Annual and Seasonal Water Level Variations of The Baltic Sea and Their Causes
(2018) In TVVR-18/5010 VVRM01 20181Division of Water Resources Engineering
- Abstract
- Water level variations occur in the Baltic Sea at many different scales in time and space due to a variety of forcing factors. This study aimed to investigate the water level variations on different scales, and further to investigate the relationship between those variations and their causing factors.
Extended historical data series from the Swedish Meteorological and Hydrological Institute (SMHI) were employed to analyze long-term trends as well as annual and seasonal water level variations in the Baltic Sea. Extensive analysis, based on statistical, spectral, and probability theory, was conducted to understand long-term variations and behavior of the Baltic Sea and also to link water level variations to wind, pressure gradients, and... (More) - Water level variations occur in the Baltic Sea at many different scales in time and space due to a variety of forcing factors. This study aimed to investigate the water level variations on different scales, and further to investigate the relationship between those variations and their causing factors.
Extended historical data series from the Swedish Meteorological and Hydrological Institute (SMHI) were employed to analyze long-term trends as well as annual and seasonal water level variations in the Baltic Sea. Extensive analysis, based on statistical, spectral, and probability theory, was conducted to understand long-term variations and behavior of the Baltic Sea and also to link water level variations to wind, pressure gradients, and other causing factors. Interesting feature that shaping the relationship between sea level and land was the land uplift which is still ongoing in the northern part of the Baltic Sea. Seasonal annual and seasonal semi-annual fluctuations were the dominant features of long-period sea level variability in the Baltic Sea. The analysis demonstrated that water circulation, pressure gradients, and wind distribution were the dominant factors of the seasonal and annual variabilities. Causing factors changed significantly during the last century resulting in behavioral change in water levels. The analysis also indicated that the Baltic Sea responds as one unit to external long-term events; moreover, the Baltic and the North Sea have shown to respond as one basin to large scale events. (Less) - Popular Abstract
- Sea level variation in the era of climate change is a highly relevant topic of great significance in science and engineering, as well as for coastal planners and managers. This study examines the long-term variations of the Baltic Sea water level using time series of water level data along the Swedish coast typically extending over a century obtained from the Swedish Meteorological and Hydrological Institute. In total data from seven water level stations were analyzed covering the entire Swedish coast of the Baltic Sea; one station on the Swedish west coast was included for reference.
The Baltic Sea is a small intra-continental semi-enclosed sea situated in northeast Europe. It has an oblong shape with its length extending from northeast... (More) - Sea level variation in the era of climate change is a highly relevant topic of great significance in science and engineering, as well as for coastal planners and managers. This study examines the long-term variations of the Baltic Sea water level using time series of water level data along the Swedish coast typically extending over a century obtained from the Swedish Meteorological and Hydrological Institute. In total data from seven water level stations were analyzed covering the entire Swedish coast of the Baltic Sea; one station on the Swedish west coast was included for reference.
The Baltic Sea is a small intra-continental semi-enclosed sea situated in northeast Europe. It has an oblong shape with its length extending from northeast to southwest over about 1200 km having a limited water exchange with the North Sea. Water level variations occur in the Baltic Sea at many different scales in time and space due to a variety of forcing factors. This study aims to investigate the long-term water level variations over seasonal and annual scales, and further to investigate the relationship between those variations and their causing factors.
Extensive analysis, using different mathematical and statistical methods, was conducted to understand behaviour of the Baltic Sea and its long-term variations in sea level; also to link the water level variations to wind, pressure gradients, and other causing factors. One characteristic feature of the Baltic Sea and the surrounding land masses is the uplift occurring after the latest glaciation. This markedly affects the relationship between sea level and land, particularly in the northern part of the Baltic Sea Basin. The effect is a linear decrease in the relative sea level that was removed before analysis of the sea level variations was carried out.
Seasonal annual and seasonal semi-annual fluctuations were found to be the dominant features of long-period sea level variability in the Baltic Sea. This study demonstrates that water exchange with the North Sea, pressure gradients over the northern hemisphere, and large-scale wind distribution are the dominant factors controlling the seasonal and annual variabilities in the sea level of the Baltic Sea. The North Atlantic Oscillation (NAO) Index was employed to characterize the forcing factors and some correlation was observed between NAO and different water level parameters at the seasonal scale. Furthermore, the analysis indicated that the Baltic Sea responds as one unit to external long-term events; thus, the Baltic and the North Sea were shown to respond as one basin to large scale events.
The maximum annual water level at the different stations was also investigated and empirical distribution functions were derived. These functions were fitted with Gumbel distributions, which in most cases produced good agreement. Based on the fitted Gumbel distributions extrapolation was performed to estimate extreme annual water levels with return periods beyond the period of measurements.
The results of this study could be used to have a better understanding of the long-term water level variations and the overall behavior of the Baltic Sea and also the connection between the Baltic Sea and the North Sea when responding to large-scale forcing. Furthermore, it could be used as a base for further analysis regarding the connection between different forcing factors and water level variations on different scales. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/8963063
- author
- Mohammed, Suhaib LU
- supervisor
- organization
- course
- VVRM01 20181
- year
- 2018
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Baltic Sea Postglacial land uplift North Sea Kattegat Skagerrak Water level Seasonal variability North Atlantic Oscillation (NAO)
- publication/series
- TVVR-18/5010
- report number
- 18/5010
- ISSN
- 1101-9824
- language
- English
- additional info
- Examiner: Hans Hanson
- id
- 8963063
- date added to LUP
- 2018-11-12 13:55:42
- date last changed
- 2018-11-12 13:55:57
@misc{8963063,
abstract = {{Water level variations occur in the Baltic Sea at many different scales in time and space due to a variety of forcing factors. This study aimed to investigate the water level variations on different scales, and further to investigate the relationship between those variations and their causing factors.
Extended historical data series from the Swedish Meteorological and Hydrological Institute (SMHI) were employed to analyze long-term trends as well as annual and seasonal water level variations in the Baltic Sea. Extensive analysis, based on statistical, spectral, and probability theory, was conducted to understand long-term variations and behavior of the Baltic Sea and also to link water level variations to wind, pressure gradients, and other causing factors. Interesting feature that shaping the relationship between sea level and land was the land uplift which is still ongoing in the northern part of the Baltic Sea. Seasonal annual and seasonal semi-annual fluctuations were the dominant features of long-period sea level variability in the Baltic Sea. The analysis demonstrated that water circulation, pressure gradients, and wind distribution were the dominant factors of the seasonal and annual variabilities. Causing factors changed significantly during the last century resulting in behavioral change in water levels. The analysis also indicated that the Baltic Sea responds as one unit to external long-term events; moreover, the Baltic and the North Sea have shown to respond as one basin to large scale events.}},
author = {{Mohammed, Suhaib}},
issn = {{1101-9824}},
language = {{eng}},
note = {{Student Paper}},
series = {{TVVR-18/5010}},
title = {{Annual and Seasonal Water Level Variations of The Baltic Sea and Their Causes}},
year = {{2018}},
}