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WAVE CLIMATE OF FIJI

Stephen F. Barstow and Ola Haug OCEANOR’

November 1994 SOPAC Technical Report 205

’ OCEANOR Oceanographic Company of Norway AS

Pir-Senteret N-7005 Trondheim

Norway

The Wave Climate of Fiji

Table of Contents

1 . INTRODUCTION .................................................................................................... 2

2 . SOME BASICS ....................................................................................................... 3

3 . OCEANIC WINDS ................................................................................................... 4 3.1 General Description ............................................................................................................... 4

3.2 Winds in the source region for swell ..................................................................................... 5

4 . OCEAN WAVES ..................................................................................................... 8 4.1 Buoy Measurements .............................................................................................................. 8

4.2 Ocean Wave Statistics .......................................................................................................... 9

5 . SPECIAL EVENTS ................................................................................................ 15 5.1 Cyclone Joni, December 1992 ............................................................................................. 15

5.2 Cyclone Raja, December 1986 ............................................................................................ 15

5.3 Cyclone Bola, February - March 1988 ................................................................................. 18

5.4 Swell .................................................................................................................................... 18

6 . CONCLUSIONS .................................................................................................... 20

7 . RECOMMENDATIONS ......................................................................................... 22

8 . ACKNOWLEDGEMENTS ..................................................................................... 23

9 . REFERENCES ...................................................................................................... 24

APPENDIXA TIME SERIES PLOTS OF WAVE AND WIND PARAMETERS; 1991 -93

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1. Introduction

The South Pacific Applied Geoscience Commission (SOPAC) acting through its Secretariat in Suva, Fiji, embarked on a wave data collection program in 1987 with the aim to map the ocean wave climate off the shores of several South Pacific island nations. The principal application of the wave data was seen to be the mapping of the wave energy resource of the islands needed to study the feasibility of developing wave power as a future energy source.

In the present report, data from the wave measurement programme, recorded by a Waverider buoy, moored off the southern coast of Kadavu Island in the Fijian archipelago are combined with satellite altimetric data and island wind measurements in building up a picture of the climatology of ocean waves in the Fiji group. Wave data from special events such as Tropical Cyclones and energetic swells are highlighted. Influence of the El-Nino Southern Oscillation phenomenon on the wave climate is also discussed.

Companion reports describing the ocean wave climate of Western Samoa, Vanuatu, Tuvalu, the Cook Islands and Tonga are also available. Further, a report has been produced discussing region-wide differences in the wave climate, entitled The Wave Climate of the South West Pacific (Barstow and Haug, 1994a) also giving further details on the various data sources used, in particular, the GEOSAT satellite altimeter data. It is recommended that readers should acquaint themselves with this report first before reading the present one.

This report was produced by the SOPAC Secretariat with assistance from the Oceanographic Company of Norway AS (OCEANOR) and the Norwegian Hydrotechnical Laboratory (NHL). The work was financed by the Norwegian Agency for International Development, NORAD.

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2. Some Basics The ocean waves we are concerned with here are those waves generated by wind as opposed to tsunamis (or tidal waves) which are generated by subterranean seismic activity or landslide and the tides caused by the gravitational attraction of the moon and sun on the earth. In the South Pacific ocean wind waves are always present, it never being perfectly calm, and the energy involved is obvious to anyone at the coast as wave after wave dissipates on the reef or beach. Ocean waves have a typical range of wave periods from 2 secs. (short wind waves) to 25 secs. (long swell).

The generation of ocean waves in response to wind depends both on the wind speed, the fetch or distance over which the wind blows and the duration of the wind in a given direction. A shift in wind direction leads to new waves growing in the new direction. There is, however, a limit to the growth of wind waves for a given wind speed. If the wind blows long enough over a long enough fetch the waves reach the so-called fully developed state.

Storm waves once created are known to attenuate very slowly and can travel many days across the ocean before dissipating on some distance shore. Ocean waves are known as swell away from their generation area.

