**3.1.1 Analysis of the surface temperature anomalies over UK in winter 2009**

In the present work, daily data for surface air temperature in UK through the period (1 December 2008 – 28 February 2009) are analyzed using of statistical anomalies methodology. Table (1) shows the anomalies in the 10-day mean of surface temperature (°C) over UK in winter 2008/2009. The results revealed that almost of UK severed from abnormal cooling whereas there are negative anomalies in the surface air temperature during December 2008. However, surface air temperature was less than its normal values by -0.5 °C. However, the normal value taken as average of the period of years 1968-1996. As shown in Figure 2a and Table 1. Meanwhile, for the month of January 2009 the temperature becomes around its normal values. Whereas, the anomalies in temperature values alternative around its normal between positive at the north of the UK, and negative values at the south of the UK, (Figure 2b and Table 1). For the month of February, the first half had a cooling and the last half had a warming rather than its normal values. In general the temperature remands around its normal values for that month (Figure 2c, and Table 1). In general, winter 2008/2009, from 1 December 2008 to 28 February 2009, had recorded a negative anomalies in surface air temperature with -0.5 °C. This cooling during that winter season occurred mainly at the central and southern parts of UK (Figure 2d).


Table 1. Anomalies in the 10-day mean of surface temperature (°C) over UK in winter 2008/2009.

#### **3.1.2 Study variability of the Atlantic-Western Africa ITCZ during summer 2008**

The movement of the ITCZ over Atlantic-Western Africa had 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. The data series begin in 1979 for Atlantic-Western Africa and the long-term means use 1979-2001 data. In the present study the changes of Atlantic-Western Africa ITCZ

In the present work, daily data for surface air temperature in UK through the period (1 December 2008 – 28 February 2009) are analyzed using of statistical anomalies methodology. Table (1) shows the anomalies in the 10-day mean of surface temperature (°C) over UK in winter 2008/2009. The results revealed that almost of UK severed from abnormal cooling whereas there are negative anomalies in the surface air temperature during December 2008. However, surface air temperature was less than its normal values by -0.5 °C. However, the normal value taken as average of the period of years 1968-1996. As shown in Figure 2a and Table 1. Meanwhile, for the month of January 2009 the temperature becomes around its normal values. Whereas, the anomalies in temperature values alternative around its normal between positive at the north of the UK, and negative values at the south of the UK, (Figure 2b and Table 1). For the month of February, the first half had a cooling and the last half had a warming rather than its normal values. In general the temperature remands around its normal values for that month (Figure 2c, and Table 1). In general, winter 2008/2009, from 1 December 2008 to 28 February 2009, had recorded a negative anomalies in surface air temperature with -0.5 °C. This cooling during that winter season occurred mainly at the

> Anomalies in the 10- day Mean surface air temperature ( °C) over UK

**3.1.1 Analysis of the surface temperature anomalies over UK in winter 2009** 

**3. Results** 

2008/2009.

**3.1 For the first case** 

central and southern parts of UK (Figure 2d).

1-10 Dec. 2008 -2.2 11-20 Dec. 2008 0.0 21-31 Dec. 2008 -0.5 1-10 Jan. 2009 -5.0 11-20 Jan. 2009 +1.2 21-31 Jan. 2009 +1.0 1-10 Feb. 2009 -3.5 11-20 Feb. 2009 +2.0 21-28 Feb. 2009 +3.5

Table 1. Anomalies in the 10-day mean of surface temperature (°C) over UK in winter

**3.1.2 Study variability of the Atlantic-Western Africa ITCZ during summer 2008** 

The movement of the ITCZ over Atlantic-Western Africa had 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. The data series begin in 1979 for Atlantic-Western Africa and the long-term means use 1979-2001 data. In the present study the changes of Atlantic-Western Africa ITCZ

Duration time (10-day interval)

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 February).

