Geophysical Research Letters

Cover image for Vol. 40 Issue 9

16 May 2013

Volume 40, Issue 9

Pages 1665–1893

  1. Regular Articles

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

      Recent Voyager 1 data indicate that on 25 August 2012 at a distance of 121.7 AU from the Sun, sudden and unprecedented intensity changes were observed in anomalous and galactic cosmic rays (pages 1665–1668)

      W. R. Webber and F. B. McDonald

      Article first published online: 12 MAY 2013 | DOI: 10.1002/grl.50383

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      Key Points

      • Boundary of heliosphere is very sudden
      • Local galactic cosmic ray spectra have peak at 60 MeV
      • Particle layers observed near heliospheric boundary
    2. Radio-induced incoherent scatter ion line enhancements with wide altitude extents in the high-latitude ionosphere (pages 1669–1674)

      A. Senior, M. T. Rietveld, I. Häggström and M. J. Kosch

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50272

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      Key Points

      • Large topside density increases seen during ionospheric heating experiments
      • Plasma line, radar scanning and tristatic observations contradict this
      • The density enhancements are a manifestation of some currently unknown effect
    3. Climate

      Tropical coral reef habitat in a geoengineered, high-CO2 world (pages 1799–1805)

      E. Couce, P. J. Irvine, L. J. Gregoire, A. Ridgwell and E. J. Hendy

      Article first published online: 10 MAY 2013 | DOI: 10.1002/grl.50340

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      Key Points

      • Large reductions in reef habitat suitability under net radiative >3 W/m2
      • Rising SSTs are greater threat for tropical coral reefs than ocean acidification
      • Solar Radiation Management may help maintain coral reef habitat over near-term
    4. Space Sciences

      Ionospheric response to earthquakes of different magnitudes: Larger quakes perturb the ionosphere stronger and longer (pages 1675–1681)

      E. Astafyeva, S. Shalimov, E. Olshanskaya and P. Lognonné

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50398

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      Key Points

      • larger earthquakes generate ionospheric perturbations of larger amplitude
      • CIDs caused by M>8.0 quakes represent N-waves with ~20-40 min negative phase
    5. Planets

      Dependence of O+ escape rate from the Venusian upper atmosphere on IMF directions (pages 1682–1685)

      K. Masunaga, Y. Futaana, G. Stenberg, S. Barabash, T. L. Zhang, A. Fedorov, S. Okano and N. Terada

      Article first published online: 11 MAY 2013 | DOI: 10.1002/grl.50392

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      Key Points

      • The Venusian O+ escape rate does not depend on the upstream IMF direction
      • Spatial distributions of escaping O+ ions from Venus depend on the IMF direction
      • Different acceleration mechanisms must balance each other for different IMF
    6. Electric potentials in magnetic dipole fields normal and oblique to a surface in plasma: Understanding the solar wind interaction with lunar magnetic anomalies (pages 1686–1690)

      X. Wang, C. T. Howes, M. Horányi and S. Robertson

      Article first published online: 14 MAY 2013 | DOI: 10.1002/grl.50367

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      Key Points

      • Laboratory studies of solar wind interaction with lunar magnetic anomalies
      • Studied the plasma sheath formation and surface charging in magnetic cusp
      • Identified kinetic features across the dipole field region
    7. Solid Earth

      Global propagation of body waves revealed by cross-correlation analysis of seismic hum (pages 1691–1696)

      K. Nishida

      Article first published online: 14 MAY 2013 | DOI: 10.1002/grl.50269

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      Key Points

      • We succeed in extracting global body-wave propagation using seismic hum.
      • SPL waves in the observation are more dominant than those in Green's functions.
      • The dominance originates from their shear-traction sources on the seafloor.
    8. B-type olivine fabric and mantle wedge serpentinization beneath the Ryukyu arc (pages 1697–1702)