The classic studies of Ocean swell propagation were carried out in the Pacific during the early 1960s (e.g., Snodgrass et all 1966) confirming the prediction of the linear wave theory that ocean waves travel across the ocean with a speed which increases with increasing wave period or wavelength. In a storm area waves of a range of wave periods are generated. When this spectrum of waves leaves the storm area, the longer waves travel faster, so that an observer at a distant point will detect the longer period swell waves first.

In reality, at a given location on the shore of a Pacific island, waves may be present arising from several different wind systems such as the local trade winds, storms in the southern ocean or northern Pacific, and occasionally from tropical cyclones. The exposure of the actual location is also very important, so that a location on the northern coast of an island will only experience swell from the northern hemisphere due to the island sheltering the location from southerly swell. It is, therefore, important to understand the variability of oceanic winds on different time scales in both the local area and source areas for swell in order to understand the variability of the wave climate. This is discussed in the next section.

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3. Oceanic Winds

3.1 General Description

A good overview of the wind climate of the South Pacific is to be found in Van Loon (1984). Another useful reference is Harrison and Luther (1 990) who presented climatological monthly mean winds from 33 island stations in the Pacific. The data were quality controlled by comparing neighbouring stations and long term averages from ship observations near to the islands. Generally, agreement is very good with differences generally no more than about 1 m/s in speed and 10 degs. in direction. Unfortunately, no station in the Fijian archipelago was analysed in that study.

The only digitised wind data for the Fijian group that could be located was data held by NlWA in New Zealand for the two airports at Nadi and Nausori. Both of these stations are, however, severely influenced by local topography and other land effects and cannot therefore be considered to be representative of ocean conditions around Fiji. It was, therefore, decided to digitise paper charts, provided by the Fijian Meteorological Service, from meteorological stations on the outlying islands. Data from stations at Udu Point, on the north west tip of the second largest island of Vanua Levu, from the airport at Vunisea on Kadavu Island and the island of Matuku (1 8.6"S, 179.75"E) were digitised with assistance from the Fijian Ministry of Energy. Examination of wind statistics from the 3 sites revealed that at Vunisea the site is affected by surrounding high ground, and that relatively low wind speeds at Matuku suggest a poorly exposed anemometer. It was concluded that the Udu Point data is the most representative of open ocean conditions and only this data set is used in the analysis of wind data in the following. It should be borne in mind that Udu Point is at some distance from the wave measurement site at Kadavu Island and should only be considered as indicative of general conditions in the Fiji group.

The monthly wind climatology at Udu Point is summarised in Fig. 1. Winds are predominantly south easterly to easterly throughout the year. South easterlies are much more frequent in winter. In summer, north easterlies and north westerlies are also quite frequent. Wind speeds are lowest in January to March and highest in July to August.

The Southern Oscillation Index (Sol) describes the well known pressure oscillation between the western part of the South Pacific, represented by Tahiti and the eastern part (Darwin in Australia), and is intimately related to the El-Nino phenomenon. When air pressure is relatively high at Darwin the SO1 is negative. A time series of the monthly SO1 is shown from 1971 to the end of 1992 in Fig. 2 together with monthly wind speed, meridional and zonal wind components for the same period. The major 1983 event is clearly seen as well as more moderate events in 1987 and a rare two year event in 1991 -1 992. These negative SO1 episodes occur about every 4-5 years on average.

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Fig. 1 Climatological statistics for winds at Udu Point, Vanua Levu, Fiji. U is the zonal (E- W) component veioclty and V the meridional (N-S) component veloclty.

Examination of Fig. 2 shows that during the two most severe El-Ninos in 1983 and 1987, south easterlies were more frequent throughout the year (more positive meridional wind speed than normal) particularly during summer. On the other hand, positive SO1 tends to give more frequent northerlies during summer.

Concerning the representativity of the wave measurement period at Kadavu with respect to long term wind conditions, it is unfortunate that synoptic wind data are only available for June 1991 to February 1992 after which time only daily average winds are available. It is clear, however, that 1991 - 1992 was an unusual climatic period due to the occurrence of a rare double-year El-Ninio. During the period for which winds are available, lower wind speeds were experienced than normal and, during winter 1991 - 1992, south easterlies were more common than normal as is usual during El-Nino years.

