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This work provides the results of the analyzed long-term trends for three air temperature categories, namely: average (Tavg), maximum (Tmax) and minimum (Tmin) on monthly, annual and seasonal bases for Alexandria. The aim was to examine possible climate changes in this famous City based on the results obtained from the analyzed trends. The study was based on examining (1) linear regression approaches, (2) trend magnitudes, (3) Mann-Kendall trend test and (4) extreme air temperature events. The air temperature data from Alexandria International Airport station were used over a period of 65 years (1957-2021). For all analyzed time series, the results showed statistically significant positive trends. The exception was for the monthly mean Tmax during January, February and December (negative trends), and March (No trend). The H1 hypothesis prevails for the three temperature categories, on different basis. Over the period of investigation, both the annual mean Tavg and Tmin rose at a rate of +0.02 °C/yr, while annual mean Tmax rose at a rate of + 0.008°C/ yr. In winter, the annual mean Tavg and Tmin had increasing trends at a rate of +0.02 °C/yr. The winter Tmax had a feeble increasing trend (almost constant), at a rate of only +0.0003 °C/yr. In summer, the three air temperature categories increased at a rate of +0.02 °C/yr, each. Extreme air temperature times were specified in this study on all bases for the three temperature categories. The findings of this study are thought to be a reliable indicator of the presence of climate change in Alexandria. Keywords: Alexandria, air temperature, climate change, trend analysis, extremes

Knowledge of sea surface temperature (SST) behaviour is vital for long-term climate scenarios. This study highlights essential outcomes about the distinguishable and unsurprising warming of the SST along the southern border of the Levantine Basin. The analysis is based on monthly SST data for the period 1948–2018. The southern Levantine Basin has undergone SST increase, during the last 71 years. In this study, a consistent warming trend has been found for the analysed SST data series, with a rate of 0.04°C/a, i.e., 0.4°C/(10 a). From 1975 to 1991 the mean annual SST was 17.1°C, and this increased to be 19.2°C, over the period 2002–2018. Results revealed two opposite trends of variability: a decreasing trend (−0.06°C/a) over the period 1975–1991, and an increasing trend (0.2°C/a) from 2002 to 2018. Over the period 1948–2018, positive mean annual SST anomalies had an average of 1.8°C, and negative anomalies had an average of −1.1°C. The lowest SST total increase was found from January to April, with values about 0.03°C, while the highest warming appeared from June to September. The driving mechanisms behind the SST changes need to be more investigated, to understand the future trends and impacts of climate change in the Levantine Basin.

The present work is a qualitative research, which aims at drawing the general behaviour of variations in the subsurface seawater temperatures within three distinctive subsurface layers in the south-eastern Mediterranean region. The work is based on hydrographic data collected over 65 years (1948–2012). The investigated layers are the subsurface, the intermediate and the deep water layers. The general trend of the mean annual temperature anomaly (MATA) was examined using the linear and quadratic regressions. Results revealed that the MATA over the water column in the south-eastern Mediterranean has the same trend, regardless of the place (layer) of investigation. Linearly, all MATA have increasing trends with different rates, with the exception of the 75 m level, which has a decreasing trend following that previously concluded for the surface water in the region. Also, the quadratic approach reflects the same trend of MATA over the water column, with different years of minimum occurrence. These same trends from the surface to deep can be attributed to the vertical convection processes in this region, and to the expanded impact of solar radiation which may reach more than 30 m depth. Keywords: South-eastern Mediterranean Sea, seawater temperature, linear regression, quadratic regression, cyclic trend

Three decades (1974-2006) of hourly sea level records at Alexandria were used to calculate both surge elevations and astronomical tide. The tidal harmonic constituents were constructed using the WORLD TIDES program. Over the study period, the mean sea level (MSL) at Alexandria has increased by 8.09 cm giving a sea level rise (SLR) rate of 2.45 mm/year. The M2 constituent (principal lunar semidiurnal constituent) has the largest amplitude among other astronomical components, being 6.5 cm. Although the sea level rises, the rate of increase in high water (5.8 mm/year) is only 1.6 times the rise in the corresponding low water (3.5 mm/year). Results revealed that the extreme high water levels (coastal flooding) will occur with increasing frequency (i.e., with reducing return period) as a result of the mean SLR. Two extreme sea level years, 1987 and 1992, appeared during the 33 years of investigation. The annual maxima, also known as regional factor, α100 is 0.9 for positive surge along the Alexandria coast, which means that coastal structures along the coast of the City are in considerable risk with the return periods of positive surges.

