31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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US Precipitation and Temperature Trends

Dr. Imke Durre

Contact: Imke.Durre@noaa.gov +1 828 271 4870

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Annual US-Averaged Precipitation

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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M

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

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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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?

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Annual US-Averaged TMAX/TMIN

1979-2005:TMAX Trend: +0.30 C/DecadeTMIN Trend: +0.31 C/Decade

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Annual US-Averaged DTR

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

24from Dai et al. (2006)

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Surface Air Temperature trends 1958-1999 (DJFM)

Component of trend that’s linearly congruent with the two leading PCs of the detrended SLP field.

Residual TrendLinear Trend

from Quadrelli and Wallace (2004)

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Trend towards fewer cold days in winter:

* Boundary layer feedbacks?

Summertime diurnal asymmetry in trends:

* Water vapor feedback?

Significant local trends:

* Natural?

Temperature: What happened and why?

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Winter Inversions: Heights of Warmest Levels

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Tucson

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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Negative Correlations Between 850-SFC Precipitable Water and Cooling Rate

31st Climate Diagnostics and Prediction WorkshopBoulder, Colorado, October 23–27, 2006

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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?

Major Challenges