jacobs - environmental protection agency · 2013-07-26 · kish tower lwouse irish hydrodata...

JACOBS

DPC 6Yr Dredging Plan

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Document Reference 72811

9

teesan Lane, Dublin 2.

Preparsd by :

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._ . Document Ref.: 728-1

CHARACTERISATION OF DREDGE SPOIL

DISPOSAL SITE

WEST OF BURFORD BANK

Premred For:-

Department of the Marine, Leeson Lane,

Dublin 2.

Prepred Bv:-

frish Hydrodata Limited, Rathmacullig West,

Ballygarvan, Co. Cork.

Ph. 021-31 1255 Fax 02 1-968604

April 1995

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rrrru Characterisation of Burford Bank Dredge Spoil Disposal Site 1995 , J

CONTENTS

** d

I

Section

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Introduction Survey Area & Scope of Work Field Measurements Bathymetric Data Tidal Data Water Circulation Data Wind Data Dredged Spoil Disposal Model Summary & Conclusion References

Page No.

1 1 2 3 4 5 8 9 13 14

Appendix A Historical Wind Data from Meteorological Stations at Dublin Airport and Kish Tower Lwouse

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Characterisation of Burford Bank Dredge Spoil Disposal Site 1995

. >'

'..-

Figure 2.1 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 6. lad Figure 6.2 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Figure 7.1

t J Figure 8.1 Figure 8.2 Figure 5.3 Figure 8.4

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LIST OF FfGURES

Survey Area Bathymetric Chart of Survey Area Typical Seabed Profile fiom Echo Sounder Depth Contours 3D Representation of Seabed Admiralty Tidal Stream Data Profile Measurements on 3 1/3/95 Scatter Plots of Observed Current Speed 3 1/3/95 Prome Measurements on 7/3/95 Scatter Plots of Observed Current Speed 7/4/95 Mean Annual Surface Water Salinity Distribution Mean Annual Surface Water Temperature Distribution Wind Rose for Stations at Dublin Airport, Kish Tower Light Schematic of Tnstantaneous Barge Dump Discharge Locations Within Disposal Area Rate of Deposition of Sediment Fractions Predicted Thickness of Dumped Spoil Material

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'$., Characterisation of Burford Bank Dredge Spoil Disposal Sire 1995

d

I. INTRODUCTION

1.1 A marine site survey was commissioned by the Department o f the Marine to establish the dispersal characteristics of a proposed dredge spoil disposal site in the Irish Sea west of the Burford Bank.

1.2 The survey sought to evaluate existing oceanographic data sets for the locality and conduct Iimited on-site measurements that would cotdim this more general information. This data was then to be used in a mathematical model to predict the fate of the material being dumped at the site.

I .3 The work was carried out in accordance with the Department of the Marine specifications of 21st June 1994 and the agreed variations and additions made prior to and during the study.

2.

2.1

0 2.2

SURVEY AREA & SCOPE OF WORK

The area was nominally taken to be a 1.4km x 1 . 5 b rectangle, the middle of which is situated approximately 2km due west of the Burford Bank at the eastern boundary of Dublin Bay. The survey area is shown in Figure 2.1 and co-ordinates are listed in Table 2.1.

Point Latitude Longitude NW Comer 53' 19' 36" N 06" 03' 45" W NE Corner 53" 19' 36"N 06" 02' 30" W SE Comer 53' 18' 45" N 06" 02' 30" W SW Corner 53' 18' 45" N 06" 03' 45" W

Table 2.1 - Propoged Disposal Site and Survey Area.

Following the survey specification the study was to address the following items:

a. b. c.

d. e, f. g. Concentration of suspended solids.

Water depths (maximum, minimum, mean); Water stratification in various seasons and weather conditions; Tidal period, orientation of tidal ellipse, velocities of minor & major axes; Mean surface drift (net): direction and velocity; Mean bottom drift (net): direction and velocity; Wind characteristics, average number of storm days per year;

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/

3.

3.1

3.2

‘i a ’ 3.3

3.4

Characterisation OF Burford Bank Dredge Spoil Disposal Site I995

FIELD MEASUREMENTS

Field measurements were conducted at the site on the 31Marl95 (spring tide) and 7/Apr/95 (neap tide) fiom the 45fi. vessel high. On both days water column speed and direction profiling took place while at anchor in the centre of the disposal area. On the second day, a bathymetric survey, temperature and salinity dips and water sampling for suspended solids concentrations were also performed.

Three Interocean S4 recording current meters were deployed from the vessel and set to record speed and duection data at depths of 7% 14m and 21m below the surface for a 12.5 hour tidal cycle. The depth at the centre of the area, based on AdmiraIty Chart No. 14 15, is approximatety 22m.

Location control was performed on the Irish National Grid using a Sercel NR53 differential G.P.S. satellite positioning system for the hydrographic survey. The shipborne receiver provided digital output of position which was recorded on computer.

An Odom ‘Echotrac’ digital sounder was used to profile the underwater topography. The unit operated at 208 lcHz and employed a amow beam (40) transducer. It was calibrated using an Odom ‘Digibar’ speed-of- souid meter. Depths were recorded on computer.

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J

4. BATHYMETRIC DATA

4.1 A general indication of the water depths at the site is given on Admiralty Chart No. 1415, a portion of which was presented in Figure 2.1. More detailed depth measurements were made at the site fir this study. This was achieved by Nnning several survey lines across the disposal site at a line spacing of 500m. Along each survey line depths were recorded digitally at 5m to 10m intervals.

4.2

4.3

The depth data was reduced to Chart Datum using predicted tidal data for the port of Dublin. A soundings and contour chart of the survey area is shown in Figure 4.1. The rnaximum depth recorded was approximately 24.9rn towards the south east comer of the site. A minimum depth of 19.lm was recorded at the western edge of the area. The mean water depth at the site is 22m. These depths compare favourably with those indicated on the Admiralty chart.

The echo sounding revealed no unusual seabed features across the site. An extract fiom the echo sounder roll, showing the bed profile along the northern bpundaq of the disposal area is presented in Figure 4.2. A colour-filled contour map is presented in Figure 4.3 while a 3D perspective of the bathymetry is given in Figure 4.4. This latter figure shows the area to slope towards its centre from both west and east.

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Northing (m I.N.G.)

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'%# 5. TIDAL DATA

5.1 Tides in the Irish Sea are semi-diurnal in f b q having a period of approximately 12.42 hours, and are primarily the resdt of tidal energy entering from the Atfantic through St George's Channel. The input fiom the North Channel is significantly lower, accounting fbr less than 10% of the tidal energy input.

5.2

5.3 ' . -

The manner in which the tidal wave propagates in the Irish Sea produces low tidal amplitudes off Courtown, in Co. Wdord, and between Antrim and Scotland. The Iargest tides occur along the Welsh and Engiisb coasts. Typical spring and neap ranges off Dublin Bay are 3.4m and 1.9m respectively.

The proposed disposal site is,about 5km from Dun L a o w e and about lOkm from Dublin which is a standard port for tidal predictions. As such, it is acceptable to assume that the tidal data for these ports applies to the site. The principal tidal levels relative to CD are given in Table 5.1.

~

Tid8t Level Dublin Port Dun Laoghaire Highest Astronomical Tide 4.7m L

Mean High Water Spring .4. Im 4.Im a

Mean High Wqer Neap 3.4m 3.4m Mean Sea Level 2.4m - Mean Low Water Neap 1.5m 1.5m Mean Low Water Spring 0.7m 0.8m Lowest Astronomical Tide O.Om - Table 5.1 - Tidal levels in metres relative to Chart Datum (from Admiralty Tide Tables 1995).

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... -67

6. WATER CIRCULATION DATA

6.1 Water movements in the Irish Sea can be categorised as either ti& or residual. The tidal currents are associated directly with the rise and fill of the tide and occur at predictable intervals, principally fiom wind, salinity variations and other non-hear forces and interactions.

Residual currents result ,

6.2

6.3

The principal features of the tidal currents are documented in the Admiralty Tidal Stream Atlas @lP256), extracts &om which are presented in Rgure 6.la-d. These show a northward flow on the flooding tide and a southward flow on the ebb. These data are based on the tindings of surface Boat and logship (long poles) tracking exercises conducted over the past century. a.

