Information of the forecast/hindcast system
 (More details are on http://www.bom.gov.au/bmrc/ocean/JAFOOS/POAMA/index.htm)
 
Predictive Ocean Atmosphere Model for Australia (POAMA) is a state-of-the-art seasonal 
to inter-annual seasonal forecast system based on a coupled ocean/ atmosphere model.
POAMA was developed in a joint project involving the Bureau of Meteorology Research 
Centre (BMRC) and CSIRO Marine Research, with support provided by the Climate 
Variability in Agriculture Program (CVAP), a consortium of rural research and 
development corporations managed by Land and Water Australia. The core of the research 
has been carried out by scientists from the Oceanography Group at BMRC and scientist 
from the Oceans and Climate Group at CSIRO Marine Research.

The POAMA system is used in real- time by the Bureau of Meteorology to produce an eight- 
month forecast every day. One of the special features of POAMA is that it uses the very 
latest observations from the world-wide ocean and atmosphere observing systems, right 
up to the last day. For example, the forecasts will have built into them the atmospheric 
and oceanic events that have taken place over the last week.

Components of the POAMA-1 system are: 

a Atmosphere model: The POAMA-1 system uses the latest version
of the Bureau of Meteorology unified atmospheric model (BAM version 3.0d). It uses a modified
convection closure that allows the model to have a good representation of the MJO. It has a horizontal
spectral resolution of T47 and has 17 vertical levels. The performance of this model forced with
observed SST is described in Colman et al (2005).

b. Ocean Model: The ocean model component is ACOM2. It was developed by CMR, and was based on the
Geophysical Fluid Dynamics Laboratory Modular Ocean Model (MOM version 2). The grid spacing is 2
degrees in the zonal direction. The meridional spacing is 0.5° within 8° of the equator, increasing
gradually to 1.5° near the poles. There are 25 levels in the vertical, with 12 in the top 185 metres.
Technical details of ACOM2 are given in Schiller et al., 1997 and Schiller et al., 2002.

c. Coupler: The ocean and atmosphere models were coupled using the Ocean-Atmosphere-Sea Ice-Soil
(OASIS) coupling software (developed by CERFACS, France; Valcke et al., 2000). 

d. Ocean data assimilation:  The ocean data assimilation scheme is based on the optimum interpolation
(OI) technique described by Smith et al., (1991). Only temperature observations are assimilated and
only measurements in the top 500m are used. There are several improvements over the scheme described
by Smith et al., (1991). The OI scheme is used to correct the model background field every 3 days
using a 3 day observation window, one and a half days either side of the assimilation time. Ocean
current increments are calculated by applying the geostrophic relationship to the temperature
corrections, similar to the method described by Burgers et al. (2002).

e. Atmospheric initial conditions:  For the real time forecasts the atmospheric component is
initialised with weather analyses from the Bureau of Meteorology's operational NWP system (GASP). This
means that the seasonal forecast model knows about the latest intra-seasonal variability in the
tropical atmosphere. 


4)Ensemble size 30 members for forecast  (run daily so ensemble of last 30 days)
Hindcast: one forecast permonth. 
(Ensemble of 15 hindcasts permonth for POAMA1.5 which is currently being run and which will replace
POAMA1 in early 2007)


6)List of parameters being
assessed T2m (temperature at 2metres) and prp (precipitation) SST (Sea Surface Temperature)

7)Lead times and for each parameter
0, 1, 2, 3, 4-month, 


9)Number of hindcasts and the dates/years of
these hindcasts 18 years from 1987 to 2001 inclusive

10) Details ofverification data sets used T2m: ERA40
Precipitation: XieArkin.  
SST: Reynolds
(ALL datasets are obtained from and described on the SVS-LRF Website:
http://www.bom.gov.au/wmo/lrfvs/datasets.shtml )