Yehia Hafez

*Cairo University, Faculty of Science Department of Astronomy, Space Science and Meteorology Egypt* 

#### **1. Introduction**

110 Atmospheric Model Applications

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Kurihara, K., Yoshizaki M. and Sato, Y. (2005). Performance of the long-term integrations of the Japan Meteorological Agency nonhydrostatic model with use of the spectral boundary coupling method. *Weather and Forecasting*, Vol.20, pp.1061For case one, the UK severed from abnormal severs cold winter season on 2009. The mean temperature for that winter was 3.2 °C, which was 0.5 °C below average of (1971-2000), provisionally making it the coldest winter since 1996/97. Whereas, Mean temperatures over the UK were 1.1 °C below the average during December 2008, 0.6 °C below average during January and 0.2 °C above average during February during that season. A generally cold first half to December was followed by a milder period, before turning very cold by the first of January see Figure (1). This very cold spell persisted for the first 10 days of January, with some severe frosts, followed by alternating milder and colder periods. Despite a cold (and snowy) first half of February, milder conditions later resulted in near-normal temperatures overall. Rainfall amounts over the UK were below the 1971-2000 average during December with 70%, January was close to average with 98% and February was drier than average with 63%. In December, parts of south-east England, East Anglia and Wales had less than 50% of the average rainfall and in February much of Wales, north-west England and western Scotland recorded less than 50% of average. Significant snowfalls occurred in the first half of February, particularly over England and Wales during the first week, when depths greater than 15 cm were recorded quite widely. The last time of that winter season a comparable snowy spell occurred was in February 1991 (MetOffice., UK, 2009). However, there are several scientific literatures challenge the abnormal weather conditions [e.g. (Cohen et al., 2001; Hafez 2007, 2008; and Rosting & Kristjansson 2008)]. In addition to that identification, oscillations, and influence of the ITCZ (Intertropical Convergence Zone) in the atmospheric cooling weather conditions had studied by (Bates 1970; Pike 1972; Citeau 1988b; Gadgil & Guruprasad 1990; Waliser 1992, 1994; Hess et al., 1993; Philander et al., 1996; Kraus 1997; Sultan & Janicot 2000; Hafez 2003a; Broccoli et al., 2006; and Raymond 2006). However, climate simulations, using models with different levels of complexity, indicated that the north-south position of the intertropical convergence zone (ITCZ) responds to changes in interhemispheric temperature contrast. The present work aims to investigate the relationship between the Atlantic Western Africa ITCZ variability and the surface air temperature over UK through months of the winter 2009. For case two, the intertropical convergence zone (ITCZ) is one of the most recognizable aspects of the global circulation that influence in the atmospheric weather. The ITCZ forms as a zonally elongated band of cloud at low latitudes nearness of the equator where the northeasterly and southeasterly

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 113

blocked the main road to the Red Sea resort of Eilat. A bridge also collapsed near a cargo crossing between Egypt and Israel. In addition to that, heavy rainfall recorded over south Turkey, Syria and Lebanon. One positive aspect of the flooding is that it helped replenish groundwater reserves. Whereas, the floods boosted groundwater reserves which are the main source of freshwater in this region. It also brought silt, which is very good for crops. Silt also reduces erosion of the coast when flood water reached the sea. The disasters information getting from Dartmouth Flood Observatory. Historical records of flash flood episodes over EM show that it was existed in autumn season of months (September, October and November) not in January. So that the present case study is outstanding extreme case. However, the flash floods problem in the EM was challenged several times in scientific literatures (e.g, Hafez, 2003b; Barnolas et al., 2007&2008, Papadopoulos & Katsafados, 2009; Houssos et al. 2009; Hatzaki et al., 2010;Michaelides et al., 2010 and Llasat et al., 2010). The previous studies referred the occurrence of these floods to deep of upper air trough of low pressure system with cold advection over the EM region. The present paper aims to uncover the rule played by ITCZ variability in the occurrence of extreme flash floods in EM in