Tidal currents in the waters adjoining the site are relatively complex due to the bathymetry and coastal topography. To the west of the site, the currents (IHD 1988) follow a clockwise rotational pattern, flowing strongly towards the LBey mouth on the flood and to the northeast towards the Bailey on the ebb. To the east of the site the current directions are aligned with the Burford Bank which runs in an approximately north-south direction. Measurements to the north of the she, off Howth Head (IDID 1994) and to the south off DaIkey (IHD 1983) show north-south flow alignments as expected fiom the topography.

6.4 Profile measurements at the site over a 111 spring tidal cycle on 3 1/Mar/95 (Dublin tide range = 3 . 5 ~ MNR = 1.9m, biSR = 3.4m) are presented in Figure 6.2. They show a peak surface (7m) flood speed of O.Sm/s directed towards 0lO"T and a peak surfkce ebb speed of 0.75mls directed towards 1900T. The orientation of the current ellipses are more clearly shown b~ Figure 6.3. The measurements made on the neap tide of 7/Apr/95'@ubh tide range = 2.2m) are shown in Figure 6.4 together with ellipse data in Figwe 6.5. The maximum flood speed at the sur&% (7m) is 0.52ds directed towards 360"T. the maximUm ebb speed is 0.4ds towards 180T. A summary of the current patterns at the site is presented in Table 6.1.

,Depth belowSurf4e S P m G TLDE N W TIDE Flood Ebb Flood Ebb

7m 0.80 0.75 0.52 0.40 14m 0.68 0.65 0.45 0.35 2 lm 0.60* 0.55 0.40 0.30

Flaw Direction OlOOT 190T 3 60"T 1 SOT Table 6.1 - Summary of current data for site. ( * estimated)


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Characterisation o l Burford Bank Dredge Spoil Disposal Site 19%

6.5 Typical spring tide depth averaged current speeds at the site are therefore 0.74ds on the flood and 0.70mls on the ebb. The neap tide depth averaged speeds are 0.53ds on the flood and 0.37ds on the ebb. The variation in current speed with depth can be represented by the power law profie, originaUy suggested by Van Veen (1938), which is:

V: = 1.14V,&-dd)”’

where V: = current speed at depth z (from the surface down), VaV = average speed, d = water depth.

Residml Currents

6.6 Residual currents are taken to be the mean flow of water after the tidal currents have been removed. These residuals can vary significantly both in speed and magnitude over a long period of time.

Residual flows have been stuked extensively over the years primarily to establish the flushing characteristics of the Irish Sea as a whole. Various published documents such as Knudsen (1907), Wilson (1974), Ramster and Hill (1969) and Ramster (1973) all indicate a predominately northward residual. However these general results are for the open Irish Sea waters and may not necessarily apply to the near shore areas.

6.7

6.8 Liinited long term current measurements have been made which are relevant to the site. Short term data (ie tidal cycle) such as the results stom this survey and previous studies (IHD 1983, 1994) confirm the general northward nearshore residual flow and suggest that it is of the order of 1- 3cds. Results &om seabed drifter studies released adjacent to the site (Crisp 1967) also suggest a northward bottom current residual.

Sdiniry and Temperature

6.9 Various data sets collected over the years (Bowden 1980) show that the Irish Sea waters are well mixed along the Holyhead-Dublin line and thus in the vicinity of the proposed disposd site fdr all seasons. The data sets also show that the vertical gradients of temperature and salinity are negligible. (Crisp 1976). This is the result of the strong current speeds and the relatively shallow waters at the site.

6.10 Typical annual Irish Sea surface water salinides are shown in Figure 6.6 and temperatures in Figure 6.7. Lowest temperatures occur in FebmaryMarch with maximum values occurring in AugustlSeptember. Typical ranges in the vicinity of the proposed disposal site are presented in Table 6.2.

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CHARACTERISATION OF DREDGE SPOIL DISPOSAL SITE

53

52'

FIGURE 6.6 MEAN ANNUAL SURFACE WATER TEMPERATURE DISTRIBUTION

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CHARACTERISATION OF DREDGE SPOIL DISPOSAL SITE '

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7. WIND DATA

7.1 A general overview of the wind pattern at the proposed disposal site may be inferred by assessing historid wiid records from the meteorological station at Dublin Airport and fiom more recent obsemtions at the Kish Tower Lighthouse which is located approximately 9km due east of the disposal site. Figure 7.1 shows wind roses fbr each of these sites and this infbrmation is also presented in tabular form in Appendix B. The Dublin data is based on the period 1962-1991 and the Kish on the period 1985- 1990. The measurements at the latter site are classed as visual observations and are taken approximately every six hours. They are not directly comparabIe with the Dublin Airport data which represent mean hourly values.

7.2 The data shows that the predominant wind directions are fiom the sector south through west. Further analysis of the data ( Table 7.1) shows that od-directional winds in excess of 34knots i.e. Beaufort Force 8 &de) can be expected for between 0. I% and 0.15% of the time at Dublin Airport and 4% of the time at the Kish Tower. The higher values for the latter reflect its exposed open water location.

Station Percentage Occprrence Dublin Airport 0.1-0.15

Kish Tower 4 Table 7.2 - AnnuaI percentage occurrence of winds in excess of 34knots.

7.4 The winds at the Kish Tower are biased to the 300' sector due to the presence of the Wicklow mountains and also the winds tends to blow fiom a southerly direction parallel to the coastline (Met. Service 1991). However despite these biases, the visual observation limitations and lack of long term records the Kish data is considered to be the better representation of the likely wind conditions at the site.

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8.

8.1

8:2

8.3 ,

8.4

8.5

DREDGED SPOIL DISPOSAL MODEL

Requirements

The specification called for the construction of a simple model of the dispersal of the dredge spoil material being discharged at the site. A suitable model in this instance was the DEID model which simulates the movement of spoil material as it M s through the water column, spreads over the seabed and f d l y is transported and diffused as suspended sediment by the ambient current.

Description of Model

The model is part of a suite of programs developed by the Corps of Engineers of the United States Army as part of their &tomated Dredging and Qisposal A_ltematives &inagement &stem (ADDAMS, 1990). Thee such models were designed to compute the fate of dredged material dumped at sea. These are: -

DIElD DIFCD DDEHD

Q&posal &om an Instantaneous Dump; asposal &om a Continuous a m p ; - Disposal Erom a Hopper Qredge.

DIFID is designed to simulate the movement of material fkom an instantaneous dump which falls as a hemispherical cloud. DIFCD is designed to compute the movement of material disposed in a continuous &shim at 8

constant discharge rate (ie pipeline). DJFHD has been constructed to simuiate the fate of material disposed from stationary hopper dredges where the n o d mode of disposal is to open first one pair of doors, then another, until the complete disposal is made.

Based on the method of disposd to be used at this particular site, a split barge, DElD was employed as the most representative predictive tool.

Summary of Model Theory

It is assumed that the behaviour of the material may be separated into three phases. The first stage is convective descent, during which the disposal cloud falls under the influence of gravity. Next is dynamic collapse, occurring when the descending cloud either impacts the seabed or arrives at a level of neutral buoyancy where descent is retarded and horizontal spreading dominates. FinaIly, passive tramporbdispersion, commencing when the transport and spreading of the mated are derermined more by ambient currents and turbulence than by the dynamics of the disposal operation. Figure 8. I shows a schematic representation of the discharge sequence.

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PASSlVE DIFFUSION

UTNAmlcI UuLbnrwc ON BOTTOM

. ENCOUNTER 6REATER THAN

1 CONVECTIVE I DESCENT

BOTTOM DlFFUStVE SPREADING

DYNAMIC SPREADINQ

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8.5


MODEL INPUT

Disposal Site Data

The oceanographic data (bathymetry, c&ents, tide) necessary to set up the model was sourced &om the information contained in chapters 4-6 of this document.

A depth grid extending lOkm x 30km, with cell size of 25Om x 250m and centred on the site was constructed. Bathymetq was taken fkom the survey and h m Admiralty Chart No. 1415. The model assumes an open coastline and does not allow for shoreline features. This is not considered a major drawback in this case as the orientation of the tidal ellipse will take the flow outside of Howth and Dalkey. The cell size was chosen such that a small cloud of material would stay witbin a cell for each time step. The horizontal component of ambient current was applied to each cell in the model grid using the profile data in TabIe 6.1. 1.

Dredged Ma feria1 Characteristics

Information on the physical characteristics of the dredged material was taken from Forb& (1994) and Eolas (1993) reports on Dublin port sediments. Data used in the model are presented in Table 8.1.

i.. .

