Precipitation Associated with Convergence Lines

Evan Weller School of Earth, Atmosphere and Environment, and Centre of Excellence for Climate System Science, Monash University, Clayton, Victoria, Australia

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Kay Shelton JBA Consulting, Skipton, United Kingdom

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Michael J. Reeder School of Earth, Atmosphere and Environment, Centre of Excellence for Climate System Science, Monash University, Clayton, Victoria, Australia

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Christian Jakob School of Earth, Atmosphere and Environment, Centre of Excellence for Climate System Science, Monash University, Clayton, Victoria, Australia

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Abstract

Precipitation is often organized along coherent lines of low-level convergence, which at longer time and space scales form well-known convergence zones over the world’s oceans. Here, an automated, objective method is used to identify instantaneous low-level convergence lines in reanalysis data and calculate their frequency for the period 1979–2013. Identified convergence lines are combined with precipitation observations to assess the extent to which precipitation around the globe is associated with convergence lines in the lower troposphere. It is shown that a large percentage of precipitation (between 65% and 90%) over the tropical oceans is associated with such convergence lines, with large regional variations of up to 30% throughout the year, especially in the eastern Pacific and Atlantic Oceans. Over land, the annual-mean proportion of precipitation associated with convergence lines ranges between 30% and 60%, and the lowest proportions (less than 15%) associated with convergence lines occur on the eastern flank of the subtropical highs. Overall, much greater precipitation is associated with long coherent lines (greater than 300 km in length) than with shorter fragmented lines (less than 300 km), and the majority of precipitation associated with shorter lines occurs over land. The proportion of precipitation not associated with any convergence line primarily occurs where both precipitation and frequency of convergence lines are low. The high temporal and spatial resolution of the climatology constructed also enables an examination of the diurnal cycle in the relationship between convergence lines and precipitation. Here an example is provided over the tropical Maritime Continent region.

© 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author e-mail: Evan Weller, evan.weller@monash.edu

Abstract

Precipitation is often organized along coherent lines of low-level convergence, which at longer time and space scales form well-known convergence zones over the world’s oceans. Here, an automated, objective method is used to identify instantaneous low-level convergence lines in reanalysis data and calculate their frequency for the period 1979–2013. Identified convergence lines are combined with precipitation observations to assess the extent to which precipitation around the globe is associated with convergence lines in the lower troposphere. It is shown that a large percentage of precipitation (between 65% and 90%) over the tropical oceans is associated with such convergence lines, with large regional variations of up to 30% throughout the year, especially in the eastern Pacific and Atlantic Oceans. Over land, the annual-mean proportion of precipitation associated with convergence lines ranges between 30% and 60%, and the lowest proportions (less than 15%) associated with convergence lines occur on the eastern flank of the subtropical highs. Overall, much greater precipitation is associated with long coherent lines (greater than 300 km in length) than with shorter fragmented lines (less than 300 km), and the majority of precipitation associated with shorter lines occurs over land. The proportion of precipitation not associated with any convergence line primarily occurs where both precipitation and frequency of convergence lines are low. The high temporal and spatial resolution of the climatology constructed also enables an examination of the diurnal cycle in the relationship between convergence lines and precipitation. Here an example is provided over the tropical Maritime Continent region.

