What are the main aspects of the impact of the ocean on climate?
The ocean is an important link in the global climate system. It plays a decisive role in regulating and stabilizing the climate through energy and material exchange with the atmosphere and water circulation. It is called the "regulator of the earth's climate" ". The ocean, which accounts for 71% of the earth's area, is the main supplier of atmospheric heat. If the world's 100-meter-thick surface water cools down by 1 degree Celsius, the heat released can warm the global atmosphere by 60 degrees Celsius. The ocean is also a major source of water vapor in the atmosphere. When seawater evaporates, a large amount of water vapor is brought from the ocean into the atmosphere. The evaporation of the ocean accounts for about 84% of the total evaporation on the surface, and it can convert 3.6 trillion cubic meters of water into water vapor every year. Therefore, the thermal conditions and evaporation conditions of the ocean directly affect the content and distribution of atmospheric heat and water vapor. At the same time, the ocean also absorbs 40% of the carbon dioxide in the atmosphere, which is considered one of the greenhouse gases that contributes to climate change.
On the other hand, climate change has also had a huge impact on the ocean. Rising temperatures have caused sea levels and seawater temperatures to rise, while excessive absorption of carbon dioxide by the oceans has triggered acidification of seawaters. All of these have caused damage to marine and coastal ecosystems, including coral bleaching, death, and the submergence of small islands. The source of a series of problems. Taking Indonesia as an example, the country’s Minister of Marine Affairs and Fisheries said that in the next few decades many islands in Indonesia will sink into the sea due to rising sea levels. Ovi, an environmental scientist at the University of Queensland in Australia, also issued a report saying that if immediate action is not taken, all coral reefs on the earth will disappear by the end of this century. In addition, climate change also changes the ocean's weather patterns and ocean currents, thereby increasing the extent of ocean disasters. In particular, seawater backflow occurs after acidification, and when it enters land, it will have a major impact on ecosystems such as estuaries and estuaries.
Oceanic climate is the most basic climate type on the earth. The general characteristic is that it is less affected by the mainland and more affected by the ocean. Under oceanic climate conditions, the annual and daily changes in temperature are relatively gentle, and the annual and daily ranges are smaller than in continental climates. Spring temperatures are lower than autumn temperatures. The highest and lowest temperatures throughout the year occur later than in continental climates; the hottest month is August and the coldest month is February.
The main factors affecting marine climate are solar radiation, marine environment and atmospheric circulation. Solar radiation is the main energy source for seawater and atmospheric warming, and is the basic driving force for many physical processes in the atmosphere. The sea surface is the underlying surface of the lower atmosphere. The specific heat of sea water is high and the reflectivity of solar radiation is small. In addition, the ocean is vast and large in volume, so the ocean has become a huge storage of heat and moisture for the earth. About half of the solar radiation energy reaching the earth's surface is absorbed and stored by seawater, and then the seawater transports heat to the atmosphere in the form of long-wave radiation, latent heat and sensible heat, promoting atmospheric movement. The ocean provides large amounts of moisture to the atmosphere in the moisture cycle. Environmental factors such as the distribution of sea and land and the cold and warm ocean currents affect the heat balance, water balance and atmospheric circulation, resulting in climate differences in various sea areas. Atmospheric circulation facilitates the exchange of heat and moisture between north and south or east and west, causing climate to be governed not only by nearby marine environments but also by other non-marine environments.
Climate formed by the action of huge water bodies in the ocean. The climate includes ocean surfaces or islands and the offshore portions of continents where prevailing air currents originate from the ocean. Marine climate has the following characteristics: ① The annual and daily changes in temperature are very small, and no daily changes are even observed on the ocean surface. The extreme value of the annual change is generally one month behind the mainland, for example, the coldest month is February and the warmest month is August. In high latitudes, the coldest month may be March, and the warmest month may be September. Autumn is warmer than spring. ②The seasonal distribution of precipitation is relatively even, with many precipitation days but low intensity. Cloudy and foggy weather with high humidity. ③ There are many storms in tropical oceans. For example, the southwestern part of the North Pacific and the South China Sea are areas where typhoons are generated and have strong impacts. Tropical storm is a very important meteorological disaster. Most continental areas near the ocean have maritime climate characteristics, and the coastal areas of Western Europe are typical maritime climate areas on the continent.
