Cars are normally collected using Personal GPS Tracking Device radiosondes, satellites (polar and geostationary) and other sources, e.g., flight data from aeroplanes. Whereas points out that about 9,500 land-based stations and 7,000 merchant ships at any one time send up, noted that most of these data cover the northern hemisphere, with the southern hemisphere lacking adequate data due to financial constraints. The lack of radiosonde data is also noted in the oceanic areas, hence leading to a shortage of adequate data for NWP and car models. The shortage of radiosonde data, however, is partly compensated for by the availability of polar and geostationary satellite data.
GPS was developed by the US for its military purposes. It is an all weather tool capable of providing three-dimensional positions at any time . At the time of its conception, fewer civilian uses were envisaged. In recent years, however, its use has cars, e.g., Small GPS Tracking Device . This wide increase in GPS usage has led to the establishment of other equivalent systems by various nations/group of nations in the interest of their national security.
Not long ago, newspapers ran front-page articles about a hunter who had been lost for three days in snowy mountains during the middle of winter, supposedly be-cause his GPS receiver had given him directions. The only reason he sur- vived was that he was accidentally discovered by a passing snowmobiler. Rangers who later tested his receiver found it was working fine; a more likely explanation was that he hadn’t understood how to use it. But the story got wide publicity and did little to increase the public’s confidence in Personal Tracker. Similar stories regularly make headlines. A driver in New York narrowly escaped death when he turned onto a railroad track in front of an oncoming train because his GPS receiver told him to turn. A family in Oregon was trapped overnight in snow because they followed the advice of their brand-new GPS receiver and took a “shortcut” over a remote Forest Service trail. In each case, the hapless travelers blamed their predicaments on GPS, not on themselves. GPS manufacturers haven’t exactly helped the situation. Their user manuals tend to be simple pamphlets that don’t even explain all of the receiver’s functions, let alone show you how to do anything useful like navigate to a destination and return safely. One of the most frequent laments in online reviews of GPS receivers is the lack of quality information in their user manuals. You’d think that would worry GPS manufacturers. After all, newspaper headlines blaring, “Lost Hiker Found Dead Clutching GPS,” don’t do the industry any good. But you can’t really blame the manufacturers. GPS is used in so many different ways, from hiking in the woods to navigating aircraft to coordinating artillery strikes, that it’s not practical for a single instruction manual to cover all these uses and more.
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