The present work affords a comprehensive tidal analysis with diverse terms and beneficial information, which can be utilised for navigational and engineering purposes, and contributes to the understanding of the sea level behaviour in Safaga Harbour. The study was built up on hourly data of sea level over 2 years from January 2012 to December 2013, with no missing data. The T_TIDE package was used to obtain the different astronomical amplitudes and phases over the study period. To correlate with the affecting meteorological conditions, simultaneous hourly meteorological records were considered. These comprised air temperature, atmospheric pressure, and wind speed. Results revealed that tides in Safaga Harbour are of semidiurnal type. The impact of the astronomical tides on the observed sea level was 1.5 times that of meteorological factors, with a spring to neap ratio of 1.3. The mean sea level (MSL) was 0.56 m, exhibiting seasonal variation with the lowest value of 0.45 m in winter (December) and the highest of 0.71 m in summer (August). According to the present findings, the calculated mean tidal level (MTL) of 0.61 m was higher by 0.05 m than the MSL, which declares the importance of the shallow-water components upon studying the sea level variations in the sheltered coastal region of Safaga Harbour as they are increasingly spatially variable. Furthermore, the detected sea level variations in the Harbour were tightly correlated with the air temperature and atmospheric pressure than with the wind speed either zonal or meridional.

Rainfall and air temperature are significant parameters to establish the climatic condition of a region and their patterns of variations are, nowadays, key elements to judge the issue of climate change. The present study affords an analysis of long-term rainfall and air temperature records to establish their trends of variations in Alexandria and to, therefore, conclude the presence or absence of climate change in this important City. The data set of the two parameters extended on monthly basis over 40 years from 1980 to 2019. The analyses and the trends of the two parameters were carried out by the MS Excel® 2010, reflecting increasing trends with rates of 2.94 mm/year and 0.04 °C/year in rainfall and air temperature, respectively. Results also revealed a positive relationship (+0.21) between mean annual rainfall and air temperature, while the mean monthly records of the two parameters reflected a negative relationship of − 0.72. From the trends investigation, it is expected that Alexandria will examine an increase in the number of rainy days in April, May and September. The mean annual rainfall anomaly was +19.38 mm an indication of an increasing rainfall trend while the mean annual air temperature anomaly for the study period was +0.3 °C showing that the mean annual temperatures are rising in the study area. Therefore, this increasing mean annual rainfall accompanied with rising mean temperatures is considered indicator of the presence of climate change that can be experienced in Alexandria.

The present work can be considered the first to examine the sea–land breeze phenomenon along the southern border of the Levantine Basin. Hourly records of wind regime (speed and direction) from five coastal meteorological stations distributed over this coastline were analyzed to characterize sea and land breezes in this region. The meteorological data also comprised simultaneous hourly air temperature and relative humidity records. The data covered 13 years from January 2007 to December 2019, with 0% missed data. The diurnal inversion of wind direction was utilized to recognize sea and land breeze days. This was verified by the reversal daily behavior of temperature and relative humidity. Statistics describing the onset, cessation, and seasonality of sea breeze occurrence are presented. Seasonally, sea breezes are most frequent in summer and early autumn months (July–October). Land breeze appears at most stations during night, with direction varying from one location to another among the five examined coastal stations.

The present paper sheds light on the main sea level characteristics and the sea level return periods at Port Said Harbour of Egypt. This type of analysis is important for coastal structure designing, development and mitigation. The work is based on hourly sea level records at Port Said Harbour over eight years (2003–2010). Tidal analysis showed that tides at Port Said Harbour are of mixed mainly semidiurnal type, with 13 cm amplitude for the principal lunar constituent (M2). Results also revealed a mean sea level of 67 cm, a ratio of 1.5 between spring and neap tidal ranges and an annual rate of sea level rise of 4.8 mm/yr. Return periods of 100 and 112 years were calculated for the sea levels of 25 cm and 100 cm, respectively.

Safaga and Qusseir are two important harbours on the Egyptian Proper Red Sea coast. To the best of the authors’ knowledge, this is the first work to describe the sea level characteristics at these two ports. The study is based on hourly sea level records over 3 years (2012–2014). There are no missed data at Qusseir site, but Safaga dataset missed 25% of records (April–December 2014). The hourly water level ranged between 0.02 m and 1.70 m at Safaga and between 0.04 m and 1.03 m at Qusseir, with a mean sea level (MSL) of 0.56 m and 0.50 m at the two Harbours, respectively. The T_TIDE package was used to produce astronomical and residual elevations at the two Harbours. Results revealed that the two Harbours examine explicit semidiurnal tidal cycle, with a bit higher astronomical amplitudes in Safaga. Moreover, the two sites exhibit almost the same seasonal sea level trend with very slight differences. The monthly mean levels at the two Harbours are always below their averages except during the summer months. The principal features of the semidiurnal tides indicated a ratio of 1.3 and 1.5 between spring and neap ranges at Safaga and Qusseir, respectively. The most pronounced sea level range at Safaga Harbour was 0.50 m, while it was 0.60 m at Qusseir Harbour. The astronomical elevations fluctuated between − 0.55 m and + 0.71 m and between − 0.47 m and + 0.53 m in Safaga and Qusseir Harbours, respectively.