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

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 117

**3.1.3 Relationship between the Atlantic-Western Africa ITCZ and abnormal cold winter** 

The relationship between the Atlantic-Western Africa ITCZ variability and abnormal cold winter 2009 over UK are studied in this section. Whereas, a 10-day time series analysis of anomalies in both of the variation of Atlantic-Western Africa ITCZ mean position during summer 2008 and the variation of mean surface temperature anomalies over UK through winter 2008/2009 are analyzed. The results revealed that there are outstanding relationship between the southward variations of Atlantic-Western Africa ITCZ and the occurrence of negative anomalies in surface air temperature over UK through winter 2009 (Figure 3). In addition to that a correlation coefficient technique analysis has been made to study this relationship. There are significant positive correlation coefficients between the southward variability of summer Atlantic-Western Africa ITCZ and the abnormal cooling weather that existed in UK through winter 2009. The highest correlation coefficient value is +0.7 at 5° W

> **15 W 10 W 5 W 0 5 E 10 E Longitudinal position of ITCZ**

Fig. 4. The variation of correlation coefficient values between 10-day Atlantic-Western Africa ITCZ mean position anomalies during summer 2008 and 10-day mean surface temperature

Through the present work, the 6-hour NCEP/NCAR reanalysis data composites for precipitation rates over the EM region [ ( 22° N- 40° N) latitudes and ( 24° E- 42° E) longitudes during the period (17 -20) January 2010 has been analyzed. Analysis of this data shows that on

**3.2.1 Distribution of precipitation values in EM during (17-20) january 2010** 

**2009 over UK** 

**0.2**

anomalies over UK through winter 2008/2009.

**3.2 For the second case** 

**0.3**

**0.4**

**0.5**

**Correlation coefficent**

**0.6**

**0.7**

**0.8**

longitude of ITCZ (Figure 4).

anomalies of its values. The maximum negative anomaly is recorded -2.351 latitudinal degrees at 15 W of ITCZ position through the 10 day interval (11-20 June 2008). In general, the outstanding southward changes of ITCZ variability existed over western part of the Greenwich longitude. Whereas, the significant negative anomalies occurred at the western part of the ITCZ through the period of study (Table 2 and Figure 3).


Table 2. Anomalies in 10-day mean position of Atlantic-Western Africa ITCZ during summer 2008.

Fig. 3. The variation of 10-day Atlantic-Western Africa ITCZ mean position anomalies during summer 2008 and the variation of 10-day mean surface temperature anomalies over UK through winter 2008/2009.

anomalies of its values. The maximum negative anomaly is recorded -2.351 latitudinal degrees at 15 W of ITCZ position through the 10 day interval (11-20 June 2008). In general, the outstanding southward changes of ITCZ variability existed over western part of the Greenwich longitude. Whereas, the significant negative anomalies occurred at the western

1-10 June 2008 -1.716 -1.719 -1.347 -0.625 -0.840 -0.488 11-20 June 2008 -2.351 -1.757 -1.250 -0.718 -0.892 -0.427 21-30 June 2008 -0.291 -0.481 -0.048 -0.090 0.059 0.071 1-10 July 2008 -1.374 -1.104 -1.565 -0.737 -0.295 -0.555 11-20 July 2008 -1.757 -2.058 -1.133 -0.808 -0.596 -0.374 21-31 July 2008 0.091 0.136 -0.213 -0.039 0.379 0.604 1-10 August 2008 -0.075 -0.846 -0.661 0.103 0.142 0.518 11-20 August 2008 0.033 0.371 0.759 1.023 1.194 1.379 21-31August 2008 0.200 0.433 0.562 0.954 0.571 0.035 Table 2. Anomalies in 10-day mean position of Atlantic-Western Africa ITCZ during

Anomalies in 10- day mean position of Atlantic-Western Africa ITCZ

(Longitude degree) 15W 10W 5W 0 5E 10E

part of the ITCZ through the period of study (Table 2 and Figure 3).

Duration time (10-day interval)

summer 2008.

**4**

**-6**

**-5**

**-4**

**-3**

**-2**

**1-10 Dec. 2008** **11-20 Dec. 2008**

UK through winter 2008/2009.