      Kimberly McCormack, Erin A. Wirth and Maureen D. Long

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50369

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      Key Points

      • Compute P-to-S receiver functions for eight stations in the Ryukyu arc
      • Thin layer of serpentinized mantle directly above the subducting slab
      • Evidence for B-type olivine fabric in the shallow mantle wedge
    9. Seismic gap beneath Logachev Seamount: Indicator for melt focusing at an ultraslow mid-ocean ridge? (pages 1703–1707)

      Vera Schlindwein, Andrea Demuth, Wolfram H. Geissler and Wilfried Jokat

      Article first published online: 13 MAY 2013 | DOI: 10.1002/grl.50329

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      Key Points

      • Earthquakes beneath the ultraslow Knipovich ridge are deeper than expected
      • Maximum hypocenter depths raise significantly beneath Logachev volcano
      • Earthquakes point to undulating lithosphere base that guides melt to volcanoes
    10. Small-scale heterogeneities in the oceanic lithosphere inferred from guided waves (pages 1708–1712)

      Azusa Shito, Daisuke Suetsugu, Takashi Furumura, Hiroko Sugioka and Aki Ito

      Article first published online: 13 MAY 2013 | DOI: 10.1002/grl.50330

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      Key Points

      • Propagation of guided waves in the oceanic lithosphere is numerically simulated
      • Guided waves propagate as multiple forward scattering due to heterogeneities
      • The random heterogeneities in the oceanic lithosphere are laterally elongated
    11. High-resolution seismic imaging in the Japan Trench axis area off Miyagi, northeastern Japan (pages 1713–1718)

      Yasuyuki Nakamura, Shuichi Kodaira, Seiichi Miura, Christine Regalla and Narumi Takahashi

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50364

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      Key Points

      • Detailed structure in the Japan Trench axis is imaged with seismic data
      • Décollement and imbricate structure of sediments are clearly observed
      • Possible scenario for the sequence of deformation in the trench is presented
    12. Sharp hemisphere boundaries in a translating inner core (pages 1719–1723)

      Z. M. Geballe, M. Lasbleis, V. F. Cormier and E. A. Day

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50372

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      Key Points

      • Sharp hemisphere boundaries in upper inner core are compatible with translation
      • Certain model parameters reproduce seismic trends in isotropic Vp and Qp
      • To match the 1.5% variation in Vp requires a highly anisotropic elasticity model
    13. Hydrology and Land Surface Studies

      Employing lidar to detail vegetation canopy architecture for prediction of aeolian transport (pages 1724–1728)

      Joel B. Sankey, Darin J. Law, David D. Breshears, Seth M. Munson and Robert H. Webb

      Article first published online: 11 MAY 2013 | DOI: 10.1002/grl.50356

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      Key Points

      • Aeolian processes in the bio and geosphere are driven by horizontal dust flux
      • Predicting dust flux depends on detailed vegetation architecture measurements
      • Accurate and rapid lidar measurements of vegetation enable dust flux estimation
    14. You have full text access to this OnlineOpen article
      Intensification of the Amazon hydrological cycle over the last two decades (pages 1729–1733)

      M. Gloor, R. J. W. Brienen, D. Galbraith, T. R. Feldpausch, J. Schöngart, J.-L. Guyot, J. C. Espinoza, J. Lloyd and O. L. Phillips

      Article first published online: 14 MAY 2013 | DOI: 10.1002/grl.50377

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      Key Points

      • Intensification of Amazon Hydrological Cycle since 1990
      • Revealed by both river discharge and precipitation records
      • In parallel onset of tropical Atlantic warming offering explanation
    15. Thermal enhancement of gas transfer velocity of CO2 in an Amazon floodplain lake revealed by eddy covariance measurements (pages 1734–1740)

      Pierre Polsenaere, Jonathan Deborde, Guillaume Detandt, Luciana O. Vidal, Marcela A. P. Pérez, Vincent Marieu and Gwenaël Abril

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50291

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      Key Points

      • First eddy covariance measurements
      • Gas exchange is enhanced
      • CO2 outgassing from floodplain lakes is larger
    16. Revisiting the hysteresis effect in surface energy budgets (pages 1741–1747)