Tropical cyclones occur occasionally in the Fiji group, mostly from November to April. On average, a little over one cyclone per year affects some part of the group, some of which cause considerable damage.

3.2 Winds in the source region for swell

The region of higher latitudes to the south and southwest is the most important source area for ocean swell observed on the southern shores of the Fiji group. An attempt has been made to quantify the variability of ocean swell on the southern shores of Fiji by looking at long term wind measurements in the source area. Unfortunately, there are very few meteorological stations in this area. The two stations most representative of open ocean conditions are those on Chatham Island at 44"S, 176.6"W, which is about 600 km to the south east of Wellington in New Zealand, and Campbell Island at 52.6"S, 169.2"E, about 650 km to the south of lnvercargill on the southern tip of South Island, New Zealand. Time series of wind speed and direction were obtained from NlWA (National Institute of Water and Atmospheric Research Ltd.) in New Zealand for the period April 1964 to February 1993 for Chatham and July 1941 to February 1993 for Campbell Island.

It was decided to compute a southerly monthly gale index defined by the number of days in each month when wind speed exceeded 10 m/s from the 170-230" sector at Chatham and 15 m/s from 200-260" at Campbell. Such winds could potentially generate waves later appearing as swell off Fiji.

The seasonal variation of this gale index at the two island stations is shown in Fig. 3 both for the long term (solid line) and for the months with wave measurements at Kadavu.

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Fig.2 Time series of a) Southern Oscillation Index from 1980 to 1992; b) wind speed; c) meridional and d) zonal wind speed components from Udu Point.

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Fig. 3 Southerly gale Index from Campbell and Chatham Island long term wind data (solid Iine) and for the duration of the wave measurements (dashed line). For Campbell the index is defined as the mean number of days in each month for which wind speed exceeds 15 m/s from 200-260"; for Chatham 10 m/s and 170-230".

Strong southerlies appear to occur at different times of the year at the two meteorological stations. At Campbell Island the gale index peaks in autumn and spring with lower frequencies in mid-winter and summer. At Chatham Island, May and June are the months with most frequent south westerly gales. In December and January, south westerly gales occur about half as often.

During the wave measurement period, the gale index at Chatham Island was higher than normal early in the year (February and March) and significantly less gales than normal were experienced from August to November. At Campbell, gales were less frequent than normal in May and from August to December. Combining the two statistics we find that southerly gales were most frequent around New Zealand during February to April and July. Gales were almost absent during January, August to October and December.

It has also been investigated whether there is any relationship between the gale index and the Southern Oscillation Index (section 3.1). This analysis based on 32 years of data (1 961 -1 993) revealed almost no correlation between the two indices overall. The time series plots in Fig. 4 show time series of the two indices from 1961 to 1993. This shows that some El-Niino years (SOI- ve) do coincide with a greater frequency of southerly gales. The 1987 El-Nino is a good example with more than average gale index for 6 months at Campbell Island. On the other hand, in the exceptional 1983 El-Niino more frequent southerly gales did not occur.

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The Wave Climate Fiji

Fig.4 Time series of the southerly gale index(solid line) and the Southern Oiscillation Index for a) Chatham Island and b) Campbell Island; 1961-1963

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4. Ocean Waves

4.1 Buoy Measurements

Wave measurements were carried out to the south west of Kadavu Island, which is located to the south of the main island Viti Levu (Fig. 5), between 7th June 1991 to 15th October 1993 with a Waverider buoy. The buoy was moored in position 19O1 8.4'S, 177O57.4'E (Fig. 5) in a water depth of 356 m. Full details of the measurements and the data analysis together with comprehensive statistics can be found in the data reports (Barstow and Olsen, 1992; Olsen and Selanger, 1993, 1994). Time series of wave parameters together with wind measurements from Udu Point are presented in Appendix A.

The Fiji Ministry of Energy initiated their own wave measurement program in December 1993 with directional wave measurements (at position 1 in Fig. 5) simultaneously with Waverider measurements on the south coast of Kadavu (Naidrodrodro Pt.). Measurements were also made at Matuku Island during April - July 1994. The Ministry of Energy measurements are not covered by this report.

