Cluster meet 2013 riyadh weather

In April, Crown Prince Abdullah met with US president George W. Bush, and Riyadh has definite seasons with a wide range of temperatures and low Consultative Council; in women were appointed to a fifth of the Council seats. households are increasingly the norm, relatives continue to cluster together. Weather · Plan a Trip to Israel · The Power of Giving · Israel Real Estate Cluster bombs and Yachts: 5 things you should know about Saudi Arabia's new Sheikh Tamim bin Hamad Al-Thani, took over from his father at 33 in Bin Salman met with U.S. President Donald Trump in the White House a. Planned Major Actors within the Saudi Manufacturing Cluster (SAM). Connell and Voola () note that participating in a business network .. These programs play a significant role in meeting the objectives of Vision. of the firm (Small, medium or large) and weather the HMF is Local or.

Admixtures of TurksIranians, Indonesians, Pakistanis, Indians, various African groups, and other non-Arab Muslim peoples appear in the Hijaz, mostly descendants of pilgrims to Mecca. Local variations in pronunciation do not prevent oral communication between people from opposite sections of the Arabian Peninsula.

The language is written in a cursive script from right to left. The 28 letters of the alphabet have initial, medial, and terminal forms; short vowels are seldom indicated. Most businesspeople and merchants in oil-producing areas and commercial centers understand English. Government correspondence must be written in Arabic. Most other Saudis are Shia Muslims. The holy city of Mecca is the center of Islam and the site of the sacred Ka'bah sanctuary, toward which all Muslims face at prayer.

Advances in Meteorology

A pilgrimage to Mecca is one of the five basic obligations of Islam and is incumbent upon every Muslim who is physically and financially able to perform it. Jews have not been allowed to enter the country since the establishment of the state of Israel inexcept under special circumstances. There is no religious freedom within the country. The government claims that the Holy Koran Quran and the Sunna tradition of the Prophet are the country's constitution.

As such, the government strictly controls all religious activities. The public worship of non-Muslim faiths is prohibited. While non-Muslim foreigners are theoretically permitted to worship privately, the guidelines that distinguish between public and private worship are ambiguous, leading to severe restrictions on non-Muslim worship.

Proselytizing of non-Muslim religions is illegal and conversion of Muslims to other faiths is a capital offense. Bythere werekm 91, mi of highway, of which 44, km 27, mi were paved. A new highway connects Saudi Arabia with Jordan, and a causeway completed in offers a direct connection with Bahrain.

Inthere were 2, passenger cars and 1, commercial vehicles registered for use. Most within-country freight is hauled by truck. As ofrailroad lines totaled 1, km mi of standard-gauge track. Inthere were an estimated airports. As ofa total of 73 had paved runways, and there were also six heliports.

Rainfall-Altitude Relationship in Saudi Arabia

The government-owned Saudi Arabian Airlines Saudia operates regular domestic and foreign flights to major cities. Because of the large distances that separate the main cities, air travel is preferred within the kingdom. Inabout Jeddah, on the Red Sea, is the chief port of entry for Muslim pilgrims going to Mecca. Saudi Arabia has the largest seaport network in the Near East, with eight major ports with piers and three smaller ports.

The traditional dhow is still used for coastal trade. Towns were established at various oases and along caravan routes.

During the 7th century ad, followers of Muhammad expanded beyond the Mecca-Medina region and within a century had conquered most of the Mediterranean region between Persia in the east and Spain in the west. Although Arabs were dominant in many parts of the Muslim world and there was a great medieval flowering of Arab civilization, the peninsula itself except for the holy cities of Mecca and Medina declined in importance and remained virtually isolated for almost a thousand years.

The foundations of the Kingdom of Saudi Arabia were laid in the 18th century by the fusion of the military power of the Sa'ud family and Wahhabism, an Islamic puritan doctrine preached by Muhammad bin 'Abd al-Wahhab. ByNajd and Al-Ahsa were occupied. A long struggle —18 finally resulted in Saudi defeat. During that time, Sa'ud died, and his son, 'Abdallah r.

When international conditions forced Muhammad 'Ali to withdraw his occupation forces inthe Saudis embarked upon a policy of reconquest. Under Faisal Faysal, r. Hijaz remained under the control of the sharifs of Mecca until After Faisal's death, conflict between his sons led to a decline in the family's fortunes.