For the first case, the daily NCEP/NCAR reanalysis data composites for mean surface air temperature, over the UK, [ ( 49° N- 61° N) latitudes and ( 11° W- 2° E) longitudes] , for the period from 1 December 2008 to 28 February 2009 (Kalnay et al., 1996) are used in this study. The available meteorological data obtained from UK meteorological office are also used in the present study. In addition to that, the Atlantic – Western Africa [ 15° W – 10° E] ITCZ mean position data for summer months June, July and august of 2008 are used. The movement of the ITCZ over Atlantic-Western Africa has been monitored by plotting the daily location of the surface 15-degree C dew point temperature at 1200 UTC for every 5 degrees of longitude, (Ilesanmi, 1971). Over Atlantic-Western Africa, a mean position for each 10-day period is calculated for the area from 15 degrees west longitude to 10 degrees east longitude. However, the ITCZ data series begin in 1979 for Atlantic - Western Africa and the long-term means use 1979-2001 data. These data were obtained from website through the internet of the Climate Prediction Centre at http://www.cpc.ncep.noaa.gov/products/monitoring\_data/. In the present work, these datasets are analyzed using the anomalies methodology and correlation coefficient technique. The formula for calculating the correlation coefficient was taken from (Spiegel, 1961). For the second case; The 6-hour and daily NCEP/NCAR reanalysis data composites for precipitation MSL pressure, gepotential height at 500 hpa level, surface vector and meridonal winds over the eastern Mediterranean region [ ( 22° N- 40° N) latitudes and ( 24° E- 42° E) longitudes] , for the period (17 - 20) January 2010 (Kalnay et al., 1996) are used in the present study. The available floods disaster data obtained from dartmouth flood observatory are also used. In addition to that, 6-hour infrared (IR) satellite images are obtained to identify the ITCZ position by using of cloud clusters through the same period. In the present work, datasets are analyzed using the anomalies methodology. These data were obtained from websites through the internet of the Climatic centers, Climate Diagnostics Centre for supporting the data used throughout this study. Plots and images were provided by the NOAA-CIRES Climate Diagnostics Centre, Boulder, Colorado, USA from their Web site at http://www.cdc.noaa.gov. Available data of flash floods disasters obtained from dartmouth

flood observatory through its website http://www.dartmouth.edu.

January 2010.

**2. Data and methodology** 

Fig. 1. Variation of UK daily mean temperature for Winter 2008/2009 [Source: MetOffice., UK, 2009: Winter Summary, 2009, ©Crow copyright]

trade winds converge. The focus of this study is to introduce the rule of ITCZ variability on the occurrence of unseasonably heavy rains, widespread flash floods, over Eastern Mediterranean (EM) in the period (17- 20) on January 2010. In fact, the topography in the EM such as high mountains, is essential factor for huge disasters of flash floods (Llasat, 2009). The flood disasters in EM through this period had been recorded and reported. Whereas, in Egypt, in the southern city of Aswan, floods and strong winds disrupted power in several neighborhoods. The floods were a surprise as North Sinai had not seen floods in 30 years. Sinai Peninsular was flash floods damage left more than 1000 homes totally destroyed, 1,076 submerged and the area suffered material losses of over US\$25.3 million. The floods ruined 59km of roads, killed 1,838 animals and felled 27,820 (mostly olive) trees. Five Egyptians died in flooding in the southern Sinai desert. All 75 patients at the El-Arish general hospital in the Sinai had to be evacuated when the first floor was flooded. Flooding wiped out large sections of a major road in Egypt's south Sinai and destroyed two dozen homes in Ras Sudr. In Palestine, Heavy rain and flooding has forced hundreds of people from their homes in Khan Younis in the south of the Gaza Strip. Over 100 families had been made homeless.. Some 300 families were also displaced. The flooding along Egypt's Red Sea coast, the border with Israel and in the south left six people dead. It also damaged the roads leading to the resorts in the Sinai desert and brought down telephone and power lines. Israel temporarily closed its southern border crossings with Egypt and Jordan. Jordanians were warned off the streets after nearly a dozen accidents in one area. Rains of this magnitude, rains reached to 90 mm/day, which are rare in this largely arid region and where heavy precipitation can result in sudden and deadly flash floods. In Israel, a woman drowned when her car was caught in a flash flood in the south, where stormy weather also blocked the main road to the Red Sea resort of Eilat. A bridge also collapsed near a cargo crossing between Egypt and Israel. In addition to that, heavy rainfall recorded over south Turkey, Syria and Lebanon. One positive aspect of the flooding is that it helped replenish groundwater reserves. Whereas, the floods boosted groundwater reserves which are the main source of freshwater in this region. It also brought silt, which is very good for crops. Silt also reduces erosion of the coast when flood water reached the sea. The disasters information getting from Dartmouth Flood Observatory. Historical records of flash flood episodes over EM show that it was existed in autumn season of months (September, October and November) not in January. So that the present case study is outstanding extreme case. However, the flash floods problem in the EM was challenged several times in scientific literatures (e.g, Hafez, 2003b; Barnolas et al., 2007&2008, Papadopoulos & Katsafados, 2009; Houssos et al. 2009; Hatzaki et al., 2010;Michaelides et al., 2010 and Llasat et al., 2010). The previous studies referred the occurrence of these floods to deep of upper air trough of low pressure system with cold advection over the EM region. The present paper aims to uncover the rule played by ITCZ variability in the occurrence of extreme flash floods in EM in January 2010.

