ARAB ACADEMY FOR SCIENCE AND TECHNOLOGY AND MARITIME TRANSPORT ,

WAVE AND SURGE FORECASTING ALONG THE EGYPTIAN COAST OF THE

Submitted By

Mamdouh Mohamed Meligy Mohamed Shalaby

A thesis submitted to the Arab Academy for Science and Technology and Maritime Transport, in fulfillment of the requirements for the award of:

Master Degree in Maritime Transport Technology (Meteorology)

Supervised By Prof. Dr. Abdel Aziz Abdel Baeth Hamed Chairman of Meteorology Program

2000

DECLARATION

I hereby certify that the source of the material in this thesis that is not my work has been identified, and that no material is included for which a degree has previously been conferred on me.

The contents of this thesis reflect my own personal views, and are not necessarily endorsed by the Arab Academy for Science and Technology and Maritime Transport.

Signature: Mamdouh Mohamed Meligy Date

Supervised by:

Prof Dr. Abde~l_.~

Chairman of Meteorology Program.

College of Maritime Transport and Technology.

Assessed by: Name: Prof Dr. Ahmed El-Gindy. f).!1.~~~ Office :Alexandria University.

Name :Commodore\ Samir A.A. Khalifa. ~ .. -J f2. ~~. t~~;--

Office :Egyptian Navy.

Name: Prof Dr. Saad Mesbah. S ~ F'i'o eLi. g ...... Office: Arab Academy for Science and Technology and Maritime Transport.

Name: Prof Dr. Refat Rashad. t ~ G Office: Arab Academy for Science and Technology and Maritime Transport . .. -11- Acknowledgement

"Praise be to Allah, who has guided us to this felicity, never could we have found guidance, had it not been for the guidance of Allah: indeed it was the truth"

I wish to express my deep gratitude to Prof. Dr. Abdel Aziz Abdel Baeth Hamed, Professor of Meteorology and Chairman of Meteorology Program, College of Maritime Transport and Technology, Arab Academy for Science and Technology and Maritime Transport for supervising the work and reading the manuscript of the thesis. I am indebted to him for his able guidance and valuable advice.

The author extends SlOcere thanks to Rear Admiral. Ahmed Saber Sleem, Commander in chief, Egyptian Navy Forces and Ret. Commodore Wagdy M. Fouad former Director of Hydrographic Department, Egyptian Navy Forces and Commodore Samir A.A. Khalifa Director of Hydrographic Department, Egyptian Navy Forces for their continuous help and support through out preparing this thesis.

The author also extends sincere thanks to Prof. Dr. Refat Rashad, Chairman of higher studies Department, College of Maritime Transport and Technology, Arab Academy for science, and Technology and Maritime Transport for his help during my study.

Many thanks are also due to the staff members of: Hydrographic Department of the Egyptian Navy Forces, Meteorology Program, College of Maritime Transport and Technology, Arab Academy for science, and Technology and Maritime Transport, and Egyptian Meteorological Authority for their valuable assistance.

-111- Abstract

Lack of sufficient knowledge of coastal wave climates and storm surges hinders management and treatment of coastal problems. This limits the data applicability for describing the basic stochastic processes, which govern beach changes along the Egyptian coast of the Mediterranean Sea.

The growth of the waves is governed by the following factors: • The depth of the water. • The strength of the wind. • The duration of the wind. • The fetch of the wind.

In this study the author discussed the available methods for wave forecasting and the most acceptable method of forecasting the waves along the Egyptian coast of the Med. Sea, as well as studying the effect of the depressions during their courses, on the state of the sea along the Egyptian coast ofMed. Sea.

The author also studied the wave characteristics from the observed waves at Alexandria, Abu Quir and Ras EI-Bar during the period 1992-1995 by the Hydrographic Department (Egyptian Navy), and estimated wave climatology along the Egyptian coast of the Mediterranean Sea during each month.

Surges are a natural Phenomenon resulting from a complex interaction between the atmosphere, ocean and earth's surface (both above and below the sea surface). They occur in tropical and extra - tropical regions. Surges represent an ocean reaction to the large - scale impact of atmospheric pressure and wind.

-lV- This study considered recent tidal data (1995 to 1998) to compare the present conditions with previous ones. Harmonic tidal constants calculated using 31 day, hourly records, and the daily mean surge calculated and discussed also. The monthly mean sea level correlated and compared with the means of the atmospheric pressure and wind speed.

