# Presentation: 279058

## Global Ocean in 2008

- Prepared by
- Climate Prediction Center, NCEP
**February ****6****, 200****9**

- _[http://](http://www.cpc.ncep.noaa.gov/products/GODAS/)__[www.cpc.ncep.noaa.gov](http://www.cpc.ncep.noaa.gov/products/GODAS/)__[/products/GODAS/](http://www.cpc.ncep.noaa.gov/products/GODAS/)_

## Overview

**Atmospheric responses to SST in 2007 and 2008**
**Historical perspective (trend and decadal variability)**
**2008 special feature discussions**
**Arctic Sea Ice and SST**
**Negative PDO phase**
**North ****America**** Western**** Coast Upwelling**
**Atlantic hurricane and non-local SST Anomalies**
**Recent trends and ENSO variability**
**2007/08 La Nina Cycle Evolution and Prediction**

_**Overview**_

## Slide 3

## Slide 4

## Yearly Mean SSTA

_**Yearly Mean**__** SST**__**A**_

** ****SST cooled down (warmed up) substantially in ****the central (eastern) tropical Pacific.**
** ****The Arctic Ocean, Bering Strait, Gulf of Alaska and most of the western coast of North America also cooled down from last year, which might be related to the persistent negative PDO phase.**

** ****Negative PDO presented in North Pacific.**
** ****Positive SSTA pattern in the western tropical Pacific extends relative symmetrically into the N and S Pacific, while the eastern Pacific SSTA is asymmetric. **
** ****Positive SSTA presented in North Atlantic and tropical Atlantic.**

## Global SSH Anomaly and Anomaly Tendency

_**Global SSH Anomaly and Anomaly Tendency**_

**  ****SSHA pattern corresponds well with SSTA pattern in the Pacific except the amplitude of positive SSHA in the western tropical Pacific is much larger than that of positive SSTA there.**
**  ****Near-normal SSH in North Atlantic is associated with above-normal SST there.**
**  ****Above-normal SSH in the tropical Indian Ocean is associated with near-normal SST there.**

**  ****SSHA ****change is largely consistent with SSTA change except near the Maritime Continent and North Atlantic.**

## SST Tendency and Net Heat Flux Anomaly

_**SST Tendency and Net Heat Flux Anomaly**_

**  ****Surface net heat flux anomalies were dominated by LH+SH (not shown).**
** ****SST tendencies in North Pacific and North Atlantic were largely determined by surface net heat flux anomalies, while SST tendency in the south-eastern Pacific was likely controlled by ocean dynamics.**

** ****Compared to 2007, more heat went into the tropical ocean, and lost in the extra-tropical ocean. **

## 5-year running mean (black line)

**  ****Global SST has a downward trend since 2005, consistent with the downward trend in tropical ocean SST. **
**  ****North Pacific in 2008 was much warmer than that in 2006/2007.**
** ****North Atlantic SST has been persistently above-normal since 1995.**
** ****Southern Ocean SST has a downward trend since 2001.**
** ****NINO 3.4 SST has a downward trend since 2004. **

**5-year running mean (black line)**

## 5-year running mean (black line)

** ****SSHA in North Pacific and the equatorial Pacific have been trending downward in the past 5-7 years.**
** ****Trends in SSHA do not agree with trends in SSTA in the tropical ocean and Southern Oceans.**

**5-year running mean (black line)**

## Atmospheric Responses to SSTA(AMIP Simulations: Averaged Jan-Nov 2008)

## OBS

**OBS**

**Models**

**Z200**

** ****Consistent with cooler tropical SSTs, 200-mb heights were lower in 2008**
** ****This feature is well simulated in the ensemble of AMIP simulations, confirming the influence of tropical SSTs on heights**
** ****Lower heights in 2008, therefore, could be attributed to changes in SSTs from 2007 to 2008.**

## Models

**Models**

**Surface Temp**

**OBS**

** ****Compared to 2007, ****land temperatures in 2008 were generally on the cooler side**
** ****Once again this feature is well simulated in the ensemble of AMIP simulations, confirming the influence of SSTs**
** ****Lower temperatures over the US had an adverse impact on the official CPC seasonal sfc. Temperature forecasts in 2008**

## Models

**Models**

**OBS**

**Prec.**

** ****Observed change in the 2008 tropical rainfall, compared to 2007 rainfall, are well replicated in the AMIP simulations (e.g., suppressed rainfall near the Dateline, and the SPCZ; enhanced rainfall over the Maritime Continent; enhanced rainfall in the tropical Atlantic etc.)**
** ****Influencing role of changes in the SSTs is confirmed by the AMIP simulations**