Meteorological conditions are key elements in the management of any harbour. The present study aims to present and analyse the meteorological conditions over Safaga Harbour of Egypt. The work is based on meteorological data recorded on hourly basis from January 2007 to December 2017 from the automated weather station in the Harbour. Results revealed a general trend of slight increase in the mean annual air temperature anomaly over the study period with a rate of 0.01 °C/year. The mean annual sea level pressure anomaly also had an increasing trend with a rate of 0.11 hPa/year. The dominant wind directions over the Harbour were N-NW-WNW during the study period. The year 2015 was the year of the lowest annual mean wind speed (9.74 kt), while 2008 was the year of the highest one (13.40 kt). There was a trend of decrease in the mean annual wind speed anomaly with a rate of −0.3 kt/year. Results also revealed a general trend of decrease in the mean annual relative humidity anomaly with a rate of −0.37%/year. Six, seven, thirteen and seventeen extreme values were detected for the air temperature, sea level pressure, wind speed and relative humidity, respectively.

The variability of sea surface temperature (SST) is widely studied due to its large impact on ocean–atmosphere interaction and on the majority of oceanographic events on different scales. SST is al...

Wind is an important factor affecting the observed sea level. This effect varies from one location to another, and depends largely on the morphometry and the position of the location itself. This paper investigates the relationship between the variations in the observed sea level at Alexandria Western Harbour and Abu-Qir Bay, of different morphometry, along Alexandria coast, and the wind pattern over the city. Simultaneous data sets of hourly sea level records at the two locations and of hourly measured wind over Alexandria from 01.01.2005 to 31.12.2006 are used. The WORLD TIDES package is used for a full sea level analysis. The wind pattern is described, and both wind rose and frequencies are also produced. Results reveal that tides in Abu Qir Bay can be classified as steric meteorological tides; greatly affected by the wind pattern than the astronomical impact. This is mainly attributed to the morphometry and open location of the Bay. In Alexandria Western Harbour, on the other hand, tides can be classified as astronomical tides mainly affected by the sheltered location and the constructions of the Harbour, which diminish the effect of the wind and, meanwhile, increase the impact of the celestial bodies on the recorded sea level.

Using 33 years (1974–2006) of hourly sea-level data, this paper plots the trend of long-term variation in the sea-level off Alexandria, representing the south-eastern Mediterranean Sea. Both linear...

A one decade (1996–2005) of daily sea level records at Alexandria has been used to calculate both astronomical tide and surge elevations. The tidal harmonic constituents have been constructed using the T_TIDE program. Surge elevations have been calculated by subtracting the astronomical height from the observed sea level. The type factor of the tidal cycle at Alexandria has been calculated and specified the mixed mainly semidiurnal tide. The minimum annual Mean Sea Level (MSL) was 48.62 cm, while the maximum was 52.96 cm. The MSL over the study period is 50.67 cm. Thirty-five tidal constituents have been produced based on the present data. Both the Mm (Lunar monthly) and the Msf (Lunisolar synodic fortnightly) constituents in the present study have the largest constituent amplitudes, being 2.03 for the former and 7.06 for the later. The surge height over the study period varied between 14.64 and 87.15 cm, with an average of 50.66 cm. The results of the present research show that astronomical tide contributes with 0.005–37.63% while, surge contributes with 62.37–99.995% in the observed sea level.

Tidal currents and ranges in the Mediterranean basin are generally low from a tidal energy perspective. The narrows through the Strait of Messina are an exception, exhibiting intensive tidal currents that have the potential for the economic exploitation. Maximum current velocities at spring peak tides through the Strait vary between 1.8m/s to more than 3m/s. Selection of suitable locations for tidal energy extraction for the exploitation of these natural tidal phenomenon is not, however, a simple process. Constraints must be satisfied, subject to basic criteria dependent upon local factors, technology limitation and economic consideration. In addition, the impact of large scale extraction on the underlying hydrodynamics, environment and ecology within the Strait has to be assessed and evaluated. This paper is a desk-based case study to show how a tidal resource may be environmentally assessed for energy extraction, using the Strait of Messina as an exemplar case

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Using 38 years (January 1973-December 2010) of hourly wind records, the present paper aims at drawing the possible long-term trends of winds and ten surface wave parameters over the west region of Scotland using the quadratic regression approach. Four dominant wind components were determined: the southern, the western, the south-western and the north-western. Two opposite groups of oscillations were proven: one for the southern groups and one for the western groups.The examined wave parameters were: the wave frequency, the wave angular frequency, the peak angular frequency, the wave spectral density, the significant wave height, the peak period, both the peak and group velocities and lastly the wave energy and the wave power. Results revealed that every examined parameter tended to have a cyclic behaviour except the wave spectral density, which appeared to be linearly decreasing. All wave frequencies were in an inverse correlation to the mean monthly wind speed. All other wave parameters appeared to be highly correlated to the mean monthly wind speed with correlation factors exceeding 0.95 except the wave power, which had a correlation factor of 0.89.In conclusion, the general behaviours of the dominant wind components over the west region of Scotland, and of the different wave parameters tend to be cyclic. A longer time series, than that presently used, will be advantageous in order to strengthen this outcome with more robust investigation. This concluded cyclic behaviour may positively impact on the engineering work within the wave energy resource off the western coasts of Scotland.