# Presentation: 834320

## Seasonal Prediction Research and Development at the Australian Bureau of Meteorology

**Guomin Wang**
- With contributions from Harry Hendon, Oscar Alves,
- Eun-Pa Lim and Claire Spillman
***Centre for Australian Weather and Climate Research:******A partnership between the Bureau of Meteorology and CSIRO***

## Outline

- POAMA (**P**redictive **O**cean **A**tmosphere        	**M**odel for **A**ustralia)
- Australian Rainfall Prediction
- Leeuwin Current Prediction

## POAMA Overview

- The Bureau Dynamical Seasonal Prediction System POAMA
- First version went operational in 2002
- A new version (POAMA1.5) became operational recently and a newer version is in development
- POAMA development evolves as part of Australian Earth System Modelling project ACCESS
- Webpage  _POAMA.BOM.GOV.AU_

## POAMA Model Components

- Atmospheric Model
- BAM T47L17 -> T63L17 -> ACCESS(UKMO+LSM)

- Ocean Model
- ACOM2 lat/lon/lev=0.5~1.5/2/25 -> AusCOM

- 3h

- OASIS Coupler

*Heat flux, P-E*

*time*

## Hindcasts Design

- Control run initialized at 00Z on the first day of each month, 1980-2006
- Extra 9 members initialized prior to control run initial time in progressively 6 hours interval
- Each hindcast is integrated for 9 months (lead 1-9)

## Skill Assessment: ACC for SST and Heat Content

**+1**
**+3**
**+5**

**    ****SST****	****	****  ****	****	****    ****	****H300****	**

## Nino3.4		            	IOD

- Nino3.4		            	IOD

- ACC
- RMS

**Skill Assessment: ****ACC for SST Pacific & Indian Ocean Indices**

## El Nino Vintage and Impact on Australian Rainfall

- Wang and Hendon (2007)

- Correlation between Australian drought index and SST

- 1997                  2002

**El Nino Vintage and Impact on Australian Rainfall**

**Notes:**
Rationale behind our attempt to bridge the tropical SST to regional australian rainfall is based on the fact that the predictibility of eastern Australina climate comes from ENSO in winter and spring. Furthermore, it’s been shown in Wand and Hendon’s paper that year 2002 drought was associated with SST anomalies over the dateline rather than SST anomalies over Nino 3 region. Therefore, it is important to get the correct details of the SST variations.
Also,  accurate prediction of the SST variations remotely associated with ENSO is also important for better prediction of Australian seasonal rainfall. 

And good news is POAMA has a world competitive skill in the prediction of ENSO. 

## Classic El Nino 

   Nino 3 Index – SSTA over the Nino3 region (210E-270E, 5S-5N)

-    **Nino 3 Index** – SSTA over the Nino3 region (210E-270E, 5S-5N)

**El Nino Modoki**
-    **EMI = [SSTA]****Central**** – (0.5[SSTA]****East**** + 0.5[SSTA]****West****)**

- (from Weng et al. 2007)

- El Nino: Classic vs Modoki

## El Nino Skill: Classic vs Modoki

##  El Nino Modoki events (EMI >= 0.7 STD): 86, 90, 91, 93, 94, 02, 04

-  El Nino Modoki events (EMI >= 0.7 STD): **86, 90, 91, 93, 94, 02, 04**

-  Classic El Nino events: **82, 87, 97**

**R ~ 0.86 at LT1**

**R ~ 0.83 at LT1**

## SST Forecast Composites

- OBS (SON)

- POAMA LT 1 (1st Sep Start)
- POAMA LT 3 (1st Jun Start)

**SST Forecast Composites**
**	****Classic El Nino                        ****	****	****	****El Nino Modoki**

## Australian Rainfall Forecast Composites

- OBS (SON)

**Australian Rainfall Forecast Composites**
**	****Classic El Nino                        ****	****	****	****El Nino Modoki**

- POAMA LT 1
- POAMA LT 3

## Cases 1997 vs 2002

-        1997                                            	2002

## Seasonal Prediction of the Leeuwin Current: Observed Features

**Freemantle sea level (FSL) is indicative of volume transport variation of the leeuwin current (M. Feng). **
**Use FSL as a proxy for Leeuwin Current strength.**

**Notes:**
The Leeuwin is one of four currents influencing life in the Australian region by regulating rainfall and temperature, fostering coastal recreation and distributing marine species. 

## Annual Mean of SST & top 300m Currents from Reanalyses 

-   Eq
- 20oS
- 40oS

- POAMA SST and UV300 clim 1982-2003

- 90oE                          120oE

- GODAS SST and UV300 clim 1982-2003

- ECOR SST and UV300 clim 1982-2003

- Annual Mean of SST & top 300m Currents from Reanalyses

- 90oE                          120oE

-            POAMA			     GOGAS/NCEP	        ODA/ECMWF

## Fremantle Sea Level and Ocean Heat Content Observation vs Forecast Skill

- Obs relationship between H300 and SLA at Freo

- H300 ACC Skill at leadtime=7

**HCNW = 15-25****o****S,112-120****o****E**

## Fremantle Sea Level and SST Observation vs Forecast Skill

- Fremantle Sea Level and SST ***Observation vs Forecast Skill***

**N34 = 5****o****S-5****o****N; 170****o****-120****o****W**

## Downscaling POAMA Forecasts to Fremantle SLA

**Downscaling POAMA Forecasts to Fremantle SLA**

## Skill of Fremantle SLA Prediction from Downscaling Scheme 

- 	NWHC
- 	Both Combined
- 	Persist

**Skill of Fremantle SLA Prediction from Downscaling Scheme**** **

## FSLA Forecasts 1982-2006

-  82    83   84    85   86   87   88    89   90   91   92    93   94   95    96   97    98   99   00    01   02    03   04   05   06
- Years

**FSLA**** Obs**
**FSLA Lead 3**
**FSLA Lead 6**
**FSLA Lead 9**

## Summary

**Introduction of The Australian Bureau’s Dynamical Seasonal Prediction System POAMA.**
**POAMA has higher skill for SST in Pacific and for heat content along NW Australia.**
**POAMA can predict short term El Nino vintage and respective Australian rainfall responses.**
**Using POAMA forecasts a downscaling scheme shows useful seasonal forecast skill for Leeuwin Current strength.**

## Summary

- Each El Nino event has different flavour
- The impact of the central Pacific warming El Nino (represented by El Nino Modoki Index) is as important as the traditional eastern Pacific warming El Nino for Australian rainfall
- POAMA has good skill to predict:
-    - the occurrence and the detailed SST structure of the central Pacific El Nino and the traditional El Nino events
-    - the Australian rainfall difference affected by these two types of El Nino events
-    - 97 and 02 El Nino events and associated Australian rainfall  the skill stems from the improved atmospheric initial conditions by ALI and the model’s atmosphere-ocean coupling ability.