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Study on the Sea Level Variations and Influence Factors in the Seas Near the Greenland

Author: JiangWeiWei
Tutor: LiLei
School: Ocean University of China
Course: Physical oceanography
Keywords: the seas near the Greenland Sea level Seasonal variation Interannual variation CCSM3
CLC: P731.23
Type: Master's thesis
Year: 2011
Downloads: 59
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Abstract

The trends and character of the sea level variations in the seas near the Greenland are studied based on the altimeter data, tidal gauges observations and results of CCSM3 (Community Climate System Model) model, and comparative analysis of wind stress, sea-ice and heat flux to sea level changes.The results of sea level variations in the seas near the Greenland On the basis of altimeter data from1993 to 2009 are as follows: Root-Mean-Square (RMS) of sea level at the seas near the Greenland is intense, but low-frequency sea level variation is week at East European sea area, it indicates that the seasonal variability of the sea level is larger than interannual variability in this area. Sea Surface Height Anomaly (SSHA) in the seas near the Greenland has the obvious seasonal variability and interannual variability, the trend of the SSHA in this area is rising, and it is 1.7mm/a. At different areas the variation is different, which means there is a larger rising velocity when the average of sea surface height anomaly is higher, and vice versa.The first EOF mode of sea surface height is seasonal mode. The whole area has the same phase, which suggests that the seasonal variations of the whole area are the same. The larger amplitude of the first mode is sea level change activity. The trend of sea level variability obtained from tidal gauges observations is consistent with altimeter data, and also the sea level change of the local sea areas.The sea level variations in the seas near the Greenland are significantly affected by the wind, sea-ice area and heat flux and so on. SSHA and sea-ice area are negative correlation, they are reached the largest negative correlation when SSHA lag of one month to sea-ice area, but the correlation of the 18-month low-pass filtered SSHA and sea-ice area is small, it indicates that the seasonal variation of the sea level in the seas near the Greenland is significantly affected by the sea-ice area, but the interannual variability has little effect. Correlative analysis shows that the low frequency components of SSHA have good positive correlation to meridional wind stress, and little negative correlation to zonal wind stress. The upper ocean is moved by wind stress, metidional wind stress affects the flows of the Atlantic Ocean and the Arctic Ocean. In a word, there is close relationship between the interannual variation of the sea level and the low frequency of wind stress. The seasonal variability of the sea level is also affected by wind stress, the sea level high is positive anomaly where the wind stress curl is negative anomaly, and vice versa. In a word, the spatial distribution of the wind stress curl anomaly is consistent with SSHA in large scale. The heat flux and SSHA are reached the largest correlation when SSHA lags of three months to heat flux, it indicates that the sea level change has three months response process to heat flux.Simulations of CCSM3 model show that the steric sea level of the seas near the Greenland is rising 0.1mm/yr from 1950 to 1999, it has different two stages of change, and it indicates that the global warming is significant effect to sea level change. It indicates that the steric sea level has little effect to sea level change in high latitude sea area comparable to the tidal gauges observations results that are the sea level long-term trends.The thermosteric sea level change in the seas near the Greenland is decrease from 1950 to 1999, and the halosteric sea level change is rise in this area. Thermosteric effect is dominant, and the thermosteric and halosteric anomalies that contribute to sea level change are very different between ocean basins. The halosteric signal is larger than thermosteric change in Greenland Sea, and the thermosteric signal is larger than halosteric change in Norwegian Sea, and the thermosteric is equivalent with the halosteric change in Iceland Sea.The steric sea level variations in the seas near the Greenland in the 21 st century ender IPCC SERE A2 scenario are predicated with the CCSM3 model, and it indicates that the steric sea level rise rate is 0.4mm/yr from 2000 to 2049, and it is four times to the rise rate that form 1950 to 1999, so it indicates that in the 21 st century steric sea level will rise in acceleration.

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