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adding decibels PowerPoint Presentation
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adding decibels

adding decibels

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adding decibels

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    1. Adding Decibels

    2. 1. The speed of sound in water is determined first by the water itself. a. The elasticity of the medium (for compression and expansion of the sound energys longitudinal wave) is the most important factor in determining the speed of sound b. The effect on the density of the medium is also very important. 2. In addition to the normal density of water, there are several factor which can cause the density of the water to change. They are salinity, pressure and temperature. 3. Salinity (has the smallest affect on sound speed) a. As salinity increases the sound speed increased. b. Salinity can be a big factor near rivers. c. Salinity increases with depth 4. Pressure a. As pressure increases sound speed increases b. Pressure increase is constant and predictable 5. Temperature (The major factor affecting sound speed above 1000 meters) a. Below 1000 meters temperature of the ocean is constant. b. One degree Celsius increase in temperature will change water speed by 3 meters/sec.1. The speed of sound in water is determined first by the water itself. a. The elasticity of the medium (for compression and expansion of the sound energys longitudinal wave) is the most important factor in determining the speed of sound b. The effect on the density of the medium is also very important. 2. In addition to the normal density of water, there are several factor which can cause the density of the water to change. They are salinity, pressure and temperature. 3. Salinity (has the smallest affect on sound speed) a. As salinity increases the sound speed increased. b. Salinity can be a big factor near rivers. c. Salinity increases with depth 4. Pressure a. As pressure increases sound speed increases b. Pressure increase is constant and predictable 5. Temperature (The major factor affecting sound speed above 1000 meters) a. Below 1000 meters temperature of the ocean is constant. b. One degree Celsius increase in temperature will change water speed by 3 meters/sec.

    3. Speed of Sound Factors Temperature Pressure or Depth Salinity

    4. Temperature, Pressure, and Salinity

    5. Class Sound Speed Data

    6. More Curve Fitting

    7. 1. We can measure the water temperature by launching and expendable bathythermograph (XBT). As it sinks it measures temperature vs depth. 2. The temperature can then be converted into a speed vs depth graph . This Graph is called a Sound Velocity(speed) Profile. 3. Of interest, Submarines are constantly measuring sound speed as they change depth. They also periodically launch an expendable bathythermograph. The submarine launched version actually measures sound speed so effects of temperature, pressure, and salinity are all measured at once and actual sound speed is measured. 4. Lead in: If you add all the effects you get a Sound Velocity Profile that1. We can measure the water temperature by launching and expendable bathythermograph (XBT). As it sinks it measures temperature vs depth. 2. The temperature can then be converted into a speed vs depth graph . This Graph is called a Sound Velocity(speed) Profile. 3. Of interest, Submarines are constantly measuring sound speed as they change depth. They also periodically launch an expendable bathythermograph. The submarine launched version actually measures sound speed so effects of temperature, pressure, and salinity are all measured at once and actual sound speed is measured. 4. Lead in: If you add all the effects you get a Sound Velocity Profile that

    8. 1. The graphic shows the typical deep ocean sound speed profile. It is the summation of the effects of destiny, salinity, pressure and normal temperatures. 2. The standard profile has four distinctive layers: 3. Surface layer: - Sound speed is susceptible to daily and local changes in heating cooling and wind mixing action. 4. Seasonal Thermocline: - Thermocline is a layer where the temp. can change rapidly with depth. - Seasonal can change with the seasons. (wind and storms can cause mixing of water temperatures) 5. Permanent Themocline - Affected only slightly by seasonal changes. 6. Deep Isothermal Layer - Has nearly a constant temperature (about 4 degrees C) 7. Ocean Currents can create an unexpected thermal layer - This layer can trap sound waves and let the sound travel further. 8. Ocean fronts are boundaries of large masses of different temperature water (like weather fronts). These can cause large horizontal gradients of Temperature and pressure. SURFACE LAYER (< 500m) T and c change with seasons due to surface heating, cooling, winds, storms, etc Winter - isothermal, slight positive gradient Summer - negative gradient Spring/Fall - Transitional MAIN THERMOCLINE (500m - 1000m) totally independent of surface layer temp decreases dramatically to 4 C or 32 F near 1000 m DEEP (ISOTHERMAL) LAYER (> 1000 m) temp constant pressure has the largest effect on c 1. The graphic shows the typical deep ocean sound speed profile. It is the summation of the effects of destiny, salinity, pressure and normal temperatures. 2. The standard profile has four distinctive layers: 3. Surface layer: - Sound speed is susceptible to daily and local changes in heating cooling and wind mixing action. 4. Seasonal Thermocline: - Thermocline is a layer where the temp. can change rapidly with depth. - Seasonal can change with the seasons. (wind and storms can cause mixing of water temperatures) 5. Permanent Themocline - Affected only slightly by seasonal changes. 6. Deep Isothermal Layer - Has nearly a constant temperature (about 4 degrees C) 7. Ocean Currents can create an unexpected thermal layer - This layer can trap sound waves and let the sound travel further. 8. Ocean fronts are boundaries of large masses of different temperature water (like weather fronts). These can cause large horizontal gradients of Temperature and pressure. SURFACE LAYER (< 500m) T and c change with seasons due to surface heating, cooling, winds, storms, etc Winter - isothermal, slight positive gradient Summer - negative gradient Spring/Fall - Transitional MAIN THERMOCLINE (500m - 1000m) totally independent of surface layer temp decreases dramatically to 4 C or 32 F near 1000 m DEEP (ISOTHERMAL) LAYER (> 1000 m) temp constant pressure has the largest effect on c

    9. Refraction

    10. Multiple Boundary Layers

    11. Simple Ray Theory

    12. Ray Theory Geometry

    13. The z (Depth) and x (Range) Directions

    14. The z (Depth) and x (Range) Directions

    15. Why is R = Radius?

    16. Summary

    17. Negative Gradient

    18. Example 1 Given: c1 = 964 m/s, c2 = 1299 m/s, q2 = 30o Dz(between 1 and 0) = 3000m Find: q1, co, g (between pt 1 and 0), R

    19. Example 2 Find gradient, g Find Radius of Curvature, R, for each ray. Skip distance i.e. the distance until the ray hits the surface again Max depth reached by each ray

    20. Backups

    22. Slope = tanq