Trade wind (trade
wind) In the lower atmosphere on both sides of the equator, the northeasterly wind blows in the northern hemisphere and the southeasterly wind blows in the southern hemisphere. The direction of this wind rarely changes, and they blow from year to year. In this way, it appears stably and is very trustworthy. This is why trade
wind is translated as "trade wind" in Chinese.
The formation of trade winds is related to the circulation of the earth. Under long-term sunlight, the equator is heated the most. The air near the ground at the equator is heated and rises, forming an equatorial low pressure zone near the ground. It forms a relatively high pressure at high altitudes. The air pressure moves in the direction of high-altitude low pressure in the north and south. Due to the influence of the geostrophic deflection force, it deflects parallel to the isobars near 30 degrees north and south latitude. The atmosphere accumulates here and is forced to sink, forming a subtropical zone near the ground. High pressure zone. At this time, a pressure difference occurs between the equatorial low pressure zone and the subtropical high pressure zone, and air flows from the subtropical high pressure zone to the equatorial low pressure zone. Under the influence of the geostrophic deflection force, when the air in the subtropical high pressure in the northern hemisphere moves southward, the air moves to the right of the pressure gradient force, forming a northeasterly wind, that is, a northeasterly trade wind. In the southern hemisphere, southeasterly trade winds form.
Monsoon is a wind system that prevails in a large area due to the temperature difference between the continent and the adjacent ocean, and the wind direction changes significantly with the seasons. Winds with this kind of atmospheric circulation characteristics are called Monsoon.
Monsoon is a large-scale convection phenomenon with a one-year cycle caused by the distribution of land and sea, atmospheric circulation, continental topography and other factors. Asia is the most famous monsoon region in the world. Its monsoon characteristics are mainly characterized by the existence of two main monsoon circulations, namely the northeast monsoon prevailing in winter and the southwest monsoon prevailing in summer. Their transitions have explosive mutation processes, and the transition in between The period is really short. Generally speaking, the winter monsoon period is from November to March of the following year, the summer monsoon period is from June to September, and the transition period between summer and winter monsoons is from April to May and October. However, seasonal differences vary in different regions, so the division of monsoons is not entirely consistent. The monsoon is a wind system that prevails over a large area and whose wind direction changes significantly with the seasons. Like the wind belt, it is a planetary-scale circulation system. Its formation is caused by the temperature difference between the ocean and land in winter and summer. The monsoon blows from the ocean to the continent in summer and from the continent to the ocean in winter.
Monsoons are formed by the differential heating of oceans and land by the sun. In summer, due to the large heat capacity of the ocean, the heating is slow, the sea surface is cold, and the air pressure is high. However, the continent has small heat capacity and heats quickly, forming a warm low pressure. The summer wind blows from the cold ocean to the warm continent; in winter, the opposite is true. Wind blows from the cold continent to the warm ocean.
The southwest wind blows in summer and the northeast wind blows in winter. This is because when the airflow crosses the equator from the southern hemisphere into the northern hemisphere in summer, due to the earth's rotation effect, the airflow will be affected by a rightward inertial force. This force is the geostrophic deflection force (Coriolis force). Due to the geostrophic deflection force, the airflow deflects to the right during its northward movement, forming a southwesterly wind. In addition, affected by the topography of the Tibetan Plateau and other factors, the monsoon in East Asia is more complex than that in South Asia.