© 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author e-mail: Evan Weller, evan.weller@monash.edu
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  • Bain, C. L., G. Magnusdottir, P. Smyth, and H. Stern, 2010: Diurnal cycle of the intertropical convergence zone in the east Pacific. J. Geophys. Res., 115, D23116, doi:10.1029/2010JD014835.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bain, C. L., J. De Paz, J. Kramer, G. Magnusdottir, P. Smyth, H. Stern, and C.-C. Wang, 2011: Detecting the ITCZ in instantaneous satellite data using spatiotemporal statistical modelling: ITCZ climatology in the east Pacific. J. Climate, 24, 216230, doi:10.1175/2010JCLI3716.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Berry, G., and M. J. Reeder, 2014: Objective identification of the intertropical convergence zone: Climatology and trends from the ERA-Interim. J. Climate, 27, 18941909, doi:10.1175/JCLI-D-13-00339.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Berry, G., C. Jakob, and M. J. Reeder, 2011a: Recent global trends in atmospheric fronts. Geophys. Res. Lett., 38, L21812, doi:10.1029/2011GL049481.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Berry, G., M. J. Reeder, and C. Jakob, 2011b: A global climatology of atmospheric fronts. Geophys. Res. Lett., 38, L04809, doi:10.1029/2010GL046451.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Birch, C. E., J. H. Marsham, D. J. Parker, and C. M. Taylor, 2014a: The scale dependence and structure of convergence fields preceding the initiation of deep convection. Geophys. Res. Lett., 41, 47694776, doi:10.1002/2014GL060493.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Birch, C. E., M. J. Reeder, and G. J. Berry, 2014b: Wave-cloud lines over the Arabian Sea. J. Geophys. Res. Atmos., 119, 44474457, doi:10.1002/2013JD021347.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Birch, C. E., M. Roberts, L. Garcia-Carreras, D. Ackerley, M. J. Reeder, A. Lock, and R. Schiemann, 2015: Sea breeze dynamics and convection initiation: The influence of convective parameterization in weather and climate model biases. J. Climate, 28, 80938108, doi:10.1175/JCLI-D-14-00850.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bony, S., G. Bellon, D. Klocke, S. Sherwood, S. Fermepin, and S. Denvil, 2013: Robust direct effect of carbon dioxide on tropical circulation and regional precipitation. Nat. Geosci., 6, 447451, doi:10.1038/ngeo1799.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bony, S., and Coauthors, 2015: Clouds, circulation and climate sensitivity. Nat. Geosci., 8, 261268, doi:10.1038/ngeo2398.

  • Catto, J. L., C. Jakob, G. Berry, and N. Nicholls, 2012: Relating global precipitation to atmospheric fronts. Geophys. Res. Lett., 39, L10805, doi:10.1029/2012GL051736.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Catto, J. L., C. Jakob, and N. Nicholls, 2013: A global evaluation of fronts and precipitation in the ACCESS model. Aust. Meteor. Oceanogr. J., 63, 191203.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Catto, J. L., C. Jakob, and N. Nicholls, 2015: Can the CMIP5 models represent winter frontal precipitation? Geophys. Res. Lett., 42, 85968604, doi:10.1002/2015GL066015.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chadwick, R., I. Boutle, and G. Martin, 2013: Spatial patterns of precipitation change in CMIP5: Why the rich do not get richer in the tropics. J. Climate, 26, 38033822, doi:10.1175/JCLI-D-12-00543.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Collins, M., and Coauthors, 2013: Long-term climate change: Projections, commitments and irreversibility. Climate Change 2013: The Physical Science Basis, T. F. Stocker et al., Eds., Cambridge University Press, 1029–1136.

  • Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553597, doi:10.1002/qj.828.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Flato, G., and Coauthors, 2013: Evaluation of climate models. Climate Change 2013: The Physical Science Basis, T. F. Stocker et al., Eds., Cambridge University Press, 741–866.

  • Goswami, B. N., V. Venugopal, D. Sengupta, M. S. Madhusoodanan, and P. K. Xavier, 2006: Increasing trend of extreme rain events over India in a warming environment. Science, 314, 14421445, doi:10.1126/science.1132027.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hastenrath, S., 1995: Climate Dynamics of the Tropics. Kluwer Academic, 488 pp.

  • Hendon, H. H., and K. Woodberry, 1993: The diurnal cycle of tropical convection. J. Geophys. Res., 98, 16 62316 637, doi:10.1029/93JD00525.

  • IPCC, 2007: Climate Change 2007: The Physical Science Basis. Cambridge University Press, 996 pp.

  • Jakob, C., 2010: Accelerating progress in global atmospheric model development through improved parameterizations: Challenges, opportunities, and strategies. Bull. Amer. Meteor. Soc., 91, 869875, doi:10.1175/2009BAMS2898.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jakob, C., 2014: Going back to basics. Nat. Climate Change, 4, 10421045, doi:10.1038/nclimate2445.

  • Joyce, R. J., and P. Xie, 2011: Kalman filter-based CMORPH. J. Hydrometeor., 12, 15471563, doi:10.1175/JHM-D-11-022.1.

