Geophysical Research Letters

Cover image for Geophysical Research Letters

28 April 2013

Volume 40, Issue 8

Pages 1457–1663

  1. Regular Articles

    1. Top of page
    2. Regular Articles
    1. Space Sciences

      You have full text access to this OnlineOpen article
      Could the collision of CMEs in the heliosphere be super‒elastic? Validation through three‒dimensional simulations (pages 1457–1461)

      Fang Shen, Chenglong Shen, Yuming Wang, Xueshang Feng and Changqing Xiang

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50336

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      Key Points

      • Collision of CMEs in the heliosphere could be super-elastic
      • Magnetic energy is the major source of kinetic energy gain
      • Extra gain of kinetic energy may influence space weather
    2. Secondary gigantic jets as possible inducers of sprites (pages 1462–1467)

      Li-Jou Lee, Rue-Ron Hsu, Han-Tzong Su, Sung-Ming Huang, Jung-Kung Chou, Cheng-Ling Kuo, Shu-Chun Chang, Yen-Jung Wu, Alfred B. Chen, Harald U. Frey, Yukihiro Takahashi and Lou-Chuang Lee

      Article first published online: 25 APR 2013 | DOI: 10.1002/grl.50300

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      Key Points

      • Three possible GJ-induced sprites observed by ISUAL are analyzed and reported
      • The high current moment GJs may be the key factor in the induction of sprites
      • The secondary GJ discharge seems to be more impulsive than the typical GJs
    3. Interstellar He+ ring-beam distributions: Observations and implications (pages 1468–1473)

      C. Drews, Lars Berger, Robert F. Wimmer-Schweingruber and Antoinette B. Galvin

      Article first published online: 28 APR 2013 | DOI: 10.1002/grl.50368

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      Key Points

      • Observation of the initial ring beam distribution of interstellar He+

      • Pitch-angle distribution of interstellar He+

      • In-situ observations of the pickup ion injection process

    4. Transition of Pi2 ULF wave polarization structure from the ionosphere to the ground (pages 1474–1478)

      P. V. Ponomarenko and C. L. Waters

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50271

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      Key Points

      • First observation of Pi2 polarisation transition from ionosphere to the ground

    5. First observations of minority ion (H+) structuring in stimulated radiation during second electron gyroharmonic heating experiments (pages 1479–1483)

      M. R. Bordikar, W. A. Scales, A. R. Samimi, P. A. Bernhardt, S. Brizcinski and M. J. McCarrick

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50327

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      Key Points

      • First observations of H+ ion structuring in SEE during heating experiment
      • Disturbed magnetic conditions imply proton precipitation likely plays a key role
      • Theory is provided to explain emissions by PDI in multi-ion plasma
    6. Planets

      Carbon dioxide ice clouds, snowfalls, and baroclinic waves in the northern winter polar atmosphere of Mars (pages 1484–1488)

      Takeshi Kuroda, Alexander S. Medvedev, Yasumasa Kasaba and Paul Hartogh

      Article first published online: 28 APR 2013 | DOI: 10.1002/grl.50326

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      Key Points

      • CO2 ice clouds in polar winter are closely aligned with planetary waves
      • CO2 ice cap is mostly formed by snowfalls from below 20 km
      • Close connection of clouds and waves can form a basis for snow storm forecasts
    7. An unidentified emission in Titan's upper atmosphere (pages 1489–1493)

      B. M. Dinelli, M. López-Puertas, A. Adriani, M. L. Moriconi, B. Funke, M. García-Comas and E. D'Aversa

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50332

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      Key Points

      • We observe an unknown emission in VIMS spectra of Titan's upper atmosphere
      • The feature is persistent, very strong, present at daytime and peaks at 950 km
      • Not caused by known Titan gases, aromatic hydrocarbons are likely carriers
    8. Solid Earth

      Eroding dynamic topography (pages 1494–1499)

      J. Braun, X. Robert and T. Simon-Labric

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50310

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      Key Points

      • A wave of dynamic topography erodes in proportion to its wavelength
      • Dynamic topography is strongly affected by fluvial erosion
      • Evidence for strong erosion of waves of dynamic topography
    9. Seismic anisotropy in eastern Africa, mantle flow, and the African superplume (pages 1500–1505)

      Brian Bagley and Andrew A. Nyblade

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50315

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      Key Points

      • The African superplume can explain all of the fast polarization directions
      • Results indicate a connection between the lower mantle and tectonic deformation
    10. Evidence for fluid-triggered slip in the 2009 Mount Rainier, Washington earthquake swarm (pages 1506–1512)