The horizontal range of sea and land breezes can reach dozens of kilometers, the vertical height can reach 1 to 2 kilometers, and the cycle is one day and night. During the day, the surface of the earth heats up due to solar radiation. Since the heat capacity of land soil is much smaller than that of sea water, land heats up much faster than the ocean. Therefore, the temperature on land is significantly higher than that on the nearby ocean. The air column on land expands due to heat, so the sea breeze starts from morning to evening every day, and the wind is strongest in the afternoon. After sunset, the land cools down faster than the ocean; at night, the sea temperature is higher than the land, and a thermal circulation opposite to that during the day occurs, forming low-level land breeze and land breeze circulation on the vertical profile. The temperature difference between sea and land is greater during the day than at night, so the sea breeze is stronger than the land breeze. If sea breezes are forced up hillsides, clouds are often produced. At the lake-land interface of larger lakes, lake-land breezes similar to sea-land breeze circulation can also be generated. Sea breeze and lake breeze have a cooling effect on coastal residents. On larger islands, the sea breeze converges from the surrounding areas to the island during the day, while the land breeze at night diverges from the island to the surrounding areas. Therefore, it is rainy during the day and sunny at night on the island. For example, in Hainan Island, China, the maximum precipitation intensity in a day occurs in the afternoon when the sea breeze is strongest.
Typhoons (hurricanes) are tropical cyclones that form over vast seas with tropical or subtropical sea surface temperatures above 26°C. According to the definition of the World Meteorological Organization: a tropical cyclone center with sustained wind speeds of magnitude 12 to 13 (ie, 32.7 meters to 41.4 meters per second) is called a typhoon or hurricane. The name hurricane is used in the North Atlantic and Eastern Pacific; The western part of the North Pacific (north of the equator, west of the international date line, and east of 100 degrees east longitude) is called a typhoon. In the summer and autumn every year, many violent storms called typhoons will occur in the northwest Pacific adjacent to my country. Some Dissipated in the ocean, some landed on land, bringing violent storms.
Tropical
Cyclone is a low-pressure vortex that occurs on the tropical or subtropical ocean. It is a powerful and deep tropical weather system. It is like a vortex advancing in a flowing river, rotating rapidly around its center while moving forward with the surrounding atmosphere. In tropical cyclones in the northern hemisphere, the airflow rotates counterclockwise around the center, while in the southern hemisphere it is the opposite. This situation is mainly affected by the Coriolis force generated by the rotation of the earth.
The life history of tropical cyclones can be divided into three stages: generation, maturity and death. Its life span is about a week on average, with the shortest being only 2-3 days, and the longest being about a month. The generation and development of tropical cyclones require huge amounts of energy, so they form on the tropical ocean surface where high temperature, high humidity and other suitable meteorological conditions exist. According to statistics, tropical cyclones are generated in all tropical oceans around the world except the southeastern Pacific.
There are at least two conditions for the formation of typhoons: 1. relatively high temperature
2. abundant water vapor. When boiling water, the water at the bottom of the pot will rise because the water at the bottom of the pot expands due to heat. The same is true for air. When the air at the bottom is heated, it will rise. In areas with higher temperatures, some highly disturbed air will rise in the atmosphere, reducing the air pressure on the ground. At this time, the peripheral air in the rising area will continue to flow into the rising area. Due to the rotation of the earth, the inflowing air will The air spins like a wheel, which is one of the causes of typhoons. When the rising air expands and cools, the water vapor in it cools and condenses into water droplets, releasing heat. This in turn encourages the lower-level air to continue to rise, causing the air pressure at the ground to drop even lower and the air to rotate more violently. This forms a typhoon. .
What place has these two conditions at the same time? Only on tropical oceans.
The temperature on the ocean surface there is very high, allowing the low-level air to fully accept water from the ocean surface. It is also the place with the richest water vapor on the earth, and this water vapor is the main driving force for the formation and development of typhoons. Without this driving force, typhoons will dissipate even if they form. Secondly, it is close to the equator, and the deflection force generated by the earth's rotation plays a certain role, which is conducive to the development of cyclonic circulation and the strengthening of airflow convergence in typhoons. Third, the tropical ocean surface conditions are simple in mid-latitudes. Therefore, the air above the same sea area can often maintain stable conditions for a long time, allowing typhoons to have sufficient time to accumulate energy and brew up typhoons. Under these conditions, typhoons will form and intensify in some tropical ocean areas as long as there is a suitable triggering mechanism, such as the occurrence of divergent airflow at high altitude or the trade winds of the northern and southern hemispheres meeting slightly north of the equator. According to statistics, in tropical oceans, typhoons often occur in areas where the ocean surface temperature exceeds 26 or 7 degrees Celsius. Mainly in the ocean east of the Philippines, the South my country Sea, the West Indies and the east coast of Australia. The sea water temperature in these places is relatively high, and they are also where the trade winds of the northern and southern hemispheres meet. Therefore, more than 20 typhoons are often born in a year.
