Navigation meteorology is the research andnavigationA subject concerned with meteorological problems.Where impacta shipThe formation and variation law of meteorological conditions for navigation, the marine hydrological conditions closely related to meteorology, and the impact and application of these conditions on navigation and ship navigation all belong to its research scope.
Marine meteorology refers to those parts of meteorology related to navigation operations. More generally, it refers to marine meteorology, which studies weather phenomena on the ocean and other vast waters, including the interaction between the atmosphere and the ocean, especially energy exchange.[1]
Influence conditions
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Wave is a kind of sea water movement produced by wind acting on the sea surface.Long term strong wind will cause huge waves, which will cause rolling, pitching and vertical motion of the ship.The biggest danger of rolling is that when the free rolling period of the ship is close to the wave period, the resonance phenomenon will occur, which will make the rolling amplitude of the ship sharply increase, thus causing the ship to capsize.Severe pitching will expose the propeller to the water surface, causing abnormal operation of the machine and loss of speed.The vertical motion of ships in waves is also likely to cause ships in shallow waters to touch the bottom.The various motions of the ship caused by the waves will cause the ship to decelerate.When navigating in the top waves above level 10, the ship can hardly move forward, and there is a great danger of capsizing.
Sea fog reduces visibility and has a great impact on ship navigation.When navigating in fog area, even with radar navigation, ship collision still occurs.The current will form the current pressure on the hull, which will make it yaw and cause danger.The surface wind is an important cause of surface currents.The correct use of current data by ships can increase the speed of ships and save fuel.
Sea ice and icebergs are a great threat to navigation in high latitudes.There have been many shipwrecks in history.In 1912, the British ship Titanic sank because an iceberg cracked its hull, killing thousands of people on board.Sea ice and icebergs will drift with the wind and current. Antarctic icebergs in the Atlantic Ocean can drift to 36 °~40 ° south latitude.
weather conditions
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The multi-year characteristics of the above important hydrometeorological conditions affecting navigation are the important basis for selecting and determining routes (climatic routes) and formulating navigation plans.These data are published in the marine hydrometeorological atlas, various navigation guides and navigation manuals.For real-time marine hydrometeorological information and forecast serviceworld meteorological organizationThe coordinated ocean meteorological service plan is issued by the national and regional level, as well as the World Meteorological Center and the Oceanographic Center.
Various weather systems such asTropical cyclone、Extratropical cycloneThey all have their own weather structure, and the distribution of sea surface meteorological element values within their range also has their own regularity.According to this regularity, using the meteorological observation values along the ship and the configuration and dynamics of the vast ocean weather system provided by the Department of Marine Meteorology and Hydrology, the position of the ship in various weather systems can be determined, and the generation and disappearance trend of fog on the sea can be judged, so that the corresponding navigation methods can be adopted;It can also verify and revise the reports, forecasts, warnings and facsimile charts of the marine meteorological and hydrological departments.
Tropical cyclone
According to the degree of threat to the ship, it can be divided into dangerous semicircle, navigable semicircle and dangerous quadrant in dangerous semicircle.Determine the position of the ship according to certain methods (seeShip typhoon prevention）。
Extratropical cyclone
It can be divided into front, warm zone and rear.In the front, from far to near, cirrus clouds appear in the sky, then become cirrostratus clouds, then become high-level clouds, and begin to appearlight rainorlight snow, and then it becomes a rain stratiform cloud, with continuity fallingmoderate rain、heavy rainormoderate snow、heavy snow。When the atmosphere is unstable, cumulus clouds and intermittent precipitation will also appear. At this time, the pressure will gradually decline, and the wind direction will be east. The closer to the center, the stronger the wind will be.In the warm zone, the place slightly away from the center is usually a little cloudy weather, and the place near the center is stratiform clouds and stratocumulus clouds;The closer to the center, the lower the cloud, the thicker the cloud layer, and drizzle, sometimes fog appears.When the cyclone deepens rapidly, the air ascending effect is strengthened, and there is continuous precipitation near the center of the warm zone.The wind direction in the warm zone is south in the northern hemisphere and north in the southern hemisphere.At the rear, from near to far, the wind direction turns to west.Sometimes the cloud rain area is relatively wide, and sometimes the convective cloud and intermittent precipitation area is relatively narrow. The weather is rapid and sunny, and the pressure gradually shows a steady rise.In the Northern Hemisphere, the wind direction in the north of the center changes counterclockwise from the front to the back and clockwise from the south of the center.The top of the warm zone of the extratropical cyclone in the southern hemisphere points to the south, and its northern wind direction also changes counterclockwise from the front to the back, and the southern wind direction changes clockwise.According to the distribution law of meteorological element values in the extratropical cyclone area above, the position of the ship in the extratropical cyclone area can be determined by using the changes of the observed values of various meteorological elements along the way.
Trend of fog generation and disappearance at sea
Admiral fog separationAdvection fog、Precipitation fog、Evaporative fogandRadiation fogFour.Each kind of fog has its own law of birth and disappearance.The dew point temperature and water temperature data measured at different times along the ship shall be filled and drawn in vertical coordinates with different symbols or colorstemperatureThe abscissa represents the time on the square paper, and then connect the dots with the same symbol or color to get twocurve。According to the distance between the two curves, the trend of fog generation and disappearance can be judged.When there is no fog, the water temperature is higher than the dew point temperature;When the distance between the two curves becomes narrower and narrower, the possibility of encountering fog becomes greater and greater;Fog occurs when the dew point temperature is higher than the water temperature.On the contrary, when the distance between the dew point temperature and the water temperature becomes larger and larger, it is impossible to encounter fog. If there is fog, it is a sign of fog disappearance.[1]