Parameter 1994 1995 Model Value % solids w/w 46 42 44 % Moisture w/w 54 58 56 Density g/cm3 1.38 1.27 1.32 Granulometry TO dry wt. >2mm 8 7 7.5 2 m 0 6 3 p - 1 17 18 17.5 <63 75 75 75

Table?l- Dredged Material Characteristics.

8.9 For each solid fraction additional information on parameters such as concentration by volume, specific gravity, settling velodty, void ratio and cohesion were assumed using published data (ADDAMS 1990).

Disposal operations &tu

8.10 The proposed disposal operations will involve the discharge of 350Ut spoil loads from IL split barge at a rate of 31000 tonnes per day. Up to 800,000 tonnes may be discharged over the project duration. For the model purposes it was assumed that these loads would be discharged at seven stages of the tide, on either a spring or a neap tide as outlined in Table 8.2.

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Characterisation of Burford Bank Dredge Spoil Disposal Sire 1995

\ !/

, 7 ‘ J

I

Tide State Model Case High Water - Slack 1 3/4 Tide - Ebb 2 Mid Tide - J3b 3 114 Tide - Ebb ‘ 4 Low Water - Slack 1 1/4 Tide - Flood 5 hGd Tide - Flood 6 314 Tide - Flood 7

Table 8.2 - Tidal States Simulated in Model.

8.11 As each load could be discharged at any point within the prescribed disposal area two alternative scenarios were examined for comparative purposes. The first was a discharge pattern restricted to 5 central grid squares as per Figure 8.2 and the second a uniform discharge over each Of 36N0.2501~1 x 250m grid squares.

I I

MODEL RESULTS

8.12 The model predicts that in all cases the seabed is encountered during the convective descent phase where the disposal cloud falls under the intluence of gravity. The discharge does not achieve neutrd’buoyancy which would allow it to be carried away from the site directly by the currents. The rate at which the various sediment hctions impact the seabed is illustrated in Figure 8.3 which plots the suspended and settled fractions at times after release for a particular neap tide simulation. Typically 92% of the material reaches the seabed within 8 minutes and 97% within 16 minutes of release.


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EPA Export 26-07-2013:23:07:34

%w* Characterisation of Burford Bank Dredge Spoil Disposal Site 1995 - f

1

8.13 -*Ad

8.14

8.15

For each of the seven tidal simulations listed in Table 8.2, on both spring and neap tides, the settlement results are similar; the sand fraction settling very rapidly within 500 seconds of discharge while for the silt and clay hctiom between 1 and 1.5% of the material is stiU in suspension after 4 hours.

The horizontal distriiution of settled material is closely related to the disposal pattern due to the speed at which it settles out. Results for the two scenarios examined are presented in Figure 8.4. &ah these assume that the flow is not constrained by the land. With the discharge restricted to 5 central e d locations the peak thickness on the seabed dl be 3m while if it is evenly distributed over the area the peak will only reach 0.6m (based on an increased voids ratio after disposal ). The model results dso show that a short distance (C500m) from the site deposited material amounts will be s d and not very sensitive to the disposal scenario adopted.

The model does not allow for re-erosion or re-suspension of deposited material by curre@ and in this- regard will over predict the thickness of material. Erosion data for sediments ( Raudkivi, 1990) indicates that for 6 3 p particles the erosion velocity is between 0.2-0.4ds while fbr the coarser fraction > 2mm it is between 0.3-0.4m/s. Thus, based on the current data of Figures 6.2 h 6.4 and the profile law of Section 6.5, erosion of the deposited material will be possible for up to eight hours per tide. Therefore over a period of time the material will be re-eroded and transported northwards by the residual current to be deposited over a wide area of the seabed.

i , ) Irish Hydrodata Limited Page No. 12 Doc. Ref. 728-1

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7 I -wt l I

Percentage of Total Material 0 0 8 g g O ' o g 8 -L

I I I I I 1 I I

0 O I 0

, -

' I I

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EPA Export 26-07-2013:23:07:34

meires x w 0

w 0 0 0

N h)

0 0 0 0

0 8 8 m 2 N N 0

0 0 0

h) 0 0 A W 0

8 8 1

1 P

E! U] TI 0

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w 0 0

0

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I

* -,

- , 9.

,%d

9.1

9.2

. \ ! ': J

9.3 .i

9.4

9.5

CharacterisatJon of Burford Sank Dredge Spoil Disposal Site I995

SUMMARY & CONCLUSION

The proposed site possesses well-defined tidal characteristics which are typical of the western Irish Sea area 'Tides are senri-diurnal with a period of 12.4 hours, a mean spring range of 3.4m and a mean neap range of 1.9m. Currents are tidally driven and strong with depth-averaged speeds in the range 0.37m.k to 0.74ds. The flow diredons correspond to 000"- OlOOT on the flood and 18Oo-190OT on the ebb. Slack waters occur approximately one hour before the high and low tides. Periods of low current speeds ( < 0.05ds) typically last for less than 10 minutes.

The seabed at the site is shaped like a shallow elongated trough e d m g north-south with an average depth of 22m. A minimum water depth of 19. Im was recorded in the western part of the area. and a maximum of 24.9m in the south-east.

Historical data indicates that significant stratification does not occur in this area due to the strong current regime. Residual drift is directed to the northerly sectors with an average speed 1 3 d s for both surface and !

a .

'

nearbed waters. i

The spoil disposal model predicts that the dredge material discharged at this location will fall quickly to the seabed with over 92% reaching it within 8 minute and 97% within 16 minutes. If the maximum 800,000 tonnes is deposited unifkrmly over the prescribed area it would result in a dredge material thickness of up to 0.6m on the seabed.

The strong current regime at the site will promote re-erosion and further spreading of the deposited material. Suitable conditions exist for up to 8 hours per tide and therefore over a period of time the sediment will be re- eroded and transported northwards by the residual current. .

Doc. Ref. 728-1 I , ) Irish Hydrodata Umited Page No. 13

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i

5..

Characterisation of Butford Bank Dredge Spoil Oisposal Site 1995

I O . REFERENCES & BIBLIOGRAPHY

1. ADDAMS (1990) Users Guide for Models of Dredged Materid Disposal in Open Water. US Army Corps of Engineers, Water Resources Support Centre, Technical Report D-90-5.

2. Admiralty Hydrographic Department (1980) Admiralty Chart (No. 3058) Co-Tiihi & CO Range Lines for the Briiish lsles and A4acent Wbters

3. Admiralty Hydrographic Department (1994) Admiralty Tide Tables I994 (NP201-94)

4. Admiralty Hydrographic Department (1974) Admiraity Tidal Stream Atlas. Irish Sea and Bristol Channel (NP256)

5. Bowden, K.F. (1950) Processes aJfecting the saliniy of the Irish Sea. Mon. Not. R W o n . Soc., Geophys. Suppl., 6: 63-90.

6. Bowden, K.F. (1980) Physical and Dynmicai Oceunography of the Irish Sea. In Banner, Collins and Massie(eds.) The North West European Seas: the sea bed and the sea in motion.

7. Crisp, D. J., (1976) Siirvey of the Emirottmental Conditiom in the LifJeV Esttmy and Dublin Bay. Unit for Marine Inv Biology, Marine Science Laboratories, Menai Bridge.

8. Daniel, RJ. and Lewis, H.M. (1929) Surface &ii bottle experimem3 in the Irish Sea, July 1925 - Acne I92 7. Lancs. Seafish Lab. Rep., 38: 36-86.

9. Irish Hydrodata Limited (1994) Environmental Survey of Howth Otitfaiil Unpublished report for M C 0' Su1Eva.n & Co. Ltd.

10. Irish Hydrodata Limited (1983) Bray Sewerage Scheme Hyhogrqhic & Geological Survey Report, Unpublished report for J. B. Barry & Partners.

11. Knudsen, M., (1907) Some remarks about the currents it2 the North Sea and Adjaceiit Waters. Cons. Perm. Int. Explor. Mer, Public. de Circ., 39: 7pp.


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12.

13.

14.

1s.

16.

17.

18.

Irish Meteorological, Service (1991) Monthly Weather Bulletin, April 199 1

Ramster, J.W. and Hill, EW. (1969) Ctrrretit systems in the northem Irish Sea Nature, 224, pp59-61.

hmster, J.W. (1973) B e residual ci&Iation of the northern ,.ish Sea with partiadar reference to Liverpool Bay. Fish lab., Lowestoft, Tech. Rep. Ser.,. No. 5.

Raudkivi, A.J. 1990 Loose Bourraby HyaFmiIics, Pergamon Press.