The thesis consists of 5 chapters and 2 appendices, the first chapter contains the general climatic conditions and the general characteristics of the Mediterranean Sea weather.

The second chapter contains the climatic conditions along the Egyptian Coast of the Mediterranean Sea.

The third chapter gives an idea about the methods of waves forecasting, the effect of depressions movement on the wind waves along the Egyptian coast of the Mediterranean Sea and the wave climatology at Alexandria, Abu-Quir, and Ras El-bar.

Chapter four discussed the general statistics of surge at Alexandria coast as well as the percentage frequency at of positive and negative surge.

Chapter five gives the conclusion of the study.

Appendix A: contains basic wave characteristics.

Appendix B: glves an idea about the pressure types and the depression tracks over the Egyptian coast of the Med. Sea

-v- CONTENTS Page

Declaration 11

Acknowledgments 111

Abstract IV

Contents VI List of Figures x List of Tables xu" , List of Abbreviations XIV Chapter 1 Introduction 1. 1 Introduction. 1 1.2 Description of the Mediterranean Sea. 2 1.3 General climatic conditions. 5 1.3 .1 Effects of topography on the weather. 5 1.3.2 Barrier effects. 6 1.3 .3 Effects of vertical motion of air. 7 1.4 General characteristics of Mediterranean weather. 7 1.4. 1 Cool season. 9 1.4.2 Warm Season. 10 1.5 Air masses. 11 1.6 Fronts. 12 1.6.1 Cold fronts. 13 1.6.2 Warm fronts. 13 1.6.3 Occlusions fronts. 13 1.7 Previous studies. 13 1.7.1 Wave predication. 13 1.7.2 Surge predication. 16 1.8 Aim of study. 18 Chapter 2: Climatic Conditions along the Egyptian Coast of the . Mediterranean sea 2.1 Introduction 19

-VI- CONTENTS Page 2.2 Regional climatic conditions along the Egyptian coast of the 19 Mediterranean sea. 2.2.1 Introduction 19 2.2.2 Air temperature. 21

2.2.3 Atmospheric pressure. 22 2.2.4 Relative humidity. 22 2.2.5 Mean scalar wind speed 26 2.2.6 Wind directions. 32 2.2.7 Stormy days. 43 2.2.8 Rainfall. 43 2.2.9 Thunderstorms. 46 2.2.10 Sand rising and sandstorms. 46 2.2.11 Sea surface temperature and salinity at Alex. 49 Chapter 3 Waves forecasting along the Egyptian coast of the Mediterranean Sea.

3.l Introduction. 51 3.2 Wave forecasting by manual methods 52 3.2.1 The USA method for predicting sea waves 55 3.2.1.1 Waves estimation. 55 3.2.l.2 Wave dissipation. 57 3.2.l.3 Waves prediction. 58 3.3 Effect of the depression tracks on the wind waves. 63 3.3.1 Winter season. 63 3.3.2 Spring season. 63 3.3.3 Summer season. 64 3.3.4 Autumn season. 64

3.4 Wave r~cording instrumentation. 73 3.4.1 (S4DW) wave gauge. 73 3.4.l.1 (S4DW) information. 73 3.4.2 CAS directional wave recording system. 74 -vu- CONTENTS Page

3.4.3 Wave climatology. 76 3.4.3.1 Wave roses at Alexandria. 76 3.4.3.1.1 Winter season. 76 3.4.3.1.2 Spring season. 76 3.4.3.1.3 Summer season. 77 3.4.3.1.4 Autumn season. 77 3.4.3.2 Wave roses at Abu Quir and Ras EL Bar. 78 3.4.3.2.1 Winter season. 78 3.4.3.2.2 Spring season. 78 3.4.3.2.3 Summer season. 78 3.4.3.2.4 Autumn season. 79 Chapter 4: Surge at Alexandria coast.

4.1 Introduction. 89 4.2 Storm surge - Tide interaction. 92 4.3 Surge heights estimation 92 4.3.1 Elimination of the predicated astronomical tide method. 93 4.3.2 Low- pass filter method. 101 4.3.3 Xo- filter method 104 4.4 General statistics of surge at Alexandria. 105 4.4.1 Percentage frequency of positive and negative surge. 107 Chapter 5 Conclusion 5.1 Introduction. 111 5.2 Results. 111 5.3 Effect of the depression tracks on the wind waves 114 5.4 Wave climatology 115 5.4.1 Wave climatology at Alexandria 115 5.4.2 Wave climatology at Abu Quir and Ras EL Bar 116 5.5 Surge at Alexandria 118

-Vlll- CONTENTS Page

References 120 Appendix A: Basic wave characteristics.

