Dr. Nat Johnson's Homepage

Nat Johnson's  Homepage

Nat Johnson

Postdoctoral Fellow at the International Pacific Research Center (IPRC)
Visiting Scholar at the Scripps Institution of Oceanography

Ph.D. in Meteorology, The Pennsylvania State University, 2009
B.A. in Environmental Sciences and Policy, Duke University, 2001

Work Address:

International Pacific Research Center (IPRC)
Pacific Ocean Science and Technology Bldg., Room 401
1680 East-West Road, University of Hawaii
Honolulu, Hawaii 96822 USA

email: natj at hawaii.edu
Tel: 808-956-5019
Fax: 808-956-9425

  • Research  interests
    • Dynamics of Climate Variability and Change
    Low-frequency variability and teleconnections,
    interactions among sea surface variability, tropical convection, and large-scale circulation, extreme weather

    Extended-Range Predictability and Forecasting
    Influence of the Madden-Julian Oscillation (MJO) and El Nino/Southern Oscillation (ENSO),
    connections to tropical convection and storm track variability

    Applications of novel statistical tools for data analysis in the atmospheric and oceanic sciences
    Neural Networks, cluster analysis, dynamic programming, Bayesian methods


  • PUBLICATIONS

    • Singh, D., D. E. Horton, M. Tsiang, M. Haugen, M. Ashfaq, R. Mei, D. Rastogi, N. C. Johnson, A. Charland, B. Rajaratnam, and N. S. Diffenbaugh, 2014: Severe precipitation in northern India in June 2013: Causes, historical context, and changes in probability. Bull. Amer. Meteor. Soc., submitted. [Main Text] [Supplementary]

    Chang, C.-H., N. C. Johnson, and N. Cassar, 2014: Neural network-based estimates of Southern Ocean net community production from in-situ O2/Ar and satellite observation: A methodological study. Biogeosciences, 11, 3279-3297. [PDF]

    Maloney, E. S., J. Camargo, E. Chang, B. Colle, R. Fu, K. Geil, Q. Hu, X. Jiang, N. C. Johnson, K. Karnauskas, J. Kinter, B. Kirtman, S. Kumar, B. Langenbrunner, K. Lombardo, L. Long, A. Mariotti, J. Meyerson, K. Mo, D. Neelin, Z. Pan, R. Seager, Y. Serra, A. Seth, J. Sheffield, J. Stroeve, J. Thibeault, S.-P. Xie, C. Wang, B. Wyman, and M. Zhou, 2014: North American climate in CMIP5 Experiments: Part III: Assessment of 21st century projections. J. Climate, 27, 2230-2270. [PDF]

    Johnson, N. C., 2014: A boost in big El Nino. Nature Climate Change, 4, 90-91. [abstract]

    Johnson, N. C., Dan C. Collins, S. B. Feldstein, M. L. L'Heureux, and E. E. Riddle, 2014: Skillful wintertime North American temperature forecasts out to four weeks based on the state of ENSO and the MJO. Wea. Forecasting, 29, 23-38. [PDF]

    Ito, H., N. C. Johnson, and S.-P. Xie, 2013: Subseasonal and interannual temperature variability in relation to extreme temperature occurrence over East Asia. J. Climate, 26, 9026-9042. [PDF]

    Li, J., S.-P. Xie, E. R. Cook, M. S. Morales, D. A. Christie, Johnson, N. C., F. Chen, R. D'Arrigo, A. M. Fowler, X. Gou, and K. Fang, 2013: El Nino modulations during the past seven centuries. Nature Climate Change, 3, 822-826, doi:10.1038/nclimate1936. [abstract]

    Sheffield, J., S. J. Camargo, R. Fu, Z. Hu, X. Jiang, N. C. Johnson, K. B. Karnauskas, J. Kinter, S. Kumar, B. Langenbrunner, E. Maloney, A. Mariotti, J. E. Meyerson, D. Neelin, Z. Pan, A. Ruiz-Barradas, R. Seager, Y. Serra, D.-Z. Sun, C. Wang, S.-P. Xie, J.-Y. Yu, T. Zhang, and M. Zhao, 2013: North American climate in CMIP5 experiments. Part II: Evaluation of 20th century intra-seasonal to decadal variability. J. Climate, in press. [PDF]

    Johnson, N. C., 2013: How many ENSO flavors can we distinguish?. J. Climate, 26, 4816-4827. [PDF]

    Riddle, E. E., M. B. Stoner, N. C. Johnson, M. L. L'Heureux, D. C. Collins, and S. B. Feldstein, 2013: The impact of the MJO on clusters of wintertime circulation anomalies over the North American region. Climate Dyn., 40, 1749-1766. [PDF]