Van Veen, J. (1938) J. Cons. Int. Exptor. Mer.,I3,7-36

Wilson, T.RS. (1974) Caesium-137 as a weer movement tracer in the St. George's Channel. Nature, 248: 125-127.

Wilson, J.G. (1989) BioIo@&l Impcts of Orgunic and InduMaI Discharges to the Irish Sea. fn: The Irish Sea A Resource at Risk. Sweeney, J.C. fed) Geog. Soc. Irl Sp. Pub. 3 116-123.

,i Irish Hydrodata Limited Page No. 15 Doc. Ref. 728-1

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Characterisation of Eurford lank Dredge Spoil Disposal Site 1995 ”,

/ -

&.

APPENDIX A

HISTORICAL WIND DATA FROM METEOROLOGICAL STATIONS AT DUBLIN AIRPORT AND KISH TOWER LIGHTHOUSE

Irish Hydrodata Lcd. Doc. Ref. 728-1

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U N

* 0

W

N In 1" N m

!o 4

w *

? m

a

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? - * N N W W W P P P P O W O W N O N N N w P P ~ P P P W ~ w h ) N ~ W w N

? ? ? ? ? ? ? ? ? ? ? ? ? ? P ? ? ? ? ? p p P P P P P P P P P P P P P P N ~ W 0 ~ r n Q ) z r 0 0 W ~ W 4 o ) a P W N W ~ Q ) 4 4 ~ r n ~ r n P P ~ W w W W ~

N N P a 4 o W N ; b b b b ; ; b ; b ; ; ~ ~ ~ ~ ~ ~ ~ a t ~ a t ~ P ~ w W N

? ? o o ? ? ? ? ? ? ~ ? ? ? ~ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ~ ~ , - ~ ~ - ~ w ~ ~ ~ o r n r n m ~ w N - - N ~ ~ N - - - ~ ~ - - - - ~ ~ +

~ p ~ ~ ~ g - * N N p n W o N - ~ ~ + + ~ ~ - - ; + * + + + + + + + + ? ? ? P S ? ? ? ? ? ? ? ~ o ? ? ? ? ? O O O O O O O O Q

o o O O O O O o O P ? ~ ? Q o O O O O O o o o o o o o o o o o o o o o o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0 0 0 + + + 0 0 0 0 0 + + + + 0 0 0 0 0 0 0 0 0 0 0 0 + + + + + + + + + + + + 0 +

0 0 0 0 0 0 ? + + + + + 4.

1

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PERCENTAGE FREOUENCY OF SLMJLT~EOUS OCCURRENCES OF SWClFIEO W E 5 OF MEM HWRLV WINO SPEEO AN0 DIRECTION OubIln Alrport

DIRECTION '' - IN OEOREES

010 020 030 040 060 060 070 080 OS0 100

I20 I30 140 I60 1 60 I70 I 80 190 200 210 220 230 240 260 260 270 280 280 300 310 320 330 340 360 360

.Ld

110

1 J

TOTAL

CALM 1-3

0. I 0. I 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.3 0.4 0.3 0.4 0.2 0.2 0.2 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.3 0 :2 0.2 0.2 0.1 0.2 0.1 0.1 .o. I 0.1

1.9 6.9

4-6

0.2 0.2 0.2 0.1 0.2 0.2 0.2 0. I 0.2 0.3 0.3 0.4 0.4 0.6 0.6 0.5 0.4 0.3 0.3 0.4 0.6 0.5 0.6 0.4 0.7 0.6 0.6 0.6 0.6 0.3 0.3 0.4 0.3 0.2 0.1 0.1

12.6

JANWIRI WLW SPEEO IN KNOTS ~~

7-10 11-16 17-21 22-27

0.1 0.2 0.1 0.2 0.2 0.1 0.3 0.2 0.3 0.3 0.5 0.S 0.5 0.7 0.9 0.8 0.1 0.4 0.6 0.7 I .o 1 . 1 1 . 1 I .a 1.6 I .8 1 .s I .3 I .o 0.6 0.6 0.4 0.3 0.2 0.2 0.2

22.2

0. I 0, 0.1 0, 0, 0.1 0.1 0, 0.2 0.1 o+ 0,3 0.1 O t 0.3 0.2 0.1 0.4 0.2 0.1 0.6 0.3 0.1 ' 0.4 0.4 0.3 0.5 0.3 0.2 0.6 0.2 0.1 0.s 0.1 0.2 0.8 0.6 0.2 1.1 0.4 0.2 1.4 0.6 0.3 1.4 0.6 0.2 0.9 0.3 0.1 0.6 0.2 0.1 0.7 0.3 0.1 1.3 0.6 0.2 1.3 0.6 0.2 2.0 0.9 0.4 2.7 1.6 0.7 2.9 1.6 0.8 2.8 1.7 0.8 2.5 1.6 0.9 1.9 0.9 5 6 1.4 0.6 0.4 0.8 0.2 0.2 0.4 0.2 O+ 0.3 0.1 O t 0.2 0.1 0.1 0.2 0.1 0.1 0.2 o+ o+ 0.1 o+ o+ 0.1 o+

31.3 16.6 7.6

28-33

O+ 04

O+ 0, oc O+

0.1 ot O+ 0, O+

0.1 0.1 0.1

O+ ot o*

0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.1

0, 0, O+ OC

I .7

(1962 TO 19911

34-40 41-47 48-55 56-63 OVER 63 TOTAL

0,

os O+ O* O t

O+

O+ o t

0.1 O t

0.1 O+ o*

0.2

o t

ot O b O+ o+ ot

O*

O* TOTAL H(HBER OF OBSERVATIONS - 22320

THE ENTRY -O** INOICATES THAT THE PERCENTAGE IS GREATER THAN ZERO BUT LESS TNrW 0.05

PERCENTAGE FREOUENCY OF SIMULTANEOUS OCCURRENCES OF SPECIFIED RAN- OF MEAN HOURLY W N O SPEEO MO DIRECTION Oublln Airport

OIRECTION 1N OHIREES CAW

010 020 030 040 os0 060 070 080 OW 100

' 110 I20 130 140 160 160 170 180 190 200 210 220 230 240 250 280 270 200 290 300 310 320 330 340 350 360

1-3

0.2 0.2 0.2 0.1 0.1 0. I 0.2 0.3 0.3 0.3 0.4 0.3 0.3 0.3 0.3 0.3 0.3 0.1 0.1 0.2 0.1 0.2 0.2 0.2 0.3 0.3 0.3 0.3 0.3 0.3 0.2 0.3 0.2 0. 1 0. 1 0.1

4-6 7-10 11-16

0.2 0.3 0.1 0.1 0.2 0.1 0.2 0.2 0.2 0.2 0.2 0.3 0.2 0.3 0.4 0.2 0.6 0.7 0.3 0.6 1.0 0.4 0.6 1.2 0.6 0.7 1.3 0.5 0.9 0.9 0.6 0.7 0.9 0.4 0.8 1.0 0.6 1.0 1 .3 0.7 1.2 1 .8 0.7 1.0 1.7 0.6 0.8 1 . 2 0.4 0.5 0.5 0.2 0.3 0 .3 0.3 0.6 0.6 0.4 0.6 0.8 0.1 0.E 1.1 0.4 0.8 1.0 0.4 0.8 1.4 0.6 1.0 1.6 0.6 1.2 2.0 0.7 1.3 2.0 0.6 1.4 1 . 3 0.5 1.0 0.9 0.6 0.9 0.7 0.4 0.6 0.5 0.4 0.4 0.3 0.5 0.4 0.3 0.4 0.4 0.3 0.3 0.3 0.3 0.2 0.3 0.2 0.1 0.2 0.1

FEBAUARY WINO SPEEO IN IOIOT.5

17-21

O+ 0.1 0.1 0.2 0.3 0.3 0.6 0.6 0.7 0.3 0.3 0.4 0.4 0.6 0.6 0.3 0.3 0. I 0.2 0.4 0.3 0.7 0.8 0.8 1 .o I .2 0.9 0.5 0 .3 0.2 0.1 0. I 0.1 0.1 Ot

