1. Waves

2. Wave characteristics and terminology
Crest
Trough
Wave height (H)
Wavelength (L)
Still water level
Orbital motion

3. Wave characteristics and terminology (continued)
If wave steepness exceeds 1/7, the wave breaks
Period (T) = the time it takes one full wave—one wavelength—to pass a fixed position

4. Orbital size decreases with depth to zero at wave base
Depth of wave base = ½ wavelength, measured from still water level
½ wave length = wave base
Below wave base – no orbits and the water is calmer
Calm water

6. Deep- and shallow-water waves
Deep-water waves
Water depth > wave base
Shallow-water waves
Water depth < 1/20 of wavelength
Transitional waves
Water depth < wave base but also > 1/20 of wavelength
Figure 8-6a & b

7. Wave speed (S) General formula: Deep-water waves:
Wave speed (S) in meters per second = 1.56 T in seconds
Wave speed (S) in feet per second = 5.12 T in seconds
Shallow-water waves: (d = water depth)

8. Wave Classification Ocean waves can be classified in various ways:
Disturbing Force- the forces which generate the waves.
Meteorological forcing (wind, air pressure); sea and swell belong to this category.
Earthquakes; they generate tsunamis, which are shallow water or long waves.
Tides (astronomical forcing); they are always shallow water or long waves.

9. The “sea” and swell Waves originate in a “sea” area
Swell describes waves that:
Have traveled out of their area of origination
Exhibit a uniform and symmetrical shape
Figure 8-9

