We have compiled time derivatives of gravity and vertical motion for a dozen sites in Fennoscandia. Time series of absolute gravimetry and permanent GPS cover a time span of about a decade. Tide gauges have operated for many decades near seven of the sites. Linear relations are found to range from −0.17 to −0.22 for the slope between gravity and vertical uplift rates. An eustatic sea level rate of 1.2 mm/year is derived from these data. This compares well with results for North America and with theoretical predictions for viscoelastic Earth models.

The postglacial movements of Fennoscandia have been monitored geometrically by terrestrial as well as space geodetic observing techniques. Vertical uplift rates relative to mean sea level have been derived to map the apparent uplift (e.g., [

Investigations of gravity changes related to the postglacial uplift of Fennoscandia began in 1966 with relative gravimeters. Longitudinal land uplift gravity lines between 56°N and 65°N were established under the auspices of the Nordic Geodetic Commission. Observations are being collected episodically [

We have compiled GPS uplift rates for a dozen sites in Fennoscandia for which time series of absolute gravimetry also exists, spanning about a decade. Seven of these sites are located at the coast with nearby tide gauges having produced times series for the last 50–100 years.

Gravity was first measured by absolute gravimeters in Fennoscandia in 1976 [

Rates of gravity change (

Site name | |||
---|---|---|---|

Tromsø | |||

Stavanger | |||

Trysil | 9.2 | ||

Onsala AN | |||

Onsala AS | |||

Mårtsbo | |||

Skellefteå | |||

Kiruna | |||

Sodankylä | |||

Vaasa AA | |||

Vaasa AB | |||

Metsähovi | |||

Joensuu |

Permanent GPS-stations have existed in Fennoscandia since 1991. National networks were subsequently established, now comprising several dozen stations in each country. Time series analysis allows vertical rates to be determined for many of these stations. Vertical rates compiled from literature sources [

Tide gauges have existed in Fennoscandia since 1774. The multinational cooperation of the “Mittel-Europäische Gradmessung” led to several tide gauges being established from 1880 onwards. Thus time series of 50–100 years exist for many coastal stations. Rates compiled from the PSMSL website (

The GPS-rates describe the land uplift of each station relative to the center of mass of the Earth. The observed sea level rates (including a eustatic rise of sea level) describe land uplift relative to the geoid. Following [

Linear regression between the gravity rate and the vertical uplift derived from tide gauges in Fennoscandia. See text for details.

A similar plot (Figure

Linear regression between the gravity rate and the vertical uplift derived from permanent GPS in Fennoscandia.

We note that tide gauges produce a better regression than GPS. For a eustatic sea level rise of 1.2 mm/year, the regression lines from both tide gauges and GPS pass through the origin (within the errors) and have similar slope values (within errors). If only coastal stations (i.e., nine gravity stations with tide gauges in Table

The ratio ^{−3}, namely,

Lambert et al. [

Numerical experiments by Wahr et al. with a viscoelastic earth model [

The gravity rates in Fennoscandia (as determined by absolute gravimetry) correlates linearly with the vertical uplift rates (as determined by GPS or tide gauge). For a eustatic sea level rise of 1.2 mm/year, the regression lines intercept the origin (within errors). The slopes are close to theoretical values by Wahr et al. [

It is a pleasure to acknowledge discussions with Tony Lambert and Tom James during a visit to the Pacific Geoscience Centre, Sidney, BC, Canada in November 2006.