0.1

22-21

0, O+ 0,

0.1 0.1 0.1 0.2 0.4 0.2 0. I 0. I 0.1 0.2 0.2 0.3 0.1 0.1 0,

0.2 0.2 0.2 0.4 0.6 0.3 0.6 0.5 0.4 0.3 0.2 0. I o* O+ 01

0. I O t o i

28-33

0.1 0.1 0.1

O+ 0, ot O+

0.1 ot

O+ 0.1 0.1 0. I 0.1

O+ 0. I 0. 1

0.1 0. I

O+ 0, ot

O+

34-40

O+

O+

O+

O+ O+ O+ O+

0.1 0.1

D+ O+ O+

0.6 0.6 0.7 0.8 0.9 0.9 1.4 1.6

1.8 1 .a 8.7 2.6 3.6 4.3 3.8 2.3

2.1 3.4 4.0 6.2 6.8 7.3 8.0 7.9 6.8 4,5 2.9 I .a 1.4 1.3 t.1 0.8 0.6 0.4

1.8

1.81

(1962 TO 1991)

41-47 18-56 56-63 OVER 63 TOTAL

O+ O+ 0,:

0.8 0.8 0.9 1.1 1.5 2.0 2.1 3.5 3.7 2.9 2.9 3.0 3.9 0 . 8 4.7 3.2 1 .9 1 . 2 2.0 2.6 3.1 3.6 4.1 4.6 5.6 6.3 5.2 3.6 3.1 2.1 1.5 t . 5

1.3 1.1 0.8 0.7

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Dublln Ai rpor t I otwcrm

. IN OEGRECS

010 020 030 010 060 060

080 Do0 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 280 260 270 280 290 300 ¶tO ¶20 330 340 ?IS0 360

TOTAL

om

CALM 1-3 4-6

0.2 0.2 0.2 0.3 0.2 0.2 0.1 0.4 0.1 0.3 0.2 0.3 0.2 0.3 0.2 0.4 0.2 0.4 0.2 0.5 0.3 0.4 0.2 0.4 0.2 0.5 0.2 0.5 0.3 0.4 0.2 0.3 0.2 0.2 0.2 0.2 0.1 0.2 0.3 0.3 0.2 0.3 0.3 0.6 0.2 0.5 0.2 0.7 0.2 0.5 0.2 0.1 0.2 0.6

.0.2 0.6 0.2 0.6 0.2 0.4 0.2 0.4 0.2 0.4 0.2 0:3 0.1 0.2 0.1 0.1 0.1 0.1

1.6

7-10

0.2 0.3 0.4 0.4 0.4 0.6 0.5 0.6 0.6 0.4 0.4 0.6 0.8 0.9 0.6 0.7 0.3 0.3 0.4 0.8 0,6 0.8 1 .o 1.1 I .T 1.6 1.6 1 .z I .2 1 .O 0.8 0.7 0.6 0.3 0.3 0. I

w m (1862 TO 1991)

WINO SPEED IN SNOTE 11-16 17-21 22-27 28-31 34-40 41-47 da-55 56-63 om 61 T o m

0.2 0.1 0.3 0.1 0.4 0.2 0.4 0.2 0.6 0.2 0.6 0.1 0.6 0.2 0.6 0.2 0.7 0.3 0.4 0.1 0.2 0.1 0.6 0.1 1.0 0.3 1.5 0.6 1.1 0.6 0.8 0.3 0.5 0.2 0.6 0.2 0.7 0.3 1.0 0.5 1.4 0.6 1.6 0.9 1.6 1.1 1.9 1.3 2.1 1.3 2.4 1.2 1.8 0.8 1.2 0.5 1.0 0.6 1.0 0.3 0.7 0.2 0.6 0.1 0.6 0.1 0.4 0.1 0.2 0.1 0.2 o+

7.1 14.0 24.7 31.0 14.1

0, 0.1 0. I 0.1 ot O*

0.1 0. 1 0, 0+

0.1 0.1 0. I 0.3 0.1 0.1

04 O t

0.1 0.1 0.1 0.3 0.4 0.6 0.6 0.8 0.4 u:4 0.2 0. I 0.1 0.1 0.1 oc

0.1 0,

6.2

O+ O b

O+

a+. 0, 01.

O+ 01

0.1 O+ O+ 0,

0, O+ o+

0.1 0.1 0.1 0.2 0.1 0. I 0. 1 O+ 0,

D+ O t

O+

1.1

ot

O* O+

O+ DI 04

ot ot

22w0

THE ENTRY *O+” INDICATES T W T M E PERCENTNE IS GREATER THAN E R 0 BUT LESS Twu( 0.05

PERCENTME FREWENCY OF SIWLTAHEWS OCCURRENCES OF SPWIFIEO RWOES OF .um HOURLY rnm spEm w OIREC~XON Oublln Mrport

OIRECTION IN OEOREES

010 010 030 040

‘ I 050 1. 9 060

080 OB0 100 110 120 130 140 160 160 170 180 190 200 210 220 230 240 260 260 270 280 290 300 310 320 330

350 360

TnTAl

om

I 1 340

CALM 1-3

0.3 0.4 0.4 0.4 0.3 0.3 0.4 0.5 0.6 0.6 0.4 0.4 0.3 0.4 0.3

0.2 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.3 0.A 0.3 0.3 0.3 0.4 0.3 0.2 0.2 0.2

in 7

a. z

id

0.3 0.5 0.s 0.6 0.6 0.7 0.6 0.7 0.6 0.6 0.6 0.6 0.6 0.6 0.4 0.2 0.1

0.1 0.2 0.2 0.3 0.4 0.6 0.5 0.7 0.6

0.7 0.8 0.7 0.6 0.6 0.A 0.3 0.2 0.3

a. 7

T ? 1

APRIL WIND apEo) IN KNOTS

7-10 (1-16 17-21

0.A 0.6 0.6 0.6 0.8 0.9 I .O 1 .o 0.8 0.7 0.4 0.6 0.8 1 .o 0.7 0.3 0.1 0.1 0.2 0.4 0.4 0.7 0.8 1 .o 1.3 1 . 4 1.3 1.3 1.3 1.0 1 .o 0.9 0.6 0.5 0.3 0.3

7e ¶

0.3 0.6 0.8 0.7 1.1 0.8 0.7 0.8 0.9 0.6 0.3 0.6 0.9 1 . 1 0.7 0.3 0.3 0.1 0.2 0.6 1 .o 1 .o 1.3 1 .A 1.6 1 .7 I .6 1.6 I .3 1 .o 0.9 0.7 0.8 0.6 0.5 0.3

7a a

0.1 0.1 0.2 0.3 0.4 0.3 0.3 0.2 0.3 0.1 0.1 0. 1 0.1 0.2 0.2 0.1 0,

0. 1 0.1 0.2 0.2 0.4 0.4 0.5 0.9

0.6 0.6 0.s 0.3 0.2 0.2 0.3 0.2 0.2 0.1

rn n

0.e

22-21

O+ 0. 1 0.1 0.1

O+ 04

0.1 O+

0.1 0, O+ 0 4 O+ 0, O+ Ob 04 0, O+ O+ O+

0.1 0.2 0.1 0.3 0.4 0.2 0.2 0.1 0.1 0.1 0.1 0.1 0.1 O+

0.1

7 1

1 .o I .4 1 .5 1.5 I .s 1.7 1.9 2.1 2.0 t-6 1.5 2.0 3.0 4.1 3.J 2.3 1.4 1.3 I .7 2.9 3.4 4.4 6.0 6.8 6.6 7.1 6.1 4.2 3.7 3.1 2.4 2.1 1 .8 1.2 1 .o 0.7

11962 TO 1991)

28-33 34-40 41-47 68-66 66-63 OMR 63 TOTAL

O+ O+ ot

O+

o t O+ ot

0.1 O+ O+ O+ O+ O+ O t 0,

0 1

O+

O+

O+

1 .A 2.3 2.6 2.6 3.0 3. I 3.0 3.2 3. I 2.6 1.6 2.2 2.6 3.2 2.5 1 .3 0.8 0.6 0.8 1 .6 2.1 2.8 3.4 3.9 4.9 5.2 4.7 4.7 4.6 3.6 3.0 2.1 2.6 1.9 1 .5 1.3

!