(15 W) ITCZ (10 W) ITCZ (5 W) ITCZ (0 E) ITCZ (5 E) ITCZ (10 E) ITCZ

> **21-31 Dec. 2008**

**1-10 Jan. 2009**

10-day mean of surface temperature in UK in winter 2008/2009

**11-20 Jan. 2009**

Fig. 3. The variation of 10-day Atlantic-Western Africa ITCZ mean position anomalies during summer 2008 and the variation of 10-day mean surface temperature anomalies over

**21-31 Jan. 2009**

**10- day interval**

**1-10 Feb. 2009** **11-20 Feb. 2009** **21-28 Feb. 2009**

**-1**

**Anomalies value**

**0**

**1**

**2**

**3**

#### **3.1.3 Relationship between the Atlantic-Western Africa ITCZ and abnormal cold winter 2009 over UK**

The relationship between the Atlantic-Western Africa ITCZ variability and abnormal cold winter 2009 over UK are studied in this section. Whereas, a 10-day time series analysis of anomalies in both of the variation of Atlantic-Western Africa ITCZ mean position during summer 2008 and the variation of mean surface temperature anomalies over UK through winter 2008/2009 are analyzed. The results revealed that there are outstanding relationship between the southward variations of Atlantic-Western Africa ITCZ and the occurrence of negative anomalies in surface air temperature over UK through winter 2009 (Figure 3). In addition to that a correlation coefficient technique analysis has been made to study this relationship. There are significant positive correlation coefficients between the southward variability of summer Atlantic-Western Africa ITCZ and the abnormal cooling weather that existed in UK through winter 2009. The highest correlation coefficient value is +0.7 at 5° W longitude of ITCZ (Figure 4).

Fig. 4. The variation of correlation coefficient values between 10-day Atlantic-Western Africa ITCZ mean position anomalies during summer 2008 and 10-day mean surface temperature anomalies over UK through winter 2008/2009.

#### **3.2 For the second case**

#### **3.2.1 Distribution of precipitation values in EM during (17-20) january 2010**

Through the present work, the 6-hour NCEP/NCAR reanalysis data composites for precipitation rates over the EM region [ ( 22° N- 40° N) latitudes and ( 24° E- 42° E) longitudes during the period (17 -20) January 2010 has been analyzed. Analysis of this data shows that on

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 119

(a) (b)

(c) (d)

(e) (f)

the first day, 17 January, the precipitation existed over the north western part of EM (Malta) and also over the south western part of EM( south west of Egypt) and Sinai and reached to its maximum value (90 mm) over South Sinai (see Table 3 and Figure 5a,b,c and d respectively). On next day, the precipitation hold eastward of EM to cover several countries include of (East Sinai, (Palestine &Israel), Jordon, North Syria and south Turkey) with maximum value of precipitation rate 90 mm/day as its clear in Table 3 and Figure 5e,f,g and h respectively. On 19 and 20 January precipitation widespread to cover all the EM region but with maximum values, 24 mm/day that less than the first two days. See Table 3 and Figure 5 (from i to p). This precipitation causing huge damages in several areas in EM and mainly lee the mountain regions. In particular, 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. Five Egyptians died in flooding in the southern Sinai desert.


Table 3. 6-hour maximum amount of precipitation in (mm) over Eastern Mediterranean during the period of 17-20 January 2010.

the first day, 17 January, the precipitation existed over the north western part of EM (Malta) and also over the south western part of EM( south west of Egypt) and Sinai and reached to its maximum value (90 mm) over South Sinai (see Table 3 and Figure 5a,b,c and d respectively). On next day, the precipitation hold eastward of EM to cover several countries include of (East Sinai, (Palestine &Israel), Jordon, North Syria and south Turkey) with maximum value of precipitation rate 90 mm/day as its clear in Table 3 and Figure 5e,f,g and h respectively. On 19 and 20 January precipitation widespread to cover all the EM region but with maximum values, 24 mm/day that less than the first two days. See Table 3 and Figure 5 (from i to p). This precipitation causing huge damages in several areas in EM and mainly lee the mountain regions. In particular, 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

Maximum amount of precipitation in (mm) over Eastern

Maximum Location

Jordon

million. Five Egyptians died in flooding in the southern Sinai desert.