Time series of selected wave parameters for the duration of the measurement period are to be found in Appendix A. A brief definition of the various wave parameters are given below:

S(f): Wave spectrum (m's). Based on a 17 min. registration of the wave elevation relative to mean water level. The wave spectrum is computed using the Fast Fourier Transform over the frequency range f = 0.025 to 0.5 Hz (wave period, T = 1 9 .

HmO: Significant wave height (m). This is numerically close to the classical definition of significant wave height which is the height of the 1/3 highest waves during the 17 min. measurement period. HmO is computed from the wave spectrum as follows:

HmO = 4(IS(f)df)l"

Tp: Peak wave period (s). This is the wave period at which the wave spectrum attains its maximum value.

Tm-IO: Energy period (s). There are many definitions of wave period. Tm-10 tends to be

Tm-10=m-,/m0

somewhat higher than Tm02. It is computed as follows:

where

mn = J S(f)fndf

Tm-IO is used in the computation of wave power.

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Tm02: Mean wave period (s).

Tm02 = ,/= JT: Wave power (kW/m)

JT = 0.49Hm02Tm -1 0

Hmax: Maximum wave height (m). Maximum wave height is the height of the highest single wave during a wave record. It is typically 1.4 - 1.6 times the significant wave height for 17 min wave records.

Fig. 5

4.2 Ocean Wave Statistics

The monthly variation of various wave parameters measured by the Waverider at Kadavu are shown in Fig. 6. Note that there was relatively low data recovery in certain months with only one month of data available for January to March, two months in April, May and October to December and three months during the winter months. This means that the monthly variation of wave parameters cannot necessarily be considered to be representative for the long term particularly when we consider that the weather patterns have been unusual during the measurement period (Section 3.1).

Location of the wave buoy (position 1) south-west of Kadavu In the Fiji group.

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Fig.6 Annual variation of a) Significant wave height, HmO, b) Energy period, Tm-10, c) Wave Power, Jt and d) Number of wave records for the wavwrider measurements at Kadavu Island, Fiji.

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The highest monthly mean wave heights are, surprisingly, in March and April. We expect highest waves in this area during mid-winter as at that time of year wind speeds are highest on average and more south easterly (the buoy location is more sheltered for north easterly wind seas), and also swell influx tends to be highest. The reason for this unexpected result is that weather conditions were unusual in the South West Pacific in March-April 1992, probably as a result of the El-Niiio of that year.

A clue to the unusual wave conditions is that March 1992 was also the coldest March on record in New Zealand due to southerly winds for most of the month. It is likely that the high wave heights observed at Kadavu at this time were a result of the abnormal weather further south manifesting itself as higher swell than normal. This is given support by the fact (section 3.3) that gales off New Zealand were more frequent than normal during March and April during the measurement period. This was also the case in July which was the third highest wave month. However, the use of this relatively simple gale index as a swell indicator is not always successful as is the case with February when frequent gales were registered off New Zealand but wave conditions at Fiji (and Tonga) were not exceptional. Inspection of weather charts shows that the weather picture was dominated by high pressure over the Tasman Sea and low pressure in the Southern Ocean to the south east of New Zealand for much of the period March-April 1992 with strongest winds to the east and south east of New Zealand. The Waverider on the south coast of Tongatapu also recorded high wave heights for the time of year during the same period (Barstow and Haug, 1 994a).

Fig. 7 shows that wave conditions at Kadavu and Tongatapu were very similar in March to April 1992 suggesting the same source of wave energy. Trade winds were more persistent from the east than normal in March-April 1992 (ref. measurements at Tongatapu, Barstow and Haug, 1994b). As the buoy location at Tongatapu is sheltered from the easterly wind seas, this confirms that the high wave conditions in March-April 1992 was due to higher swell levels.

Fig. 7 Time serles of significant wave height at a) Tongatapu and b) Kadavu during February to March 1992 showing a high degree of correlation in March - April.

