1. Synoptic Dendroclimatology and Dendrohydrology: Past, Present, & Process
Katie Hirschboeck
70th Anniversary Tree-Ring Symposium
Laboratory of Tree-Ring Research

2. In what ways can we make valid connections between:
Past . . .
Present . . .
& Process?
1993 floods
drought

3. How can our understanding of these connections be applied to solve critical environmental problems?
&
Acknowledgments:

4. A record of EXTREME EVENTS
The Skeleton Plot
Narrow Rings = low growth extremes
Wide “big” Rings = high growth extremes
A record of EXTREME EVENTS

5. 1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
. . . as well as the Upper and Lower Tails of the Probability Distribution Function used to statistically evaluate and manipulate the data
These extreme events shape the Upper and Lower Tails of the Sampling Distribution . . .

6. In the case of climate-sensitive tree rings, the environmental processes that shape the Upper and Lower Tails are distinctly different from a meteorological and hydroclimatologic perspective.

7. Synoptic dendroclimatology:
“ using dated tree rings to study and reconstruct present and past climates from the viewpoint
of the climate’s constituent weather components
. . . and the way in which these components are related to atmospheric circulation at all scales."
(from Hirschboeck et al., “Synoptic Dendroclimatology: Overview and Outlook” )

8. FLOOD STUDIES

9. Process-Sensitive “Telescoping” Back in Time
The PAST: What is the Process-Based Interpretation of a Tree-Ring Reconstruction?
Process-Sensitive “Telescoping” Back in Time

10. The PRESENT: How do different hydroclimatic processes manifest themselves in trees vs river basins?

11. Verde River Basin Comparison: Observed, Reconstructed, & Instantaneous Peak Flows
Water Year

12. Verde River Basin Instantaneous Peak Flows Classified by Synoptic Type
Water Year
Synoptic Convective Tropical Storm
Jan 1993
Mar 1938
Feb 1995
Dec /Jan 2005
Winters of
Dec /Jan 1952
Feb 1927
TS Norma Sep 1970
1950s convective dominance

13. Synoptic pattern for record-breaking floods of winter 1992-93 in Arizona

14. Importance of BLOCKING circulation anomaly patterns
Blocking leads to the PERSISTENCE of circulation features that produce EXTREMES
drought /

15. Verde River Basin Comparison:
Observed, Reconstructed,
& Instantaneous Peak Flows
Water Year
700 mb Anomaly Patterns associated with “Upper and Lower Tail” Extreme Events
1993
1996 & 2002
1950s + Drought
Current Drought
1970

16. PROCESS: analyzing the reconstruction mechanistically
Synoptic Convective Tropical Storm
PROCESS: analyzing the reconstruction mechanistically
Both reconstructed & observed annual flows track the magnitude of the instantaneous peak better during synoptic (winter) events

17. Newly reconstructed Verde River Annual Flow
Analysis of present “telescoped” extremes (i.e., instantaneous vs. mean annual flow) to better interpret reconstruction
Verde River study of paleoflood data vs. tree-ring based annual streamflow reconstruction
(based on Graybill reconstruction & linked to paleofloods by: House, Pearthree, and
Newly reconstructed Verde River Annual Flow

18. SUMMARY, INSIGHTS & IMPLICATIONS

19. On Upper & Lower Tails:
 Wide rings can occur in otherwise narrow-ring sequences, high flows and/or large floods can occur during periods of drought / low flows
 The probability of such occurrences can be computed using a long-record reconstruction  an important statistic for water supply managers for “drought relief”

20. On Blocking & Persistent Anomalies:
 CIRCULATION ANOMALIES involving quasi-stationary patterns such as blocking ridges and cutoff lows are key synoptic mechanisms that make skeleton plotting, pattern matching, & cross-dating possible.
 Since the characteristic drought circulation pattern in the United States is a strong middle- and upper-level ridge (and occasional blocking high) . . .
it should not be surprising that extreme flooding and persistent drought occasionally coincide, at least in adjacent regions.

21. On Interpreting the Past based on Our Present Understanding of Proceses:
 Synoptic dendroclimatology / hydrology has demonstrated that shifts in storm track locations and other anomalous circulation behaviors are clearly linked to notable ring widths, streamflow and drought behavior
 Such shifts are likely to be the factors most directly responsible for persistent and unusual sequences and episodes seen in long chronolgies and reconstructions

22. On Process- Sensitive Upscaling & Telescoping Back in Time:
 Persistence bridges meteorological and climatological time scales
 Persistence = underlying factor in atmosphere / river basin / landscape synergy and especially, DROUGHT!