      Ting Sun, Zhi-Hua Wang and Guang-Heng Ni

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50385

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      Key Points

      • We physically characterize the hysteresis effect between Rn and G0
      • Wave phase evolution dictates the pattern of hysteresis loops
      • Model predictions are consistent with field measurements and empirical models
    17. Cryosphere

      Environmental controls of frost cracking revealed through in situ acoustic emission measurements in steep bedrock (pages 1748–1753)

      Lucas Girard, Stephan Gruber, Samuel Weber and Jan Beutel

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50384

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      Key Points

      • Rock liquid water content has an important impact on the freezing-induced damage
      • Sustained freezing can yield stronger damage than repeated freeze-thaw cycling
      • Frost cracking occurs on a wide range of temperatures extending from 0 to -15C
    18. Oceans

      You have full text access to this OnlineOpen article
      Distinctive climate signals in reanalysis of global ocean heat content (pages 1754–1759)

      Magdalena A. Balmaseda, Kevin E. Trenberth and Erland Källén

      Article first published online: 10 MAY 2013 | DOI: 10.1002/grl.50382

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      Key Points

      • Absence of recent global warming hiatus when depths below 700m are considered
      • Deep ocean heat uptake is linked to wind variability
      • Total ocean heat content affected by ENSO and volcanic eruptions
    19. Radiation of inertial kinetic energy as near-inertial waves forced by tropical Pacific Easterly waves (pages 1760–1765)

      S. M. Soares and K. J. Richards

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50387

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      Key Points

      • Easterly wave forcing and high stratification produce strong NIW radiation
      • 50-60% of the wind inertial kinetic energy input is radiated away as NIWs
      • The NIW energy flux increases linearly with the wind work
    20. You have full text access to this OnlineOpen article
      Equatorial upwelling enhances nitrogen fixation in the Atlantic Ocean (pages 1766–1771)

      Ajit Subramaniam, Claire Mahaffey, William Johns and Natalie Mahowald

      Article first published online: 10 MAY 2013 | DOI: 10.1002/grl.50250

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      Key Points

      • Nitrogen fixation rates are higher during upwelling than non-upwelling times
      • Diazotrophy is fueled by low N:P, iron rich water that is upwelled
      • Annually, 47 Gmol of new nitrogen is fixed in upwelled waters
    21. You have full text access to this OnlineOpen article
      Prevalence of strong bottom currents in the greater Agulhas system (pages 1772–1776)

      Meghan F. Cronin, Tomoki Tozuka, Arne Biastoch, Jonathan V. Durgadoo and Lisa M. Beal

      Article first published online: 10 MAY 2013 | DOI: 10.1002/grl.50400

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      Key Points

      • Strong bottom currents are prevalent beneath surface currents in the greater Agulhas system
      • Surface currents can affect formation of contourites
      • Noncohesive sediment is lifted more easily by dust storms than by benthic storms
    22. A summer monsoon pump to keep the Bay of Bengal salty (pages 1777–1782)

      P. N. Vinayachandran, D. Shankar, Siddharth Vernekar, K. K. Sandeep, P. Amol, C. P. Neema and Abhisek Chatterjee

      Article first published online: 14 MAY 2013 | DOI: 10.1002/grl.50274

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      Key Points

      • We report the discovery of a monsoonal salt pump into the Bay of Bengal.
      • The salt-pump is located to east of Sri Lanka, along with the monsoon current.
      • The salt pump prevents continuous freshening of the bay.
    23. Climate

      More hurricanes to hit western Europe due to global warming (pages 1783–1788)

      Reindert J. Haarsma, Wilco Hazeleger, Camiel Severijns, Hylke de Vries, Andreas Sterl, Richard Bintanja, Geert Jan van Oldenborgh and Henk W. van den Brink

      Article first published online: 11 MAY 2013 | DOI: 10.1002/grl.50360

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      Key Points

      • Hurricanes will hit Europe in future climate
      • Storm season will shift from winter to early autumn
      • New results from very high resolution global climate model
    24. Could a future “Grand Solar Minimum” like the Maunder Minimum stop global warming? (pages 1789–1793)