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PERCENTAGE FREwENcr O F SIMVLTANEOUS OCCURRENCES OF SPECtFlEO W O E S OF ruH WURLY WINO 6PEEO *rr6 OIRECTION OubUn A i r p o r t IMY (1962 TO 19911

OIRECTION WINO ¶PEE0 IN KNOTS IN OEWIEES

010 020 030 WO OW 060 070 080 090 100 410 120 IS0 140 I 60 160 I 70 1 BO I so 200 210 220 230 240 260 260 270 280 290 300 310 320 330 340 350 360

TOTAL

i d

! 7 .I

CALM 1-3 A-6

0.3 0.5 0.4 0.5 0.1 0.5 0.1 0.1 0.3 0.6 0.4 0.6 0.6 0.6 0.6 0.8 0.6 0.6 0.6 0.6 0.6 0.7 0.6 0.7 0.6 0.7 0.6 1.0 0.4 0.7 0.3 0.3 0.2 0.2 0.2 0.1 0.1 0.2 0.2 0.A 0.2 0.4 0.3 0.4 0.3 0.6 0.3 0.8 0.4 0.9 0.4 0.8 0.4 0.6 0.4 0 .7 0.3 0.7 0.4 0.6 0 .3 0.5 0.s 0.5 0.4 0.A 0.3 0 .3 0.2 0.3 0.2 0.3

4.2 13.2 19.6

7-10 11-16

0.1 0.3 0.7 0.6 0.7 0.6 0.8 0.1 0.8 0 .7 1 . 1 0.8 0.9 0.6 0.9 0.4 0.7 0.3 0.6 0.3 0.4 0 . 2 0.9 0.4 1.6 1.0 1.7 1.6 1.0 1.0 0.4 0.6 0 .3 0.2 0.1 0.2 0.4 0 . 3 0.6 0.6 0.8 1 . 1 0.9 1.0 0.3 1.2 l.2 1.4 1.4 l.A 1.5 1.4 1 . 1 1 . 1 0.3 1.0 1.2 0.7 0.3 0 . 7 0.9 0.8 0.3 0.7 0.7 0.5 0.6 0.4 0.3 0.1 0.s 0.3

29.4 25.2

11-21

0, 0.1 0.1 0.1 0. I 0.1 0.1

O+ O* 0,

0.1 0.2 0.3 0.3 0. I 0.1 0. I 0.1 0.1 0.3 0.3

.0.4 0.6 0.6 0.6 0.4 0.4 0.3 0.2 0.1 0.1 0.2 0.1 0.1 O*

6.4

22-27

O I 0.1 0. I

OC

O+ O* O+ O+ O+

0.1 0.1 0.1 0.1 0.2 0.2 0.1 0;1 0.1 0.1

O* O*

O t 0,

1 .E

28-33 34-40 AI-47 46-55 56-63 OVER 63 TOTAL

O b

O b O+

0, O*

O+ 0, O+ O* O+ 04 O+

0.2

0, O+ 0, ot

I . A 2. I 2.4 2.4 2.5 3.0 2.7 2.5 2.3 2.0 I .8 2.7 4.2 6.2 3.4 I .7 0.9 0 . 7 1 . 1 2.0 2.8 3.1 3.6 4.3 6.0 4.8 4.0 3.6 3.4 2.9 2.7 . 2.7 1.2 I .6 1 . 1 1 . 1

O+ TOTAL -ER OF OBSERVATIONS - 22320

THE ENTRY 'O+" INDICATES THAr ME PERCENrACiE IS GREATER W ZERO BUT LESS TlWl 0.05

PERCUITACE FREOUENCY OF SIWLTAHEOUS OCCVRRENCES OF SPECIFIEO W E S OF lduH HOURLY WINO SPEED AND OIRECfION Dubttn Airport

DIRECTION IN DEOREES CALM

010 020 030 040 .4 :: om OB0 090 100 I10 1 20 130 140 150 I60 I 70 180 I90

200 210 220 230 240 250 260 270 280 290 300 I 310 320 330 3 A0 350 360

1-3

0 .3 0 .3 0. A

0.4 0 .4 0.4 0.5 0.6 0.6 0.6 0.6 0.6 0.7 0.6 0.4 0.2 0.2 0.2 0.2 0.3 0.2 0.4 0.4 0.6 0.5 0.5 0.5 0 . 6 0.4 0.5 0.4 0.4 0.3 0.2 0.2 0.2

A-6

0 . 3 0.4 0. A 0.4

0.6 0.6 0.6 0.6 0.6 0.7 0.6 0.8 1 .o 0.9 0.6 0.3 0.2 0.1

0.2 0 .3 0.3 0.6 0.8 1.1 I .2 1 . 3 0 . 9 1 .O 0 .9 0.8 0.6 0.6 0.4 0.2 0 .2 0.2

7-10 11-16 17-21

JWE WINO SPEED IN KNOTS

0.1 0.4

0.6 0.5 0.6 0.8 0.6 0.6 0.6 0.6 0.4 0.9 1.2 1.3 0.0 0.4 0.2 0.1 0.3 0.5 0.8 1 .2 1 .A I .6 1.9 I .9 I .6 I .6 I .3 1 .o 0.7 0.7 0.6 0.3 0.2 0.2

0.1 o+ 0.3 0.1 0.3 O+ 0.4 O+ 0.4 O+ 0.6 0.1 0 .4 0.1 0.4 0.1 0.2 01. 0.2 0.1 0.2 0.7 0.1 1.0 0.1 0.6 0.1 0.3 O+ 0.2 0.1 0. I 0.3 O+ 0.5 0.1 0.8 0.2 1.2 0.2 1.6 0.2 1.7 0.3 2.1 0.4 2 . 3 0.6 1.7 0.6 1.5 0.5 1.4 0 .3 0 .9 0 .2 0 .7 0.1 0.5 0.1 0.6 0.1 0 . 3 0, 0.2 o+ 0.1 0,

(1962 TO 19911

22-27 28-33 34-40 41-47 48-55 66-83 OVER 63 TOTAL

Q* O+ OC

0, 0, 0,

O+

ot ot

O+ OC

O+ 0.1 0.1 0.1 0.1 0. I 0.1 O+ O* ot O+ 01 O+

. _

ot

o t O* 0, O+

O+ 0,

- .

O+

0.8 I .6 I .8 I .7 1.9 2.6 2.2 2.1 1.9 2.0 I .7 2.6 3.5 4.0 2.6 I .2 0.8 0.6 0.9 1 .I 2.3 3.6 4.5 6.3 6.2 6.7 5.6 6.2 4 . 4 3.3 2.6 2.3 1.8 1 . l 0 .8 0.6

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. - - . - - ._ ~ : . , i PERCENTAGE FRENIWCY OF SIMILTANEOUS OCCURRENCES OF SPECIFXEO RAHCES OF UEAH HOURLY W M O SPEED AND OIRECTIW

OubLln Alrport OIRECrION

' ) IN DEGREES

010 ?& 020

030 060 050 060 070 080 050 la0 110 120 I JO 140 150 160

180

200 210 220 230 240 260 260 270 280 290 300 310 320

340 550 360

TOTAL

im

im

a30

CAM 1-3

0.2 0.3 0.3 0.4 0.3 0.3 0.4 0.6 0.6 0.7 0.6 0.6 0.6 0.6 0.4 0.3 0.2 0.2 0. I a. 2 0.3 0.3 0.4 0.6 0.6 0.5 0.4 0.6 0.6 0.5 0.4 0.6 0.3 0.2 0.1 0.1

4-6

0.3 0 .3 0 .4 0 .3 0.3 0 .4 0.5 0.5 0.6 0.6 0.7 0.9 0.9 0.8 0.5 0.3 0.1 0.1 0.2 0.3 0.4 0.6 0.8 1.1 I .3 1.3 1.2 I .1 1 .o 0.9 0.7 0.8 0.5 0.2 0.2 0.2

7-10

0.2 0.5 0.4 0.4 0.4 0.6 0.6 0.4 0.6 0.4 0.4 0.9 1.4 I .2 0.5 0.3 0.1 0.2 0.2 0.6 0.7 I .o 1.5

2.4 1.6 2.2 2.2 1.8 1.6 1 .2 1 .o 0.8 0.4 0.2 0.2

I .e

4.2 13.9 21.1 31.2

11-16

0. I 0.3 0.2 0.3 0.2 0.2 0.2 0.1 0.1 0.1 o+

0.2 0.6

0.4 0.3 0.1 0.1 0.2 0.6 0.8 1.1 I .6 2.1 2.6 2.9 2.4 1.9 4.6 1 .o 0.6 0.7 0.6 0.3 0.1 0.1

