What properties drive the movement of deep ocean currents and how does heat from the Sun drives wind and ocean currents?
Rk Naresh
The ability to extract ocean currents depends on the data product used. However, when working with Single Look Complex (SLC) SAR data, we can retrieve ocean currents through Doppler centroid estimation, as discussed in "Doppler Centroid Estimation for Ocean Surface Current Retrieval from Sentinel-1 SAR Data"
Yes, Ocean currents are often influenced by the wind, necessitating corrections for various factors, including wind effects. These corrections aim to eliminate non-geophysical terms. In this context, researchers utilized the OCN product to estimate currents within the image domain, as outlined in "Direct Comparison of Sea Surface Velocity Estimated From Sentinel-1 and TanDEM-X SAR Data."
In the attached image, it's evident that the Doppler value is zero over land (static) but dynamic over ocean waves, particularly near the coastline (waves striking). This dynamic Doppler signature can be effectively utilized for estimating ocean surface currents.
Surface wind-driven currents generate upwelling currents in conjunction with landforms, creating deepwater currents. Currents may also be caused by density differences in water masses due to temperature (thermo) and salinity (haline) variations via a process known as thermohaline circulation. These deep-ocean currents are driven by differences in the water's density, which is controlled by temperature (thermo) and salinity (haline). This process is known as thermohaline circulation. These depths are also subject to extreme pressure, from about 40 to over 110 times the pressure of Earth's atmosphere. This means the “deep” is the part of our ocean that is dark, cold, food-poor, subject to intense pressure, and typically deeper than 200 meters. The deep-sea is defined as the part of the ocean below 200 meters depth. This environment Is considered extremely harsh with temperatures of below 5 degrees Celsius, extreme pressure (2,000 meters equals about 200 times the atmospheric pressure at sea level), and no sunlight. The global ocean conveyor belt is a constantly moving system of deep-ocean circulation driven by temperature and salinity. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest. These types of waves are found globally across the open ocean and along the coast. More potentially hazardous waves can be caused by severe weather, like a hurricane.There are amazing and unique habitats in the deep sea: the abyssal plains, hydrothermal vents and cold seeps, seamounts (underwater mountains) and the deep-water column. These all have distinct types of life. Heat, a form of energy, helps Drive Ocean and atmospheric circulation. The ocean absorbs and stores more heat than the atmosphere. Both the atmosphere and ocean are moving; the atmosphere does this quickly, the ocean slowly. Ocean currents are the continuous, predictable, directional movement of seawater driven by gravity, wind (Coriolis Effect), and water density. Ocean water moves in two directions: horizontally and vertically. Horizontal movements are referred to as currents, while vertical changes are called upwelling or downwellings. Strong ocean currents are generated from a combination of temperature, wind, salinity, bathymetry, and the rotation of the earth. The sun acts as the primary driving force, causing winds and temperature differences that impact currents. Besides gravity, the most important forces that cause and affect ocean currents are horizontal pressure-gradient forces, Coriolis forces, and frictional forces. This is why warm air and water rise, and cooler air and water sinking. This type of heat transfer is called convection, and the circular path the molecules take is called convection current. The convection of air causes wind and ocean surface currents. The sun heats the air, and the warm air rises. This rising warm air makes the cooler air from the surrounding areas come in to replace it. This then creates the wind. Ocean currents operate similarly. Over 96% of total global water is in the ocean, so let's start there. Energy from the sun causes water on the surface to evaporate into water vapor a gas. This invisible vapor rises into the atmosphere, where the air is colder, and condenses into clouds. Air currents move these clouds all around the earth. Sunlight plays a very important role in sustaining life in the ocean. It first penetrates the water column, heats it, generates currents, and finally, is absorbed by phytoplankton, which uses this source of energy captured by pigments such as chlorophylls to synthesize organic matter from water and inorganic nutrients.
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