## **2. Data and methodology**

112 Atmospheric Model Applications

Fig. 1. Variation of UK daily mean temperature for Winter 2008/2009 [Source: MetOffice.,

trade winds converge. The focus of this study is to introduce the rule of ITCZ variability on the occurrence of unseasonably heavy rains, widespread flash floods, over Eastern Mediterranean (EM) in the period (17- 20) on January 2010. In fact, the topography in the EM such as high mountains, is essential factor for huge disasters of flash floods (Llasat, 2009). The flood disasters in EM through this period had been recorded and reported. Whereas, in Egypt, in the southern city of Aswan, floods and strong winds disrupted power in several neighborhoods. The floods were a surprise as North Sinai had not seen floods in 30 years. Sinai Peninsular was flash floods damage left more than 1000 homes totally destroyed, 1,076 submerged and the area suffered material losses of over US\$25.3 million. The floods ruined 59km of roads, killed 1,838 animals and felled 27,820 (mostly olive) trees. Five Egyptians died in flooding in the southern Sinai desert. All 75 patients at the El-Arish general hospital in the Sinai had to be evacuated when the first floor was flooded. Flooding wiped out large sections of a major road in Egypt's south Sinai and destroyed two dozen homes in Ras Sudr. In Palestine, Heavy rain and flooding has forced hundreds of people from their homes in Khan Younis in the south of the Gaza Strip. Over 100 families had been made homeless.. Some 300 families were also displaced. The flooding along Egypt's Red Sea coast, the border with Israel and in the south left six people dead. It also damaged the roads leading to the resorts in the Sinai desert and brought down telephone and power lines. Israel temporarily closed its southern border crossings with Egypt and Jordan. Jordanians were warned off the streets after nearly a dozen accidents in one area. Rains of this magnitude, rains reached to 90 mm/day, which are rare in this largely arid region and where heavy precipitation can result in sudden and deadly flash floods. In Israel, a woman drowned when her car was caught in a flash flood in the south, where stormy weather also

UK, 2009: Winter Summary, 2009, ©Crow copyright]

For the first case, the daily NCEP/NCAR reanalysis data composites for mean surface air temperature, over the UK, [ ( 49° N- 61° N) latitudes and ( 11° W- 2° E) longitudes] , for the period from 1 December 2008 to 28 February 2009 (Kalnay et al., 1996) are used in this study. The available meteorological data obtained from UK meteorological office are also used in the present study. In addition to that, the Atlantic – Western Africa [ 15° W – 10° E] ITCZ mean position data for summer months June, July and august of 2008 are used. The movement of the ITCZ over Atlantic-Western Africa has been monitored by plotting the daily location of the surface 15-degree C dew point temperature at 1200 UTC for every 5 degrees of longitude, (Ilesanmi, 1971). Over Atlantic-Western Africa, a mean position for each 10-day period is calculated for the area from 15 degrees west longitude to 10 degrees east longitude. However, the ITCZ data series begin in 1979 for Atlantic - Western Africa and the long-term means use 1979-2001 data. These data were obtained from website through the internet of the Climate Prediction Centre at http://www.cpc.ncep.noaa.gov/products/monitoring\_data/. In the present work, these datasets are analyzed using the anomalies methodology and correlation coefficient technique. The formula for calculating the correlation coefficient was taken from (Spiegel, 1961). For the second case; The 6-hour and daily NCEP/NCAR reanalysis data composites for precipitation MSL pressure, gepotential height at 500 hpa level, surface vector and meridonal winds over the eastern Mediterranean region [ ( 22° N- 40° N) latitudes and ( 24° E- 42° E) longitudes] , for the period (17 - 20) January 2010 (Kalnay et al., 1996) are used in the present study. The available floods disaster data obtained from dartmouth flood observatory are also used. In addition to that, 6-hour infrared (IR) satellite images are obtained to identify the ITCZ position by using of cloud clusters through the same period. In the present work, datasets are analyzed using the anomalies methodology. These data were obtained from websites through the internet of the Climatic centers, Climate Diagnostics Centre for supporting the data used throughout this study. Plots and images were provided by the NOAA-CIRES Climate Diagnostics Centre, Boulder, Colorado, USA from their Web site at http://www.cdc.noaa.gov. Available data of flash floods disasters obtained from dartmouth flood observatory through its website http://www.dartmouth.edu.

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 115

(a) (b)

(c) (d)

February).

Fig. 2. The distribution of mean surface air temperature anomalies ( °C) over UK for winter 2008/2009, (a) For month of December 2008, (b) For month of January 2009, (c) For month of February 2009 and (d) For months of winter season 2008/2009 (December, January and

variability through the period (1 June 2008 – 31 August 2008) are analyzed using of anomalies methodology. The result shows that the Atlantic-Western Africa ITCZ moved southward direction south of its average position from 1 June to 20 July with negative
