the associatedauroral signatures of reconnection. Cassini crossed the northern cusp around noon local time along apoleward trajectory. The spacecraft observed ion energy-latitude dispersions—a characteristic signature ofthe terrestrial cusp. This ion dispersion is “stepped,” which shows that the reconnection is pulsed. The ionenergy-pitch angle dispersions suggest that the field-aligned distance from the cusp to the reconnectionsite varies between ∼27 and 51 RS. An intensification of lower frequencies of the Saturn kilometricradiation emissions suggests the prior arrival of a solar wind shock front, compressing the magnetosphereand providing more favorable conditions for magnetopause reconnection.
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Journal articleHartmann DL, Ceppi P, 2014, , Journal of Climate, Vol: 27, Pages: 2444-2456, ISSN: 0894-8755
The Clouds and the Earth’s Radiant Energy System (CERES) observations of global top-of-atmosphere radiative energy fluxes for the period March 2000–February 2013 are examined for robust trends and variability. The trend in Arctic ice is clearly evident in the time series of reflected shortwave radiation, which closely follows the record of ice extent. The data indicate that, for every 106 km2 decrease in September sea ice extent, annual-mean absorbed solar radiation averaged over 75°–90°N increases by 2.5 W m−2, or about 6 W m−2 between 2000 and 2012. CMIP5 models generally show a much smaller change in sea ice extent over the 1970–2012 period, but the relationship of sea ice extent to reflected shortwave is in good agreement with recent observations. Another robust trend during this period is an increase in reflected shortwave radiation in the zonal belt from 45° to 65°S. This trend is mostly related to increases in sea ice concentrations in the Southern Ocean and less directly related to cloudiness trends associated with the annular variability of the Southern Hemisphere. Models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) produce a scaling of cloud reflection to zonal wind increase that is similar to trend observations in regions separated from the direct effects of sea ice. Atmospheric Model Intercomparison Project (AMIP) model responses over the Southern Ocean are not consistent with each other or with the observed shortwave trends in regions removed from the direct effect of sea ice.
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Journal articleSouthwood DJ, Cowley SWH, 2014, , Journal of Geophysical 91桃色: Space Physics, Vol: 119, Pages: 1563-1571, ISSN: 2169-9380
The recent survey by Andrews et al. (2012) of the separate northern and southern ~10.7 h periodic magnetic signals in Saturn's magnetosphere limits very much their governing current systems. The existence of signals with pure or close to pure northern or southern periods in respective polar caps taken with the relatively narrow bandwidth of the signals indicates that the actual periodicities are imposed independently from northern and southern polar regions, i.e., the open field line regions. Field鈥恆ligned currents must flow on the boundaries of these regions to exclude signals from the other hemisphere. Equatorward of the polar cap, on closed magnetic shells, there are distinct north and south “cam” source currents, the distinction being made clear by a difference in polarization. We outline the consequences for the governing current systems and the implications for sustaining the energy and power dissipation in the system.
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Journal articleMistry R, Dougherty MK, Masters A, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 1514-1522, ISSN: 2169-9380
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- Citations: 5
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Journal articleLiu YD, Luhmann JG, Kajdic P, et al., 2014, , NATURE COMMUNICATIONS, Vol: 5, ISSN: 2041-1723
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- Citations: 251
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Journal articleSchwartz SJ, 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 1507-1512, ISSN: 2169-9380
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- Citations: 10
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Journal articleSchmidt GA, Kelley M, Nazarenko L, et al., 2014, , JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS, Vol: 6, Pages: 141-184
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- Citations: 539
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Journal articleSimon S, Neubauer FM, Wennmacher A, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2024-2037, ISSN: 2169-9380
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- Citations: 9
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Journal articleCui J, Yelle RV, Li T, et al., 2014, , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 490-518, ISSN: 2169-9380
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Book chapterMueller-Wodarg ICF, 2014,
Titan's upper atmosphere: thermal structure, dynamics, and energetics
, Titan: Interior, Surface, Atmosphere, and Space Environment, Editors: Müller-Wodarg, Griffith, Lellouch, Cravens, Publisher: Cambridge University Press, ISBN: 9780521199926Titan, the largest of Saturn's moons, shares remarkable similarities with Earth. Its thick atmosphere is composed primarily of nitrogen; it features the most complex organic chemistry known outside of Earth and, uniquely, hosts an analog to Earth's hydrological cycle, with methane forming clouds, rain and seas. Using the latest data from the ongoing Cassini–Huygens missions, laboratory measurements and numerical simulations, this comprehensive reference examines the physical processes that shape Titan's fascinating atmospheric structure and chemistry, weather, climate, circulation and surface geology. The text also surveys leading theories about Titan's origin and evolution, and assesses their implications for understanding the formation of other complex planetary bodies. Written by an international team of specialists, chapters offer detailed, comparative treatments of Titan's known properties and discuss the latest frontiers in the Cassini–Huygens mission, offering students and researchers of planetary science, geology, astronomy and space physics an insightful reference and guide.
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Journal articleWicks RT, Roberts DA, Mallet A, et al., 2014, , ASTROPHYSICAL JOURNAL, Vol: 782, ISSN: 0004-637X
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- Citations: 1
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Journal articleGryspeerdt E, Stier P, Partridge DG, 2014, , Atmospheric Chemistry and Physics, Vol: 14, Pages: 1141-1158, ISSN: 1680-7324
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Journal articleWeiss Z, Steers EBM, Pickering JC, et al., 2014, , SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY, Vol: 92, Pages: 70-83, ISSN: 0584-8547
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- Citations: 14
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Journal articleSouthwood D, 2014,
Saturn's mysterious magnetism
, ASTRONOMY & GEOPHYSICS, Vol: 55, Pages: 13-18, ISSN: 1366-8781
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