Taking advantage of these quarrels, the Ibn-Rashids, a former Saudi vassal family, gained control of Najd and conquered Riyadh. The Saudi family fled to Kuwait in At a decisive battle inthe Rashidi power was broken. Inthe Saudis again brought Al-Ahsa under their control, and in DecemberIbn-Sa'ud signed a treaty with the British that placed Saudi foreign relations under British control in return for a sizable subsidy.

Warfare broke out again in Arabia inwhen Hussein ibn'Ali Husayn ibn-'Alithe sharif of Mecca, who had become an independent king, attacked the Saudis.

Country statistics

Hussein was defeated, and Ibn-Sa'ud annexed 'Asir. Inhe finally rid Arabia of the Rashids, and byhe had consolidated his kingdom by occupying the districts west and north of Ha'il. Hussein of Mecca provoked another conflict with Ibn-Sa'ud in March by proclaiming himself caliph. This increase in Ibn-Sa'ud's territory was acknowledged by the British in a treaty of 20 May that annulled the agreement and recognized his independence. On 22 Septemberthe various parts of the realm were amalgamated into the Kingdom of Saudi Arabia, with much the same boundaries that exist today.

With the discovery of oil in the s, the history of Saudi Arabia was irrevocably altered. Reserves have proved vast—about one-fourth of the world's total—and production, begun in earnest after World War IIhas provided a huge income, much of it expended on infrastructure and social services. Saudi Arabia's petroleum derived wealth has considerably enhanced the country's influence in world economic and political forums. This move had stunning consequences for the world economy and also caused a dramatic upsurge in Saudi Arabia's wealth and power.

Since the s, the government has regulated its petroleum production to stabilize the international oil market and has used its influence as the most powerful moderate member of OPEC to restrain the more radical members. Political life in Saudi Arabia remained basically stable in the last third of the 20th century, despite several abrupt changes of leadership.

His first act as prime minister was to announce a sweeping reorganization of the government, and his major social reform was the abolition of slavery. In MarchKing Faisal was assassinated by a nephew in an apparently isolated act of revenge. King Fahd encouraged continuing modernization while seeking to preserve the nation's social stability and Islamic heritage.

King Fahd, who had been frail since suffering a debilitating stroke indied at the age of 82 on 1 August He had delegated the daily affairs of state to Crown Prince Abdullah bin Abd al-Aziz al Sa'ud, his half-brother, since his stroke.

Upon Fahd's death, Abdullah became king. As the custodian of the holy Muslim shrines at Mecca and Medina, the monarchy has been deeply embarrassed by several incidents: Misfortune continued inwhen a stampede in Mecca killed pilgrims rushing toward a cavern for a symbolic stoning ritual, and inwhen as many as pilgrims were killed in a fire at a campsite outside the holy city.

Ina stampede during the Hajj pilgrimage left dead. When Iraq invaded Kuwait inSaudi Arabia, fearing Iraqi aggression, radically altered its traditional policy to permit the stationing of foreign troops on its soil.

The government was criticized by senior Saudi religious scholars for taking this step. Riyadh made substantial contributions of arms, oil, and funds to the allied victory. Saudi Arabia's wealth and selective generosity has given it great political influence throughout the world and especially in the Middle East.

It suspended aid to Egypt after that country's peace talks with Israel at Camp DavidMarylandbut renewed relations in It secretly made substantial funds available to US president Ronald Reagan's administration for combating Marxist regimes in Central America. It actively supported Iraq during the war with Iran and tried, in vain, to prevent the conflict with Kuwait.

Each of those studies applied HCA to multi-model ensembles, with the general finding that ensemble members clustered together by model. In contrast, in this study we apply HCA to a single model, multi physics ensemble to focus on the question of how many ensemble members are needed to represent model error from a single modeling system i. An HCA data vector is defined initially as the normalized forecast errors of an ensemble member that corresponds to a singleton cluster.

At each step of the algorithm, the two clusters that are closest to each other according to some distance metric are combined. If uninterrupted, this process continues until eventually all of the data vectors are combined into a single cluster. In this study we stop the clustering procedure while there are still several clusters, and the criterion we use to do that is described below.

