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US Precipitation and Temperature Trends

US Precipitation and Temperature Trends. Dr. Imke Durre. Contact: Imke.Durre@noaa.gov +1 828 271 4870. Annual US-Averaged Precipitation. M. Model precipitation projections, smoothed with a 13-year filter. Precipitation: What happened and why?.

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US Precipitation and Temperature Trends

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  1. US Precipitation and Temperature Trends Dr. Imke Durre Contact: Imke.Durre@noaa.gov +1 828 271 4870

  2. Annual US-Averaged Precipitation

  3. M Model precipitation projections, smoothed with a 13-year filter.

  4. Precipitation: What happened and why? Seasonal differences in spatial patterns of trends in amount: * Precise seasonal evolution of trends? * Relevant factors? Increased frequency of heavy events during the past three decades: * Sensitivity to analysis technique? * Interdecadal variability or global warming? Frequency distribution of amounts: * Are we observing it correctly? * Do we understand its variations?

  5. Annual US-Averaged TMAX/TMIN 1979-2005: TMAX Trend: +0.30 C/Decade TMIN Trend: +0.31 C/Decade

  6. Annual US-Averaged DTR

  7. from Dai et al. (2006)

  8. Surface Air Temperature trends 1958-1999 (DJFM) from Quadrelli and Wallace (2004) Linear Trend Component of trend that’s linearly congruent with the two leading PCs of the detrended SLP field. Residual Trend

  9. Temperature: What happened and why? Trend towards fewer cold days in winter: * Boundary layer feedbacks? Summertime diurnal asymmetry in trends: * Water vapor feedback? Significant local trends: * Natural?

  10. Winter Inversions: Heights of Warmest Levels

  11. Tucson

  12. Negative Correlations Between 850-SFC Precipitable Water and Cooling Rate

  13. Major Challenges What's natural and what isn't? * Significant local temperature trends * Precipitation characteristics and changes Addressing shortcomings of linear trends: * Need for less arbitrary methods for analyzing variations * Need for diagnosing simultaneous observed variations in multiple variables Local versus large-scale feedbacks * Relative importance? * Interactions? Role of the boundary layer?

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