Mediterranean

17 January 2010 (0600UTC) 16 Malta and south west of Egypt

18 January 2010 (0000UTC) 90 East Sinai, (Palestine &Israel) and

18 January 2010 (0600UTC) 65 Jordon, Lebanon and south Syria 18 January 2010 (1200UTC) 55 North Syria and south Turkey

19 January 2010 (0600UTC) 14 Eastern Mediterranean sea region

19 January 2010 (1800UTC) 20 Eastern Mediterranean sea region

20 January 2010 (0600UTC) 21 Eastern Mediterranean sea region 20 January 2010 (1200UTC) 24 Cyprus, west Syria and Lebanon 20 January 2010 (1800UTC) 24 Cyprus, west Syria and Lebanon

Table 3. 6-hour maximum amount of precipitation in (mm) over Eastern Mediterranean

20 January 2010 (0000UTC) 22 Eastern Mediterranean region

value

17 January 2010 (1200UTC) 27 south west of Egypt

17 January 2010 (1800UTC) 90 South Sinai

18 January 2010 (1800UTC) 50 North Syria

19 January 2010 (1200UTC) 16 Cyprus

during the period of 17-20 January 2010.

19 January 2010 (0000UTC) 12 Cyprus and Lebanon

17 January 2010 (0000UTC) 21 mm Malta

Precipitation amount

(mm)

(6-hour) Time

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 121

(m) (n)

(o) (p)

Fig. 5. The 6-hour precipitation values (mm) distribution over the Eastern Mediterranean

Traditionally, the ITCZ has been identified in terms of time-averaged fields, either in terms of the seasonal mean outgoing longwave radiation (OLR) or, in more recent years, in terms of the seasonal mean precipitation. For example, (Waliser et al., 1993) used thresholding of mean OLR in combination with mean high reflectivity to identify the ITCZ. Previous observational studies of the global climatological ITCZ (e.g., Mitchell & Wallace 1992; Waliser et al., 1993) focused on the annual cycle in different regions. They found very distinct longitudinal variations in the ITCZ. In the western Pacific region the summer ITCZ is broad in latitude and ill-defined due to the extensive warm pool in the ocean and monsoonal circulations. However, in the east Pacific the mean summer ITCZ is narrow and long, generally located at the southern boundary of the east Pacific warm pool, north of the strongest meridional gradient of sea surface temperature (Raymond et al., 2006). During the summer the east Pacific ITCZ is particularly visible in instantaneous satellite fields. During

**3.2.2 Study the ITCZ variability over eastern Africa on (17-20) january 2010** 

(g) (h)

(i) (j)

(k) (l)

Fig. 5. The 6-hour precipitation values (mm) distribution over the Eastern Mediterranean

#### **3.2.2 Study the ITCZ variability over eastern Africa on (17-20) january 2010**

Traditionally, the ITCZ has been identified in terms of time-averaged fields, either in terms of the seasonal mean outgoing longwave radiation (OLR) or, in more recent years, in terms of the seasonal mean precipitation. For example, (Waliser et al., 1993) used thresholding of mean OLR in combination with mean high reflectivity to identify the ITCZ. Previous observational studies of the global climatological ITCZ (e.g., Mitchell & Wallace 1992; Waliser et al., 1993) focused on the annual cycle in different regions. They found very distinct longitudinal variations in the ITCZ. In the western Pacific region the summer ITCZ is broad in latitude and ill-defined due to the extensive warm pool in the ocean and monsoonal circulations. However, in the east Pacific the mean summer ITCZ is narrow and long, generally located at the southern boundary of the east Pacific warm pool, north of the strongest meridional gradient of sea surface temperature (Raymond et al., 2006). During the summer the east Pacific ITCZ is particularly visible in instantaneous satellite fields. During

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 123

(a)

(b)

(c)

(d)

Northern Hemisphere winter the ITCZ remains in the Northern Hemisphere, but its signature is considerably weaker and gets mixed in with signatures of extratropical frontal systems owing to cold air outbreaks (Wang & Magnusdottir 2006). The variability of the ITCZ presents a serious challenge to its automatic detection in instantaneous data. Here we want to focus on the ITCZ as a weather feature that has long been recognized by satellite meteorologists who analyze instantaneous fields. In the present study, 6-hour infrared (IR) satellite images for the period (17-20) January are obtained to identify the ITCZ position by using of cloud clusters. The following criteria to define the ITCZ (Bain et al.,2011 ).



iii. The ITCZ is a large-scale feature and isolated tropical disturbances, unconnected to larger cloudy regions, are not part of the ITCZ.

