Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 37) Show all publications
Blenckner, T., Omstedt, A. & Rummukainen, M. (2002). A Swedish case study of contemporary and possible future consequences of climate change on lake function. Aquatic Sciences, 64(2), 171-184
Open this publication in new window or tab >>A Swedish case study of contemporary and possible future consequences of climate change on lake function
2002 (English)In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 64, no 2, p. 171-184Article in journal (Refereed) Published
Abstract [en]

A physical lake model was employed to obtain a basis of discussing the impact of climate variability and climate change on the ecology of Lake Erken, Sweden. The validity of this approach was tested by running the PROBE-lake model for a 30-year period (STD) with observed meteorological data. The lake is adequately modelled, as seen in the comparison with actual lake observations. The validated lake model was then forced with meteorological data obtained from a regional climate model (RCM) with a horizontal resolution of 44 km for present (CLTR) and 2 x CO(2) (SCEN) climate conditions. The CUR lake simulation compares reasonably with the STD. Applying the SCEN simulation leads to a climate change scenario for the lake. The physical changes include elevated temperatures, shorter periods of ice cover combined with two of ten years being totally ice-free, and changes in the mixing regime. The ecological consequences of the physical simulation results are derived from the historical dataset of Lake Erken. Consequences of a warmer climate could imply increased nutrient cycling and lake productivity. The results suggest that an application of RCMs with a suitable resolution for lakes in combination with physical lake models allows projection of the responses of lakes to a future climate.

Keywords
regional climate model, lake model, Lake Erken
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-1394 (URN)10.1007/s00027-002-8065-x (DOI)000176983900007 ()
Available from: 2015-07-31 Created: 2015-07-29 Last updated: 2018-05-24Bibliographically approved
Rutgersson, A., Omstedt, A. & Räisänen, J. (2002). Net precipitation over the Baltic Sea during present and future climate conditions. Climate Research (CR), 22(1), 27-39
Open this publication in new window or tab >>Net precipitation over the Baltic Sea during present and future climate conditions
2002 (English)In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 22, no 1, p. 27-39Article in journal (Refereed) Published
Abstract [en]

By using a process-oriented ocean model forced with data from a gridded synoptic database, net precipitation values (precipitation minus evaporation) over the Baltic Sea are obtained. For a range of realistic meteorological forcing the average annual value obtained from an 18 yr (1981-1998) simulation ranges between 1100 and 2500 m(3) s(-1). The monthly variations are significant with the highest values occurring in early summer and even negative values in late autumn. Ice is an important factor, and the net precipitation is close to zero in the southern basins with no ice. Calculated net precipitation for a 98 yr period (1901-1998) using river runoff and maximum ice extent indicates that the investigated 18 yr period was wetter than the almost 100 yr climate mean. A realistic climate estimate of net precipitation during the 20th century is estimated to be 1500 +/-1000 m(3) s(-1). The evaluation of 2 present day regional climate simulations indicated high precipitation, low evaporation, and thus excessive net precipitation compared to the climate estimate from this investigation. When simulating the effect of increased greenhouse gases, the change in net precipitation was positive but small due to the compensating effects of increased precipitation and increased evaporation associated with increased temperature and reduced ice.

Keywords
water cycle, Baltic Sea, precipitation, evaporation, climate
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-1377 (URN)10.3354/cr022027 (DOI)000178207000003 ()
Available from: 2015-08-06 Created: 2015-07-29 Last updated: 2018-05-22Bibliographically approved
Rummukainen, M., Räisänen, J., Bringfelt, B., Ullerstig, A., Omstedt, A., Willen, U., . . . Jones, C. (2001). A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations. Climate Dynamics, 17(5-6), 339-359
Open this publication in new window or tab >>A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations
Show others...
2001 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 17, no 5-6, p. 339-359Article in journal (Refereed) Published
Abstract [en]

This work presents a regional climate model, the Rossby Centre regional Atmospheric model(RCA1), recently developed from the High Resolution Limited Area Model (HIRLAM). The changes in the HIRLAM parametrizations, necessary for climate-length integrations, are described. A regional Baltic Sea ocean model and a modeling system for the Nordic inland lake systems have been coupled with RCA1. The coupled system has been used to downscale 10-year time slices from two different general circulation model (GCM) simulations to provide high-resolution regional interpretation of large-scale modeling. A selection of the results from the control runs, i.e. the present-day climate simulations, are presented: large-scale free atmospheric fields, the surface temperature and precipitation results and results for the on-line simulated regional ocean and lake surface climates. The regional model modifies the surface climate description compared to the GCM simulations, but it is also substantially affected by the biases in the GCM simulations. The regional model also improves the representation of the regional ocean and the inland lakes, compared to the GCM results.