  • Joyce, R. J., J. E. Janowiak, P. A. Arkin, and P. Xie, 2004: CMORPH: A method that produces global precipitation estimates from passive microwave and infrared data at high spatial and temporal resolution. J. Hydrometeor., 5, 487503, doi:10.1175/1525-7541(2004)005<0487:CAMTPG>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lambert, F. H., and M. J. Webb, 2008: Dependency of global mean precipitation on surface temperature. Geophys. Res. Lett., 35, L16706, doi:10.1029/2008GL034838.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lindzen, R. S., and S. Nigam, 1987: On the role of sea surface temperature gradients in forcing low-level winds and convergence in the tropics. J. Atmos. Sci., 44, 24182436, doi:10.1175/1520-0469(1987)044<2418:OTROSS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Liu, W. T., and X. Xie, 2002: Double intertropical convergence zones—A new look using scatterometer. Geophys. Res. Lett., 29, 2072, doi:10.1029/2002GL015431.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meenu, S., K. Rajeev, K. Parameswaran, and C. Suresh Raju, 2007: Characteristics of the double intertropical convergence zone over the tropical Indian Ocean. J. Geophys. Res., 112, D11106, doi:10.1029/2006JD007950.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nicholson, S. E., 2000: The nature of rainfall variability over Africa on time scales of decades to millennia. Global Planet. Change, 26, 137158, doi:10.1016/S0921-8181(00)00040-0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Preethi, B., T. P. Sabin, J. A. Adedoyin, and K. Ashok, 2015: Impacts of the ENSO Modoki and other tropical Indo-Pacific climate-drivers on African rainfall. Sci. Rep., 5, 16653, doi:10.1038/srep16653.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reeder, M. J., and R. K. Smith, 1998: Mesoscale meteorology. Meteorology of the Southern Hemisphere, D. Vincent and D. J. Karoly, Eds., Amer. Meteor. Soc., 201–241.

    • Crossref
    • Export Citation
  • Reeder, M. J., R. K. Smith, D. J. Low, J. Taylor, S. J. Arnup, L. C. Muir, and G. Thomsen, 2013: Diurnally forced convergence lines in the Australian tropics. Quart. J. Roy. Meteor. Soc., 139, 12831297, doi:10.1002/qj.2021.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rowell, D., 2012: Sources of uncertainty in future changes in local precipitation. Climate Dyn., 39, 19291950, doi:10.1007/s00382-011-1210-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rybka, H., and H. Tost, 2014: Uncertainties in future climate predictions due to convection parameterisations. Atmos. Chem. Phys., 14, 55615576, doi:10.5194/acp-14-5561-2014.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stephens, G. L., 2005: Cloud feedbacks in the climate system: A critical review. J. Climate, 18, 237273, doi:10.1175/JCLI-3243.1.

  • Stephens, G. L., and Coauthors, 2010: Dreary state of precipitation in global models. J. Geophys. Res., 115, D24211, doi:10.1029/2010JD014532.

    • Search Google Scholar
    • Export Citation
  • Stevens, B., and S. Bony, 2013: What are climate models missing? Science, 340, 10531054, doi:10.1126/science.1237554.

  • Waliser, D. E., and C. Gautier, 1993: A satellite-derived climatology of the ITCZ. J. Climate, 6, 21622174, doi:10.1175/1520-0442(1993)006<2162:ASDCOT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Widlansky, M. J., P. J. Webster, and C. D. Hoyos, 2011: On the location and orientation of the South Pacific convergence zone. Climate Dyn., 36, 561578, doi:10.1007/s00382-010-0871-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Widlansky, M. J., A. Timmermann, K. Stein, S. McGregor, N. Schneider, M. H. England, M. Lengaigne, and W. Cai, 2013: Changes in South Pacific rainfall bands in a warming climate. Nat. Climate Change, 3, 417423, doi:10.1038/nclimate1726.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wills, R. C., M. P. Byrne, and T. Schneider, 2016: Thermodynamic and dynamic controls on changes in the zonally anomalous hydrological cycle. Geophys. Res. Lett., 43, 46404649, doi:10.1002/2016GL068418.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wodzicki, K. R., and A. D. Rapp, 2016: Long-term characterization of the Pacific ITCZ using TRMM, GPCP, and ERA-Interim. J. Geophys. Res. Atmos., 121, 31533170, doi:10.1002/2015JD024458.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yang, G. Y., and J. Slingo, 2001: The diurnal cycle in the tropics. Mon. Wea. Rev., 129, 784801, doi:10.1175/1520-0493(2001)129<0784:TDCITT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, C., 2001: Double ITCZs. J. Geophys. Res., 106, 11 78511 792, doi:10.1029/2001JD900046.

  • Zhang, X., W. Lin, and M. Zhang, 2007: Toward understanding the double intertropical convergence zone pathology in coupled ocean–atmosphere general circulation models. J. Geophys. Res., 112, D12102, doi:10.1029/2006JD007878.

    • Crossref
    • Search Google Scholar
    • Export Citation
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