Table 4. The 6-hour locations of ITCZ over Eastern Africa during the period 17-20 January 2010.

Northern Hemisphere winter the ITCZ remains in the Northern Hemisphere, but its signature is considerably weaker and gets mixed in with signatures of extratropical frontal systems owing to cold air outbreaks (Wang & Magnusdottir 2006). The variability of the ITCZ presents a serious challenge to its automatic detection in instantaneous data. Here we want to focus on the ITCZ as a weather feature that has long been recognized by satellite meteorologists who analyze instantaneous fields. In the present study, 6-hour infrared (IR) satellite images for the period (17-20) January are obtained to identify the ITCZ position by

ii. It is cloudy but there may be cloud-free regions within the envelope of convection and the convection may be shallow (as represented by rather warm cloud-top

iii. The ITCZ is a large-scale feature and isolated tropical disturbances, unconnected to

17 January 2010 (1200UTC) Sudan and extends towards north Red Sea over South east

Location of Intertropical conversion zone (ITCZ)

using of cloud clusters. The following criteria to define the ITCZ (Bain et al.,2011 ).

17 January 2010 (0000UTC) Shift to north west Sudan and north east Ethiopia

17 January 2010 (1800UTC) Sudan, north Red Sea and eastern part of Egypt

17 January 2010 (0600UTC) South west Sudan and north east Ethiopia

of Egypt

19 January 2010 (1800UTC) Extended to Sudan, Ethiopia and Red Sea 20 January 2010 (0000UTC) Extended eastward over south Red Sea

20 January 2010 (0600UTC) Shift widespread eastward to Saudi Arabia

Table 4. The 6-hour locations of ITCZ over Eastern Africa during the period 17-20 January

i. The ITCZ is a predominantly zonal feature.

larger cloudy regions, are not part of the ITCZ.

18 January 2010 (0000UTC) North Sudan and Sinai 18 January 2010 (0600UTC) North Sudan and Sinai

19 January 2010 (1200UTC) Extended to north Sudan

18 January 2010 (1200UTC) South Sudan 18 January 2010 (1800UTC) South Sudan 19 January 2010 (0000UTC) South Sudan 19 January 2010 (0600UTC) South Sudan

20 January 2010 (1200UTC) Saudi Arabia

20 January 2010 (1800UTC) Ethiopia

2010.

temperatures).

Variability of ITCZ

(6-hour) Time

(a)

(b)

(c)

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 125

(i)

(j)

(k)

(l)

(e)

(f)

(g)

(h)

(e)

(f)

(g)

(h)

(i)

(j)

(k)

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 127

We use satellite fields of infrared IR to find large-scale zonally connected regions of convection. Table 2 shows the 6 –hour location of ITCZ over eastern Africa during the period of the present case study according to the interpretation of Mollweide composite IR satellite images. From day to day it is clear that there is a shift of ITCZ over eastern Africa toward north east direction mainly over north Sudan, Ethiopia and Red Sea and reached to Sinai during the period of study. Whereas, on the first day, 17 January, ITCZ Shift to north west Sudan and north east Ethiopia and extends towards north Red Sea over South east of Egypt(see Table 4 and Figure 6a, b, c and d). During 18 January ITCZ its maximum northward extension reached to Sinai as it is clear from Table 4 and Figure 6e,f,g and h). In fact, it is abnormal that ITCZ reach to Sinai in month of January or in winter season. On 19 January, ITCZ oscillates over Sudan and extended to north Sudan, Ethiopia and Red Sea. See Table 4 and Figure 6i, j, k, and l. The eastward extension of ITCZ reach its maximum widespread eastward to reach Saudi Arabia as it is clear from Table 4 and Figure 6m, n, o,