Appendix B: The pressure types and the depression tracks over the Egyptian coast of the Med. Sea

-lX- List of Figures No Fieures Paee

1. 1 The Mediterranean geographical features. 4 1.2 Main regional winds of the Mediterranean sea. 8

2-1 Egyptian weather station. 20 2-2 The monthly average temperature. 23 2-3 Monthly mean atmospheric pressure (Hpa) corrected to M. S.L. 24 2-4 The monthly mean relative humidity. 25 2-5 Surface wind speeds through out the period 61-90 at SaIl urn. 27 2-6 Surface wind speeds through out the period 61-90 at . 28 2-7 Surface wind speeds through out the period 61-90 at Alex. 29 2-8 Surface wind speeds through out the period 61-90 at . 30 2-9 Surface wind speeds through out the period 83 - 97 at El . 31 2-10 Directions surface wind through out the period 61- 90 at . 33 2-11 Directions surface wind through out the period 61- 90 at Mersa Matruh. 35 2-12 Directions surface wind through out the period 61- 90 at Alex. 37 2-13 Directions surface wind through out the period 61- 90 at Port Said. 39 2-14 Directions surface wind through out the period 83 - 97 at El Arish. 41 2-15 The occurrence of storm days. 44 2-16 The monthly amounts of rain fall. 45 2-17 The thunderstorms days. 47 2-18 The monthly mean of sandrising & sandstorms. 48 2-19 Temperature and salinity in Alex. 50

3-1 Manual wave forecasting diagram (from Groen and Dorrestien, 1976). 54

3-2 Deep - water wave forecasting curves as a function of wind speed, fetch 59 length and wind duration, for fetches of 1 to 1000 miles.

3-3 Deep - water wave forecasting curves as a function of wind speed, fetch 60 length and wind duration, for fetches ofl 00 to> 1000 miles.

3-4 Wave period at end of decay distance, travel time, and ratio between 61 wave height at end of decay distance and at end of fetch as functions of decay distance and wave period at end of fetch.

3-5 Increases of swell period and decrease of swell height as functions of 62 decay distance and fetch length.

-x- List of Figures No Figures Pa2e

3-6 Wave recording locations. 75 3-7 Waves direction along Alex. coast. 80 3-8 Waves direction along Abu Quir coast. 81 3-9 Waves direction along Ras EI-Bar coast. 82 3-10 Wave height in meters. 83 3-11 Wave length in meters. 84 3-12 Wave period in sec. 85

4.1 The monthly means of surge in (em), atmospheric pressure in (Hpa), and 103 wind speed in (kn.) at Alexandria (1995-1998).

4.2 Monthly surges frequency at Alexandria from January to June. 109

4.3 Monthly surges frequency at Alexandria from July to December. 110

. -Xl- List of Tables I -NO. I Tables I Pagel

2.1 Sea surface temperature and salinity at Alexandria. 49

3.1 The effect of the depression track T 1 on the wind waves along 65 the Egyptian coast.

3.2 The effect of the depression track T2 on the wind waves along 65 the Egyptian coast.

3.3 The effect of the depression track T3 on the wind waves along 66 the Egyptian coast

3.4 The effect of the depression track T 4 on the ';Vind waves along 66 the Egyptian coast • 3.5 The effect of the depression track T5 on the wind waves along 67 the Egyptian coast.

3.6 The effect of the depression track T6 on the wind waves along 67 The Egyptian coast.

3.7 The effect of the depression track T7 on the wind waves along 68 the Egyptian coast

3.8 The effect of the depression track T8 on the wind waves along 68 the Egyptian coast

3.9 The effect of the depression track T9 on the wind waves along 69 the Egyptian coast.

3.10 The effect of the depression track T lOon the wind waves along 69 the Egyptian coast.

3.11 The effect of the depression track TIl on the wind waves along 70 the Egyptian coast The effect of the depression track T12 on the wind waves along 3.12 70 the Egyptian coast

