PEAC Seasonal Sea Level Outlook

The following sections describe: (i) the Canonical Correlation Analysis (CCA)-based forecasts for the monthly MEAN and MAXIMUM sea level deviations in the October - November - December (OND) 2009 season, and (ii) the monthly sea level deviations observed in the previous season (July - August - September 2009). See Figure 2 at right for location of USAPI tide guage stations.

All units are in inches. 'Deviation’ is defined here as 'the observed or forecast difference between the monthly mean [or maximum] and the climatological monthly mean values (from the period 1975- 1995) computed at each station’. Also, note that the forecasting technique adapted here does not account for sea level deviations created by other atmospheric or geological conditions such as tropical cyclones, storm surges or tsunamis.

Based on the independent SST values observed in the July - August - September 2009 season, the resulting CCA model has been used to forecast the sea-level for the OND 2009 season (see Table 1).

Table 1 : Forecasts of MEAN and MAX sea level deviation in inches for OND 2009

Tide Gauge Station	Forecast Deviations for Oct-Nov-Dec (OND) 2009
	MEAN Deviations (in inches) with Standard Deviations in parenthesis	MAX Deviations (in inches) with Standard Deviations in parenthesis
Marianas, Guam	-0.4 (4.0)	+16.7 (3.5)
Malakal, Palau	+0.7 (4.0)	+36.6 (4.1)
Yap, FSM	-0.2 (4.1)	+27.1 (4.1)
Chuuk, FSM**	0 (NA)	0 (N/A)
Pohnpei, FSM	+1.4 (4.7)	+31.9 (4.9)
Kapingamarangi, FSM	+3.3 (3.1)	+31.6 (3.8)
Majuro, RMI	+2.0 (3.7)	+42 (3.8)
Kwajalein, RMI	+0.6 (3.1)	+38.5 (3.2)
Pago Pago, American Samoa	+2.5 (2.5)	+26.4 (2.2)
Honolulu, Hawaii	+2.9 (1.8)	+21.6 (2.6)
Hilo, Hawaii	+3.6 (1.8)	+24.4 (2.2)
() Data Unavailable.* Values for Chuuk () are guesstimated based on estimates from neighboring tide stations and observations from WSO Chuuk. Deviations between 0~±1 inch are considered to be negligible and are denoted by *. Deviations withing the range of (+/-) 2 inches are unlikely to cause any advers climatic impact. Remarks: The forecast values for OND provide a clear indication of considerable fall in all stations. Some stations (Guam, Yap) are likely to record negative deviations in the forthcoming seasons. This trend is supportive to the moderate-to-strong El Nino condition. *N.B. We have received data for Pago Pago. The data for Kapingamarangi is still missing*

(ii) Observed Monthly Sea Level Deviation in July - August - September(JAS) 2009

The monthly time series (July - September 2009) for sea level deviations have been taken from the UH Sea Level Center. As compared to August 2009, the mean/maxima of sea-level in September 2009 recorded a fall in most stations. In general, the sea-level at all the USAPI stations remains slightly elevated (based on 1975-95 mean), but there is a clear trend of sea-level fall. Conversely, the Hawaiian stations recorded a slight rise and currently portray positive deviations.

Tide Gauge Station	Observed Deviation from MEAN			Observed Deviation from MAX
	Jul.	Aug.	Sep.	Jul.	Aug.	Sep.
Marianas, Guam	+8.2	+5.9	+4.7	+23.8	+21.3	+18.9
Malakal, Palau	+5.7	+4.3	+5.1	+39.4	+41.6	+40.4
Yap, FSM	+4.1	+4.3	+2.7	+31.6	+32.4	+29.8
Chuuk, FSM**	*	*	*	*	*	*
Pohnpei, FSM	+3.9	*	*	+33.6	*	*
Kapingamarangi, FSM	*	*	*	*	*	*
Majuro, RMI	+2.0	*	*	+43.5	*	*
Kwajalein, RMI	+2.7	+2.0	+1.1	+40.9	+38.9	+37.2
Pago Pago, American Samoa	*	*	+4.2	*	*	+27.2
Honolulu, Hawaii	+0.7	+2.8	+2.4	+22.6	+23.2	+17.7
Hilo, Hawaii	+0.6	+5.1	+1.6	+26.8	+27.7	+18.8
* Denotes where data is unavailable. ** Sea level data for Chuuk is based on estimates from neighboring tide stations (Yap and Pohnpei) and observations from WSO Chuuk.

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