Research ArticleCLIMATOLOGY

Strong future increases in Arctic precipitation variability linked to poleward moisture transport

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Science Advances  12 Feb 2020:
Vol. 6, no. 7, eaax6869
DOI: 10.1126/sciadv.aax6869
  • Fig. 1 Long-term changes in Arctic moisture budget components (precipitation, surface evaporation, and moisture transport across 70°N).

    (A) Mean values and (B) interannual variability, defined as the SD of consecutive detrended 30-year segments. All values represent the multimodel mean [35 Coupled Model Intercomparison Project, Phase 5 (CMIP5) models] subtracted from the average over the period 1870–1980. Uncertainty envelopes express the interquartile ranges of intermodel differences, evaluated after subtracting the respective 1870–1980 means. The gray bar denotes the “current” period 1981–2010, represented by the values at 1995 (black line).

  • Fig. 2 Changes in Arctic precipitation variability.

    (A) Multimodel-mean relative changes in Arctic precipitation variability in terms of fractional area exhibiting a certain change (thick line, multimodel-mean values; thin lines, intermodel uncertainty expressed as the 1 − σ SD from the mean). (B) Intermodel dependence of trends in Arctic precipitation variability and poleward moisture transport variability. Each square represents one CMIP5 climate model (the first member; see Materials and Methods), and the red line is the best linear fit (coefficients in the lower-right corner).

  • Fig. 3 Changes in the variability of Arctic hydrological cycle components.

    (A) Sensitivity in Arctic moisture budget components with respect to mean changes and changes in the interannual variability [defined as percentage change per degree warming (2): ΔX/(XΔT), where T is the Arctic mean surface air temperature, and X is the precipitation, surface evaporation, or atmospheric moisture transport through 70°N]. Crosses represent individual climate models. Black open squares are the multimodel means with the black error bars being the intermodel SDs. The horizontal green and pink lines represent the Clausius-Clapeyron relation for atmospheric water vapor changes (~7%/K) and the global mean precipitation sensitivity (~2%/K), respectively. (B) Intermodel dependence of trends in Arctic precipitation variability and poleward moisture transport variability. Every square represents one CMIP5 climate model, and the red line is the best linear fit (coefficients in the lower-right corner).

  • Fig. 4 Seasonal and geographical patterns of multimodel-mean 21st-century changes in Arctic moisture budget variability.

    (A) Seasonal changes for precipitation (blue), poleward moisture transport through 70°N (green), and surface evaporation (red). Error bars indicate intermodel uncertainty defined as the 1 − σ SD from the mean. (B) Geographical distribution of relative changes in interannual precipitation variability.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/7/eaax6869/DC1

    Climate model validation of Arctic precipitation (mean and variability)

    Model-based interannual versus decadal variability

    Separating interannual and decadal variability

    Changes in convective (small-scale) precipitation in the Arctic

    Intermodel differences and decadal variations in interannual precipitation variability uncertainty

    Intermodel versus intramodel uncertainties in interannual precipitation variability trends

    Fig. S1. Arctic (70° to 90°N) mean and annual mean precipitation (average and interannual variability) as simulated by 35 CMIP5 global climate models compared with six observation- driven reanalysis datasets for the period 1981–2010.

    Fig. S2. Arctic (70° to 90°N) mean and annual mean precipitation, surface evaporation, and poleward moisture transport across 70°N for each of the 16 randomly chosen initial conditions in the 2000-year EC-Earth climate model ensemble of the present-day climate.

    Fig. S3. Relations between mean and variability of Arctic moisture budget components.

    Fig. S4. Arctic (70° to 90°N) and annual mean precipitation anomaly (i.e., mean value subtracted) for a 400-year simulation of the current climate using the global climate model EC-Earth.

    Fig. S5. Arctic moisture budget component variability estimates of the current climate and the 2xCO2 climate (both 400-year quasi-equilibrium climates simulated by EC-Earth) for the complete time series (ALL), only decadal variations (DEC), and only interannual variations (INT).

    Fig. S6. Time scale–dependent correlations between time series of annual mean Arctic precipitation and moisture transport at 70°N (blue lines) and precipitation and surface evaporation (red lines) for the current climate (full lines) and the 2xCO2 climate (dashed lines).

    Fig. S7. Model-simulated (EC-Earth) change in convective precipitation in the Arctic between a 2xCO2 and a 1xCO2 simulation expressed as the difference in the ratio (in percentage) of convective to total precipitation occurrence, evaluated using annual means.

    Fig. S8. Arctic precipitation variability and its uncertainty in CMIP5 preindustrial simulations, determined by taking the SD over subsequent 30-year detrended periods (annual means), per model.

    Fig. S9. Arctic interannual precipitation variability trends (1980–2100) and their intermodel (between models) and intramodel (within one model) uncertainties for six state-of-the-art global climate models, determined by taking the SD over subsequent 30-year detrended periods (annual means) and then taking a linear regression of the resulting time series in variability.

    References (2831)

  • Supplementary Materials

    This PDF file includes:

    • Climate model validation of Arctic precipitation (mean and variability)
    • Model-based interannual versus decadal variability
    • Separating interannual and decadal variability
    • Changes in convective (small-scale) precipitation in the Arctic
    • Intermodel differences and decadal variations in interannual precipitation variability uncertainty
    • Intermodel versus intramodel uncertainties in interannual precipitation variability trends
    • Fig. S1. Arctic (70° to 90°N) mean and annual mean precipitation (average and interannual variability) as simulated by 35 CMIP5 global climate models compared with six observation- driven reanalysis datasets for the period 1981–2010.
    • Fig. S2. Arctic (70° to 90°N) mean and annual mean precipitation, surface evaporation, and poleward moisture transport across 70°N for each of the 16 randomly chosen initial conditions in the 2000-year EC-Earth climate model ensemble of the present-day climate.
    • Fig. S3. Relations between mean and variability of Arctic moisture budget components.
    • Fig. S4. Arctic (70° to 90°N) and annual mean precipitation anomaly (i.e., mean value subtracted) for a 400-year simulation of the current climate using the global climate model EC-Earth.
    • Fig. S5. Arctic moisture budget component variability estimates of the current climate and the 2xCO2 climate (both 400-year quasi-equilibrium climates simulated by EC-Earth) for the complete time series (ALL), only decadal variations (DEC), and only interannual variations (INT).
    • Fig. S6. Time scale–dependent correlations between time series of annual mean Arctic precipitation and moisture transport at 70°N (blue lines) and precipitation and surface evaporation (red lines) for the current climate (full lines) and the 2xCO2 climate (dashed lines).
    • Fig. S7. Model-simulated (EC-Earth) change in convective precipitation in the Arctic between a 2xCO2 and a 1xCO2 simulation expressed as the difference in the ratio (in percentage) of convective to total precipitation occurrence, evaluated using annual means.
    • Fig. S8. Arctic precipitation variability and its uncertainty in CMIP5 preindustrial simulations, determined by taking the SD over subsequent 30-year detrended periods (annual means), per model.
    • Fig. S9. Arctic interannual precipitation variability trends (1980–2100) and their intermodel (between models) and intramodel (within one model) uncertainties for six state-of-the-art global climate models, determined by taking the SD over subsequent 30-year detrended periods (annual means) and then taking a linear regression of the resulting time series in variability.
    • References (2831)

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