      Gerald A. Meehl, Julie M. Arblaster and Daniel R. Marsh

      Article first published online: 13 MAY 2013 | DOI: 10.1002/grl.50361

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      Key Points

      • a future grand solar minimum slightly reduces global warming
      • when the solar minimum ends, warming returns to reference levels
      • a grand solar minimum will not stop global warming
    25. Multiyear climate predictions using two initialization strategies (pages 1794–1798)

      W. Hazeleger, V. Guemas, B. Wouters, S. Corti, I. Andreu‒Burillo, F. J. Doblas‒Reyes, K. Wyser and M. Caian

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50355

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      Key Points

      • Multiyear climate variability is predictable
      • Different initialization strategies give similar results
      • There is scope for probabilistic predictability in Europe
    26. Intermediate water ventilation in the Nordic seas during MIS 2 (pages 1805–1810)

      Kari-Lise Rørvik, Tine L. Rasmussen, Morten Hald and Katrine Husum

      Article first published online: 11 MAY 2013 | DOI: 10.1002/grl.50325

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      Key Points

      • MIS2 oceanographic changes the in the Nordic seas
      • Reduced ventilation of intermediate water
      • Meltwater flow and surface water cooling
    27. Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains, U.S. (pages 1811–1816)

      Gregory T. Pederson, Julio L. Betancourt and Gregory J. McCabe

      Article first published online: 12 MAY 2013 | DOI: 10.1002/grl.50424

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      Key Points

      • Post-1980s west-wide snowpack declines are driven by spring (Feb-Mar) warming
      • Low to middle elevation spring snow cover declined by 20%
      • Recent declines reflect a positive reinforcement of anthropogenic warming
    28. Consistent large-scale temperature responses in warm and cold climates (pages 1817–1823)

      Kenji Izumi, Patrick J. Bartlein and Sandy P. Harrison

      Article first published online: 13 MAY 2013 | DOI: 10.1002/grl.50350

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      Key Points

      • CMIP5/PMIP3 simulations show land/ocean, latitudinal and seasonal contrasts
      • CMIP5/PMIP3 simulations are also consistent with modern and paleo observations
      • Magnitudes of responses are proportional, nearly linear across climate states
    29. Sensitivity of summer precipitation to tropical sea surface temperatures over East Asia in the GRIMs GMP (pages 1824–1831)

      Eun-Chul Chang, Sang-Wook Yeh, Song-You Hong and Renguang Wu

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50389

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      Key Points

      • A sensitivity of tropical Ocean SST on the precipitation over East Asia
      • A role of tropics on the East Asia precipitation
      • Explanation of recent weakening of the East Asia monsoon
    30. Global modes of climate variability (pages 1832–1837)

      O. de Viron, J. O. Dickey and M. Ghil

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50386

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      Key Points

      • Most of the climate indices are cross-correlated significantly
      • Most of their variability can be captured with only four principal components
      • Those components are associated with global signatures in the SST
    31. Atmospheric Science

      Vertical structure of warming consistent with an upward shift in the middle and upper troposphere (pages 1838–1842)

      Paul A. O'Gorman and Martin S. Singh

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50328

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      Key Points

      • Upward shift with warming in middle and upper troposphere
      • Model scatter in vertical structure of warming accounted for by upward shift
      • Observed temperature trends from radiosondes also consistent with upward shift
    32. The role of moist convection in the West African monsoon system: Insights from continental-scale convection-permitting simulations (pages 1843–1849)

      John H. Marsham, Nick S. Dixon, Luis Garcia-Carreras, Grenville M. S. Lister, Douglas J. Parker, Peter Knippertz and Cathryn E. Birch

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50347

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      Key Points

      • Simulations of West African Monsoon with explicit and parameterized convection
      • More realistic explicit convection weakens monsoon and delays diurnal cycle
      • Cold storm outflows are a significant component of the monsoon in explicit runs
    33. Detecting overlapping gravity waves using the S-Transform (pages 1850–1855)

