Solid State Phenomena Vol. 113 (2006) pp 483-488 Online available since 2006/Jun/15 at www.scientific.net © (2006) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/SSP.113.483
Measurement Techniques of a European Sea Level Service Site in KLAIPEDA E. Parseliunas, P. Viskontas, M. Grigas, R. Obuchovski, L. Marozas Institute of Geodesy, Vilnius Gediminas Technical University, Sauletekio al. 11, LT-10223 Vilnius-40, Lithuania
[email protected] Keywords: tide gauge, digital float tide gauge, conductivity sensor, air temperature, pressure humidity sensor, wind sensor, GPS station
Abstract. The technical equipment including hardware and software of European Sea Level Service (ESEAS) station KLAIPEDA (KLPD) is presented in the paper. The tide gauge Klaipeda (previous name – Memel) was established in 1811 in the east part of the Baltic Sea, at the estuaries of Curonian Lagoon. KLAIPEDA ID number at the Permanent Service of Mean Sea Level (PSMSL) is 080161. Upgrading of the station is done according to the ESEAS-RI project (Contract No EVR1-CT-2002-40025). KLPD site was equipped with a digital float tide gauge, sea-water conductivity sensor, air temperature, pressure and humidity sensors, wind speed and direction sensor and GPS receiver with antenna. The four characters ID KLPD and IERS DOMES number 10802M001 was assigned to the permanent GPS station KLAIPEDA. Tide gauge KLAIPEDA was certified as ESEAS Operational Site in 2003. It provides near real time (hourly) data to corresponding data servers. The data warehouse system is built on Gentoo Linux, with Apache2, MySQL 4.0.22 and PHP 4.3.9. The communication structure and software applications are also presented in the paper. Introduction European Sea Level Service (ESEAS) is an international collaboration of governmental and non-governmental organizations operating tide gauges along European coasts or providing sea-level related information originating from other sources such as satellite altimetry, GPS and absolute gravity measurements at tide gauges. ESEAS aims to provide quality-assured sea-level and sealevel related information for European waters to a broad range of scientific and non-scientific users. Tide gauge KLAIPEDA was certified as ESEAS Operational Site in 2003. In this paper technical equipment including hardware and software of ESEAS station KLAIPEDA (KLPD) is presented. The tide gauge KLAIPEDA (previous name – Memel) was established in 1811 in the east part of the Baltic Sea, at the estuaries of Curonian Lagoon. Information about tide gauge in Memel could be found in reports of Prussia [1, 2]. Unfortunately data of sea level are available only from 1898. KLAIPEDA ID number at Permanent Service of Mean Sea Level (PSMSL) is 080161. Upgrading of the station is done according to the ESEAS-RI project (Contract No EVR1-CT-2002-40025). KLPD site was equipped with digital float tide gauge, sea-water conductivity sensor, air temperature, pressure and humidity sensors, wind speed and direction sensor and GPS receiver with antenna. The four characters ID KLPD and IERS DOMES number 10802M001 was assigned to the permanent GPS station KLAIPEDA. It provides near real time (hourly) data to corresponding data servers. The basic purpose of the KLAIPEDA tide gauge was to measure water level and water temperature. Now, after upgrading the station according to the ESEAS-RI project, the fields of observation are: water level, temperature and salinity, air meteorological parameters, wind speed and direction and earth crust deformations.
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Mechatronic Systems and Materials
Site Description The site is located at Klaipeda Seaport (Lithuania). Geographic position and coordinates are given in Fig 1.
Fig 1. KLPD site location The tide gauge house, where the tide gauge and meteorological sensors are placed, is actually situated in a shipyard; therefore problems with communications and power supply have occurred. There was no possibility to put in a new communications cable, as the whole area is solid concrete, and that is why an old, not very reliable, telephone line was used as the best solution to this problem. During gales, electricity is turned off in the whole of area for 24 hours or more. This is another factor, causing data loss. To prevent this, a powerful uninterruptible power supply system has to be built, as having a separate power cable is as impossible as having a separate communications cable. GPS receiver, its antenna and wind sensor are placed on the roof of the port office, in this case no problems with power or communications have occurred. Technical Equipment and Software Technical equipment for each observable aspect is as follows: water level – Sutron Shaft encoder [3], water temperature and conductivity – Aanderaa sensor 3919B [4], air parameters – Vaisala PTU200 combined transmitter [5], wind speed and direction – Vaisala Ultrasonic Wind Sensor WS425 [6], and earth crust deformations are measured with GPS receiver Ashtech Z12 combined with Dorne Margolin Choke Ring Antenna. All sensors are attached to computers by the RS-232 connection. Connections of technical equipment are presented in Fig 2. The Sutron Shaft encoder is connected to PC running Linux OS for data capture and transfer in near real time mode (hourly files). The special Perl script was written for these purposes. Also, data from the Sutron Shaft encoder is logged with Sutron Xpert data logger [7] for intermediate data storage. It is possible, if necessary, to download the data using MS Windows based software Xconnect [8] that creates hourly plain-text data files (values are comma separated). A single record example is as follows:
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10.09.2004 17:00:01, KLPD.Battery, 14.0435, KLPD.Battery: 2, OK, KLPD.VANDENST, 12.3, KLPD.VANDENST: 2, OK, KLPD.Waterlevel, 0.30483, KLPD.Waterlevel: 2, OK, KLPD.Temperature, 17.8000, KLPD.Temperature: 2, OK
Fig 2. Technical equipment connections Output from the PTU200 combined receiver goes as plain-text right to the COM1 port. To store this data a Perl script was written. It clears out the unnecessary data, finds the mean values of the last minute (transmitter gives output every five seconds), adds a timestamp and stores the oneminute record to an hourly data file (values are tab separated). Raw data example: 989.6hPa 2.7’C 90.7Hg The Perl script for data capture through COM1 port and clearing out unnecessary data could be as follows: #!/usr/bin/perl use POSIX qw(setsid); system "stty -F /dev/ttyS0 parenb cs7 9600"; system "echo \"r\" > /dev/ttyS0"; open (COM1,"