Wave height data from the GEOSAT satellite altimeter (see Barstow and Haug, 1994a for more details on these satellite measurements of waves and winds) have been analysed for the period November 1986 to September 1989. Average wave heights in the sea area to the south of Kadavu, and also to the north of the main islands, are given in the table below for 2 month periods.

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Table 1 Mean significant wave height south and north of Fiji on a bi-monthly basis derived from the GEOSAT data from 1986-89.

The seasonal variation in wave heights derived from the satellite data is similar to that from the buoy with highest values from March-August and significantly lower wave heights over the remainder of the year. The period for which the GEOSAT data are available (1 986-89) contains a fairly intense El-Nino in 1987. We have suggested earlier that high buoy measured wave heights in March-April 1992 were a result of higher than normal swells from persistent southerly gales off New Zealand which in turn were a result of El-Niiio induced weather patterns. However, similar high swells did not occur during the 1987 El-Nino. In fact relatively high wave heights in March- April in the GEOSAT data are due to high levels in 1988 rather than 1987 (Fig. 8). In 1987, unusually high wave heights affected the Cook Islands further to the east (Barstow and Haug, 1994c) particularly in March-April. Thus, there is no simple relationship between El-Nino and wave heights in the South Pacific but in both 1987 and 1992 El-Ninos, wave heights were higher than normal somewhere in the region.

Year Fig. 8 A composite of monthly mean significant wave height for a) GEOSAT Altimeter

data averaged over the sea area to the south of Kadavu (+) and b) Waverlder data (A).

The satellite data also allows us to estimate the wave conditions elsewhere in the Fiji group. To the north of the group Table 1 shows the seasonal distribution of wave heights. Wave heights are in general lower due to this area being sheltered from southerly swell. Wave height is also more steady through the year being more akin to the wave climate of near equatorial waters. The statistics in Table 1 is an area average between 177-180"E and 14.5 to 16.5"s. The monthly variation over this area is shown for the duration of the GEOSAT mission in Fig. 9. Although the spatial average shows little temporal variation, there is in fact a strong gradient in wave height towards the northern shores of the group. This is illustrated in Fig. 10 which shows the mean significant wave height along GEOSAT ground tracks for 1986-89 around the Fiji group. The satellite follows a so-called exact repeat orbit returning to the same ground track each 17 days. Northern coasts are also somewhat sheltered from easterly wind seas, having a more westerly aspect, with the result that mean significant wave height drops to around 1.3 m close to the

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coast. An indication of wave conditions in other parts of the Fiji group can also be determined from this figure.

In Fig. 6, the seasonal variation of the mean wave period (Tm-10) was also shown. It is seen that wave periods are somewhat higher in winter, particularly May-June, at about 9.5 secs., declining to about 8.5 secs. in summer and reflecting the greater long period swell contribution in the winter months.

The product of significant wave height squared and the mean wave period is proportional to the wave power (kW/m). During the measurement period the monthly average wave power (Fig. 6) varies from 15 kW/m to almost 35 kW/m (in March), but, more typically, lies around 25 kW/m in the winter months and 17.5 kW/m during summer.

Coastal wave power levels will be a little lower than the numbers quoted above on the southern coasts in the Fiji group than the values above depending on the exposure of the site in question. On the northern coasts of Fiji we do not expect significantly more than 5-6 kW/m with, perhaps stronger seasonality than shown by the satellite data above due to variation in northerly swell levels throughout the year. Northerly swells occur mostly during the northern hemisphere winter (October-March) .

Offshore wave direction is important in determining the coastal power levels at any given location. Directional wave measurements have recently been made by the Fiji Ministry of Energy in the buoy location to the south of Kadavu. However, these data are not included here and will be reported separately. However, wave directions reflect the main sources of wave energy, i.e. predominantly southerly swells and east to south easterly wind seas.