Dendrograms display the order in which sub-clusters merge together in HCA; two sub-clusters that merge at a relatively low height on the dendrogram are considered to be similar to one another. An example dendrogram for the DJF experiment is shown in Figure 2.

To determine the number of clusters present in the data for each experiment, we use the height on the dendrogram at which each cluster has at least three members. The HCA down-selected subset ensembles are comprised of the ensemble members that are closest to each cluster centroid. The HCA is performed on bias corrected, normalized temperature errors and normalized vector wind differences VWD over the training period for each experiment, combining data from all four forecast lead times at all four levels.

The down-selection is performed prior to calibrating the ensemble with BMA to avoid adding an unnecessary layer of complexity to assessing the impact of downselection.

Down-selection can be performed in either a univariate framework on temperature errors and VWD separately or in a multivariate framework normalizing and then combining temperature errors and VWD into a single data vector. Lee [ 10 ] demonstrated that there is little change in verification results between subset ensembles from univariate down-selection and multivariate down-selection.

Therefore, we perform a single, multivariate down-selection for each experiment here, as it is more straightforward to analyze. For additional simplification, we combine the model data from all four lead times for down-selection, instead of performing a separate downselection on each lead time, because there is little difference between the two approaches [ 10 ].

For additional demonstration that down-selection using HCA has value, we also compare HCA to a random down-selection method. By relaxing our requirement that each cluster have at least three members, we can examine a range of ensemble sizes and also assess whether there is an ensemble size above which additional members no longer add forecast skill.

Results Sensitivity to training window and season The HCA clusters that result from the one-month training experiments are shown in Table 4, the clusters from the two-month training experiments are listed in Table 5, and the clusters from the First, members cluster differently in different seasons. Tables show this clearly, with several identical clusters in the experiments that have overlapping training periods.

This behavior is seen within each season, though somewhat more strongly in winter and summer than in transition seasons. In each experiment every cluster has at least one physics scheme that is common among all members of that cluster. The right-most column of Tables indicates whether the cluster members share the same land surface scheme Lboundary layer scheme Bcumulus scheme Clongwave and shortwave radiation schemes Rmicrophysics scheme Mor some combination thereof.

For the vast majority of the clusters in all the experiments, the cluster members share a common land surface scheme. Boundary layer and cumulus parameterizations generally appear to be of secondary importance to the clustering.

In this region, cumulus parameterization schemes often have a more direct impact on model temperatures and winds than do microphysics and radiation schemes.

The Asir Mountains in the southwestern region exhibit moderate temperatures and high average annual rainfall, while average annual rainfall is very low for the rest of the country and irregular. The temperature is high and humidity is low, with the exception of small strips of coastal areas [ 4748 ]. The climate of Saudi Arabia can be explained by considering the different air mass movements, which influence the rainfall distribution [ 49 ].

There are three major fronts of moisture flowing into the Kingdom, including i maritime tropical air masses monsoon typewhich originate from the Indian Ocean and the Arabian Sea, bringing warm and moist air, which produces large amounts of rainfall in the south, southwest, and southeast. This front prevails during late fall and summer; ii continental tropical air masses from the Atlantic Ocean through the middle and north of the African continent, which bring warm and moist air to the western coast and prevail in the winter season producing moderate to low amounts of rainfall; iii maritime polar air masses, which originate from the eastern Mediterranean Sea and affect the north and northwest area of Saudi Arabia.

They prevail in the winter season and produce high to moderate amounts of rainfall [ 48 — 51 ]. Average annual rainfall in Saudi Arabia is generally low and falls chiefly during winter and spring, except in the southwestern region, where the average annual rainfall is relatively high and occurs throughout the year due to the monsoonal conditions during summer and the north westerly Mediterranean air masses during winter [ 35 ].

In Saudi Arabia, rainfall during spring contributes the largest amount of total annual rainfall The maximum mean annual rainfall occurs during fall mm and summer mmfollowed by spring mm and winter mm. Figure 4 shows the mean annual and seasonal rainfall distribution in Saudi Arabia between and During the winter period, rainfall is influenced chiefly by the cyclonic system and the highest rainfalls 43— mm occur in the southwest and northeast.