      C. J. Wright and J. C. Gille

      Article first published online: 9 MAY 2013 | DOI: 10.1002/grl.50378

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      Key Points

      • Including secondary waves increases measured MF by 68%
      • The geographic distribution is altered
      • This is most important in convective regions
    34. Variations of OH radical in an urban plume inferred from NO2 column measurements (pages 1856–1860)

      L. C. Valin, A. R. Russell and R. C. Cohen

      Article first published online: 10 MAY 2013 | DOI: 10.1002/grl.50267

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      Key Points

      • The lifetime of NOx depends on the wind speed
      • NO2 spatial patterns depend on wind speed
      • Inferring the NOx lifetime from space requires spatially-detailed measurements
    35. Secondary planetary waves in the middle and upper atmosphere following the stratospheric sudden warming event of January 2012 (pages 1861–1867)

      A. Chandran, R. R. Garcia, R. L. Collins and L. C. Chang

      Article first published online: 12 MAY 2013 | DOI: 10.1002/grl.50373

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      Key Points

      • 2012 SSW is a minor SSW with an elevated stratopause
      • SSWs lead to wind reversals and reversal of potential vorticity gradient
      • PV gradient reversal leads to instability driven secondary PWs in MLT
    36. You have full text access to this OnlineOpen article
      Are vegetation-related roughness changes the cause of the recent decrease in dust emission from the Sahel? (pages 1868–1872)

      Sophie M. Cowie, Peter Knippertz and John H. Marsham

      Article first published online: 13 MAY 2013 | DOI: 10.1002/grl.50273

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      Key Points

      • Decadal Sahel dust trends analyzed with surface observations and new diagnostics
      • Wind-speed changes dominate over soil changes in recent dust emission decrease
      • Vegetation-induced roughness changes are the main control on wind-speed trends
    37. Impacts of introducing a convective gravity-wave parameterization upon the QBO in the Met Office Unified Model (pages 1873–1877)

      Y.-H. Kim, A. C. Bushell, D. R. Jackson and H.-Y. Chun

      Article first published online: 14 MAY 2013 | DOI: 10.1002/grl.50353

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      Key Points

      • Introducing a convective GW parameterization increases variations in the QBO
      • Introducing the parameterization strengthens the annual cycle of tropical wind
      • Introducing the parameterization allows for seasonal modulation of the SAO
    38. ATMOSPHERIC SCIENCE

      You have full text access to this OnlineOpen article
      An ocean coupling potential intensity index for tropical cyclones (pages 1878–1882)

      I.-I. Lin, P. Black, J. F. Price, C.-Y. Yang, S. S. Chen, C.-C. Lien, P. Harr, N.-H. Chi, C.-C. Wu and E. A. D'Asaro

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50091

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      Key Points

      • Current potential intensity index considers only ocean's surface contribution
      • Inclusion of ocean's subsurface information to improve estimation
      • Based on a valuable in situ data set from the ITOP field campaign
    39. Atmospheric Science

      The application of decision tree to intensity change classification of tropical cyclones in western North Pacific (pages 1883–1887)

      Wei Zhang, Si Gao, Bin Chen and Kai Cao

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50280

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      Key Points

      • The C4.5 algorithm is applied to classify 24-h typhoon intensity change
      • A decision tree with three variables and five leaf nodes is built
      • The decision tree shows high classification accuracy
    40. The response of atmospheric nitrous oxide to climate variations during the last glacial period (pages 1888–1893)

      Adrian Schilt, Matthias Baumgartner, Olivier Eicher, Jérôme Chappellaz, Jakob Schwander, Hubertus Fischer and Thomas F. Stocker

      Article first published online: 15 MAY 2013 | DOI: 10.1002/grl.50380

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      Key Points

      • High-resolution record of atmospheric N2O from 11 to 120 kyr BP
      • Substantial N2O response to the last glacial-interglacial transition (T1)
      • DO and Heinrich event cycles visible in the atmospheric N2O concentration

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