National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-1485 (URN)10.1007/s003820000109 (DOI)000167527300001 ()
Available from: 2015-08-25 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Winsor, P., Rodhe, J. & Omstedt, A. (2001). Baltic Sea ocean climate: an analysis of 100 yr of hydrographic data with focus on the freshwater budget. Paper presented at 30th Annual International Symposium of the Estuarine and Coastal Sciences Association (ECSA), AUG 10-13, 2000, HAMBURY, GERMANY. Climate Research (CR), 18(1-2), 5-15
Open this publication in new window or tab >>Baltic Sea ocean climate: an analysis of 100 yr of hydrographic data with focus on the freshwater budget
2001 (English)In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 18, no 1-2, p. 5-15Article in journal (Refereed) Published
Abstract [en]

The Baltic Sea climate is analysed based upon long-term oceanographic measurements. The objective of the work is to study the natural variability of present day climate with focus on the freshwater budget. The results are designed to be used for validation of climate models and for discrimination of the significance of modelled climate change scenarios. Almost 100 yr of observations are used in the study, including data for river runoff, water exchange through the Danish Straits (as calculated from river runoff and from sea level data from the Kattegat), salinity data from the Baltic Sea and the Kattegat, and oxygen content in the deep Baltic Sea. The analyses illustrate that freshwater supply to the Baltic shows large variations on time scales up to several decades. The long-term variations in freshwater storage are closely correlated to accumulated changes in river runoff. This indicates strong positive feedback between the amount of outflowing surface water from the Baltic Sea and the salinity of the inflowing Kattegat water. One implication of the study is that climate control simulations must cover several decades, probably up to 100 yr in order to capture the natural variability of present day climate. Also, models designed to study climate change for the Baltic Sea probably need to start integrating from the present day.

Keywords
Baltic Sea, climate, salinity, freshwater, river runoff, oxygen
National Category
Climate Research Oceanography, Hydrology and Water Resources
Research subject
Climate; Oceanography
Identifiers
urn:nbn:se:smhi:diva-1470 (URN)10.3354/cr018005 (DOI)000172936300003 ()
Conference
30th Annual International Symposium of the Estuarine and Coastal Sciences Association (ECSA), AUG 10-13, 2000, HAMBURY, GERMANY
Available from: 2015-08-31 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Omstedt, A. & Axell, L. (2001). Fourth Workshop on Baltic Sea Ice Climate. Norrköping, Sweden 22-24 May, 2002. Conference Proceedings. SMHI
Open this publication in new window or tab >>Fourth Workshop on Baltic Sea Ice Climate. Norrköping, Sweden 22-24 May, 2002. Conference Proceedings
2001 (English)Report (Other academic)
Place, publisher, year, edition, pages
SMHI, 2001. p. 77
Series
Oceanography, ISSN 0283-7714 ; 72
National Category
Oceanography, Hydrology and Water Resources
Research subject
Oceanography
Identifiers
urn:nbn:se:smhi:diva-2338 (URN)Oceanografi, Rapporter, Serie Oceanografi (Local ID)Oceanografi, Rapporter, Serie Oceanografi (Archive number)Oceanografi, Rapporter, Serie Oceanografi (OAI)
Available from: 2001-05-13 Created: 2016-07-08 Last updated: 2018-05-22Bibliographically approved
Omstedt, A. & Chen, D. L. (2001). Influence of atmospheric circulation on the maximum ice extent in the Baltic Sea. Journal of Geophysical Research, 106(C3), 4493-4500
Open this publication in new window or tab >>Influence of atmospheric circulation on the maximum ice extent in the Baltic Sea
2001 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 106, no C3, p. 4493-4500Article in journal (Refereed) Published
Abstract [en]

