James H. Ruppert, Jr.

James H. Ruppert, Jr.

  • Assistant Research Professor
626 Walker Building
University Park, PA 16802
Email: james.ruppert@psu.edu


Google Scholar

I am an Assistant Research Professor in the Department of Meteorology and Atmospheric Science at Penn State University. I have always been fascinated by how clouds, moist convection, and radiation affect and interact with both weather systems and climate. My research draws heavily from theory, observations from the field, and cloud-resolving/permitting numerical models.


  • Postdoc: 2015–2018, Max Planck Institute for Meteorology, Hamburg, Germany, funded through NSF-AGS Postdoctoral Research Fellowship and Alexander von Humboldt Foundation Postdoctoral Fellowship
  • Ph.D., 2015, Atmospheric Science, Colorado State University
  • M.S., 2012, Atmospheric Science, Colorado State University
  • B.S. 2009, Atmospheric Science, University at Albany


  • Diurnal cycle and time-scale feedbacks.  I am greatly fascinated by how clouds and moist convection create links across scales, both in space and time. An excellent example of "time-scale feedback" is the effect that the 24-hr diurnal cycle has on the background weather and climate states in which it operates. During my PhD I studied this problem using data from an international field campaign in the context of the Madden–Julian oscillation. We then conducted controlled hypothesis testing using cloud-resolving numerical modeling, which helped us identify and understand the diurnal time-scale feedback.
  • Gravity waves and diurnal circulation changes.  Through interactions between clouds and radiation, the diurnal cycle drives pronounced mesoscale circulation changes in organized convective systems. This occurs because of how rapidly gravity waves propagate, which results in a rapid circulation adjustment into balance with changes in latent and diabatic heating. Our research suggests that this effect causes a diurnal cycle of the Hadley Cell and the ITCZ coupled with it.
  • The Maritime Continent.  An excellent example of where the diurnal cycle fundamentally affects climate is in the Maritime Continent - the island archipleago that includes Indonesia. I have recently examined how diurnal deep convection here excites long-lived gravity waves of a scale ~1500 km, which diurnally phase lock over multiple islands (Borneo and Sumatra), linking the diurnal burst of convection in one island with that of another on the next day. I am currently investigating mechanisms of climatological island rainfall enhancement in this region through such feedbacks.
  • Hurricanes and radiation feedback.  Both incoming solar radiation and outgoing infrared radiation strongly interact with hurricanes (including typhoons, cyclones). The interaction between clouds and solar radiation, in particular, causes dramatic diurnal circulation changes in the hurricane core that may affect the evolution of hurricanes and their outer rainbands. My research on this topic with Morgan O'Neill was recently featured in an Eos Research Spotlight. Our ongoing work is investigating how longwave–cloud radiation interaction, in particular, accelerates the intensification of tropical cyclones in nature.


In process

  • Ruppert, J. H., Jr., A. A. Wing, X. Tang, and E. L. Duran, 2019: The critical role of cloud–infrared radiation feedback in tropical cyclones, Science, in review.
  • Ruppert, J. H., Jr., X. Chen, and F. Zhang, 2019: Convectively forced diurnal gravity waves in the Maritime Continent, J. Atmos. Sci., in review.


  • Ruppert, J. H., Jr., and F. Zhang, 2019: Diurnal forcing and phase locking of gravity waves in the Maritime Continent, J. Atmos. Sci., doi:10.1175/JAS-D-19-0061.1.
  • Ruppert, J. H., Jr., and D. Klocke, 2019: The two diurnal modes of tropical upward motion, Geophysical Research Letters, doi:10.1029/2018GL081806.
  • Chen, X, F. Zhang, and J. H. Ruppert, Jr., 2019: Modulations of Coastal Rainfall Diurnal Cycle Over South China by the Boreal Summer Intraseasonal Oscillation, J. Climate, doi:10.1175/JCLI-D-18-0786.1.
  • Ruppert, J. H., Jr., and M. E O’Neill, 2019*: Diurnal cloud and circulation changes in tropical cyclones, Geophysical Research Letters, doi:10.1029/2018GL081302.

* Eos Research Spotlight: Underwood, E., 2019: A better understanding of tropical cyclones, Eos, 100. DOI: 10.1029/2019EO118381.


  • Ruppert, J. H., Jr., and C. Hohenegger, 2018: Diurnal circulation adjustment and organized deep convection, J. Climatedoi:10.1175/JCLI-D-17-0693.1.
  • Ciesielski, P. E., R. H. Johnson, W. H. Schubert, and J. H. Ruppert, Jr., 2018: Diurnal cycle of the ITCZ in DYNAMO, J. Climatedoi:10.1175/JCLI-D-17-0670.1.


  • Bony, S., B. Stevens, F. Ament, S. Bigorre, P. Chazette, S. Crewel, J. Delanoë, K. Emanuel, D. Farrell, C. Flamant, S. Gross, L. Hirsch, J. Karstensen, B. Mayer, L. Nuijens, J. H. Ruppert, Jr., I. Sandu, P. Siebesma, S. Speich, F. Szczap, J. Totems, R. Vogel, M. Wendisch, M. Wirth, 2017: EUREC4A: a field campaign to elucidate the couplings between clouds, convection and circulation, Surveys in Geophysics, doi:10.1007/s10712-017-9428-0.


  • Ruppert, J. H., Jr., 2016: Diurnal timescale feedbacks in the tropical cumulus regime. Journal of Advances in Modeling Earth Systems, doi:10.1002/2016MS000713.
  • Ruppert, J. H., Jr., and R. H. Johnson, 2016: On the cumulus diurnal cycle over the tropical warm pool. Journal of Advances in Modeling Earth Systems, doi:10.1002/2015MS000610.


  • Ruppert, J. H., Jr., and R. H. Johnson, 2015: Diurnally modulated cumulus moistening in the pre-onset stage of the Madden–Julian oscillation during DYNAMO, Journal of the Atmospheric Sciences, 72, 1622–1647. doi:10.1175/JAS-D-14-0218.1.
  • Johnson, R. H., P. E. Ciesielski, J. H. Ruppert, Jr., and M. Katsumata, 2015: Sounding-based thermodynamic budgets for DYNAMO, Journal of the Atmospheric Sciences, 72, 598–622. doi:10.1175/JAS-D-14-0202.1.


  • Ruppert, J. H., Jr., and L. F. Bosart, 2014: A case study of the interaction of a mesoscale gravity wave with a mesoscale convective system. Monthly Weather Review, 142, 1403–1429. doi:10.1175/MWR-D-13-00274.1.
  • Johnson, R. H., R. S. Schumacher, J. H. Ruppert, Jr., D. T. Lindsey, J. E. Ruthford, and L. Kriederman, 2014: The role of convective outflow in the Waldo Canyon Fire, Monthly Weather Review, 142, 3061–3080. doi:10.1175/MWR-D-13-00361.1.


  • Ruppert, J. H., Jr., R. H. Johnson, and A. K. Rowe, 2013: Diurnal circulations and rainfall in Taiwan during SoWMEX/TiMREX (2008). Monthly Weather Review, 141, 3851–3872. doi:10.1175/JAS-D-14-0218.1.