East Pacific .pdf

Dear Bob,
Thank you for this nice question. I think it includes several questions. At first I want to answer
about East Pacific, because it is more easy. I think you question may be reformulated as follows:
You hypothesized that in late 80th SST has upward shift of about 0.3 °C and East Pacific hasn't
warmed in last 31 years, how these features corresponds with each other.
My opinion on this issue is the following. Consider SST in this region from 1900 till 2012
(Fig. 1). I used HadSST3 dataset from Climate Explorer site. It is clearly seen that most of
variability here directly linearly associated with ENSO Nino34 index. And according to our
hypothesis there should be two upward shifts in somewhere in 1925/1926 and 1987/1988. So we
performed linear regression on this two factors and obtained quite adequate reconstruction (Fig.
2). Last years from 1981 are presented on Figure 3. So from my point of view SST anomalies in
East Pacific during last 31 years could be explained by direct linear associating with ENSO
index and upward shift of about 0.25 °C at the end of 1987. Without this shift temperatures will
have cooling trend, because Nino34 has cooling trend during these years (Fig. 4).
I have performed calculations using HadSST3 dataset in order to have view on the period from
1900. I think differences during last 31 years of this dataset with obtained by remote sensing are
not very important. As a proxy for ENSO I used the Nino34 index obtained from HadISST1 at
Climate Explorer site and used it without lag. All the calculations presented below were made in
Excel by means of standard functions. File could be downloaded by following link:
https://www.dropbox.com/s/33sjoz526bfo24e/East%20pacific.xls
It should be intuitively understandable (if needed I can provide additional explanations).
Situation in South Atlantic, Indian and West Pacific oceans is more complex. I also have what to
write about them but need some time for preparation. I'll try to do it during next week. And
please if you are interested in my answer give at least short reply on my opinion about East
Pacific.
Best wishes,
Pavel Belolipetsky

0.9
0.7
Anomaly, °C

0.5
0.3
0.1
-0.1
-0.3
-0.5
-0.7
-0.9
1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

Fig. 1. SST anomalies in East Pacific (90S-90N 180W-80W), HadSST3 dataset.

2000

2010

a) Regression

0.9

Correlation coefficient 0.82

0.7
Anomaly, °C

0.5
0.3
0.1
-0.1
-0.3
-0.5
-0.7
-0.9
1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

2010

b) ENSO influence
Anom
aly, °C

1
0.5
0
-0.5
-1

c) Climate regime influence
Anom
aly, °C

0.4
0.2
0
-0.2
-0.4

Fig. 2. a) Blue line - anomalies in East Pacific (90S-90N 180W-80W), red line - linear
regression on ENSO and climate regime, studied by 1900-2012 years; b) ENSO influence; c)
climate regime influence.

a) Regression

Correlation coefficient 0.83

0.9
0.7
Anomaly, °C

0.5
0.3
0.1
-0.1
-0.3
-0.5
-0.7
-0.9
1981

1991

2001

2011

b) ENSO influence
Anom
aly, °C

1
0.5
0
-0.5
-1

c) Climate regime influence
Anom
aly, °C

0.3
0.2
0.1
0

Fig. 3. Enlarged part of figure 2.

0.9
0.7
Anomaly, °C

0.5
0.3
0.1
-0.1
-0.3
-0.5
-0.7
-0.9
1981.8334

1991.8334

2001.8334

Fig. 4. Illustration of cooling without 1987 upward shift.

2011.8334