26.0

0.8

JULY WINO SPEED IN K H D F

17-21

0, O+ O+ OC

O+ O b

02

O b o+ Ob

O+ 0.1

0, In O+ O+ O+

0.1 0.2 0.1 0.3 0.3 0.6 0.s 0.6 0.3 0.3 0.2 0.1 0.1

O+ O+ O+ 0,

4.0

22-21

04 O+

0, O+ O+

0.1 0.1 0.1 0.1 0.1 0 ,1

OC

O+

0.6

(1962 TO 19911

28-33 14-40 41-47 AB-55 56-63 OVER 63 TOTAL

0, O+ O+ O+ 04

0.1

0.8 1.4 1.4 1.4 I .3 1.4 1.7 1.4 1.6 I .e I .? 2.5 3.4 3.4 1.9 1 .2 0.8 0 .6 0.7 I .6 2.4 3.2 6.7 6.8 7.6 8.0 6.8 6.2 6.1 1.1 5.0 2.8 2.0 1.2 0.7 0.6

TOTAL N-ER OF 08SERVATIONS - 22320

THE ENTRY "0," INDICATES THAT TNE PERCENTME IS OAEATER THAn ZERO 8UT LESS TKW 0.05

PERCENTME FREQUENCY OF SINULTANEOUS OCCURRENCES OF SPECIFIED WOES OF UGW w a u WIND SPEED AND DIRECTZON AUCUST 11962 TO 1991)

WINO SPEEO fN KNOTS DubLln Alrpori

OIRECTIOH IN OMREES

010 020 030 odo OS0 060 070 080 090 IO0 110 I30 130 140 160 160 1 70 100 190 200 210 220 230 240 260 260 270 280 290 300 310 320 330 340 350 360

TOTAL

CAM 1-3

0.3 0.4 0.6 0.3 0.4 0.4 0.4 0.4 0.6 0.6 0.6 0.6 0.7 0.6 0.6 0.2 0.2 0.2 0.2 0.3 0.3 0.4 0.4 0.6 0.6 0.5 0.6 0.5 0.6 0.6 0.4 0.3 0.4 0.2 0.1 0.2

5 . 3 15.0

4-6

0.3 0.6 0.4 0 .4 0.4 0.6 0.6 0.7 0.7 0.7 0.6 0.6 1 .o 0.9 0.6 0.3 0.2 0.2 0.3 0 .4 0.6 0.7 0.9 1.2 I .2 1 .3 1.3 I .o

0.8 0.7 0.6 0.4 0.3 0.2 0.2

12.3

0.9

7-10 11-16

0.3 0.2 0.4 0 .2 0.4 0.2 0.3 0.2 0.4 0.1 0.6 0.1 0.6 0.1 0.4 o+ 0.6 0.1 0.6 0.2 0.6 0.2 0.7 0.3 1.2 0.5 1.5 U.8 0.6 0.6 0.4 0.2 0.2 0.1 0.2 0.2 0.3 0.2 0.7 0.7

1.3 1.2 1.8 1.7 1.9 2.0 2.2 2.1 2.2 2.3 1.7 1.7 1.5 1.4 1.5 1.2 1.0 1.0 0.9 0.6 0.6 0.6 0.5 0.4 0.3 0.3 0.1 0.1 0.2 0.1

18.9 22.7

0.e 1.0

17-21 22-27

O+ O+ Ot O+ O+

o+ o+ o+ o+ Ot o+ or

0.1 a+ 0, o+ O+ o+ o+ O t O+ O+

0.2 at 0.2 o* 0.3 O+ 0.3 0.1 0.3 0.1 0.5 0.2 0.6 0.2 0.5 0.1 0.5 0.1 0.3 O+ 0.2 o+ 0.1 ot 0.1 o+ 0, O t

0.1 o+ oc 0, O+

4.6 1.1

28-33 34-40 41-47 68-55 56-63 OVER 63 ' TOTAL

O+

0, O+ O+ o+ O+

O+ 02 O+

O+ O+ oi at O+

O+ O+ 0,

0,

0.2

O+ O+ O+

ot

01

1.1 1.5 1.4 1.3 1.3 1 .6 1.6 1.6 1.9 2.1 1.7 2.3 3.6 3.7 2.2 1 .l 0.7 0.8 1 .o 2.2 3.0 4.0 6.1 6.0 6.7 7.1 6.9 6.1 4.4 3.7 2.7 2.2 1 .8 I .1 0.6 0.7

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i

:"E E:,:=, :. -.,L&;.,.*+ , 7 A . :-< -';..E.. ., ,a<; =i -L.. -i-. :. -5:; ..;., :.-:

PERCENTAGE FREOUENC* OF SWLTAHEOUS OCCURRENCES OF SPECIFIEO RANGES OF Uw( HWRLY WiHO SPEEO AN0 OIRECrlON OubLin Airport SEPfnsER (1962 TO 19911

OIRECTIOH WINO SPEW IN (VKITS IN DEGREES CALM 1-3 4-6 7-10 11-16 17-21 22-27 28-33 34-40 41-47 de-55 56-83 OVER 63 TOTAL

010 0.3 0.3 0.2 0.1 01 01 O+ 0.9 020 0.3 0.2 0.2 0.2 o+ o+ 0.9 030 0.3 0.2 0.3 0.1 0.1 01 1 .l 010 0.2 0.3 0.3 0.2 0.1 o+ 1 .O OS0 0.2 0.4 0.4 0.2 o+ O+ 1.1

* 060 0.2 0.3 0.3 0.1 0, 0.9 070 0.2 0.4 0.3 0.1 O+ 0, , 1.1

1.3 1 .I

100 0.4 0.6 0.2 0.1 O+ 1 .3 I to 0.4 . 0.8 0.3 0.1 O+ I .2 120 0.5 0.6 0.6 0.2, 0.1 0, 2.0 130 0.S 0.9 1.0 0.5 0.1 O+' .2.a 140 0.6 0.8 1.1 0.9 0.1 o+ 3.3 I& 0.9 0.7 1 . 1 0.9 . 0.1 O+ 0, 3.3 160 0.3 0.4 0.6 0.7 0.1 O+ 2.1 1 70 0.3 0.3 0.4 0.4 0.1 O t I .6 I eo 0.3 0.1 0.2 0.2 O+ O+ I .o 190 0.3 0.4 0.4 0.4 0.1 0.1 O+ 1.6 200 0.3 0.6 0.9 0.e 0.2 o+ o+ 2.8 210 0.4 0.7 1.2 1.4 0.3 0.1 4.0 220 0.5 0.9 1.5 1.9 0.6 0.2 O+ 6.6 230 0.5 1.0 1.9 2.4 0.8 0.1 O+ 6.7 240 0.S 1.2 1.9 2.2 0.7 0.3 O+ 6.8 280 0,s 1.3 2.9 2.5 0.9 0.4 O+ 7.8 260 0.6 1.0 2.1 2.2 0.8 0.2 0.1 o+ 7.1 270 0.6 0.9 1.6 1.6 0.7 0.2 0, 6.6 280 0.5 0.9 1.3 1.4 0.6 0.2 (H 4.e 280 0.6 0.8 1.0 1.0 0.3 0.1 3.7 aw 0.5 0.7 0.8 0.7 O.? O t 2.8 ai0 0.4 0.5 0.6 0.1 0.1 O t 2.1 320 0.3 0.5 0.5 0.4 0.1 O+ 1.8 130 0.3 0.3 0.5 0.4 0.1 0.1 1.6 340 0.3 0.2 0.3 0.3 o+ 0, o+ 1.2 360 0.2 0.2 0.2 0.2 o+ o+ 0.8 350 0.2 0.2 0.2 0.1 o+ o+ 0.7

OEO 0.3 0.d 0.3 0.2 0.1 O+, DBO 0.3 0.4 0.3 0.2 O+ O+

TOTAL 4.2 13.0 19.9 27.3 25.9 7.2 2.3 0.2 O+ TOTAL W E R OF 08SEWATKoN9 .I 21600

7HE W R Y "O+- INOICATES THAT THE PERCENTAGE IS GREATER THAN E R 0 BUT LESS THAN 0.05

PERCENTAGE FRWW OF SXWULTANEOUS OcctuIRENCES OF SPECIFIED luHDES OF MEAN HOURLY WINO SPEED AN0 OIRECTION OubUn AIrport OCTOBER (1962 TO 19911

OLRECTI ON WLHO SPEEO IH Mors frf OEOREES CALM 1-3 4-6 7-10 11-16 17-21 22-27 28-33 34-40 41-47 48-56 56-63 OVER 63 TOTAL

U10 020 030 odo ow 060 010 OB0 WO loo 110 I20 130 140 1 so 160 1 70 180 IS0 200 If 0 220 230 240 260 260 270 280 290 300 310 320 330 340 350 360