Year

significant wave height from the GEOSAT altimeter averaged over 177 to 180 E for 1986 to 1989

Fig. 9 Monthly mean 14.5 to 16.5S,

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I I A A

I I I I


5. Special Events In this section, available wave data during tropical cyclones affecting the Fiji group are described. During the Waverider measurement period south of Kadavu very high sea states were recorded only on one occasion, during Tropical Cyclone Joni in December 1992. Further, 4 m seas occurred in November 1991 associated with Cyclone Tia as it moved east of the Vanuatu group (see Barstow and Haug, 1994d) and Cyclone Fran passed in a south westerly direction to the north of the Fiji group on 8th March 1992. This is described in section 5.1. This is followed by a description of cyclone data obtained from the GEOSAT satellite during 1986-89.

5.1 Cyclone Joni, December 1992 Cyclone Joni developed in the Tuvalu group on 6th December 1992 and moved first on a south west track (Fig. l l b ) , then south passing close to the Yasawa group in northwest Fiji, subsequently curving around the south west corner of Viti Levu before passing directly over the island of Kadavu close to the Waverider measurement site. Eyewitness reports from the island the day after the cyclone related to one of the authors confirmed the passage of the eye of the storm over the island with very high winds from one direction, followed by a calm and then very high winds from the opposite direction (the eyewitnesses went for a walk during the calm thinking it was all over!). The cyclone was luckily fairly moderate in strength so that damage on the island was limited to wave-induced erosion, loss of a few trees and crop damage. The wave data (Fig 12a) shows a very rapid increase in significant wave height on the 1 1 th, peaking at midday, at the time of nearest approach of the storm, at 7.2 m with a peak wave period a little under 10 seconds. The intense relatively short duration winds produced very high steep waves.

5.2 Cyclone Raja, December 1986

The only cyclone to severely affect Fiji during the lifetime of the GEOSAT satellite (1986-1989) was Cyclone Raja, which developed in the Tuvalu group around 21 st December 1986. It followed an erratic track, passing Rotuma on its way south early on 24th (Fig. 12). It performed a loop close to the Futuna group (1 4.2"S, 178"W) during 26th-29th, attaining hurricane strength on 27th (Krishna, 1987). On 26th at about 0300 UTC a GEOSAT ground track passed within about 15 km of the eye of the storm. The wave data are shown both as a colour coded track in Fig. 12a and as a time series plot in Fig. 13 where both significant wave height and wind speed are plotted as a function of latitude.

The satellite passes southwards towards Fiji and wave heights gradually increase as GEOSAT approaches the Futuna group, reaching a peak of 8-9 m significant wave height just north of the islands. Winds also increase reaching Beaufort 11 just north of the islands. As the satellite passes over the land the altimeter wave sensor is disturbed and takes some time to re-adjust to the signal again, resulting in the loss of some data. Data flow is resumed just north of the closest approach to the eye of the storm, and we see the characteristic drop in wind speed towards the storm centre followed by a rapid increase again to the south reaching hurricane force. Krishna (1987) estimates maximum sustained winds of 70-75 knots associated with this storm. The satellite winds, which reach over 40 m/s, are possibly a little too high but do seem reasonably consistent with the storm position and suggests a size of about 200 km (path length with higher

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than ambient wind speeds). Wave heights are as expected lower at about 3 m in the relatively sheltered Lau group to the south of the storm than in the open seas to the north although wind speeds are similar in both regions.

Fig. 11 a) Time series of significant wave height and peak wave period during the passage of Cyclone Joni on December 1 l t h 1992. The ground track of the storm is shown In b). All times are local Fijian time (UTC + 12).

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b)

14.0 13.0 12.0 11.0 10.0 9.0 8.0 7.0 6.0 5.0

-10.0

-15.0

-20.0

-25.0

-10.0

-15.0

20.0

-25.0

175.0 180.0 165.0 1 90,Q fig. 12 a) Satellite significant wave height measurements exceeding 5 m close to the track

of Tropical Cyclone Raja. The Location of the storm centre at 0000 UTC on each day from 22nd December to 31st December 1986 is Indicated. The day of each satellite pass is also shown. The blue shaded area lndicates the region which experienced hurricane force winds.

b) Tlme serles of wind speed (Ws) and wind direction from Udu Point during 15th - 31st December.

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i

5.3 Cyclone Bola,

Cyclone Bola passed Fiji of the group and then at a This cyclone was unusual winds. Gales were experienced reaching 5 m in Fijian waters. (1 994).