## Special Feature Discussions

**Negative PDO Phase**
**North America Western Coast Upwelling**
**Atlantic hurricane and non-local SSTA**
**Recent trends and ENSO variability**
**2007/08 La Nina Cycle Evolution and Prediction**

_**Special Feature Discussions**_

##  Arctic sea ice extent in 2008 is the second lowest since 1979, only slightly larger than the 2007 historical low. 

** ****Arctic sea ice extent in 2008 is the second lowest since 1979, only slightly larger than the 2007 historical low. **
** ****Decreasing of Arctic sea ice extent since 2002 is associated with the above-normal SST during each summer melting season since 2002.**

## 5-year running mean (black line)

**5-year running mean (black line)**

**  ****PDO is the lowest since 1971.**

**  ****PDO has been in the negative phase since September 2007, that has lasted 17 months by Jan. 09.**

**PDO index downloaded from UW/NOAA JISAO PDO page**** **

## North America Western Coastal Upwelling from GODAS

** ****200****8**** upwelling season is ****above-****normal****.**
** ****The ****above-normal upwelling**** season is associated with the negative PDO phase.**
** ****The early onset of strong upwelling in 2008 (similar to 2007) may be the cause of high biological productivity during 2008 (****Bograd et al., 2009, GRL).**** **
** ****Upwelling has been extremely strong during winters of 2007 and 2008, and likely continue in winter of 2009.**
** ****A shift to a strong upwelling regime may have occurred in late 2005. **

_**North**__** **__**America Western Coastal Upwelling from GODAS**_

** ****Area below (above) black line indicates climatological upwelling (downwelling) season**
** ****Climatologically upwelling season progresses from March to July along the west coast of North America from 36****o****N to 57****o****N.**

**7-month running mean**

**SWFSC****, NOAA Fisheries Service**

## TNA_nolocal

**Accumulated Cyclone Energy (ACE) downloaded from http://en.wikipedia.org**

**Nolocal SST index: **
**Swanson (2008); **
**Vecchi & Soden (2007)  **

**Correlation with ACE**
**TNA_nolocal    0.64**
**TNA ****	****       0.44**
**NINO3.4         -0.11**

**  ****TNA relative to the global tropical mean SSTA is a better index for explaining Atlantic hurricane activity than either TNA or NINO 3.4 alone.**

**TNA_nolocal**

**TNA**

## Recent Trends and ENSO Variability

##   Above-normal SST has persisted in the far western tropical Pacific since 1999.

**  ****Above-normal SST has persisted in the far western tropical Pacific since 1999.**
** ****Above-normal heat content has persisted west of the Dateline since 1999.**
** ****Above-normal surface zonal winds have persisted near the Dateline since 1999.**

##   Above-normal SST has persisted in the far western tropical Pacific since 1999.

**  ****Above-normal SST has persisted in the far western tropical Pacific since 1999.**
** ****Above-normal heat content has persisted west of the Dateline since 1999.**
** ****Above-normal surface zonal winds have persisted near the Dateline since 1999.**

** ****Based on the NINO 3.4 index, there has been 3 La Nina and 3 El Nino episodes since 1999 (CPC’s web site).**
** ****All except the 99/00 La Nina lasted less than 11 months, much shorter than the duration of the major episodes in 1980-1998.**
** ****Persistent surface easterly wind anomalies were La Nina-like.**
** ****The recent trend may have altered ENSO characteristics, making them weaker and less persistent than they were before 1999.**
** ****If the trend continues, we may continue to observe short-lived ENSO events in the near future.**

## 2007/08 La Nina Cycle: Evolution and Prediction

## NINO3.4 SST Index

** ****The 07/08 La Nina has a similar strength as that of the 99/00 La Nina.**
** ****The moderate 07/08 La Nina was noteworthy since ENSO variability has been relatively weak during 01-06.**

## Evolution of Equatorial Pacific SST, Heat Content, TAUX, and Surface Zonal Current Anomaly 

** ****Both ****SSTA ****and zonal wind stress anomalies ****propagated westward****.**
** ****H****eat content  (upper 300m temperature average) anomaly ****was largely stationary.**
** ****Warming in the far E. Pac. during early spring 08 accompanied by westerly wind anomalies.**
** ****S****urface zonal current anomaly (ZCA) switched ****from westward ****to eastward in February 08.**