0.2 0.2 0.3 0.1 0.2 0.3 0.1 0.2 0.2 0.2 0.2 0.1 0.2 0.2 0.2 0.1 0.2 0.2 0.3 0.2 0.2 0.2 0.2 0.3 0.2 0.3 0.3 0.3 0.3 0.4 0.6 0.4 0.3 0.4 0.4 0.3 0.3 0.4 0.4 0.2 0.4 0.4 0.3 0.2 0.5 0.6 0.5 0.6 0.6 0.6 1.0 0.9 0.6 0.e 1.4 1 . 3 0.5 0.E 1.3 1.9 0.5 0.7 0.9 1.0 0.d 0.5 0.5 0.5 0.4 0.3 0.5 0.3 0.3 0.6 0.S 0.6 0.3 0.7 1.0 1.1 0.3 0.7 1.2 l . d

0.3 0.7 1.4 1.7 0.3 0.8 1.6 2.3 0.4 0.8 1.9 2.3 Q.4 0.9 2.0 2.1 0.3 0.8 2.0 2.0 0.5 0.9 1.3 1.3

0.3 0.5 1.0 0.8 0.3 0.6 0.9 1.4

0.2 0.4 0.7 0.7 0.2 0.4 0.6 0.6 0.3 0.3 0.6 0.5 0.2 0.3 0.4 0.3 0.2 0.3 0.3 0.2 0.1 0.2 0.2 0.2 0.1 0.1 0.1 0.1

0.1 0.1

0, O+ 0, OC

O+ 0. 1

O+ ot 0,

0. I 0.2 0.4 0.5 0.2 0.1 0.1 0.3 0.4 0.d 0.6 1 .1 I .2 1 . I 0.e 0.6 0.5 0.3 0.1 0.1 0.1 0.1

OC

0.1 0.1

O+ 0.1 0,

OC

O+

ot 0.1 0.1 0.1

0, 0, O+ O+

0.1 0.1 0.2 0.3 0.4 0.3 0.5 0.3 0.2 0 .1 0. I

ot

O t O+

ot O+

O+ 04

ot 0.1 01. o+ U+ 0, o+

0.1 O+

0.1 O+ O+

0.9 0.9 0.8 0.8 I .o 0.9 1 . 1 1.6 1.4 1 .S 1 .a 2.1 3.2 4.6 4.6 3.3 2.0 1 .7 2.2 3.6 4.2 6.0 6.4 7.2 6.9 6.5 6.9 3.9 3.1 2.2 1.9 I .e 1 .3 1.1 0.6 0.6

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OubCIn Alroort j OIRECTION

IN OH1ReE3 . .

010

OJO MO 050 060

. :i) 020

om o m 090 100 1 10 120 130 140 160 160 1 70 1 80 I90 200 210 220 230 240 260 260 210 280 290 300 310 320 330 340 350 360

TOTAL

CAW 1-3

0.2 0.1 0.2 0.2 0.1 0.2 0.1 0.1 0.1 0.1 0.2 0.3 0.3 0.3 0.3 0.3 0.2 0.2 0.1 0.3 0.2 0.2 0.2 0.3 0.2 0.3 0.1 0.6 0.4 0.3 0.2 0.2 0.2 0.1 0. I 0.1

2.3 8.3

N-ER WINO SPEED IN KNOTS

(1962 TO 1990

4-6 7-10 11-16 17-21

0.2 0.2 0.2 0.1

0.2 0.3 0.3 0.4 0.2 0.4 0.2 0.3 0.3 0.4 0.2 0.4 0.3 0.4 0.3 0.4 0.4 0.4 0.4 0.4 0.6 0.7 0.5 0.8 0.6 0.6 0.4 0.5 0.3 0.3 0.A 0.6 0.4 0.9 0.4 0.9 0.6 1.2 0.6 1 . 3 0.7 I . ? 0.7 2.1 0.8 2.3 0.8 1.9 0.8 1.4 0.6 1.1 0.4 0.9 0.A 0.7 0.4 0.6 0.3 0.6 0.3 0.4 0.2 0.3 0.2 0.2

14.3 26.0

o.a 0.2

0.2 0.1 0.1 0.1 0.2 0.1 0.1 o+ 0.2 0.1 0.4 0.1 0.3 0.2 0.4 0.2 0.5 0.2 0.4 0.1 0.3 0.2 0.3 0.1

0.9 0.3 0.9 0.3 0.7 0.3 0.6 0.1 0.4 0.1 0.7 0.3 1.1 0.4 1.5 0.6 1.9 1.0 2.7 1.5 2.5 1.1 2.9 1.2 2.9 1.0 2.0 0.8 1.4 0.7 1.2 0.4 0.9 0.2 0.7 0.1 0.7 0.1 0.4 0.1 0.3 0.1 0.3 0.1 0.1 0.1

31.5 12.3

0.6 0.1

22-27

O+ 0. 1

O+ O+ O+ O+

0.1 0, '

0.1 O+ O+

0.1 0,

0.1 0.1 0.1 OC 0, 0.1 0.1 0.2 0.3 0.6 0.6 0.6 0.6 0:3 0.2 0.1 OI 04

O+ O*

0.1 0. 1 O+

4.5

28-33 34-40 41-47 40-65 56-63 OVER 63 TOTAL

ot O+ 01 01

OC

O*

04

O+ OC

0. I 0.1 0.1 0.1 0. I 0.1 0, O+ O+

O+ O I

0.7

0, O+ O* 0, O+

0.8 0.0 0.9

1.1 I .3 1.3 1 .4 1 .6 1.5 1.3 1.5 1 .8 2.1 2.9 2.4 1.7 1.3 2.2

4.0 5. I 6.8 6.8 7.7 1.9 6.4 6.0 3.7 2.7 2.2 2.0 1.6 1 .3 1 .z 0.8

0.a

3.a

0.1 TOTAL HUBER OF 08S~ATIONP .I 21600

THE ENTRY "O+" INDICATES THAT THE PERCENTAGE 15 OREATER THAN ZERO BUT LESS THAN 0.05

PERCENTAGE F R E O U W OF SIWLTANEWS OCCURRENCES OF SPECIFIED RANOES OF MEAN HOURLY WINO Dublin Alrport

OIREClWN IN OEOREES CALM

010 020 030 040 050 OM) 010 080 O S l 100 110 120 130 140 160 160 I70 I 80 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360

1-3

0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.1 0.3 0.3 0.3 0.3 0.3 0.2 0.2 0.3 0.2 0.3 0.2 0.3 0.2 0.3 0.3 0.3 0.3 0.2 0.2 0.2 0 . 1 0. I 0.1 0.1

4-6

0. I 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.3 0.9 0.3 0.3 0.3 0.6 0.6 0.5 0.3 0.3 0.d 0.6 0 .5 0.6 0.6 0.5 0.5 0.8 0.6 0.7 0.5 0.4 0.4 0.3 0.2 0.2 0.1 u.1

1-10

0. I 0. I 0.1 0.2 0.2 0.2 0.3 0.3 0.4 0.3 0.Q 0.4 0.6 0.8 I .o 0.8 0.6 0.3 0.4 0.7 I .o 1.1 I .3 1 .I 1.9 2.1 1.7 I .3 1 .2 1 .o 0.7 0.6 0.3 0.3 0.2 0.1

11-18

0.1 0.1 0.2 0.3 0.3 0.2 0.4 0.6 0.6 0.5 0.4 0.4 0.6 1 .a 1.1 0.9 0.5 0.4 0.5 1.1 1.5 1 .8 2.9 2.8 3.1 2.9 2.2 1.3 0.9 0.7 0.5 0.4 0.3 0.3 0.2 0.1

OECEfAER WINO SPEED IN KNOTS

11-21 22-21

01

O+ 0.1 0.2 0.2 0.1 0.2 0.3 0.3 0.3 0. I 0.3 0.4 0.3 0.3 0.3 0.2 0.2 0.2 0.6 0.8 0.9 1.3 1.4 I .4 I .3 I .o 0 .5 0.4 0.2 0.1 0.1 0.1

O+ 0.1 01

. .

04 O+ O I O+ 0.1

O+ 0.1 0.2 0.1 o+ 04 0.2 0.3 0.2 0.1 0.1

O+ 0, 0.1 0.3 0.3 0.4 0.6 0.7 0.8 0.6 0.3 0.2 0.1 0. I

O+ O+ O+ OC

0.1 04

.~

28-33

0, O+ 0,

0, 0. I

04

ot OC

O+ 0, ot OC

O* ot O+

0, O I

0. I 0. I 0.2 0.3 0.2 0.1 ot 0, O+ O+

O+

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