Transcript Worst PowerPoint Ever 2010

Seasonal shifts in
hydroclimatology over the
Western United States
Regonda, Rahagopalan, Clark, and Pitlick
2005. Journal of Climate, 18:372-384
Presented by ScienceWoman
Outline
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Introduction
Methods
Results
Conclusions
Introduction
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A) Background
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Increased land and ocean temperatures particularly over
midlatitude regions
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0.5C in last 50 years (0.1C/decade)
Increased frequency of extreme weather events (floods,
droughts, etc.)
Shifts in seasonal cycles –
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early occurrence of spring
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Increased vegetation cover
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Early blossom of plants
 lilac
Early spring flows
And extended growing period
B) Global trends and western U.S. hydroclimatology
Globel and wetern hydoclimatology*
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“Recently a group of reseraecahres evaluatied futreu climate
change impacts on western US water resources management as
a part of the Accelerated Climate Prediction Invitivae (ACPI).
The climate change scenarios of projected “business as usual”
(BAU) greenhouse gas emmisssions were simulated using the
National Center of Atmosphere Research (NCAR)/Departmetn
of Energy (DOE) parallel climate model (PCM). The BAU
scenarios exhibited an average warming of about 1-2C and
both decrease and increase in precipitation across the western
United States. Downscaling these scenarios to the Colorado
river basin, Christensen et al. (2004) find a signficiant decrease
in april SWE (-30%), annual runoff (-17%), total basin storage
(-40%), and reservori leveells (-33%) by the end of the 21st
century.”
methods
• streamflow
– hcdn database
– various criteria = 89 stations
• swe
– nrcs april 1
– 469, 501, 239
• precipitation and temperature
– nws coop
– Julian day warm spell
• regression anal.
– streamflow, swe, precipitation, temperature
Figure 4
Figure 5
Figure 2 and 3
Tornado Alley
More
Results
Figure 6
More Results
Figure 7
• Scatterplots showing
relationships between
weather station elevation and
trends in (a) warm day spells,
(b) winter precipitation), ©
winter tempeature, (d) a map
illustrating the spatial
distribution of coop stations
below 800 m (squares),
between 800 and 2500 m
(open circles), and above
2500 (filled circles). Note
that there are very few
COOP stations at high
elevations.
More Results
Even more results
Conclusions
 Advancement in the timing of spring temperature spells
over the western United States has resulted in the earlier
occurrence of peak snowmelt flows in many mountain
basins.
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Changes in the timing of snowmelt are most evident in
basins in the Pacific Northwest, which fall below 2500-m
elevation.
Changes in the timing of snowmelt in high-elevation
basins in the interior west are, for the most part, not
statistically significant.
 Increases in March and April streamflows and decreases
in May and June streamflows at a number of sites
suggest a broad shift in spring peak flow timing.
Conclusions (page 2)
 Snowcourse measurements show a decreasing
trend in the snow water equivalent (SWE) in
April and May, which is also indicative of
reduced snow and early melt.
 Winter precipitation seems to be generally
increasing, but there is no clear increase in
spring streamflows.
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This result suggests that in recent decades more of
the precipitation is coming in the form of rain rather
than snow.
Conclusions
Acknowledge
ments
• I want to thank my dog
for not chewing up more
than one copy of my
paper.
• I want to thank my dear,
sweet wonderful (and
hot!) husband for making
me coffee while I stayed
up all nite working on this
*%$#* assignment.
•Thanks for
listening!!!!!!!!!!
•Questions?
[email protected]