Current Applications for an Array of Water Level Gauge Stations
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Transcript of Current Applications for an Array of Water Level Gauge Stations
Current Applications for an Array of Water Level Gauge StationsNEW DISCOVERIES IN THE SEICHE BAND AND THE METEOROLOGICAL-OCEANIC BAND
Edwin Alfonso-Sosa, Ph. D.Ocean Physics Education, Inc. , 2014
A Tide Gauge is a Water Level Gauge (WLG)
The term “tide-gauge” is inadequate to describe or contain all the current applications of this kind of oceanographic instrument. A more proper name should be a Water Level Gauge (WLG), because it measures changes or oscillations in water levels due to a myriad of oceanographic and atmospheric phenomena. Tides are just one contributor to water level variability.
Physical Parameters Measured by WLG’sA single station can record: Water Level Height
Amplitude of the oscillation
Time
Time scale of the oscillation
Period or Frequency of oscillation
Arrival time of a particular oscillation
Form
Linear or nonlinear form
Symmetric or asymmetric form
Single or mixed form
An array of stations allow us to determine the: Coherence between
stations
Age or lag time of any event.
Important for warning systems.
Spreading or Spatial Coverage of an event
Wave Speed or Celerity
Pinpoint the Source Area of a particular event
Ocean Phenomena and Some Applications of WLG's COASTAL SEICHES
Meteorological Origin
Meteotsunami
Oceanic Origin
Internal Solitary Waves (Internal Solitons)
Seismic Origin
Tsunamis
TIDES Hydrography
Prediction of Tidal Heights
Tidal Datum, Chart Datum
LONG-TERM TRENDS OF SEA LEVEL
MSL Trend due to Global Warming
Vertical Motions of the Earth’s Crust
METEOROLOGICAL-OCEANIC EFFECTS
Changes in Atmospheric Pressure and Winds
Storm surge
Changes in Ocean Circulation
Geostrophic currents
Oceanic eddies
Kelvin waves
Coastal trapped waves (CTW’s)
Edge waves
Climatic Processes
Thermal Heating
WLG’s measure oceans phenomena
in a wide range of space-time scales Phenomena Time Scale
Coastal Seiches 6 minutes to 2 hours
Tides 3 hours to 18 years
Meteorological-Oceanic Hours to Months
Long-term trends in Mean Sea Level Years to Centuries
Phenomena Space Scale
Coastal Seiches Less than 50 Kilometers
Tides Hundreds or Thousands of Kilometers
Meteorological-Oceanic Local to Regional
Long-term trends in Mean Sea Level Regional to Global
An Array of WLG’s is a Sensitive Instrument Capable of New
Discoveries Let’s see some recent discoveries made possible by the
WLG’s array.
In the Seiche Band 2011-Discovery of the Magueyes Cycle of extreme seiche
activity (T= 6202.2 ± 1.3 days, 16.98 years)
2011-Discovery of Meteotsunamis generated by pressure jumps associated with the arrival of strong tropical waves
2013-First measurements of a Transatlantic Meteotsunami
In the Meteorological-Oceanic Band 2011-Discovery of Edge Waves trapped on the Cabo Rojo-
Mayaguez Shelf, about 30 hours after the passage of Hurricane Irene over Puerto Rico
In the Long-Term Band 2012-Two stations confirm a positive trend of Sea Level Rise
around Puerto Rico.
Meteotsunami
The term Meteotsunami is used to designate a series of waves in a harbor (bay) that show a similar frequency or amplitude to that of a tsunami generated by earthquakes, landslides or volcanic eruption but unlike these, its origin is associated with an atmospheric disturbance able to generate a barotropic long wave in the open sea, resonate with it (Proudman resonance) as approaches the coast. Once reaches the harbor (bay) is capable of forcing a number of waves, which enter in a second resonance with the harbor (bay) which amplifies it again. The meteotsunami only occurs in certain harbors (bays) where this double resonance is possible. Atmospheric disturbances
a jump in atmospheric pressure atmospheric gravity waves the passage of a front a line of strong winds (squall)
WLG Station Time of MAX Height (LST) Height (feet) Height (cm)
Puerto de Fajardo
14:30 0.61 18.6
Bahía Salinas 16:30 0.61 18.6
Puerto Real (C2) 16:30 0.48 14.6
Puerto de Yabucoa
14:12 0.44 13.4
Puerto Real (C1) 16:30 0.42 12.7
Santa Isabel 15:00 0.35 10.7
Isla Magueyes 13:48 0.30 9.0
Puerto de Mayagüez
16:24 0.22 6.7
Meteotsunamis are easier to detect in wider platforms and narrow harbors
Water Level Record Detided Signal
Some Derechos can generate Meteotsunamis
A derecho is a widespread, long-lived wind storm. Derechos are associated with bands of rapidly moving showers or thunderstorms variously known as bow echoes, squall lines, Wind damage extends for more than 240 miles (about 400 kilometers), includes wind gusts of at least 58 mph (93 km/h) along most of its length, and several, well-separated 75 mph (121 km/h) or greater gusts.
Extracted from the web site: ABOUT DERECHOS
Part of the NOAA-NWS-NCEP Storm Prediction Center web sitePrepared by Stephen F. Corfidi, Jeffry S. Evans, and Robert H.
Johns (with the help of many others)
http://www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm
June 13 2013 Derechohttp://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2013/06/SPC_low_end_derecho.png
Four WLG’s made possible to measure the meteotsunami’s speedJune 13 2013
DART buoy Sta. 44402, H=2443 m, 39.399 N 70.942 W, located 186 miles east of Atlantic City, NJ. Travelled 1478 miles in 3.25 h.
Detected by WLG’s located at: Arecibo, Punta Cana and Mona Island.