The California drought and what can be expected from the...
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The California drought and what can be expected from the 2015/16 El Nino Richard Seager, Marty Hoerling, Siegfried Schubert, Hailan Wang, Brad Lyon, Arun Kumar, Jennie Nakamura, Naomi Henderson The NOAA DTF California team Mingfang Ting and Bor-Ting Jong Lamont Doherty Earth Observatory Thursday, September 24, 15
Transcript of The California drought and what can be expected from the...
The California drought and what can be expected from the
2015/16 El Nino
Richard Seager, Marty Hoerling, Siegfried Schubert, Hailan Wang, Brad Lyon, Arun Kumar, Jennie Nakamura, Naomi
HendersonThe NOAA DTF California team
Mingfang Ting and Bor-Ting JongLamont Doherty Earth Observatory
Thursday, September 24, 15
Causes of the ongoing California drought2011-2014 Winter SSTA (ocean), Precip (land), 200 mb Height (contour)
(a) Observed
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-30
-20 -20
-10
-10
0
0
0
10
10
10
20
20
20
20
30
30
30
40
40
50
60
(b) 7 Model Average
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚Wlongitude
0˚30˚N
60˚N
latit
ude
0
0
0
10
10
20
20
30
30
4050
-2 -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 2Temperature
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1precipitation [mm/day]
SST-forced models (average across ensemble means from 7 models) reproduce ~1/3 of west coast ridge and precipitation drop in 2011/14.Drought forced by tropical SSTs + weather
~3/4 of PDSI drop caused by P drop, ~1/4 by high temperature. Long term warming
contributed to the high temperatures, expanding
area with exceptional drought.
Seager et al. 2015 J. Climate, Williams et al. 2015 GRLThursday, September 24, 15
No surprise SST-forced models do not fully capture CA P variability
A composite of observed CA dry winters shows the off-coast ridge but no impressive sea surface temperature anomalies
Winter CA Precip(land), SSTA(ocean), 500mb Height(contour)
(A) Dry Years
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-30
-20-10
-100
0
0
00
10
10
20
(B) Wet Years
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-20-10
0
0
10
10
20
-1.5 -1 -0.5 0 0.5 1 1.5Temperature
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1precipitation [mm/day]
Winter CA Precip(land), SSTA(ocean), 500mb Height(contour)
(A) Dry Years
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-30
-20-10
-100
0
0
00
10
10
20
(B) Wet Years
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-20-10
0
0
10
10
20
-1.5 -1 -0.5 0 0.5 1 1.5Temperature
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1precipitation [mm/day]
Thursday, September 24, 15
In contrast, observed wet California winters tend to be caused by El Nino events
Winter CA Precip(land), SSTA(ocean), 500mb Height(contour)
(A) Dry Years
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-30
-20-10
-100
0
0
00
10
10
20
(B) Wet Years
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W 30˚WLongitude
0˚30˚N
60˚N
Latit
ude
-20-10
0
0
10
10
20
-1.5 -1 -0.5 0 0.5 1 1.5Temperature
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1precipitation [mm/day]
Thursday, September 24, 15
Seasonal(Dependence(of(California(Precip(and(El(Niño(Correla5on(
60.2(
60.1(
0(
0.1(
0.2(
0.3(
0.4(
0.5(
2( 3( 4( 5( 6( 7( 8( 9(NDJ$ DJF$ JFM$ FMA$SON$ OND$ NDJFMA$
N.$Cal.$
S.$Cal.$
strengthens as winter progresses and stronger in SoCal than NoCal
Thursday, September 24, 15
Composite)for)top)15%)wet)vs.)non3wet)California)seasons)(NDJFMA))that)are)also)El)Niño!
