Decadal Hydrologic Regimes in the San Joaquin Basin, California
James A. Johnstone, Department of Geography, University of California, Berkeley jajstone@berkeley.edu
Abstract: Century-long records of inputs to California’s San Joaquin River show significant decadal (12-15 yr) and biennial (2.0-2.3 yr) modes of variability. These modes are
shown to be mathematically and physically coupled in a manner which produces weak biennial variability during decadal dry intervals. This coupling has contributed to a recent
tendency for prolonged multi-year droughts in California and the central Western U.S., most evident during the late 1980s and early 2000s. Conversely, the biennial mode
displays strong activity during decadal wet periods, producing a tendency for extreme annual flows when both modes act in combination. The linkage between these cyclical
modes yields a tendency for alternating active-wet and stable-dry regimes of ~5-7 years in the San Joaquin Basin, a pattern most evident since 1950. Similar behavior is also
seen in winter precipitation variability throughout the Western U.S., and is attributed to a pair of annular mode oscillations in the Northern Hemisphere circulation.
San Joaquin Variability: San Joaquin annual flows are strongly correlated with winter precipitation in the central Sierra Nevada of California. The 1901-2007 record exhibits
significant biennial (2.16 yr) and decadal (12.8 yr) oscillations.
San Joaquin basin (shaded) and correlations
with local winter precipitation throughout the
Western U.S. Strongest correlation (r = 0.93)
is found at Yosemite Park Headquarters in the
central Sierra Nevada of California (x).
Biennial-Decadal Coupling:
Biennial and decadal modes are
linked, such that the period of
biennial cycle amplitude
modulation corresponds closely to
that of the decadal oscillation.
Top Panel: San Joaquin annual flows are illustrated
in comparison to band pass filtered biennial (2.0-2.3
yr) and decadal (10-20 yr) modes. The biennial mode
exhibits a pattern of decadal amplitude modulation due
to its ~26-month period, slightly longer than two years.
An ideal process of this length will advance in
seasonality by 2 months with each iteration,
completing a revolution through the calendar in 13
years. When biennial cycle extremes align with the
California winter precipitation season, hydrologic
effects are maximized; when extremes are out of
season (i.e. in summer), effects on San Joaquin flow
are minimal, and the biennial amplitude becomes
muted. Biennial amplitude pulses have tended to
occur just prior, or during decadal wet conditions,
producing alternating active-wet and stable-dry
regimes of ~5-7 years' length. Biennial quiescence
has tended to occur during decadal droughts,
inhibiting potential drought relief in any individual year
by the biennial cycle. Such cycle interaction can
account for consecutive flow deficits from 2000-2004
and 1987-1992 Similar, though less severe runs
occurred from 1970-72, 1959-62, 1946-50, 1928-31,
1923-26, and 1918-20.
1901-2007 time series of annual water-year (Oct-Sep) inflows to
the San Joaquin River, in million acre-feet (maf). Data consist of
measured unimpaired inflows in four San Joaquin tributaries. Data
were obtained from the California Department of Water
Resources. http://cdec.water.ca.gov/cgi-progs/iodir/wsihist
San Joaquin River
Power spectra of the San Joaquin record (top) and winter (NovApr) means of the Southern Oscillation Index (SOI) (bottom). The
San Joaquin spectrum includes significant biennial (2.16-yr) and
decadal (~12.8 yr) peaks, features not strongly apparent in the
SOI spectrum.
Northern Hemisphere SLP Correlations:
Band passed biennial and decadal modes of San Joaquin flow were
correlated against identically filtered gridded NCAR sea-level pressure
(SLP) data (Trenberth and Paolino, 1980). Both oscillations show
evidence of hemispheric Annular Mode patterns, characterized by a
contrast between polar and midlatitude SLP anomalies. The San
Joaquin cycles are attributed here to Biennial and Decadal Annular
Mode Oscillations (BAMO and DAMO). Decadal variability is illustrated
for the San Joaquin, and for winter SLP over the NE Pacific and the N
Atlantic (see boxes on lower map), which display anti-phased variability
on the decadal time scale.
Regional and global evidence for a tropospheric
quasi-biennial oscillation of 2.1-2.2 yrs
United States:
California
N. America West Coast
Western US
Great Salt Lake
United States
United States
NE, SW US
United States
25-26 mo.
25 months
26 months
2.2 years
2.2 years
2.1 years
25.6 mo
25 months
Granger 1977
McGuirk 1982
Dettinger et al. 1998
Mann, et al. 1995
Dettinger et al. 1995
Walsh and Mostek 1980
Rasmusson et al. 1981, p.594
Clayton 1884
Worldwide:
Region
California
N. American West
Coast
Western U.S.
Western U.S. (Great
Salt Lake)
United States
Variable
Precipitation
Precipitation
Period
25-26 months
25 months
Ref.
[Granger, 1977]
[McGuirk, 1982]
Precipitation
Lake level
26 months
2.2 years
[Dettinger, et al., 1998]
[Mann, et al., 1995]
2.2 years
[Dettinger, et al., 1995]
United States
Temp., precip.,
pressure
Temp., precip..