The former can be attributed to the maritime polar air mass from the Mediterranean Sea and Atlantic Ocean, which is combined with local effects of the Red Sea and the Hijaz-Asir Escarpment, where orographic rainfall occurs, while the latter can be attributed to fronts from the Mediterranean, which bring moist and cool air masses to produce convective rainfalls [ 52 ].

Moderate rainfall 26—42 mm occurs in the central part and low rainfall in the north and the central south 0—25 mm. During spring, the highest rainfall 71— mm occurs in the southwest, due to the effect of the monsoonal moist air penetration from the Indian Ocean. This region is also affected largely by the escarpment of the Asir Mountains.

There is moderate rainfall 39—70 mm in the central part, while the west, north, and east regions receive the lowest rainfall 0—38 mm due to the dry northern air masses. During summer, the highest rainfall 45— mm occurs in the southwest, which is a result of the convectional instabilities in the air. The moisture continues to be supplied from the southwesterly flow of monsoonal air, which produces thunder-storms in the south and along the Red Sea escarpment [ 4 ].

During fall, high and moderate rainfall 45— mm and 33—56 mm occurs in the southwest region and in the south part of the west region, while low rainfall 14—32 mm occurs in the west and in parts of the central and eastern regions.

The lowest rainfall 0—13 mm is in the north, central-south, and on the east lee ward side of the Asir Mountains. During this season, the southwesterly air flow diminishes and the westerly air from the Mediterranean brings air moisture, which gives way to tropical winter conditions. The southern area comes under the influence of a combination of the Red Sea trough and the Mediterranean depression, causing rainfall [ 53 ]. Results and Discussion This study set out to explore and understand the spatial variation in the relations between altitude and annual and seasonal rainfalls in Saudi Arabia using global OLS and local GWR models.

The adaptive kernel rather than the fixed kernel was selected because the rainfall stations are not regularly positioned in the study area; that is, they are inhomogeneous and clustered in some areas. As mentioned earlier, several scientific studies reported in the literature have shown that smoothed altitude values of rainfall stations i.

Firstly, OLS and GWR analyses were performed using different smoothing window sizes for annual and seasonal rainfalls to assess the performance through the coefficient of determination.

In order to assess the influence of the smoothing window size on the relationship between altitude and rainfall and to decide on the most appropriate window size, six spatial smoothing window sizes were tested against the annual and seasonal rainfalls.

Figure 5 shows the global coefficient of determination derived with OLS models against different smoothing window sizes of mean altitude values. This might be attributed to the fact that the largest proportion of annual rainfall Orographic rainfall occurs regularly in the Asir Mountains, while convective rainfall usually occurs in the foothills of these highlands.

Although both orographic and convective rainfalls occur, after the influence by altitude, the former are affected to a much greater degree than the latter. In terms of window sizes, the spring rainfall is highly related to altitude using 1 km windows followed by 30 m, 5 km, and 10 km, while 20 km and 25 km windows showed the lowest relation and 36. The average for annual and seasonal OLS models for each window size are 0.

Weather History for Riyadh, Saudi Arabia | Weather Underground

Figure 6 shows the local coefficient of determination derived with GWR models against different smoothing window sizes of mean altitude values. Note that the annual and seasonal rainfalls were spatially associated with altitude by using the seven smoothing windows with ranging between 0.

The average using 30 m and 1 km, using 5 km and 10 km, using 15 km and 20 km, and using 25 km window size. As the average of the coefficient of determination was low 0. The selected window size in this study will be 15 km, as it produced the highest value of value using the GWR model. As suggested by Burnham and Anderson [ 54 ], the difference of AICs between two models is considered significant if it is greater than 6.

The result implies that the GWR models explained much more of the variations in the relation between altitude and rainfall than did the OLS models. The OLS models failed to account for most of the spatial variation of rainfall during all seasons except spring, as the and AICs values show, so the GWR model was used to fit the model and the results are presented and discussed below. The results were comparable to those found by [ 333455 ].

For example, Lloyd [ 55 ] found that using monthly precipitation of Great Britain inthe relationship between elevation and precipitation using the OLS seemed to be weakly relatedwhile the relationship improved using GWR.