_**Evolution of Equatorial Pacific SST, Heat Content**__**, **__**TAUX, and Surface Zonal Current **__**Anomaly**__** **_

## JFM

_**Equatorial  Average of Heat Content (HC) and Zonal Current (ZC) Anomaly**_

**Equatorial HC**

**Western  HC**

**Eastern  HC**

**Equatorial ZC**

**JFM**

**JFM**

**NINO3.4**

**NINO3.4**

**NINO3.4**

**NINO3.4**

**Heat Content**

**Heat Content**

**Heat Content**

**Heat Content**

## Circuit Propagation of Heat Content Anomaly

_**Circuit Propagation of Heat Content Anomaly**_

**4 N**

**0 N**

**130E**

**90W**

**A**

**B**

**C**

**D**

**A**

**B**

**A**

**B**

**D**

**C**

## MJO-related Winds

** ****Strong ****MJO****-related easterly**** ****wind anomalies ****during Nov-Dec 06 contributed**** to the sudden demise of the 06/07 El Nino.**
** ****MJO-related westerly and easterly wind anomalies during summer 07 and winter 07/08 had substantial  impacts on the evolution of the event (see next slides).**

_**MJO-related Winds**_

## Oceanic Kelvin Waves: Heat Content Anomaly

** ****Upwelling Kelvin waves forced by ****MJO-related easterly wind anomaly during Nov-Dec 06 contributed to the sudden switch of heat content anomaly from positive to negative in January-February 2007.**
** ****Downwelling Kelvin waves forced by MJO-related westerly wind anomalies during ****Jan 08 contributed to the ****weakening**** of ****negative ****heat content anomaly**** in Feb-Mar 08, but were not the cause for the decay.**

_**Oceanic Kelvin Waves:**__** Heat Content Anomaly**_

## Most of statistical models missed the onset, but some dynamical models 

**Most of statistical models missed the onset, but some dynamical models **
**such as ****NCEP CFS**** forecast the cooling too early.**

**Most of models forecast the decay phase well, but ****NCEP CFS ****extended the cold phase**** ****by 2-3 months..**

## NINO3.4

**NINO3.4**

**Warm Water Volume**

**large initialization shock in Jun-Aug 07**

**too early onset in Mar-Apr**

**Mar 07**

**Apr 07**

**Jul 07**

**May 07**

**Aug 07**

**Jun 07**

## NINO3.4

**NINO3.4**

**Warm Water Volume**

**too large amplitude**

**locked into a steady La Nina phase**

**Sep 07**

**Oct 07**

**Nov 07**

**Dec 08**

**Jan 08**

**Feb 08**

** ****spring difficulty**

## Slide 32

## Data Sources and References

**  ****Optimal Interpolation SST (OI SST) version 2 (Reynolds et al. 2002) **
**  ****Merged Land-Ocean Surface Temperature Analysis (ERSST v3b, Smith et al. 2008)**
**  ****SST 1971-2000 base period means (Xue et al. 2003)**
**  ****NCEP/NCAR CDAS winds, surface radiation ****and**** heat fluxes**
**  ****NESDIS Outgoing Long-wave Radiation**
**  ****PMEL TAO equatorial temperature analysis**
**  ****NCEP’s Global Ocean Data Assimilation System temperature, heat content, ****currents (Behringer and Xue 2004)**
**  ****Aviso Altimetry Sea Surface Height**
**  ****Ocean Surface Current Analyses – Realtime (OSCAR)****‏**

## Backup Slides(monthly Indices)

## Early or Aborted IOD

## Indian Ocean Dipole Indices

_**Indian Ocean Dipole**__** Indices**_

** ****Positive ****IOD events in SON 2006 and SO 2007.**
** ****Aborted IOD event in JJA 2008, that occurred three months earlier than typical IOD events do.**

** ****Three consecutive IOD events in the past three years.**

**SON**

**SO**

**JJA**

## Slide 37

## Summer Development of Positive Meridional SST Gradient Mode in Tropical Atlantic

## Tropical Atlantic SST Indices

## Global Heat Content (0-750m) Anomaly

_**Global Heat Content (0-750m) Anomaly**_

**  ****East-west HC dipole in tropical Pacific ****due to**** 2007****/08**** La Nina**
** ****Below-normal HC in Gulf of Alaska**

**  ****HC increased ****(decreased) ****in ****western (central) tropical Pacific. **
**  ****HC increased ****(decrease) ****in ****eastern (western) ****tropical Indian**** Ocean.**
** ****The global mean difference is **

**Likely problematic due to lack of observations**