This work analyzes long-term changes in the annual maximum ice extent in the Baltic Sea and Skagerrak between 1720 and 1997. It focuses on the sensitivity of the ice extent to changes in air temperature and on the relationships between the ice extent and large-scale atmospheric circulation. A significant regime shift in 1877 explains the decreasing trend in the ice extent. The regime shift indicates a change from a relatively cold climate regime to a relatively warm one, which is likely a result of changed atmospheric circulation. In addition, the analysis shows that a colder climate is associated with higher variability in the ice extent and with higher sensitivity of the ice extent to changes in winter air temperature. Moreover, the ice extent is fairly well correlated with the North Atlantic Oscillation (NAO) index during winter, which supports the results of earlier studies. However, the moving correlation analysis shows that the relationship between the NAO index and the ice extent is not stationary over time. A statistical model was established that links the ice extent and a set of circulation indices. It not only confirms the importance of the zonal how but also implies the impact of meridional wind and vorticity. The usefulness of the statistical model is demonstrated by comparing its performance with that of a numerical model and with independent observations. The statistical model achieves a skill close to that of the numerical model. We conclude that this model can be a useful tool in estimating the mean conditions of the ice extent from monthly pressures, allowing for the use of the general circulation model output for predictions of mean ice extent.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Oceanography
Identifiers
urn:nbn:se:smhi:diva-1481 (URN)10.1029/1999JC000173 (DOI)000167409600011 ()
Available from: 2015-08-26 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Rutgersson, A., Smedman, A. S. & Omstedt, A. (2001). Measured and simulated latent and sensible heat fluxes at two marine sites in the Baltic Sea. Boundary-layer Meteorology, 99(1), 53-84
Open this publication in new window or tab >>Measured and simulated latent and sensible heat fluxes at two marine sites in the Baltic Sea
2001 (English)In: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 99, no 1, p. 53-84Article in journal (Refereed) Published
Abstract [en]

In this study, turbulent heat flux data from two sites within the Baltic Sea are compared with estimates from two models. The main focus is on the latent heat flux. The measuring sites are located on small islands close to the islands of Bornholm and Gotland. Both sites have a wide wind direction sector with undisturbed over-water fetch. Mean parameters and direct fluxes were measured on masts during May to December 1998. The two models used in this study are the regional-scale atmospheric model HIRLAM and the ocean model PROBE-Baltic. It is shown that both models overestimate the sensible and latent heat fluxes. The overestimation can, to a large extent, be explained by errors in the air-water temperature and humidity differences. From comparing observed and modelled data, the estimated 8-month mean errors in temperature and humidity are up to 1 degreesC and 1 g kg(-1),respectively. The mean errors in the sensible and latent heat fluxes for the same period are approximately 15 and 30 W m(-2), respectively. Bulk transfer coefficients used for calculating heat and humidity fluxes at the surface were shown to agree rather well with the measurements, at least for the unstable data. For stable stratification, the scatter in data is generally large, and it appears that the bulk formulation chosen overestimates turbulent heat fluxes.

Keywords
air-sea interaction, BALTEX, Baltic Sea measurements, bulk transfer coefficients, flux parameterisation, turbulent heat fluxes
National Category
Climate Research Oceanography, Hydrology and Water Resources
Research subject
Climate; Oceanography
Identifiers
urn:nbn:se:smhi:diva-1479 (URN)10.1023/A:1018799227854 (DOI)000167734500003 ()
Available from: 2015-08-27 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Rutgersson, A., Bumke, K., Clemens, M., Foltescu, V., Lindau, R., Michelson, D. & Omstedt, A. (2001). Precipitation estimates over the Baltic Sea: Present state of the art. Nordic Hydrology, 32(4-5), 285-314
Open this publication in new window or tab >>Precipitation estimates over the Baltic Sea: Present state of the art
Show others...
2001 (English)In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 32, no 4-5, p. 285-314Article in journal (Refereed) Published
Abstract [en]