**3.2.3 Relationship between variability of ITCZ over eastern Africa and occurrence of** 

Other studies (e.g., Serra & Houze, 2002) have referred to the ITCZ as a geographical region along which westward propagating disturbances (WPDs) tend to propagate zonally. Weak WPDs (or easterly waves) have been observed to propagate through the ITCZ cloud envelope (e.g., Scharenbroich et al., 2010) and, in general, it is impractical to attempt to separate the easterly wave signal out of the ITCZ signal. (Magnusdottir & Wang, 2008) reached the same conclusion when using spectral analysis on 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) 850-hPa relative vorticity. The line of thinking that easterly waves or WPDs are inseparable from the ITCZ accommodates the idea that the ITCZ is composed of WPDs. Through the present work, in the pervious section 3.2.2, analysis of cloud clusters using of satellite images show that from day to day the location of the ITCZ is highly dynamic and changeable during the period of study. The ITCZ can form as a narrow band of convection stretched over an extensive longitudinal distance. From analysis of mean sea level pressure using of method of anomaly, it is clear there are negative anomalies (-5hpa) over EM during the period of study. As it is shown from Figure 7a, b, c and d and Table 5. In addition to that in the upper air at 500 hpa level there upper air trough of low pressure system over EM with negative anomalies less than (-75 m) of geopotential height. These anomalies persisted all the time of flash floods that existed. See Figure 8a, b, c, and d and Table 5. Also, analysis of vector wind in the tropical region revealed that there are positive anomalies more than +7 m/sec over all EM region and Red Sea through the period of study. Which mean that there was a strong westerly air current flow in EM as it is clear from Figure 9a, b, c, and d and Table 5. Meridonal wind component analysis shows that there existed a positive anomalies more than + 4 m/s over EM during the time of existing of flash floods over this region. It is clear in Figure 10a,b,c, and d and illustrated in Table 5. These results means that the south wind component is the common component in the vector wind field in EM through the period from 17-20 January 2010.The south wind component comes from the northward shift of ITCZ as unusual to exist in January month. So that, the variability of ITCZ to north and north east toward several countries in the EM region across Red Sea and Sinai carry out the convective cloud

and p.

**flash floods over EM on January 2010** 

systems from tropics to EM and cause of flash floods.

(p)

Fig. 6. The 6-hour Mollweide composite IR satellite images through the period 17-20 January 2010

(m)

(n)

(o)

(p) Fig. 6. The 6-hour Mollweide composite IR satellite images through the period 17-20 January

2010

We use satellite fields of infrared IR to find large-scale zonally connected regions of convection. Table 2 shows the 6 –hour location of ITCZ over eastern Africa during the period of the present case study according to the interpretation of Mollweide composite IR satellite images. From day to day it is clear that there is a shift of ITCZ over eastern Africa toward north east direction mainly over north Sudan, Ethiopia and Red Sea and reached to Sinai during the period of study. Whereas, on the first day, 17 January, ITCZ Shift to north west Sudan and north east Ethiopia and extends towards north Red Sea over South east of Egypt(see Table 4 and Figure 6a, b, c and d). During 18 January ITCZ its maximum northward extension reached to Sinai as it is clear from Table 4 and Figure 6e,f,g and h). In fact, it is abnormal that ITCZ reach to Sinai in month of January or in winter season. On 19 January, ITCZ oscillates over Sudan and extended to north Sudan, Ethiopia and Red Sea. See Table 4 and Figure 6i, j, k, and l. The eastward extension of ITCZ reach its maximum widespread eastward to reach Saudi Arabia as it is clear from Table 4 and Figure 6m, n, o, and p.

#### **3.2.3 Relationship between variability of ITCZ over eastern Africa and occurrence of flash floods over EM on January 2010**