2.1 years
United States
Temperature
25.6 months
Atlantic Ocean
N. Atlantic
26 months
2.2 years
N. Atlantic
N. Atlantic
N. Atlantic
SST, SLP
SST, zonal wind,
SLP
SST
SLP
SLP
N. Pacific
SLP
25-30 months
ENSO-Arctic-N.
Atlantic
Arctic
SLP, sea ice
2.2 years
SLP, sea ice
2.1 years
East Africa
Precipitation
2.1-2.2 years
India (subregions)
NW Pacific
monsoon rainfall
cyclone, typhoon
freq.
SST
SST, SLP
2.0-2.3 years
25.6 mo (cross
spec. with SOI)
25 months
2.2 years
[Walsh and Mostek,
1980]
[Rasmusson, et al.,
1981]
[Tourre, et al., 1999]
[Deser and Blackmon,
1993]
[Moron, et al., 1998]
[Kelly, 1977]
[Angell, et al., 1969;
Angell and Korshover,
1974]
[Angell, et al., 1969;
Angell and Korshover,
1974]
[Jevrejeva, et al.,
2004]
[Venegas and Mysak,
2000]
[Rodhe and Virji,
1976]
[Kane, 1995]
[Chan, 1985]
winds
SST
SLP, SST
26 months
2.2 years
25.8 months
Precipitation
Stream flow
2.0-2.1 years
26 months
E. Equatorial Pacific
Indian Ocean
Tropical Ind.-Pac.
Indian Ocean
Australia / New
Zealand
Patagonia
S. America
Center Panel: Composite biennial-decadal cycle,
centered on biennial peaks (lag zero). (Lags on xaxis in years). Amplitudes normalized to emphasize
phase relationships.
25 months
2.2 years
25-30 months
Northern
Hemisphere
Globe
Globe
Temp., SLP
2.1-2.2 years
Precipitation
Temp., SLP
26 months
2.2 years
Globe
Temp., SLP
2.0-2.4 years
Globe
Temperature
2.2 years
[Moron, et al., 1998]
[Tourre and White,
2003]
[Barnett, 1983]
[Ashok, et al., 2004a]
[Trenberth, 1975a;
1980b]
[Villalba, et al., 1998]
[Robertson and
Mechoso, 1998]
[Mann and Park, 1996]
[Lau and Sheu, 1988]
[White and Tourre,
2003]
[White and Allan,
2001]
[Mann and Park, 1994]
Paleoclimate:
Lower Panel: Period of modulation produced by
annual sampling of a quasi-biennial cycle, plotted as a
function of the biennial period. TMOD = (TANN - 2TB-1)-1,
e.g. 13 = (1 – 2 · 2.167 -1)-1. The actual combination of
biennial and decadal spectral peaks (2.16 and 12.8
yrs) is plotted as a point, and falls on the theoretical
line.
This connection indicates an intrinsic
mathematical connection between the two oscillations,
via the annual cycle.
Discussion: A regular alternation between active-wet
and stable-dry regimes generates a natural tendency
for persistent multi-year droughts in the San Joaquin
basin, as seen in recent decades over California and
the broader Western U.S. The alignment of biennial
and decadal modes also tends to produce extreme
annual flows when the positive phases of the
oscillations coincide.
Extrapolating these curves
forward, peak flows may occur in the next several
years, and the next multi-year drought is expected to
occur in years surrounding 2015.
The biennialdecadal linkage suggests that the decadal oscillation
may result from interaction of the biennial mode with
the annual cycle.
Precipitation
Precipitation
Precipitation
Lake level
Temp., precip., pressure
Temp., precip..
Temperature
Pressure, Temp.
Region
California
Nile River
Nile River
Quelccaya, Peru
Patagonia
Seychelles
NE USA
Recent Biennial Activity:
The biennial mode in tropospheric pressure remains active up to the present.
Deseasonalized 500 hPa geopotential height anomalies near Seattle, WA
display clear evidence of a persistent biennial process which operates in all
seasons. Vertical grid lines mark Januaries. Biennial extremes were aligned
with the winter season during the early 1990s, the last high-amplitude stage of
San Joaquin biennial variability, with positive flow anomalies and negative
pressure anomalies occurring in odd years. While the oscillation in pressure is
evident in recent data, early evidence suggests that San Joaquin flows in 2008
will fall below normal.
Variable
Tree ring widths
(Precip.), last
1000 yrs.
Flood intensity,
629-1520 AD
High, low water
years 622-1922
AD
Ice sheet δ18O
Period
2.2 years
Ref.
[Diaz and
Pulwarty, 1994]
2.2 years
[Diaz and
Pulwarty, 1994]
[Kondrashov, et
al., 2005]
Tree-ring widths
(Precip., SLP),
past 250 yrs.
Coral growth band
18
th
δ O, 20 century
Lake varve
thickness, 13-15
kya
2.2 years
2.2 years
2.2 years
2.1 years
2.1 years
[Diaz and
Pulwarty, 1994]
[Villalba, et al.,
1998]
[Charles, et al.,
1997]
[Rittenour, et al.,
2000]