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Building%20a%20Water%20Budget%20for%20the%20Middle%20Rio%20Grande

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... regime shift' of 1977 profoundly changed ENSO-based predictability ... Nevertheless decadal variability is profoundly important for ecosystems and human society ... – PowerPoint PPT presentation

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Title: Building%20a%20Water%20Budget%20for%20the%20Middle%20Rio%20Grande


1
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2
Pacific Decadal Oscillation in SSTMantua et
al. 1997
warm phase AK salmon ? PNW salmon ?
cold phase AK salmon ? PNW salmon ?
Updated time series available online
at http//tao.atmos.washington.edu/pdo/
3
Updated North Pacific IndexJim Hurrell, NCAR
Available online at http//www.cgd.ucar.edu/jhur
rell/np.html
4
Current Pacific SST anomaly mapNOAA Climate
Diagnostics Center
Available online at http//www.cdc.noaa.gov/map/i
mages/sst/
5
ENSO/PDO/AO effects on US precipitationHiggins
et al. 2000
  • ENSO effect
  • Strongest along Gulf coast

Add PDO effect esp. important across SW?
AO effect Ohio River Valley
6
Current winter precipitation outlookNOAA Climate
Prediction Center
Available online at http//www.cpc.ncep.noaa.gov/
products/predictions/multi_season/
7
Time series of ENSO/PDO and winter precipitation
in New Mexico
Time series of equatorial SST (Niño3) and PDO
(Mantua et al.) ending in late summer, 1951-1997
Gutzler et al. 2002
Time series of subsequent winter precipitation
in Southwest NM (Climate Div 4 and town of Ft
Bayard), DJFM 1951/52 1997/98
8
Quantification of seasonal predictability with a
modified Brier Score
Consider the distribution of 16 upper tercile
Niño3 years Tercile distribution of precip is 5 /
1 / 10 whereas random distribution would be 5.33
/ 5.33 / 5.33 Modified 1-tailed Brier Score S
Each annual hit 0 1-bin error 1 2-bin
error 2 (not 4) Sum annual scores, divide by
N so for 5/1/10, S11/160.69 Perfect skill
S0.0 No skill S1.0
Informally, we find Sgt0.9 no utility 0.75ltSlt0.9
modest utility 0.6ltSlt0.75 marked skewness Slt0.6
forecasters dream
9
ENSO extrema 1951-1997 provide significant
predictability of SW US winter precip
Gutzler et al. 2002
Predictability of a dry winter following
negative JAS Niño3
Perfect skill 0.00 Zero skill 1.0 or
higher Skill ? darker shading
Predictability of a wet winter following
positive JAS Niño3 (better for El Niño than La
Niña)
10
but PDO has a relatively modest effect on SW
US winter precip predictability
Gutzler et al. 2002
Predictability of a dry winter following
negative PDO year
Perfect skill 0.00 Zero skill 1.0 or
higher Skill ? darker shading
Predictability of a wet winter following
positive PDO year
11
Decadal modulation of ENSO predictabilityis the
primary influence of PDO
Gutzler et al. 2002
Pre-1977
Post-1977
Dry winter following JAS La Niña (good
predictability pre-77 none post-77)
Wet winter following JAS El Niño (good
predictability post-77 none pre-77)
12
The climate regime shift of 1977 profoundly
changed ENSO-based predictability have we
changed back to pre-1977 conditions?
  • Characterization of low-frequency variability is
    extremely difficult to get right the first time
  • At present there is neither a universally
    accepted index of PDO/NPO nor a satisfactory
    theory
  • Not all PDO indices show a shift circa 1998
  • In mid-continent, including SW North America, the
    ocean is not the whole decadal climate story
  • Decadal climate variability bedevils monitoring
    of long-term change and prediction of short-term
    anomalies
  • Nevertheless decadal variability is profoundly
    important for ecosystems and human society
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