      David R. Shelly, Seth C. Moran and Weston A. Thelen

      Article first published online: 27 APR 2013 | DOI: 10.1002/grl.50354

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      Key Points

      • New methods allow high-resolution tracking of earthquake swarms
      • The results suggest the swarm was triggered by diffusing high-pressure fluids
      • Earthquake locations and focal mechanisms suggest fault mesh failure
    11. Variations in Mid-Continent Rift magma volumes consistent with microplate evolution (pages 1513–1516)

      Miguel Merino, G. Randy Keller, Seth Stein and Carol Stein

      Article first published online: 28 APR 2013 | DOI: 10.1002/grl.50295

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      Key Points

      • The west arm of the MCRS experienced more magmatism than the east arm.
      • Distribution of magma is consistent with flow from a hotspot.
      • Magma distribution in the MCRS is consistent with a microplate model.
    12. The synchronous occurrence of shallow tremor and very low frequency earthquakes offshore of the Nicoya Peninsula, Costa Rica (pages 1517–1522)

      Jacob I. Walter, Susan Y. Schwartz, Marino Protti and Victor Gonzalez

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50213

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      Key Points

      • First observation of very-low frequency earthquakes (VLFEs) outside of Japan
      • Synchronous evidence of offshore slow slip, tremor, and VLFEs
      • Offshore tremor and slow slip adjacent to 2012 Mw 7.6 megathrust earthquake
    13. An interpretation of tsunami earthquake based on a simple dynamic model: Failure of shallow megathrust earthquake (pages 1523–1527)

      Yuta Mitsui and Yuji Yagi

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50266

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      Key Points

      • Modeling of shallow megathrust and tsunami earthquakes by the same system

      • Sensitive dependence of stress conditions on earthquake characteristics

    14. You have full text access to this OnlineOpen article
      Thermal structure and megathrust seismogenic potential of the Makran subduction zone (pages 1528–1533)

      Gemma L. Smith, Lisa C. McNeill, Kelin Wang, Jiangheng He and Timothy J. Henstock

      Article first published online: 30 APR 2013 | DOI: 10.1002/grl.50374

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      Key Points

      • Thermal model of the Makran subduction zone to estimate seismogenic potential
      • Megathrust potentially seismogenic to shallow depths due to thick sediment cover
      • Wide potential seismogenic zone (>~350 km) with potential magnitudes of M>9
    15. Hydrology and Land Surface Studies

      Hot fire, cool soil (pages 1534–1539)

      Cathelijne R. Stoof, Demie Moore, Paulo M. Fernandes, Jetse J. Stoorvogel, Ricardo E. S. Fernandes, António J. D. Ferreira and Coen J. Ritsema

      Article first published online: 25 APR 2013 | DOI: 10.1002/grl.50299

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      Key Points

      • Effects of fuel and fire on soil temperatures are studied at watershed scale
      • Soil was cool under intense fire, and hot where fire was mild and fuel sparse
      • Changes the understanding of areas at risk for post-fire land degradation
    16. Hydrodynamic and geomorphic controls on mouth bar evolution (pages 1540–1545)

      Christopher R. Esposito, Ioannis Y. Georgiou and Alexander S. Kolker

      Article first published online: 26 APR 2013 | DOI: 10.1002/grl.50333

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      Key Points

      • We show field data showing seasonal sedimentation and transport on a mouth bar
      • Sedimentation in mouth bars occurs across the hydrographic cycle
      • Crevasse splay channels can transport sand long distances
    17. Cryosphere

      Contribution of Icelandic ice caps to sea level rise: Trends and variability since the Little Ice Age (pages 1546–1550)

      Helgi Björnsson, Finnur Pálsson, Sverrir Gudmundsson, Eyjólfur Magnússon, Gudfinna Adalgeirsdóttir, Tómas Jóhannesson, Etienne Berthier, Oddur Sigurdsson and Thorsteinn Thorsteinsson

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50278

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      Key Points

      • Icelandic ice caps both gained and lost mass since end of the 19th century

      • mass variability driven by climate and temporary volcanic events

      • mass balance variations relate to air temperature rather than precipitation

    18. Multi-system seasonal predictions of Arctic sea ice (pages 1551–1556)

      W. J. Merryfield, W.-S. Lee, W. Wang, M. Chen and A. Kumar

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50317

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      Key Points

      • Climate model-based seasonal sea ice prediction is only starting to be explored

