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.

Locally Generated MeteotsunamisDISCOVERED BY MEANS OF THE WLG’S ARRAY

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)

AUG-16-2011 Tropical Wave

Atmospheric Pressure Jumps

Meteotsunami on AUG-16-2011 detected by the WLG’s array

10 km

25 km

50 km

Meteotsunami detected by a WLG at

Puerto Real, Cabo Rojo

Units are feet

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

Meteotsunami Genesis in three steps for Fajardo Harbor

Path length of the Meteotsunami, 51 km

Meteotsunamis are frequent on August Six events between 2011 and 2014

Meteotsunamis are easier to detect in wider platforms and narrow harbors

Water Level Record Detided Signal

Speed of a Transatlantic MeteotsunamiDISCOVERED BY MEANS OF THE WLG’S ARRAY

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.

Meteotsunami Height in Deep-Water was 2.1 cm

Meteotsunami: Bermuda and Mona

Meteotsunami speed was 455 MPH

Three Previous Transatlantic Meteotsunamis in Mona Island

Average Speed is 427 MPH

Do larger meteotsunamis show faster speeds? We need more data.

Mean Sea Level trend in Puerto Rico DISCOVERED BY MEANS OF THE WLG’S ARRAY

WLG’s Records in Puerto Rico (1955-2012)

Magueyes Island 1.81 mm/yr

San Juan Harbor 2.19 mm/yr

Acknowledgements

We acknowledge the use of WLG’s Data and Ocean Buoy Data provided by the following:

CariCOOS

IOC

CIMSS - University of Wisconsin-Madison

NOAA / NOS / CO-OPS

NOAA / NDBC / DART Program

NOAA / NWS