Plot - Digital 3-minute data from 8 stations on the coast of South Africa
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Ruth Farre
Superintendent Tidal information, Republic of South Africa

The data had some problems
(see the explanations and additional details sent by (Ruth Farre -A- to Alexander B. Rabinovich -Q- ):

-Q- > (2) The main problem is with East London. Can you check this station?
-A - I HAVE CHECKED THIS STATION. WHAT SEEMS TO BE THE PROBLEM?

-Q- > (3) What is the meaning of "A" in the data? Error? Doubtful data?
- A- "A" IS AN ERROR IN THE DATA AND THERE IS UNFORTUNATELY NOTHING WE CAN DO ABOUT
THIS. SORRY

-Q- > (4) There are lots of spikes in some data. Are they related to instrumental problem?
-A- THE GAUGE IS AN SRD ACOUSTIC GAUGE, WE ARE CURRENTLY REPLACING THE SRD
GAUGES WITH KALESTO RADAR GAUGES ( RICHARDS BAY AND PORT NOLLOTH IS RADAR DATA)
THE DATA THAT WE RECEIVE FROM THE SRD GAUGES HAS ALWAYS BEEN VERY SPIKY AND
THERE SPIKES ARE REMOVED DURING ANALYSIS. THE RADAR DATA IS A LOT SMOOTHER.
IT WOULD APPEAR TO BE SPIKY LIKE THAT DUE TO THE AVERAGING PERIOD. THE SRD TASKES
ONE READING EVERY MINUTE AND AVERAGES IT OVER 3 MIN. THE RADAR TAKES 40 READING
AND AVERAGES IT OVER 17 SEC, THEN THOSE 17 SEC READINGS ARE AVERAGED OVER 3 MIN.


Alexander B. Rabinovich edited the data, corrected the spikes and interpolated the gaps.
The records in the plot have been de-tided and high-pass filtered with Kaiser-Bessel 6-hour window.
I believe that the records are beautiful and we should thank Ruth Ferry!

The approximate statistical parameters are the following:

*after the main shock

Contact:

Ruth Farre
Superintendent Tidal Information
Hydrographic Office
Private Bag X1
Tokai 7966 South Africa
Tel: +27 21 787 2408
Fax: +27 21 7872228
E-mail: hydrosan@iafrica.com

Alexander B. Rabinovich, D.Sc.
Institute of Ocean Sciences
9860 West Saanich Rd.
Sidney, BC, V8L 4B2 Canada
Fax: (+1-250)-363-6746
Tel: (+1-250)-363-6668
E-mail: RabinovichA@pac.dfo-mpo.gc.ca