Ocean currents, also called ocean currents, refer to the relatively stable flow of ocean surface water in a certain direction on a large scale all year round. Ocean currents are the main regulator of the thermal environment on the Earth's surface. The huge ocean current system promotes energy exchange in high and low latitudes of the Earth. The environmental characteristics of ocean currents and the areas they pass through also change through energy exchange. The ocean currents surrounding the subtropical high become the subtropical gyre. The center of this circulation is approximately 25 to 30 degrees north and south latitude. Near the equator, the combined effects of the northeasterly trade wind and the southeasterly trade wind form an equatorial ocean current flowing from east to west, which separates the equatorial ocean currents in the northern and southern hemispheres.
Ocean currents can be divided into warm currents and cold currents. If the water temperature of the ocean current is higher than the water temperature reaching the sea area, it is called a warm current; if the water temperature of the ocean current is lower than the water temperature reaching the sea area, it is called a cold current. Generally, ocean currents flowing from low latitudes to high latitudes are warm currents, and ocean currents flowing from high latitudes to low latitudes are cold currents. Sea-going ships sailing along ocean currents can save fuel and speed up. When warm and cold currents meet, sea fog often forms, which is detrimental to maritime navigation. In addition, ocean currents carry icebergs southward from the Arctic region, posing a greater threat to maritime shipping.
After entering the 1970s, abnormal weather that occurred around the world was characterized by wide scope, severe disasters, and long duration. In this series of abnormal weather, scientists have discovered that the "El Niño (el
nino)" trend, one of the important phenomena of the ocean and atmospheric system, plays an important role. "El Niño" is the transliteration of Spanish, el is the masculine definite article, and the original meaning of nino is "child prodigy" or "son of sage". According to legend, a long time ago, the ancient Indians who lived along the coasts of Peru and Ecuador paid great attention to the relationship between the ocean and the weather. They found that if the nearby seawater is exceptionally warmer than usual around Christmas, heavy rain will soon fall, accompanied by strange phenomena such as seabird migration in groups. Out of superstition, the ancient Indians called this abnormally warm trend the "Prodigy" trend, or the "El Niño" trend.
El Niño is an abnormal natural phenomenon in the Pacific Ocean. On the west coast of South America and the eastern part of the South Pacific, a famous Peruvian cold current flows from south to north. The summer in the southern hemisphere is from November to March of the following year. The water temperature in the southern hemisphere generally rises, and the equatorial warm current flowing eastward is strengthened. At this time, the global air pressure and wind belts move southward, and the northeast trade wind crosses the equator and is deflected to the left by the self-biasing force (also called the rotational deflection force) of the southern hemisphere to become the northwest monsoon. The northwest monsoon not only weakens the offshore winds on the west coast of Peru - the southeast trade winds, causing the Peruvian cold current to weaken or even disappear, but also blows the equatorial warm current with higher water temperature southward, causing the water temperature of the Peruvian cold current to rise abnormally. This silent, irregular ocean current is called the "El Niño warm current."
La Nina is the transliteration of the Spanish "La
Nia", La is the feminine definite article, Nia is the little girl, the meaning of the saint, which is the opposite of the El Niño phenomenon, also known as Referred to as an "anti-El Niño" or "cold event", it refers to a phenomenon in which the water temperature in the eastern Pacific near the equator drops abnormally, manifesting itself as a significant cooling of the eastern Pacific. It is also accompanied by global climate chaos and always appears after an El Niño event. .
Our country has a long coastline, vast territorial waters, and numerous islands
In order to develop seafood fishing and aquaculture, develop marine resources, develop maritime trade and protect the motherland’s maritime borders, we should Vigorously develop marine research, develop islands, increase island meteorological observation points, establish remote sensing weather stations, and provide civil and military meteorological services.