      • Multi-model combination is known to improve forecasts e.g. of temperature

      • Multi-model combination is found to improve sea ice predictions as well

    19. Oceans

      An inverse relationship between production and export efficiency in the Southern Ocean (pages 1557–1561)

      Kanchan Maiti, Matthew A. Charette, Ken O. Buesseler and Mati Kahru

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50219

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      Key Points

      • reduced estimate of biological export in the Southern Ocean
      • Inverse relationship between primary production and export
      • Revised relation between production and export in Sothern Ocean
    20. The stability of an evolving Atlantic meridional overturning circulation (pages 1562–1568)

      Wei Liu, Zhengyu Liu and Aixue Hu

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50365

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      Key Points

      • A generalized stability indicator is developed for the slowly evolving AMOC
    21. How does Arctic summer wind modulate sea ice-ocean heat balance in the Canada Basin? (pages 1569–1574)

      Eiji Watanabe and Masayo Ogi

      Article first published online: 25 APR 2013 | DOI: 10.1002/grl.50363

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      Key Points

      • Wind-driven ice-ocean heat processes with upwelling/mixing events are addressed.
      • Interannual variability in ocean heat balance is quantitatively addressed.
      • Possible scenario on a record minimum extent of Arctic sea ice is proposed.
    22. Chromophoric dissolved organic matter export from U.S. rivers (pages 1575–1579)

      Robert G. M. Spencer, George R. Aiken, Mark M. Dornblaser, Kenna D. Butler, R. Max Holmes, Greg Fiske, Paul J. Mann and Aron Stubbins

      Article first published online: 26 APR 2013 | DOI: 10.1002/grl.50357

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      Key points

      • Multisite CDOM load and DOC load relationship
      • Development of CDOM yields shows important regions for future study
      • First estimate of CDOM flux from major U.S. Rivers
    23. Observations of enhanced nonlinear instability in the surface reflection of internal tides (pages 1580–1586)

      Xiaohui Xie, Xiaodong Shang, Hans van Haren and Guiying Chen

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50322

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      Key Points

      • Internal tides reflect from the sea-surface in the South China Sea
      • Internal tide subharmonic instability is rapidly enhanced in the reflection area
      • A mean flow is generated by nonlinear interaction between internal tides
    24. Interhemispheric asymmetry in transient global warming: The role of Drake Passage (pages 1587–1593)

      David K. Hutchinson, Matthew H. England, Agus Santoso and Andrew McC. Hogg

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50341

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      Key Points

      • The ACC causes part of the interhemispheric asymmetry in global warming
      • This asymmetry is greater in sea surface temperature than air temperature
      • The ACC enables a much greater sea ice extent in the Southern Ocean
    25. A new constraint on global air-sea CO2 fluxes using bottle carbon data (pages 1594–1599)

      Tristan P. Sasse, Ben I. McNeil and Gab Abramowitz

      Article first published online: 30 APR 2013 | DOI: 10.1002/grl.50342

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      Key Points

      • New data-based approach to diagnose monthly surface ocean p CO2 distributions
      • Independent constraint on global air-sea CO2 flux distribution and magnitude
      • Southern Hemisphere carbon uptake is five times the magnitude of the Northern Hemisphere
    26. Climate

      Climate models without preindustrial volcanic forcing underestimate historical ocean thermal expansion (pages 1600–1604)

      J.M. Gregory, D. Bi, M.A. Collier, M.R. Dix, A.C. Hirst, A. Hu, M. Huber, R. Knutti, S.J. Marsland, M. Meinshausen, H.A. Rashid, L.D. Rotstayn, A. Schurer and J.A. Church

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50339

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      Key Points

      • Volcanic forcing is often omitted from AOGCM control experiments
      • This causes a substantial underestimate of historical ocean thermal expansion
      • A method to correct the underestimate is described and verified
    27. Extratropical forcing of ENSO (pages 1605–1611)

      Ghyslaine Boschat, Pascal Terray and Sébastien Masson

      Article first published online: 26 APR 2013 | DOI: 10.1002/grl.50229

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      Key Points

      • definition of a new extratropical SST precursor for ENSO predictability
      • the new precursor offers an independent source of forcing for ENSO
      • accurate prediction of the amplitude of ENSO events during recent decades
    28. The 1970's shift in ENSO dynamics: A linear inverse model perspective (pages 1612–1617)