    Chowdary, J. S., S.-P. Xie, H. Tokinaga, Y. M. Okumura, H. Kubota, N. C. Johnson, and X.-T. Zheng, 2012: Inter-decadal variations in ENSO teleconnection to the Indo-western Pacific for 1870-2007. J. Climate, 25, 1722-1744. [PDF]

    Lee, S., T. Gong, N. C. Johnson , S. B. Feldstein, and D. Pollard, 2011: On the possible link between tropical convection and the Northern Hemisphere Arctic surface air temperature change between 1958-2001.       J. Climate, 24, 4350-4367. [PDF]

    Small, A. A., J. B. Stefic, J. Verlinde, and N. C. Johnson, 2011: The cloud hunter's problem: An automated decision algorithm to improve the productivity of scientific data collection in stochastic environments.      Mon. Wea. Rev., 139, 2276-2289. [PDF]

    Johnson, N. C., and S.-P. Xie, 2010: Changes in the sea surface temperature threshold for tropical convection. Nature Geosci., 3, 842-845. [abstract] [Magazine cover] [Commentary]

    Johnson, N. C., and S. B. Feldstein, 2010: The continuum of North Pacific sea level pressure patterns: Intraseasonal, interannual, and interdecadal variability. J. Climate, 23, 851-867. [PDF]

    Johnson, N. C., S. B. Feldstein, and B. Tremblay, 2008:  The continuum of Northern  Hemisphere teleconnection patterns and a description of the NAO shift with the use of self-organizing maps.  J. Climate, 21, 6354-6371. [PDF]

    Lebo, Z. J., N. C. Johnson, and J. Y. Harrington, 2008: Radiative influences on ice crystal and droplet growth within mixed-phase stratus clouds. J. Geophys. Res., 113, D09203, doi:10.1029/2007JD009262. [PDF]

    Verlinde, J., J. Y. Harrington, G. M. McFarquhar, V. T. Yannuzzi, A. Avramov, S. Greenberg, N. C. Johnson, G. Zhang, M. R. Poellot, J. H. Mather, D. D. Turner, E. W. Eloranta, B. D. Zak, A. J. Prenni, J. S. Daniel, G. L. Kok, D. C. Tobin, R. Holz, K. Sassen, D. Spangenberg, P. Minnis, T. P. Tooman, M. D. Ivey, S. J. Richardson, C. P. Bahrmann, M. Shupe, P. J. DeMott, A. J. Heymsfield, and R. Schofield, 2007: The Mixed-Phase Arctic Cloud Experiment. Bull. Amer. Meteor. Soc., 88, 205-221. [PDF]

  • FIELD WORK

    • In autumn of 2004, I had the pleasure of participating in the Mixed-Phase Arctic Cloud Experiment (MPACE) on the North Slope of Alaska. My primary responsibility was to launch radiosondes both in Barrow and in Atqusuk. It was quite an experience! You can read more about the experiment here

    Nat Johnson     Nat Johnson     Nat Johnson



    I also had the good fortune of participating in all phases of the Pennsylvania Area Mobile Radar Experiment (PAMREX). I operated the Doppler on Wheels (DOW) trucks and radar equipment and collected and analyzed the radar data. We collected data during stratiform rain events, frontal passages, thunderstorms, and (my personal favorite) lake-effect snow storms. This project captured all phases of field research - exhaustion, excitement, frustration, and adrenaline rushes. You can read more about PAMREX here

    Nat Johnson     Nat Johnson


    • AVAILABLE DATASETS


    NORTH PACIFIC CONTINUUM

    The amplitude time series for 24 North Pacific (SLP) cluster patterns similar to those in Johnson and Feldstein (2010). [TXT]
    These data are for the winter season, defined as the months of December through March. Please see Johnson and Feldstein (2010) for information on the methodology. The 24 cluster patterns can be seen in this figure.

    The amplitude time series for the 24 North Pacific (SLP) cluster patterns for September through November. [TXT]

    In the above datasets, the first three columns are the dates, followed by the 24 amplitude time series.


    NORTH ATLANTIC CONTINUUM

    The amplitude time series for 20 (SLP) cluster patterns similar to those in Johnson, Feldstein, Tremblay (2008). [TXT]
    These data are for the winter season, defined as the months of December through March. Please see Johnson et al. (2008) for information on the methodology. The 20 SOM patterns can be seen in the attached figure. The first three columns are the date and the last 20 columns correspond to the SOM patterns. The patterns are numbered as follows. Pattern 1 corresponds to the pattern in the top left corner, pattern 5 is the last pattern in the first row (top right corner), pattern 6 is the first pattern in the second row, etc.