Putting Meteorological and Oceanographic Data to Work - Caris

Putting Meteorological andOceanographic Data to WorkAn Exploration into Internet-Based Geospatial Technology forNew Applications for the Royal Malaysian NavyBy Chantale CaronProject CoordinatorCARISFredericton, CanadaThe Royal Malaysian Navy(RMN) has a responsibility tothe mariners that use the waterwaysin and around Malaysia to provideaccurate and up-to-date informationto allow for the safest passage possible.Meteorological and oceanographic(metocean) data has beenrecognized as an important factor inmeeting this responsibility.Weather data is becoming an increasinglycritical part of everydaylife, beyond its typical use in predictingthe weather forecast overthe next few days. Oceanographicand forecast data now play animportant role in many major industries,whether it is to predict thecourse of an oil spill, to calculatethe best path for the installation of apipeline or to aid in search and rescueoperations.The RMN recognized the importanceof acquiring such informationand contracted Maicons TechnologySdn Bhd, in partnership with WNIOceanographers and Meteorologists(now a part of MetOcean Engineerspty Ltd.) and CARIS, to deliver acomplete metocean acquisition, monitoringand forecasting system. Thisarticle will provide a brief overview ofthe data collection process, introduce asystem used by the RMN and explainthe functionality and benefits of thisintegrated solution. It will focus on thepotential for such a system as a solutionfor harnessing and building uponvast amounts of meteorological andoceanographic data.Mean sea level (MSL) pressure, tropicalcyclone path and satellite windsare displayed over basemap data. Thelegend on the right is displays thepressure classification next to a satelliteimage and a weather report alongthe bottom.Data Collection and ProcessingThe first step toward delivery ofweather data in a meaningful, interactiveimage was to collect and processthe data. To collect data, sensors weredeployed and calibrated. These sensorswere used to provide raw data tothe RMN that will also be used as inputdata for the analysis tools for modelingattribute data at different depthsover the entire South China Sea.MetOcean Engineers completed amodeling tool to interpolate the oceanattributes for each point in the specifiedgrid. In this case, the grid consistedof approximately 18,000 points perdepth over the entire South China Sea.The modeled data is stored in a networkcommon data form (NetCDF)before being introduced into a softwareapplication delivered by CARISMetOcean Manager.Database Management and DisplayMetOcean Manager is a visualizationtool for near-real-time weatherforecast information and observationdata on the Internet. The applicationwas developed to interpolate and displaymeteorological and oceanographicdata. The MetOcean Manager isReprinted with permission from Sea Technology magazine.For more information about the magazine, visit www.sea-technology.com

(Top) Tide height data displayed overbasemap data. The legend on the rightoutlines ocean temperature classification.(Middle) Web mapping service data andocean winds are displayed over basemapdata. The legend on the right representsthe classification and symbols forthe winds.(Bottom) Ocean temperature data displayedover basemap data. The legendon the right outlines ocean temperatureclassification.made up of two main components: adatabase and an end-user application.The data collected for display into thesystem consists of meteorological andoceanographic data obtained or modeledon an hourly basis. The end-userapplication, which could consist of either adesktop or a Internet-based client, is used to displaydetailed maps containing raster productssuch as ocean temperature, salinity, density andspeed of sound, as well as vector-based productswhich include ocean winds and currents. Thisinformation may be used by a variety of RMNstakeholders to build informative and dynamicallychanging meteorological and oceanographicmaps. Combining this data with anInternet-based geospatial solution gives theRMN a new product that increases safety formariners by providing more accurate weatherforecasting, aid in emergency planning and inthe supply of information to a host of potentialnew users.Raster AttributesMetOcean attributes may be displayed withinthe RMN system using colors, contour lines or acombination of the two. Contour lines are customizablein that the user may choosethe density of the contours as well aswhether corresponding annotations(numbers) should be displayed.Temperature, Depth and the Speed ofSound. Ocean temperature, in conjunctionwith other variables such as salinityand ocean depth, may be used for a largevariety of purposes such as calculatingthe speed of sound at a given depth ormeasuring and predicting the effects ofglobal warming for a particular area inthe ocean. Temperatures of the ocean ator near its surface are generally warmerthan those found at greater depths.These temperatures also tend to fluctuateon a more regular interval, whiletemperatures at greater depths tend toremain more constant.Speed of sound in the ocean is highlydependent on the temperature and depthof the water. In general, the speed of

“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

“MetOcean Manager is a visualization toolfor near-real-time weather forecast informationand observation data on the Internet.”of the ocean. The new, cooler water then displaces the waterthat existed previously toward the equator. This circulationpattern is known as thermohaline circulation.ConclusionsTypical geographical information system (GIS) functionalityincludes data entry, spatial and textual querying, dataanalysis, data management and the production of hardcopyimages and maps. Overall, the GIS functionality in theRMN MetOcean system provides the flexibility and powernot only to harness vast quantities of data, but also convertthat data into powerful information. This information canassist a variety of industries in making important decisionson a daily, and even hourly, basis. /st/For more information, visit our website at www.sea-technology.com.Chantale Caron is the product coordinator for the CARIS Met-Ocean Manager. She has over five years’experience providing tailoredgeomatics software for clients varying from fleet managementsolutions to municipal and government-based solutions.