SST)(shading),)200hPa)Hgt)(black)contours),)and)850)hPa)Wind) PrecipitaPon)
Strong El Niños more
reliably cause wet California
than weaker El Niños
Thursday, September 24, 15
N. America Composite AnomaliesPrecipitation Percent of Climatology (land), SSTA (ocean), 200 mb Height (contour)
NDJ FMAWeak El Nino: 0.5!C < NINO3.4 < 1.0!C
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-20
-10
-10
-100
0
10
10
10
20
30
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-30-20
-20-10
0
0
10
10
20
30
30
Moderate to Strong El Nino: 1.0!C < NINO3.4
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-40
-30
-20
-20
-10
-10
-10
0
0
0
10
10
10
2020
20
30
40
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-80
-70-60
-60-50-40
-40
-30-20
-10
0
0
10
10
10
20
20
30
30
40
40
50
50
60
60
-2˚C -1.6˚C -1.2˚C -0.8˚C -0.4˚C 0˚C 0.4˚C 0.8˚C 1.2˚C 1.6˚C 2˚C
SSTA
-100 -80 -60 -40 -20 0 20 40 60 80 100Precipitation [Percent]
Wet California during El Niño more favored:1) during strong events2) during late rather than early winter3) in the south than the north
Thursday, September 24, 15
GOGA N. America Composite AnomaliesPrecipitation Percent of Climatology (land), SSTA (ocean), 200 mb Height (contour)
NDJ FMAWeak El Nino: 0.5!C < NINO3.4 < 1.0!C
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-30
-20
-10
-10
-10 0
10
10
20
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-50-40-20
-20-10
-10
0
0
10
10
20
20
30
40
Strong El Nino: 1.0!C < NINO3.4
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-60
-50-40-30-20
-20
-10
-10-10
0
10
20
30
40
40
50
50
60
60
120˚E 150˚E 180˚ 150˚W 120˚W 90˚W 60˚W
Longitude
0˚
30˚N
60˚N
Latitude
-90-80
-70-60-50-40
-40-30
-20
-10
0 10
20
30
40
40
40
50
50
60
60
70
80
-2˚C -1.6˚C -1.2˚C -0.8˚C -0.4˚C 0˚C 0.4˚C 0.8˚C 1.2˚C 1.6˚C 2˚C
SSTA
-100 -80 -60 -40 -20 0 20 40 60 80 100Precipitation [Percent]
The ENSO- California P connection
simulated well in 16-member CCM3
ensemble.
ENSO teleconnections
strengthen from early to late winter even as
tropical SST anomalies weaken.
Why?
Thursday, September 24, 15
Dynamical model average
NINO3.4
NDJ 2.5KFMA 1.8K
If FMA forecast
correct it would be a seasonal record
Thursday, September 24, 15
Thursday, September 24, 15
! Climatology!for!NDJFMA!(mm)!
Sum!of!P!anomalies1!from!11/2011~04/20152!(mm)!
Percentage!(column!3/column!2!*100%)!
Northern! 504.83! I745.35! !147.64%(Southern! 198.90! I388.35! !195.25%(!1!Precipitation!anomalies:!remove!monthly!climatology!2!Include!MayIOct!of!2012~2014,!i.e.!every!month!within!Nov/2011~Apr/2015!!!!For!each!winter!from!2011/12!to!2014/15!(precipitation!anomalies!in!%):!
! Clim!(mm)! 11/12!NDJFMA!
12/13!NDJFMA!
13/14!NDJFMA!
14/15!NDJFMA! Total!deficit!
Northern! 504.83! I24.21%!(I122.21)!
I35.64%!(I179.92)!
I44.91%!(I226.80)!
I36.17%!(I182.58)! !140.92%(
Southern! 198.90! I33.45%!(I66.54)!
I48.76%!(I96.98)!
I59.60%!(I118.54)!
I47.83%!(I95.14)! !189.64%(
Removal of the 4 years
statewide accumulated precipitation
deficit requires a record rainfall
anomaly in 2015/16
Forecast)NINO3.4)for)15/16)based)on)IRI/CPC)dynamical)(orange)lines))and))staBsBcal)(green)lines))models))
Thursday, September 24, 15
Conclusions
California is undergoing a 5 year roller coaster ride of SST driving of winter precipitation
Four winters of drought have left precipitation deficits about 150% (north) and 200% (south) of the climatological normal
Strong El Niños tend to make CA wet but more so in the south than the north and in the late winter than the early winter
Forecasts are for a strong El Niño persisting through to the late winter
A wet winter is likely but record wet needed to erase the accumulated precipitation deficit
(Soil moisture, reservoir storage may need less precipitation to return to “normal”
Thursday, September 24, 15