3.13 The effect of the depression track T 13 on the wind waves along 71 the Egyptian coast.

.. -Xll- List of Tables NO. Tables Page

3.14 The effect of the depression track T 14 on the wind waves along 71 the Egyptian coast. 3.15 The effect of the depression track T150n the wind waves along 72 the Egyptian coast. 3.16 The effect of the depression track T 16 on the wind waves along 72 the Egyptian coast 3.17 Wave height in meter comparison between the selected sites. 86 3.18 Wave length in meter comparison between the selected sites. 87 3.19 Wave period in sec comparison between the selected sites. 88

4.1 Harmonic analysis results at Alexandria in 1995. 96 4.2 Harmonic analysis results at Alexandria in 1996. 97 4.3 Harmonic analysis results at Alexandria in 1997. 98 4.4 Harmonic analysis results at Alexandria in 1998. 99 4.5 Average harmonic analysis results at Alex. 100 4.6 Average sea level at Alexandria in cm (1995-1998). 102 4.7 The statistical measures of daily mean surge at Alexandria in 106 (cm) during the period (1995-1998). 4.8 Frequency percentage distributions of daily mean surge in (cm) 108 at Alexandria from 1995 to 1998

-Xlll- LIST OF ABBREVIATIONS

Abbreviation Definition symbol A Wave amplitude - m (ft)

ASCI American standard for information interchange. .- ab Distance between two wave rays Co Degree Celsius CERC Coastal Engineering Research Center (US) CMOS Computer Memory Operating System CMC Canadian Meteorological Center CAS Cassette Acquisition System Deg Measure of angle, degree Dp Duration of wave generation - h e,exp Exponential constant 2.71828 E, Etotal Wave energy (variance) per unit - m 2 per area Wave spectral energy density as function of frequency and direction - E (F, 9) m2/Hlrad

e Spectral Bandwidth FFT Fast Fourier Transformed f Wave frequency. F Fetch Fi Correction Factor tidal Components Ft Unit of length. Foot

G Acceleration due to gravity - m/ S2 G, (ug, Vg) Geostrophic wind velocity; speed - m/s (Kn) h Unit of time, hour Hb Breaker wave height - m (ft)

-xv- LIST OF ABBREVIATIONS Abbreviation Definition symbol

Hc Characteristic wave height -m (ft) Hmax Maximum wave height for specified period time- m (ft) Hsea Wind wave height - m (ft) Hswell Swell height - m (ft) H1I3 Significant wave height HF High Frequency Hi Amplitude of the tidal components Hffio The spectrally based significant wave height Hpa Hecto paschal I The Considered tidal Components 1m Knot Mph Mile Per hour M.S.L Mean Sea Level mls Unit of speed, metre per second N A given number of waves, years, etc. n (j,8) Wave action density NMC National Meteorological Center NMS National Meteorological Service P Atmospheric pressure - hpa. PPT Part per thouthand. Qb The fraction of braking waves. Q(H) Probability of exceeding the wave height H R Residual height in cm RAM Random access memory RMSE Root - mean - square error S Unit of time, second

. -XVI- LIST OF ABBREVIATIONS

Abbreviation Definition symbol So Mean sea level S4DW Sea Wave Recorder SWAMP Sea Wave Modelling projection T Track Tc Characteristic wave period -so

TH1/3 Significant wave period: average period of the 1/3 highest waves-s Tm The period of the peak of the wave spectrum. Tp Peak period: wave period at the peak of the spectrum (modal period)-s Ts Significant or peak period according to specification Tz Zero crossing period

u~u Wind speed; wind velocity - mis, (lm) UlO Wind speed at the 10 m level- mis, (lm)

(ug, v~, G;G Geostrophic wind velocity; speed - mls,(kn) UA Wind stress factor. UTC Universal time Coordinates VOS Voluntary Observing ships W.H Wave height WMO World Meteorological organization

yZ Height variable

'Y Peak - enhancement parameter in Jonswap spectrum 11 (x,t) Elevation of water surface at position x and time t

-xvii- LIST OF ABBREVIATIONS Abbreviation Definition symbol , 1] Mean water surface elevation a Direction of wave propagation aD Vector mean wave direction K Karman constant. A, As Wavelength, wavelength of sea.

1l A constant; 3.14159 P; pw; po Density; density of water; density of air

a Wave ferquency associated with a (current modified) ai Phase of the tidal components (in degree) q Wave steepness.

ro Angular frequency = 21l f 'P Stability function for atmospheric boundary layer wind direction l/J Phase of sinusoidal wave

... -XVIII-