Classification of Sandstorms in Saudi Arabia

The aim of the study is to classify the Sandstorms according to year seasons as well as their spatial variation in Saudi Arabia. Factor analysis has been used for data collection. Three factors have been presented: the first factor related to Spring as a prime Season for Dust Sandstorms. Factor two shows that Sa-mar months concern as ascend season for Sandstorms, while the Autumn Season comes as a third period for Dust Sandstorms. With regard to spatial variation, Al-Ahsa station came as the most closely related station in the spring season, followed by Hafr Elbatten, Jazan and Al-Jouf stations, while Jazan and Yenbo stations were the most connected stations in the summer season, Turaif is more closely related, to Fall season. By the end of the study several results and recommendations have been addressed.


Introduction
Sandstorm is meteorological phenomenon in which the wind speed increases to reach between 54 and 63 km/h, the relative humidity drops to less than 70%, and is loaded with dust and sand raised from topsoil, sand wedge, sand dune, where the winds raise the dust to high altitudes of thousand meters. The horizontal vision weakens to less than 1000 meters causing white-out [1]. Sand or dust storm formed as a high dust wall "approximately 3000 meters" wide and tens and hundreds of kilometers wide.
Sandstorms are considered one of the most important weather phenomena characterizing KSA. This phenomenon is affected by many factors that have contributed to the variation of spatial and temporal classification. Among the most prominent of these factors is the geographical location in the far south-west of the continent of Asia, the astronomical position between Longitude 16 and 32, and

Methodology
This study relied on the Analytical method based on the deductive approach derived from the data obtained from 27 meteorological stations spread across the king dam's regions. The study mainly used Factor Analysis Method, by which sandstorms were classified according to the season of the year, as well as to their spatial distribution and variation in Saudi Arabia.

Previous Studies
There are many studies concerned with the issue of sandstorm in different regions, some of those studies will be referred to: Al-Qalawi Study (1983) on climate and its impact on the environment in the Western Desert of Egypt [3], which showed its impact of sandstorm on the environment in the western desert of Egypt, as well as their direct effects on green spaces in oases, roads, human and animal health. The study also confirmed that the cause of such storms as activity of the pentathlon depressions in the spring, and the fast winds accompanying them, as well as high temperature and low humidity. Safar (1985) reviewed the dust and sandstorm in Kuwait, where it focused on dust storms and confirmed the number of days of their occurrence [4]. The study also showed that each type of weather phenomenon differs in terms of its  [5].
He also indicated that the northern part of the Arabian Gulf is exposed to sandstorms more than its southern part. As for the seasonal variation, he mentioned that the summer season is exposed to sandstorms more than any other season, and dust storms tend to occur in the day more than at any other time, while they decrease in the early morning.
Taher study (1996) explained sand and dust storms and their impact on the soil of agricultural fields in Al-Ahsa-KSA and focused on highlighting their relationship [6], as it was concerned with determining the number of days of drifting and blowing sand and dust. It also aimed at showing the relationship between wind speed and various other specific weather elements such as air pressure, humidity and temperature, and analyzing the effect of this sand drift on the agricultural fields' soils. Salim study (2000) reviewed storms and their dangers, especially tropical storms in terms of their origins [7], routes and geographical distribution. The study also reviewed khamsin winds and showed that they are hot winds, whose temperature rises sometimes to 45˚ and is also dusty and very dry, and blows intermittently in the spring and its formation refer to the Mediterranean depressions. The study also explained that it has an impact on the environment, especially plants. Tayyib and Jarar study (2002) about sand pollution. The two researchers dealt with both accumulated dust and suspended dust [8], and then clarified the most important dangers of dust to humans, animals, plants, and various environmental systems according to their size and different chemical nature, and the most important controlling standards highlighted air pollution with dust.
Salem study (2004) the researcher dealt with sand and dust storms and their impact on agriculture in the Jazan region [9]. The study aimed at finding out the causes of their occurrence, geographical distribution, in addition to their impact on some agricultural crops. This study concluded that storms have a direct and indirect effect on crops, especially vegetables such as tomatoes and fruit trees such as mangoes, bananas, papayas, and palms, especially in the western region where Tihama plain and the study recommended the continuation of climate research in the Jazan region.
Arishi study (2008): the researcher reviewed the effect of sand and dust storms and thunderstorms on the environmental development in the Jazan region [10]. It also showed that the most frequent seasons show the occurrence of sandstorms in the Jazan region that occur in summer season, as sand and dust storms increase compared to the winter season. The study concluded that there are many problems that face the population when sand and dust storms occur in the Jazan region, the most important of which is the difficulty of movement and walking on roads due to poor horizontal vision.
Al-Mutairi study (2015) entitled "Dust storms in the regions of Riyadh and Qassim, and the climatic factors affecting them" [11]. The study concluded that sandstorms in the city of Riyadh increase in the spring and summer and de-crease in Fall. Also, it reached a strong direct correlation between the frequency of dust and sandstorms and the group of patients with allergic chest disease, as well as between it and wind speed and finally recommended support for applied research in the field of climate.
Abd Al-Halim study, (2015) entitled "sandstorms and their impact on some agricultural crops in the western part of the Republic of Northern Sudan". The study results indicated that the high temperature and the decrease in atmospheric pressure helped in increasing the activity of sandstorms in western Sudan [12], and led to economic losses in agriculture represented by, in the diminishing productivity of acre. The study recommended using remote sensing technology in early detection of sandstorms.
Habib study (2016) entitled "Monitoring and analyzing violent sand storms in the Kingdom of Saudi Arabia using satellite images" [13]. The study found that the wind speed increases in the spring season in the north and center of the Kingdom, which helps in the occurrence of violent storms in these areas, as a result of the activity of exciting household load currents. The study also highlighted the presence of two types of storms in the Kingdom, the first is less severe storms that move to the Kingdom from Africa through the Red Sea, and the second violent storms originating from sandy areas in the Kingdom and affected by the atmospheric pressure areas over the Arabian Peninsula.
Al-Loula study (2017) entitled "sand storms and their impact on agricultural crops in the central region of the Kingdom of Saudi Arabia, from 2001 till 2016" [14]. The study reviewed natural and human factors affecting the occurrence of sandstorms in the middle of the Kingdom. The study concluded that sandstorms affect 56% of agricultural crops, and the effect increases during the winter compared to the summer and finally concluded with many recommendations.
From the analysis of previous studies with their various topics of locations, it can be mentioned that this study comes within the system of those studies, taking advantage of analysis of sandstorms. The method used and the results of those studies. However, his study is one of the applied climate studies that provides a clear analytical view on sandstorms in Saudi Arabia, based on one quantitative analysis such as the Factor Analysis Method, through which the sandstorm phenomenon in Saudi Arabia was classified accurately in accordance with time factor associated with months of year as well as spatial factor associated with the regions of the country.

