Research ArticleATMOSPHERIC SCIENCE

Northwestern Pacific typhoon intensity controlled by changes in ocean temperatures

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Science Advances  29 May 2015:
Vol. 1, no. 4, e1500014
DOI: 10.1126/sciadv.1500014
  • Fig. 1 Interannual-to-decadal variability of various typhoon metrics.

    (A to C) Seasonal mean (A) lifetime peak intensity (Embedded Image), (B) intensification rate (Embedded Image), and (C) intensification duration (Embedded Image) of typhoons in the northwestern Pacific as a function of time (thin solid black curve). The thick black curve in each panel shows the 9-year running averages. Error bars shown as shading are calculated by dividing the SD by the square root of the number of storms in each year. The thin dashed red curve in (A) is obtained as v0 + Embedded Image × Embedded Image, and its correlation with Embedded Image (thin solid black curve) is 0.89.

  • Fig. 2 Typhoon intensification rate versus ocean temperatures.

    (A) Correlation between seasonal mean intensification rate and summer (July–September) ocean temperatures at different depths (black dots) and PI (red dot) averaged over the intensification region. Gray and red bars show the 95% credible intervals. (B) Time series of seasonal mean intensification rate (blue curve) and ocean temperature at 75-m depth averaged over the intensification region (red curve). (C) Scatter plot of seasonal mean frequency of rapid intensification per storm versus ocean temperature at 75-m depth averaged over the intensification region. Solid blue line shows the linear regression, with dashed blue curves showing the 95% confidence bands.

  • Fig. 3 Modulation of typhoon intensification duration by PDO.

    Time series of normalized seasonal mean duration of typhoon intensification (blue curve) and normalized PDO index during the typhoon peak season (red curve). The correlation coefficient between them is 0.43.

  • Fig. 4 Observed and projected typhoon lifetime peak intensity.

    Observed (thin red), predicted (1950–2009; thin black), and projected (2006–2100; thin black) seasonal mean typhoon lifetime peak intensity (m s−1) and their 9-year running means (thick curves). Two projections are given: one (solid) considers both changes in SST and subsurface stratification with continuous gray shading showing error bars, and the other (dashed) ignores changes in subsurface stratification with error bars shown discretely for years 2006, 2016, …, and 2096. See Materials and Methods for details. The colors on the right y axis denote the range of typhoon intensity from category 2 up to category 5 based on the Saffir-Simpson hurricane scale.

  • Table 1 Correlation between typhoon intensification rate and various atmospheric and oceanic variables.

    V|200−850, full shear; |Δu|200−850, shear of zonal wind; |Δv|200−850, shear of meridional wind; ζ850, 850-hPa vorticity; ω500, 500-hPa pressure velocity; SLP, sea-level pressure; PIinten, PI over the main intensification region; PIgenesis, PI over the main genesis region defined in ref. (21); RSST, SST over the typhoon intensification region relative to global tropical mean SST; T75m, ocean temperature at 75-m depth; rupper and rlower, the upper and lower bounds, respectively, for a 95% credible interval.

    V|u|v|ζ850ω500SLPPIintenPIgenesisSSTRSSTT75m
    r−0.170.13−0.03−0.180.070.160.33−0.030.320.090.58
    rupper0.100.380.240.090.330.410.540.230.540.350.36
    rlower−0.42−0.14−0.29−0.43−0.20−0.110.07−0.300.05−0.180.73

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/4/e1500014/DC1

    Materials and Methods

    Fig. S1. Evolution of seasonal mean lifetime peak intensity of typhoons.

    Fig. S2. Changes in proportions of TCs of different intensity.

    Fig. S3. Main typhoon intensification region.

    Fig. S4. Vertical profiles of temperature and salinity used to initialize the ROMS simulation.

    Fig. S5. Drag coefficient as a function of surface wind speed used in ROMS simulations.

    Fig. S6. Typhoon-induced changes in tracer content simulated by ROMS.

    Fig. S7. Observed and simulated changes in ocean temperatures.

    Fig. S8. High-frequency variations in typhoon metrics and their modulation by oceanic and climate variables.

    Fig. S9. Simulated changes in various atmospheric thermodynamic variables.

    Table S1. Correlation between the duration of typhoon intensification and various variables.

    Table S2. Details of the ocean component of the CMIP5 models in use.

    References (8090)

  • Supplementary Materials

    This PDF file includes:

    • Materials and Methods
    • Fig. S1. Evolution of seasonal mean lifetime peak intensity of typhoons.
    • Fig. S2. Changes in proportions of TCs of different intensity.
    • Fig. S3. Main typhoon intensification region.
    • Fig. S4. Vertical profiles of temperature and salinity used to initialize the ROMS simulation.
    • Fig. S5. Drag coefficient as a function of surface wind speed used in ROMS simulations.
    • Fig. S6. Typhoon-induced changes in tracer content simulated by ROMS.
    • Fig. S7. Observed and simulated changes in ocean temperatures.
    • Fig. S8. High-frequency variations in typhoon metrics and their modulation by oceanic and climate variables.
    • Fig. S9. Simulated changes in various atmospheric thermodynamic variables.
    • Table S1. Correlation between the duration of typhoon intensification and various variables.
    • Table S2. Details of the ocean component of the CMIP5 models in use.
    • References (8090)

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