10. Hurricane Katrina Hurricane Iniki September 1992 August 29, 2005
Hurricanes rarely hit Hawaii By Jack Williams, USATODAY.comThe danger of a hurricane hitting Hawaii any single year is very low, but both meteorology and history tell you not to ignore the possibility, especially if you're building or buying a home there.First the meteorology.
Hawaii is in the tropics and while the oceans around the state aren't as warm as those of the Caribbean Sea or Gulf of Mexico, the state does not have a chilly water barrier, like California's, which has helped keep any hurricanes from hitting that state — as far as anyone knows. (Related: California's tropical cyclones).
In addition, hurricanes and tropical storms approach Hawaii from both the east and the south, with storms that form in the eastern Pacific Ocean off the Mexican Coast being the most common. (Related: Understanding Eastern Pacific hurricanes)
The normal, east-to-west winds across the tropical Pacific push storms toward Hawaii, with a storm making it all of the way from time to time and many continuing west past Hawaii.
Storm that wouldn't die
From time to time, a hurricane sails past Hawaii to cross the International Date Line, which makes it a typhoon. In 1994, Hurricane John did even better.
It formed over the eastern Pacific and grew into a hurricane on Aug. 11, with winds reaching 170 mph at one time.
John weakened before hitting Johnson Island, south of Hawaii, where the U.S. Army destroys chemical weapons, but still did $15 million damage. All of the people on the island were evacuated before the storm hit.
John crossed the Date Line on Aug. 28, becoming Typhoon John. It then turned around and crossed back to the east side of the Date Line on Sept. 8, to become Hurricane John again. before dying on Sept. 31.
John covered a total of about 4,000 miles during its month as a storm.
Also, a few tropical storms and hurricane form south of Hawaii and head north toward the islands.
In fact, Hawaii's most devastating storm, Iniki in 1992, came from the south to pass directly over the Island of Kauai on Sept , 1992 killing six people and doing $2.3 billion damage.
Which brings us to Hawaii's hurricane history.
Meteorologists have no doubt that hurricanes have been hitting Hawaii since the islands first pushed up from the bottom of the Pacific as volcanoes.
Hawaiians had stories of storms from before Europeans and Americans arrived, but none seemed to be as aboujt storms as fierce as those told of in the legends of the people who lived around the Caribbean Sea before the Arrival of Europeans in the New World's tropics in the 15th century.
In fact, even Weather Bureau meteorologists didn't realize until 1950 that some of the strong storms that hit Hawaii from time to time were tropical cyclones. (Hurricanes are tropical cyclones over the Atlantic Basin or the Pacific east of the International Date Line.)
Robert Simpson and his staff at the Weather Bureau (It's now the National Weather Service) office in Honolulu recognized that a storm spotted east of the islands on Aug. 12, 1950 was a tropical cyclone, not an extratropical storm. (Related: How tropical, extratropical storms differ)
They called it Hurricane Able because at the time forecasters used the World War II vintage international phonetic alphabet — Able, Baker, Charlie and so on — to name storms. This storm was later given the Hawaiian name Hiki.
Simpson went on to become a towering figure in hurricane research and forecasting.
He organized and ran the USA's and the world's first large hurricane research program, which continues today as the National Oceanic and Atmospheric Administration's Hurricane Research Division and to head the National Hurricane Center. He's the "Simpson" in the Saffir-Simpson hurricane damage scale. (Related: The Saffir-Simpson scale)
Before 1950, meteorologists hadn't seen the differences between Hawaii's tropical cyclones and the island's extratropical "Kona" storms, which hit during the winter. The late summer, fall hurricane season can overlap the Kona season.
Today, a bright eighth grader who has stayed awake during Earth science class could probably tell you many times which storms seen in satellite photos are tropical and which are extratropical cyclones.
Simpson, and his 1950s colleagues, of course didn't have satellite photos and, as far as that goes, hardly any data about storms over the ocean except readings radioed from unfortunate ships that happened to stumble into a high winds and towering waves.
Figuring out that "Able" was a hurricane was like putting together a jigsaw puzzle with many missing pieces.
Since 1950, two hurricanes, including Iniki, have hit Hawaii. Here, "hit" means the storm's center came ashore on one of the islands. Others have come close enough to bring 74 mph "hurricane force" winds and to cause serious damage and to kill a few people.
Hawaii's mountains can increase a hurricane's damage.
First, mountains enhance rain, whether the state's normal day-to-day rain or rain from a storm. Rainwater rushing down mountains causes floods and flash floods. (Related: Trade winds govern Hawaii's weather).
Sometimes a storm squeezes winds through valleys, making it speed up.
Finally, in the past, and surely in the future, huge waves kicked up by far-away storms crash against Hawaii's beaches to wash higher than normal waves or eat away sand.
The hurricanes to hit Hawaii were:
•Dot, August Meteorologists on Air Force hurricane hunter airplanes estimated Dot's winds as 150 mph or faster on Aug. 2, which makes it the strongest hurricane ever recorded in the Central Pacific. But the storm weakened by the time at hit Kauai the night of August 6 with sustained winds measured up to 81 mph. At the time, Kauai was mostly agricultural but damages were estimated at $6 million in 1959 dollars mostly to the sugar, macadamia nuts and pineapple crops.
•Iniki, September Iniki formed southeast of Hawaii and was heading toward the north when its eye went inland near Waimea on Kauai on Sept. 11 with peak, sustained winds estimated at 130 mph and gusts up to 160 mph. The fastest measured winds were just below 100 mph at Lihue. Iniki's winds caused widespread damage and storm surge and high waves did extensive damage on both Kauai and the Island of Oahu.
Other notable Hawaiian storms included:
•Nina, November After forming near Palmyra Island south of Hawaii, Nina headed north with its center coming within 120 miles of Kauai, but this was close enough for winds up to 92 mph to hit Kilauea Point, Kauai, and for heavy rain to cause serious floods. The fastest wind ever recorded at Honolulu International Airport — 65 mph — occurred during Nina. High surf on Kauai's southern shore accounted for most of the estimated $100,000 (in 1957 dollars) damage.
•Iwa, November Iwa, like Nina, formed south of Hawaii and moved north to brush Kauai. It didn't produce 74 mph or faster hurricane force winds at any weather station, but the wind at Lihue came very close, 73 mph. Even without hurricane-force winds, Iwa did an estimated $239 million damage, mostly to hotels, and other tourist facilities and the growing number of homes that were replacing farms. It also knocked out power across Oahu, the island where Honolulu is located.
•Estelle, July This storm come from the east, but was heading directly toward Hawaii when it was most intense — it then jogged to the south to miss the Big Island. Still, Estelle sent very large waves into beaches on the Big Island and Maui. Even though the storm's highest winds didn't hit Hawaii, the high waves did more than $2 million in damage.
August 29, 2005

11. "Tsunami" - a Japanese word meaning "great wave in harbor".
It is a series of ocean waves commonly caused by violent movement of the sea floor by submarine faulting, landslides, or volcanic activity. A tsunami travels at the speed of nearly 500 miles per hour outward from the site of the violent movement.
The Great Wave off Kanagawa by Katsushika Hokusai ( )
The Pacific Tsunami Warning Center (PTWC) relies on water-level data from stations throughout the Pacific as a means of judging the severity of tsunamis. Their interpretation of the water-level data received in real and near real time is still somewhat subjective and is based upon data from past events and the fundamental physics of tsunami waves. The goal of this research is to develop an algorithm to quantitatively predict the tsunami height offshore of Hawaii based on water-level data near the tsunami source.