Seasonal Classification of Sandstorm in Saudi Arabia
The data of the monthly average frequency of sandstorms during the period  Appendix Table A1). The study data were ana- 1) Extracting KMO value in order to verify quality of data analysis in the selected monitoring stations, and to verify their suitability for the analysis, this requires that its value exceeds (0.60). In the event that the value is less than this number, re-analysis is required. Table 2 shows that value as it reached (0.734), and the level of statistical significance (0.00) confirms the adequacy of the data used to achieve the results of the study.
2) Determining communalities values which refer to total contributions to the derivative factors representing one of global analysis outputs. The results of this analysis are evident in Table 3, and through it, the percentage of the contribution of each month of the year is clear, and the highest value recorded in the month of August, with a value of (0.95%), that is what is equivalent to this percentage of basic information in this month has been interpreted in the three derived factors, followed by October at a rate of (0.91%), and the same is the case in the rest of the other months for which the table indicates high contribution to the variance ratio.  3) Analyzing the derivative factors and variance ratios for each factor depending on the "cut off point" which was determined on the basis of "Eigen Values" which exceed (1). According to Table 4 and Figure 2, it was clear that three main factors have been identified that exceed (1) integer. the first factor is the most important of these factors because it included large Initial Eigenvalues amounting 5561 and 45,510% of variance, and Cumulative % in the main variables, then the values decreased in the second factor till the Initial Eigenvalues reached 3175 with variance of 26,459 and cumulative percent 71,969% and the lowest value of Initial Eigenvalues was recorded in the third factor, which ranks last, as this factor was stopped with Initial Eigenvalues amounted 1392 and variance ration amounted 11,602 and cumulative percent amounted 83,571. Thus three important factors specific to the frequency of sandstorms in the Kingdom of Saudi Arabia have been identified. 4) Determining the correlation of months with the derived factors, by extracting factor loading as indicated in Table 5. They are values indicating the amount of correlations between the variables on the one hand and the factors that have been identified on the other hand. The factor loading was determined by relying on the Varimax Rotation method, which is one of the most important methods by which the values of loading can be rotated, because it aims to maximize the variance set for the squares of the factor loading, so that each variable has one high loading on one of the factors, that is, to be Close to one integer at the same time, it is low on the other factor, by whether it is zero or close to zero, and the higher the correlation relationship between the variable and the factor is high, the more this indicates the correlation and dependence of months on the factor, and accordingly the association of months was determined with the derived factors, as follows:

