Putting Meteorological and Oceanographic Data to Work - Caris

“Weather data is becoming an increasinglycritical part of everyday life, beyond its typicaluse in predicting the weather forecastover the next few days.”sound at or near the surface of the ocean is approximatelyfour times the speed of sound in the air, while the speed ofsound in cooler water, such as that found at greater oceandepths, is far slower. Speed of sound is important, as it canbe used to accurately calculate other attributes such as distancefrom one object to another, ocean depth, wave speedand a variety of other ocean properties.As mentioned, ocean depth plays an important role intemperature and speed of sound. It also has other practicalapplications that could be used by a number of organizationsincluding navies, oil companies and marine scientists.Such examples of other applications include, but are notlimited to, optimal and/or safe depths for submarines, calculatingpathways to lay underwater piping or searching forparticular organisms that tend to live at particular depthsand temperatures.Salinity and Density. Over the past 100 years, the definitionof ocean salinity has been altered many times in anattempt to switch from scientifically correct to practical,and then back to a combination of the two. Early definitionswould state that salinity is the amount of solid materials, ingrams, that is dissolved into one kilogram of seawater.However, this definition was also dependent upon thestates, conversions and oxidization of other elements suchas carbonate oxide and other organic matters. For the easeof understanding, this article will use the simplest of definitionsand say that salinity is simply the amount of dissolvedmaterial, in grams, in one kilogram of seawater. From thisdefinition and the statistics provided above, it could be seenthat salinity and ocean density are related.Changes in salinity and temperature cause fluctuations inocean density. For example, a high-density section of waterwould exist where the ocean has high salinity and coolertemperatures.An area of the ocean with low density would have a combinationof warmer water and low salinity. Although salinityof the ocean changes very little, it is still important in calculatingaccurate densities, temperatures and speed ofsound.Another use of water density is the ability to calculatecurrents. One of the causes of the circulation of ocean wateris the difference in densities. Warm water tends to flowtoward water of lower density, while cooler water flowstoward higher dense areas. This explains how warm watermoves across the surface away from the equator, and coldwater moves below the surface toward the equator.Sonic Layer Depth and Deep-Sound Channel/AxialDepth. It is often desired, when calculating data sets, to findthe limits or boundaries for a particular experiment. As canbe seen in all of the raster attributes mentioned above(directly or indirectly), speed of sound is affected by everything,whether it be density, temperature, depth, etc. Soniclayer depth and deep-sound channel/axial depth weredefined in an attempt to find the boundaries (limits) ofspeed of sound in the ocean. Deep-sound channel is a termused to represent a channel that exists at a particular depth,known as the axial depth, where the speed of sound is at aminimum. Sonic layer depth is related to the deep-soundchannel in that it describes the depth where the maximumspeed of sound exists between the axial depth and theocean’s surface. Because of the properties of sound inwater, and the fact that it behaves and refracts differently atvarious depths and densities, these two measurements canbe very useful in situations such as naval warfare where anavy would desire to find the optimal depth to place a submarineto avoid detection from surface vessels.Vector AttributesThe term vector, in regard to this article, will be used todescribe meteorological and oceanographic attributes that“The first step toward delivery of weatherdata in a meaningful, interactive image wasto collect and process the data.”have an associated magnitude and direction. All vectorattributes may be displayed within MetOcean Managerusing either arrows or wind symbols. As with raster attributes,vector attributes are customizable. The user may definea color range when dealing with a particular classification.An example classification could be to display windsthat are three knots or less in blue, winds that are betweenthree and eight knots in yellow and winds that are betweeneight and 12 knots in red.The length of an arrow (or line) varies with the magnitudeof the attribute and is relative to the amount and size ofother data being viewed. A legend is given within the applicationto help understand the magnitude of a particulararrow.Currents play a vital role in many oceanic projects,including tracking certain types of marine activity, navigationand even search and rescue. Currents often differ for aparticular point depending on the depth. Because of this,currents are displayed with respect to a particular oceandepth. Three major components: wind, Earth’s rotation anddensity affect surface currents. In general, winds tend to circulateclockwise in the Northern Hemisphere and counterclockwisein the Southern Hemisphere. These winds applya force to the water particles near the surface of the ocean,causing them to move in the direction of the wind.In addition to the force applied to the water particles nearthe surface due to wind, the Earth’s rotation also causes aforce to be applied to the water. Currents that are caused bythe Earth’s rotation that flow toward the magnetic polestend to be narrower and stronger as they flow in the samedirection as the winds. However, currents caused by theEarth’s rotation that flow toward the equator apply anopposing force to those caused by the wind and, thus, createless powerful movement.Deep-water currents are affected by thermohaline circulation.When warm water from the equator moves towardthe poles, cooler water is then displaced toward the bottom