12. Tsunami Tsunami terminology Created by movement of the ocean floor by:
Often called “tidal waves” but have nothing to do with the tides
Japanese term meaning “harbor wave”
Also called “seismic sea waves”
Created by movement of the ocean floor by:
Underwater fault movement
Underwater avalanches
Underwater volcanic eruptions

13. Tsunamis are described by the same physical characteristics as wind-generated waves (length, period and height) but with dimensions that are vastly different. When a significant underwater event occurs, energy is transmitted upwards in the shape of a dome or mound. This force creates a series of waves as the water settles. In deep ocean, the wave height of a tsunami is normally only a few feet. Since the wave length is usually considerably more than 100 miles, the wave is not really noticeable at sea. Their wave periods in deep water vary between 15 to 60 minutes with a speed of more than 400 knots. When the tsunami enters shallow water, it undergoes changes similar to, but more dramatic than, those experienced by regular waves. Because of its great speed in deep ocean, the forward speed diminishes and the height increases at a much greater rate than in an ordinary wave. It is possible to predict the arrival of a tsunami wave at a distant beach, because the speed of the advancing wave in shallow water (water depth less than half the tsunami's wave length) is determined by the water depth.

14. Most tsunami originate from underwater fault movement
Figure 8-21a

15. Tsunami
Fault displacement under water displaces water, water moves to fill vacuum, generating large waves.

16. Tsunami characteristics
Affect entire water column, so carry more energy than surface waves
Can travel at speeds over 700 kilometers (435 miles) per hour
Small wave height in the open ocean, so pass beneath ships unnoticed
Build up to extreme heights in shallow coastal areas

17. Coastal effects of tsunami
If trough arrives first, appear as a strong withdrawal of water (similar to an extreme and suddenly-occurring low tide)
If crest arrives first, appear as a strong surge of water that can raise sea level many meters and flood inland areas
Tsunami often occur as a series of surges and withdrawals

18. Tsunami since 1900
Most tsunami are created near the margins of the Pacific Ocean along the Pacific “Ring of Fire”

19. Puunene Avenue Aftermath of a Tsunami in Kahului, 1960
Maui
Puunene Avenue Aftermath of a Tsunami in Kahului, 1960
Tsunamis struck Kahului in 1946, 1957, 1960, and The earliest historically recorded tsunami in Kahului occurred on November 7, 1837, when a large tsunami traveled 800 yards inland and destroyed a Hawaiian village. The 1960 tsunami was caused by a violent earthquake in Chile on May 22, It took approximately 15 hours for the tsunami to travel from Chile to the Hawaiian Islands. The tsunami killed 61 people in Hilo on the Big Island, but there were no other human casualties on any of the other islands. The tsunami caused moderate damage in Kahului.

20. A giant wave engulfs the Hilo pier during the 1946 tsunami
A giant wave engulfs the Hilo pier during the 1946 tsunami. The red arrow points to a man who was swept away seconds later.

21. Tsunami warning system
Seismic listening stations track underwater earthquakes that could produce tsunami
Once a large earthquake occurs, the tsunami must be verified at a nearby station
If verified, a tsunami warning is issued
Successful in preventing loss of life (if people heed warnings)
Damage to property has been increasing

23. tides w/out tsunami
Earthquake originated in Anchorage, AK
Passage of a tsunami as seen in a sea level record from Hilo, Hawaii. The observed sea level shows high frequency variations with a period of approximately 20 minutes and an initial amplitude of nearly two meters (total tsunami wave height 3.7 m)

24. This mathematical simulation (above) shows the tsunami created by the Cascadia Subduction Zone earthquake on January 26, 1700, as it reaches Hawaii on its way across the Pacific Ocean (5 hrs).

25. No tsunami ocean buoy in Indian Ocean
Tsunami India Ocean Dec. 26, 2004
No tsunami ocean buoy in Indian Ocean
Scientists say this happened when two of the major plates that make up the Earth's crust, the India plate and the Burma plate, collided and created a tsunami, or extremely powerful waves.
"[The earthquake] causes large-scale immediate uplifting of the terrain under the water that creates a massive wave. That wave travels very efficiently across the ocean. And so it shows up hundreds and even thousands of miles away with much of the same energy that it started with," said Jim Devine, a senior science adviser to the director of the U.S. Geological Survey, the government agency in charge of monitoring earthquakes.
These large wave swells, some of which traveled 3,000 miles to the African coast of Somalia, caused the majority of the death and destruction throughout Sri Lanka, India, Indonesia, Thailand and Malaysia.
The most powerful earthquake in 40 years
Measured 9.0 on the Richter scale
Occurred approximately four miles below the Indian Ocean near the Indonesian Island of Sumatra.

