# Presentation: 861416

## Equatorial Heat Content and ENSO Prediction

**Equatorial Heat Content and ENSO Prediction**

-  Wednesday, 24th October 2007

- NOAA 32nd Climate Diagnostics Workshop
-                            Session 6

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-                              Meinen & McPhaden 2000; Clarke et al. 2007]

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- Mixed layer heat balance equation for a mixed layer of depth H:

- Main interannual balance near the date line

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- Based on Clarke et al., 2007.

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- of NINO3.4.

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-                                                       Walker & Bliss 1932, 1937]

- From Clarke 2008:  *An Introduction to the Dynamics of El Ni**ño and the Southern *
*                                **Oscillation*, Academic Press.

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- following March.    Suggests we write NINO3.4
- as an annual time series multiplied by a calendar
- month structure function

- Use EOF analysis.  First EOF 85% of variance.

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- and NINO3.4
- [black].
- correlation = 0.924

*S(m)Y(y)*

- [red]

- From Clarke 2008:
*An Introduction to the *
*Dynamics of El Ni**ño and the Southern Oscillation*, Academic Press.

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- We can characterize El Niño by just a single annual time series.
- Red (El Niño), blue (La Niña) and green (Neutral).
- Thresholds were chosen so that *S(m) Y(y)* exceeds 0.5oC
-   or is less than -0.5oC for at least 3 calendar months.

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- Lead correlations of the anomalous equatorial heat content
- for each calendar month with NINO3.4 (*t*+lead) for the period
- Jan 1980 - Dec 2001.  A positive lead corresponds to      leading NINO3.4.
- The 20oC isotherm depth is used to estimate         .   The first month in
- each quarter is solid, the second is dashed and the third is dot-dashed.
- [Adapted from Clarke and Van Gorder 2003].

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- Clarke & Van Gorder (2003) ENSO prediction model
**        ****(“*****FSU REGR”*****)**

- =   wind precursor anomaly

- =   heat content precursor (monthly
-      anomalous depth of the 20oC isotherm
-      averaged across the Pacific

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**Wind precursor anomaly**

- From Clarke & Van Gorder 2003.

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**The model cross-verified predictions ****(1980-2001) are better than the operational ****predictions from Jan 2002.  (Short record?)**

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## The End.

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- From Clarke 2008:  *An Introduction to the Dynamics of El Ni**ño and the Southern *
*                                **Oscillation*, Academic Press

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- Correlation of “predictions” of NINO3.4 with observed NINO3.4 by 6 dynamical coupled ocean-atmosphere models.  The solid circles represent the Lamont model (LDEO5) [Chen et al., 2004], the solid squares the NCEP (CFS) model [Saha et al., 2006], the solid triangles and dashed lines the ECHAM-MOM model [DeWitt, 2005], the open circles the ECMWF (S2) model [Van Oldenborgh et al., 2005], the open squares the COLA model [Kirtman, 2003] and the open triangles the Korean hybrid model [Kang and Kug, 2000; Kug et al., 2001].  In most cases the “predictions” werehindcasts.  The heavy dashed line with closed circles is the persistence forecast.  [Taken from Clarke (2008)]

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- Correlation performance as a function of forecast lead for predicting the El Niño index NINO3.4:  open circles, dashed line, the Canonical Correlation Analysis model   of  Barnston and Ropelewski (1992) for the period 1957-1990; closed circles, dotted line, the Linear Inverse Model of Penland &

- Magorian (1993) and Penland & Sardeshmukh (1995) for the period 1970-1993; open circles, solid line, the Constructed Analogue (CA) model of van den Dool (1994a, 1994b) for the period 1981-2001; open triangles, solid line, the CA model for the period 1955-2001; closed circles, light dashed line, the climatology and persistence (CLIPER) model of Knaff & Landsea (1997) for the period January 1993 to November 2006; red closed circles, red solid line, the Clarke & Van Gorder model for the period 1981 to 2001.  All correlation results are cross-verified hindcasts except for the Knaff & Landsea (1997) CLIPER model for which the correlation results are from operational forecasts. Two time intervals are plotted for the CA model, one over the long  record  1955 - 2001  and the other over the more recent period 1981-2001 when the data were more accurate and complete and there were two large El Niños.  There is little difference in the lead correlations. The heavy dashed line with closed circles is the persistence forecast. [Taken from Clarke (2008)]

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## The End