First Factor
This factor is considered one of the strongest factors, due to the high value of the roots inherent in it, as previously mentioned, which reached 5461. It is also characterized by the high values of the interpreted variance, which amounted to 0.5

Second Factor
In terms of importance, this factor comes in the second place as it included Initial Eigenvalues amounted 3175, the variance value amounted 26,459% of the variance ratio explained in the original variables, and this factor has been associated with a number of positive variables whose correlations exceed 0.5. Table 5 showed that the number of months associated with this factor has reached three.
August comes in the 1st place with loading amount equal to 0.919 followed by September with loading amount 0.805 and followed by July with loading amount 0.687.
According to the correlations between the three months and the second factor, it can be said that the second period of sandstorm recurrence is from July to September, and where the period includes two months of the summer months, which is July and August. This factor was called the "Summer season" factor.

Third Factor
In terms of importance, this factor comes in the second place as it included Initial Eigenvalues amounted (1392), the variance value amounted 11,602% of the variance ratio explained in the original variables. The percentage of the contribution of this factor in explaining the information contained in the original variables does not mean that it is not important, but rather has a characteristic as a separate axis from the rest of the axes, to clarify the frequency of sandstorms in the rest of the months of the year, as this factor is associated with one positive variable according to its correlations of more than 50%, as shown in Table 5, and represented in October with loading degree of 0.630. This factor was called the "Autumn season" factor.

Spatial Variation of Sandstorms in Saudi Arabia
The cates the weakness of its importance, and the following is an analysis of the spatial variation of the frequency of sandstorms according to the degrees of each of the factors that were previously determined, as shown in Table 6 and Figure 3, as follows:

Spatial Variance According to First Factor (Spring)
This factor was called "Spring Season Factor" for the frequency of sandstorms.
The factor degrees associated with it came between positive and negative degrees, as shown in previous Table 5. Accordingly, kingdom stations were divided according to the degrees of this factor into categories, as shown in Table 6 and Figure 3, as follows:

Spatial Variance of Sandstorm Reoccurrence According to Factor 2 (Summer)
In terms of importance Second factor came (which was called "summer factor") for the frequency of sandstorms, ranked second. The degrees of the factor, as shown in Table 6 and Figure 3, came between positive and negative values, and in light of these values, the kingdom's stations can be divided according to factor into the following categories: Stations including positive values higher than integer (1): Jazan Station ranked 1st among the regions of the Kingdom in the frequency of sand storms within this category according to the summer season factor, with a very high value of (4220) due to the fact that Jazan region is exposed to a state of air instability, during summer, due to high temperature during the day, which leads to the presence of ascending air currents that lift dust with it, in addition to the predominance of the southwest winds under the influence of India's seasonal depression, which raises large quantities of dust and sand, in addition to the northwest winds that raise dust from the local environment in the west of the region, where coastal sand dunes gatherings that extend longitudinally along the coast of the Red Sea [2]. Yenbo station ranked 2nd in this category with a value of (1650 degrees), due to the dominance of the northwestern winds that are active due to meteorological phenomenon above the Mediterranean Sea which results in stirring dust and dirt in the west of the Kingdom. Stations with positive values less than integer (1): Sharorah station ranked 1st with a value of (0.503), followed by Najran station with an amount of (0.434) followed by the rest stations Tabuk, Taif, Khamis Mushait, Makkah and Abha with a value equal to (0.029). This is due to the confluence of the average eastern depression with the depressions coming from North Africa, such as the seasonal depression of Sudan on the Sarawat Mountains, which results in the occurrence of dust and sand storms in the southwestern regions of the Kingdom, as the surface is hot, which leads to A state of instability in the lower parts of the air, which helps the activity of the rising currents that carry dust and dust to the upper atmosphere.

Spatial Variance According to Factor 3 (Autumn)
In terms of importance, Factor (3) ranked in the last place. This factor was called "Autumn factor". Despite the low contribution of this factor, it highlights certain periods in which sandstorms are concentrated, and the grades of the factor, as shown in Table 6 and Figure

Conclusions
The