Other studies (e.g., Serra & Houze, 2002) have referred to the ITCZ as a geographical region along which westward propagating disturbances (WPDs) tend to propagate zonally. Weak WPDs (or easterly waves) have been observed to propagate through the ITCZ cloud envelope (e.g., Scharenbroich et al., 2010) and, in general, it is impractical to attempt to separate the easterly wave signal out of the ITCZ signal. (Magnusdottir & Wang, 2008) reached the same conclusion when using spectral analysis on 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) 850-hPa relative vorticity. The line of thinking that easterly waves or WPDs are inseparable from the ITCZ accommodates the idea that the ITCZ is composed of WPDs. Through the present work, in the pervious section 3.2.2, analysis of cloud clusters using of satellite images show that from day to day the location of the ITCZ is highly dynamic and changeable during the period of study. The ITCZ can form as a narrow band of convection stretched over an extensive longitudinal distance. From analysis of mean sea level pressure using of method of anomaly, it is clear there are negative anomalies (-5hpa) over EM during the period of study. As it is shown from Figure 7a, b, c and d and Table 5. In addition to that in the upper air at 500 hpa level there upper air trough of low pressure system over EM with negative anomalies less than (-75 m) of geopotential height. These anomalies persisted all the time of flash floods that existed. See Figure 8a, b, c, and d and Table 5. Also, analysis of vector wind in the tropical region revealed that there are positive anomalies more than +7 m/sec over all EM region and Red Sea through the period of study. Which mean that there was a strong westerly air current flow in EM as it is clear from Figure 9a, b, c, and d and Table 5. Meridonal wind component analysis shows that there existed a positive anomalies more than + 4 m/s over EM during the time of existing of flash floods over this region. It is clear in Figure 10a,b,c, and d and illustrated in Table 5. These results means that the south wind component is the common component in the vector wind field in EM through the period from 17-20 January 2010.The south wind component comes from the northward shift of ITCZ as unusual to exist in January month. So that, the variability of ITCZ to north and north east toward several countries in the EM region across Red Sea and Sinai carry out the convective cloud systems from tropics to EM and cause of flash floods.

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 129

(a)

(b)

(c)

(d) Fig. 8. The daily geopotential height (m) composite anomaly distribution for the period 17-

20 January 2010

Fig. 7. The daily sea level pressure (mb) composite anomaly distribution for the period 17-20 January 2010

(a)

(b)

(c)

(d) Fig. 7. The daily sea level pressure (mb) composite anomaly distribution for the period 17-20

January 2010

Fig. 8. The daily geopotential height (m) composite anomaly distribution for the period 17- 20 January 2010

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 131

(a)

(b)

(c )

(d) Fig. 10. The daily surface meridional wind (m/s) composite anomaly distribution for the

period 17-20 January 2010

Fig. 9. The daily surface vector wind (m/s) composite anomaly distribution for the period 17-20 January 2010

(a)

(b)

(c)

(d) Fig. 9. The daily surface vector wind (m/s) composite anomaly distribution for the period

17-20 January 2010

Fig. 10. The daily surface meridional wind (m/s) composite anomaly distribution for the period 17-20 January 2010

Variability of Intertropical Convergence Zone (ITCZ) and Extreme Weather Events 133

Northern Hemisphere. However, Figure 11 shows the longitudinal variations band in the ITCZ over the globe through January and July months. Satellite images show that from day to day the ITCZ is highly dynamic and changeable. This dynamic ITCZ has been the subject of dynamical modeling studies (Ferreira and Schubert 1997; Wang et al. 2010) . In a northern summer monsoon, the prevailing winds at the low levels are from the southeast. At high levels, the wind direction reverses. This configuration produces a large vertical wind shear not occur elsewhere in the tropics. In the monsoon onset process, the ITCZ shifts from near the equator to more than 10 degrees away in days. Compared with the movement of the Earth's tilt toward the Sun, this change is rapid. The shifts and preferred latitudes of the ITCZ observations and theory were investigated in several scientific studies (Bates,1970;

Fig. 11. The longitudinal distribution of ITCZ in winter season represents by January and in

It is a pleasure to the author to thank the 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. Also, thanks to the Climate Prediction Centre for supporting the summer Atlantic - Western Africa ITCZ data which obtained through the website http://www.cpc.ncep.noaa.gov/products/monitoring\_data/., and the UK Meteorological Office for its support of summary of winter 2008/2009 that obtained from the website http://www.metoffice.gov.uk/. Also, thanks to the 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. Also, great thanks for dartmouth flood

summer season represents by July.[source: Wikipedia, the free encyclopedia.mht]

Philander et al., 1996 and Hafez ,2003c).

**5. Acknowledgments** 


Table 5. Daily Anomalies amount in the meteorological elements and its location in the eastern Mediterranean region through the period 17-20 January