      Christopher M. Aiken, Agus Santoso, Shayne McGregor and Matthew H. England

      Article first published online: 26 APR 2013 | DOI: 10.1002/grl.50264

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      Key Points

      • Observed changes in the direction of SST propagation imply altered ENSO dynamics
      • ENSO amplitude/frequency changes are not discernible from natural variability
      • Linear Inverse Models capture the 1970s shift in ENSO character
    29. Iron speciation in aerosol dust influences iron bioavailability over glacial-interglacial timescales (pages 1618–1623)

      A. Spolaor, P. Vallelonga, G. Cozzi, J. Gabrieli, C. Varin, N. Kehrwald, P. Zennaro, C. Boutron and C. Barbante

      Article first published online: 26 APR 2013 | DOI: 10.1002/grl.50296

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      Key Points

      • The first work recording iron speciation in ice core in glacial-interglacial
      • Importance of iron species in the bioavailability of iron
      • It demonstrates that the addition of iron species results in CO2 drawdown
    30. Climate impacts of a large-scale biofuels expansion (pages 1624–1630)

      Willow Hallgren, C. Adam Schlosser, Erwan Monier, David Kicklighter, Andrei Sokolov and Jerry Melillo

      Article first published online: 28 APR 2013 | DOI: 10.1002/grl.50352

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      Key Points

      • Land-use changes from a global bioenergy program will impact the climate by 2050
      • Biofuels have a negligible impact on global climate but large regional impacts
      • The climate impact of biofuels is influenced by the land use policy framework
    31. Atmospheric Science

      Lower tropospheric ozone at northern midlatitudes: Changing seasonal cycle (pages 1631–1636)

      D. D. Parrish, K. S. Law, J. Staehelin, R. Derwent, O. R. Cooper, H. Tanimoto, A. Volz-Thomas, S. Gilge, H.-E. Scheel, M. Steinbacher and E. Chan

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50303

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      Key Points

      • The date of the maximum of tropospheric ozone has moved to earlier in the year
      • Change has been approximately constant at 3 to 6 days per decade since the 1970s
      • Cause of change may be due to changing climate and/or anthropogenic emissions
    32. Properties of unipolar magnetic field pulse trains generated by lightning discharges (pages 1637–1641)

      Ivana Kolmašová and Ondřej Santolík

      Article first published online: 23 APR 2013 | DOI: 10.1002/grl.50366

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      Key Points

      • Trains of pulses generated by lightning are measured using a new instrument
      • First systematic analysis of pulse amplitudes and inter-pulse intervals done
      • Proposed interpretation based on charge structures interacting with leaders
    33. The agricultural history of human-nitrogen interactions as recorded in ice core δ15N-NO3 (pages 1642–1646)

      J. David Felix and Emily M. Elliott

      Article first published online: 25 APR 2013 | DOI: 10.1002/grl.50209

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      Key Points

      • Agricultural advances had a profound impact on soil N cycling and NOx emissions
      • Ice core d15N is a powerful tool for inferring changes in NOx emission sources
      • Earthquake locations and focal mechanisms suggest fault mesh failure
    34. The impact of convective cold pool outflows on model biases in the Sahara (pages 1647–1652)

      L. Garcia-Carreras, J. H. Marsham, D. J. Parker, C. L. Bain, S. Milton, A. Saci, M. Salah-Ferroudj, B. Ouchene and R. Washington

      Article first published online: 26 APR 2013 | DOI: 10.1002/grl.50239

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      Key Points

      • First in-situ profiles from the central Sahara are used to evaluate model biases
      • Lack of cold pools outflows from convection is main cause of warm dry model bias
      • This error from convection has a regional impact, important in all global models
    35. Isomap nonlinear dimensionality reduction and bimodality of Asian monsoon convection (pages 1653–1658)

      A. Hannachi and A.G. Turner

      Article first published online: 29 APR 2013 | DOI: 10.1002/grl.50351

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      Key Points

      • Paper demonstrates bimodality in monsoon intraseasonal variability

      • Methodology combines both the nonlinearity and high dimensionality of monsoon

      • Suggests enhanced predictability of active/break monsoon phases variability

    36. Seasonal measurements of OH, NOx, and J(O1D) at Mace Head, Ireland (pages 1659–1663)

      H. Berresheim, J. McGrath, M. Adam, R.L. Mauldin III, B. Bohn and F. Rohrer

      Article first published online: 28 APR 2013 | DOI: 10.1002/grl.50345

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      Key Points

      • First long-term measurements of OH in mid-latitude marine air are presented
      • OH-J(O1D) correlations are determined for different NOx regimes
      • OH variance analysis is presented for a 2-year period

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