26. Tsunami: Thailand

31. Free Waves, Forced Waves
Free waves- a wave that is formed by a disturbing force such as a storm. Waves continue to move without additional wind energy
Forced wave- a wave that is maintained by its disturbing force, e.g., tides

32. Restoring Force
Force necessary to restore the water surface to flatness after a wave has formed in it
Capillary waves- wavelength < 1.73 cm
Gravity waves- wavelength > 1.73 cm

33. Deep-water, Transitional, & Shallow-water waves
Wavelength- determines the size of the orbits of water molecules within a wave
Water depth- determines the shape of the orbits
Deep-water waves
Water depth > wave base
More circular orbits
Shallow-water waves
Water depth < 1/20 of wavelength
Orbits are more flattened
Transitional waves
Water depth < wave base but also > 1/20 of wavelength
Intermediate-shaped orbits

35. Wind Waves- gravity waves formed by the transfer of wind energy into water
Wave ht- usually <3m
Wave length m
Factors that affect wind wave development:
Wind strength
Wind duration
Fetch- the uninterrupted distance the wind blows

36. Fetch

37. Interference and Rogue Waves
Interference waves: when waves from different storm systems overtake one another. They add (constructive interference) or subtract (destructive interference) from the other.
Constructive interference- rogue waves, where several crests or several troughs coincide
Constructive
Destructive
Mixed

38. Rogue waves: freak waves that come out of nowhere
created by constructive interference
formed by the interaction of a wind wave and a swift surface current
common in southeastern tip of Africa

39. Waves approaching shore
Types of Breaking Waves:
Plunging breaker
Spilling breaker
Surging breaker
Factors that determine the position and nature of the breaking wave:
Slope
Contour
Composition

40. Entire wave front steepens, curls and collapses or plunges forward
Plunging Breaker - associated with beaches with steeper gradients; where wave energy is released suddenly as the crest curls and then descends violently. This is a typical “surfer” wave, it breaks very quickly and with substantial force

41. a gradual sloping bottom generates a milder wave
The upper part of the crest oversteepens and spills downward continually breaking and slowing loosing its energy
Spilling Breaker - most common, associated with a moderate beach gradient (1 : 15 to 1 : flat or gentle) . Spilling breakers are waves that break slowly as they approach the shore. The wave energy is gradually released over time and the beach.
a gradual sloping bottom generates a milder wave

42. Surging Breaker
Surging Breaker - waves that do not break in the traditional sense. This wave starts as a plunging, then the wave catches up with the crest, and the breaker surges up the beach face as a wall of water (with the wave crest and base traveling at the same speed). This results in a quickly rising and falling water level on the beach face
Surging breakers are usually found on a beach with a very steep or near vertical slope.
doesn't break, because it never reaches critical wave steepness
breaker diminishes in size and looses momentum
Found on beach with a very steep or near vertical slope

43. What type wave are these?
Sunset Beach
Waikiki
Plunging wave
What type wave are these?

44. Wave refraction
As waves approach shore, the part of the wave in shallow water slows down
The part of the wave in deep water continues at its original speed
Causes wave crests to refract (bend)
Results in waves lining up nearly parallel to shore
Creates odd surf patterns

45. Wave Refraction
Excellent for surfing

46. Wave Diffraction- Propagation of a wave around an obstacle

47. The Wedge, Newport Harbor, Ca
waves
Wave Reflection
Wave energy is reflected (bounced back) when it hits a solid object