5.4 Swell

Although damaging swells northern hemisphere storms discuss briefly some of the

The highest winter wave significant wave height period of 15 - 16 secs. An ir winds to the north and east

In late July 1992, extensive resulting from a deep low peak sea state of 5.2 m off

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Fig.13 Variation in a) significant wave height and b)wind speed along GEOSAT track which passed the eye of Cyclone Raja on 28th December 1986 at 0300 UTC.

February - March 1988

twice, first in its developing stage on 25th February passing north west distance of about 300 km to the south west during its hurricane stage. in having associated with it an unusually large area with gale force

in south west Fiji but damage was minor, significant wave height A fuller description of this storm is given in Barstow and Haug

from the north are known in the South Pacific, originating from (e.g. Matthews, 1971), southerly swells are more common. We

more energetic events in the Waverider data base in the following.

t-eights at the measurement site occurred on 19th July 1993 when rea:hed 5.9 m. The wave spectrum was swell dominated with a peak

tense storm located at about 30°S, 170"W with very strong southerly of New Zealand was the main cause of these high sea states.

40 knot southerly winds both to the east and west of New Zealand at 65"s off Antarctica and a high over Eastern Australia produced a Kadavu. Peak wave period reached 20 seconds during this event.

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In the final section we give recommendations as to how the wave climate can be estimated away from the measurement site and what future work would be beneficial. All data collected in this project has been installed at the SOPAC Secretariat in Suva, Fiji.

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7. Recommen In the course of this pr number of training work present time, in-count operation and maint region. In order to maxim the next natural stage of Ministry of Energy h potential at 3 or 4 covered by fossil fuels.

Short term measur measurement locat chosen sites as PO question using Cali data.

It is also recomme

ion to the wave measurements and wave climatology work, a have been held for nations of several countries including Fiji. At the

f ocean waves, wave power technology and Waverider buoy ome wave measuring equipment is also available in the

benefits from this training activity it is imperative to continue to assessments for wave power. In fact, the Fiji

ts own wave power programme to look at the wave power Archipelago where energy requirements are presently

s) made using a Directional Waverider at an offshore with Waverider measurements as close to each of the sed to construct a long term wave climate at the site in ode1 data, coastal wave modelling and available satellite

uces a regionwide brochure describing the results of the the wave energy resource, the state-of-the-art of wave potential in the South Pacific. This document would then e within the countries themselves and to attract foreign

that the measurement series is probably not of the rare double year El-NiAo which occurred onsidered to be worthwhile to extend the data atellite measurements from the ERS-1 and T, which is widely used in this report. These coastal science projects. Cyclone data are, in

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8. Acknowledgements We would like to thank John Revfeim of the Fijian Meteorological Service for useful discussions and for providing us with some useful reports on the climate of Fiji. Thanks are also due to Ravindra Deo and colleagues of the Fiji Ministry of Energy for assistance in digitising wind data from Fiji.

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9. References Barstow, S.F. and Olsen, E., 1992: Wave Data Collection, Kadavu, Fiji, June 1991 - December 1991. SOPAC Technical Report 153,44 pp.

Barstow, S.F. and Haug, O., 1994a: The Wave climate of the South West Pacific, SOPAC Technical Report No. 206.

Barstow, S.F. and Haug, O., 1994b: The Wave Climate of the Kingdom of Tonga. SOPAC Technical Report No. 201.

Barstow, S.F. and Haug, O., 1994c: The Wave Climate of the Cook Islands. SOPAC Technical Report No. 200.

Barstow, S.F. and Haug, O., 1994d: The Wave Climate of Vanuatu. SOPAC Technical Report No. 202.

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- A259, 431 -97.

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Appendix A

Time series plots of waveand wind parameters; 1991 - 93

Significant wave height (m) Udu Point, Vanua Levu (direction from which) Spectral peak wave period (s) Energy (wave) period (s) Mean wave period (s) Measurements from Udu Point, Vanua Levu (direction from which)

Wind speed (m/s): HmO:

Tp: Tm-1 0: Tm02: Wind direction:

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