48. Rip Current
A rip current is strong narrow channel of water that flows from the surf-zone out to sea. It develops when breaking waves push onshore, then gravity pulls the water back out to sea. If the water converges into a narrow river like channel moving away from shore, a Rip Current forms.  Rip Currents are sometimes mistakenly called an undertow. However, a rip current will not pull you under the water surface.  Rip currents can be 50 feet to 50 yards in width, and the strength of the current can be up to 3 to 5 mph, which can carry even a strong swimmer into deeper water beyond the sandbar.  The development and persistence of a Rip Current requires a mass transport of water from WIND...WAVES and/or SWELL. The swell or waves produce a greater than normal mass transport of water onto the beach, causing an above normal volume of receding water, and the channel or Rip Current is formed. 
RIPS  Rip currents are the major cause of swimmer difficulties necessitating surf rescues. A rip current is formed by water seeking its own level, usually as a result of large sets of waves approaching the beach and building up water which later returns to sea to even out water levels, thus causing a drag outwards. The larger the surf, the more intense the rip
Common signs of a rip are:  • Discoloured brown water, due to sand which has been stirred off the bottom.  • Foam on the surface extending beyond the break  • Waves breaking further out on both sides of the rip  • Debris floating seaward  • A rippled appearance, where the surrounding water is generally calm  What to do if you are caught in a rip  • Don't Panic! A swimmer with limited ability should ride the rip out from the beach.  • Swim parallel to the shore for metres. Return to the shore where the waves are breaking, parallel to the rip.  • Raise one hand straight up in the air to signal for assistance.  • Remain calm and wait for a lifesaver. 

49. RIP CURRENTS: Another consideration of longshore currents is the rip current, often called "rip tide". Rip currents are formed when longshore currents, moving parallel to the coastline, are deflected seaward by bottom irregularities, or meet another current deflecting the flow to seaward. Development depends upon wave conditions. Large incoming waves on a long, straight beach will produce rips.
Rip currents consist of feeders, a neck, and a head. The feeder is usually the longshore current that flows parallel to the beach inside the breakers. The neck is the main channel of the rip current where feeder currents converge and flow outwards at a speed of one to three knots through a weak point in the breakers. The head is where the current widens and slackens outside the breaker line. A number of swimmers are lost every summer when caught up in rips and swept out to sea. If trapped in this situation, swim parallel to the shoreline until out of the rip rather than swimming directly into the current, then swim back to shore.

50. Internal Waves- at thermocline/pycnocline layer
USS Thresher

51. Internal Waves- surface view
USS Thresher

52. Wave exposed environment:
constant coral species turnover associated with mortality
and recruitment
rarely thicker than a single coral colony

53. Mortality on wave exposed environment due to:
Breakage
Scour
Abrasion

54. Depth- lack of coral accretion in shallow open ocean coastline due to wave energy
Absence of mature barrier reef in Hawaiian Islands

55. Wave climate in Hawaii
5 types of open ocean swells that cause disturbance to coral:
Destructive waves-causes high mortality on reef building corals:
North Pacific winter waves on north and western coastline
hurricane generated swells on south or southwest coastline (40 yr cycle)

56. Low moderate nondestructive waves- optimizes mixing and nutrient uptake or exchange, usually beneficial due to increased circulation and nutrients between water and organisms:
3. Tradewinds generated from northeast or east; ht. of 1-3 m, occurs 90% of summertime and 55-65% of wintertime
4. Long period southerly swell from southern ocean during the Austral winter; common between April and September (1-2 m in ht)
5. Kona storm generated waves (~4m); occasionally may be destructive and cause beach and shoreline erosion 

57. Reef Front in a Low Energy Environment

58. Reef Front in a High Energy Environment
Algal Ridge

59. Upper Reef Slope of a High Energy Environment

60. Upper Reef Slope

61. Upper Reef Slope of a Lower Energy Environment

62. Table 1. Community structure and growth of coral reef at sites selected for study. Attributes of community structure are based on one 50 m transect at each station. Annual coral growth rates are averages of 10 colonies.
Site
Depth (m)
Coral cover %
Coral Diversity (H’)
Algal Cover %
Bare Limestone %
Sand %
Dominant coral, algae
Coral growth (mm/y)
Kaneohe Bay 1
2±5
0.16 5 95
P.c.
Negligible
2-5
69±20
0.35 9 3 19
M.v
7.66
Hanauma Bay
<1
<0.01 90 10
P.o. 12
73±14
0.87
P.l.
8.13
Mamala Bay
6±3
0.15
P.m.
10±5 2 40
P.l
10.1
Sunset Beach
9±8
0.53 60 20
15±13
0.68 65
8.08
P.l.- Porites lobata; P.C.- Porites compressa; M.v.- Motipora verrucosa, P.m.- Pocillopora meandrina; P.o.- Porolithon oncodes (coralline algae)

63. Inquiry Tsunamis are caused by ______. A fetch is _______.
Waves that approach shore and bend so that they are parallel with the shore line are called _____.
Waves with a wavelength greater than 1.73 cm are ______ waves.
Internal waves occur at the __________.
Waves from different storms systems that don’t have coinciding troughs or crests form _____waves.
Waves that approach a steep shore and never really break are _______ waves.