Precipitation is one of the main components in the water balance, and probably the component determined with the greatest uncertainties. In the present paper we focus on precipitation (mainly rain) over the Baltic Sea as a part of the BAL-TEX project to examine the present state of the art concerning different precipitation estimates over that area. Several methods are used, with the focus on 1) interpolation of available synoptic stations; 2) a mesoscale analysis system including synoptic, automatic, and climate stations, as well as weather radar and an atmospheric model; and 3) measurements performed on ships. The investigated time scales are monthly and yearly and also some long-term considerations are discussed. The comparison shows that the differences between most of the estimates, when averaged over an extended period and a larger area, are in the order of 10-20%, which is in the same range as the correction of the synoptic gauge measurements due to wind and evaporation losses. In all data sets using gauge data it is important to include corrections for high winds. To improve the structure of precipitation over sea more focus is to be put on the use of radar data and combinations of radar data and other data. Interpolation methods that do not consider orographic effects must treat areas with large horizontal precipitation gradients with care. Due to the large variability in precipitation in time and space, it is important to use long time periods for climate estimates of precipitation. Ship measurements are a valuable contribution to precipitation information over sea, especially for seasonal and annual time scales.

National Category
Climate Research Oceanography, Hydrology and Water Resources
Research subject
Climate; Oceanography
Identifiers
urn:nbn:se:smhi:diva-1494 (URN)000173580900002 ()
Available from: 2015-08-24 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Raschke, E., Meywerk, J., Warrach, K., Andrae, U., Bergström, S., Beyrich, F., . . . Stigebrandt, A. (2001). The Baltic Sea Experiment (BALTEX): A European contribution to the investigation of the energy and water cycle over a large drainage basin. Bulletin of The American Meteorological Society - (BAMS), 82(11), 2389-2413
Open this publication in new window or tab >>The Baltic Sea Experiment (BALTEX): A European contribution to the investigation of the energy and water cycle over a large drainage basin
Show others...
2001 (English)In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 82, no 11, p. 2389-2413Article, review/survey (Refereed) Published
Abstract [en]

The Baltic Sea Experiment (BALTEX) is one of the five continental-scale experiments of the Global Energy and Water Cycle Experiment (GEWEX). More than 50 research groups from 14 European countries are participating in this project to measure and model the energy and water cycle over the large drainage basin of the Baltic Sea in northern Europe. BALTEX aims to provide a better understanding of the processes of the climate system and to improve and to validate the water cycle in regional numerical models for weather forecasting and climate studies. A major effort is undertaken to couple interactively the atmosphere with the vegetated continental surfaces and the Baltic Sea including its sea ice. The intensive observational and modeling phase BRIDGE, which is a contribution to the Coordinated Enhanced Observing Period of GEWEX, will provide enhanced datasets for the period October 1999-February 2002 to validate numerical models and satellite products. Major achievements have been obtained in an improved understanding of related exchange processes. For the first time an interactive atmosphere-ocean-land surface model for the Baltic Sea was tested. This paper reports on major activities and some results.

National Category
Meteorology and Atmospheric Sciences
Research subject
Meteorology
Identifiers
urn:nbn:se:smhi:diva-1469 (URN)10.1175/1520-0477(2001)082<2389:TBSEBA>2.3.CO;2 (DOI)000171929700003 ()
Available from: 2015-08-28 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Omstedt, A. & Rutgersson, A. (2000). Closing the water and heat cycles of the Baltic Sea. Paper presented at 2nd Study Conference on Baltic Sea Experiment (BALTEX), MAY 25-29, 1998, JULIUSRUH, GERMANY. Meteorologische Zeitschrift, 9(1), 59-66
Open this publication in new window or tab >>Closing the water and heat cycles of the Baltic Sea
2000 (English)In: Meteorologische Zeitschrift, ISSN 0941-2948, E-ISSN 1610-1227, Vol. 9, no 1, p. 59-66Article in journal (Refereed) Published
Abstract [en]

The objective of the present paper is to analyze the water and heat cycles of the Baltic Sea. The closure equations fur the water and heat cycles are formulated and the appropriate fluxes are calculated using the ocean model PROBE-Baltic forced by meteorological fields, river runoff and sea level data from the Kattegat. The time period considered is from November 1980 to November 1995. In the closing of the water cycle it is clear that river runoff, net precipitation (precipitation minus evaporation), in- and outflows through the Baltic Sea entrance area are the dominating flows. From the ocean model it is illustrated that the long-term water balance is consistent with the salinity in the Baltic Sea and that the net precipitation is positive during the studied period. For the closing of the heat cycle, the net heat loss to the atmosphere from the open water surface, as an annual moan, is in close balance with the solar radiation. The dominating fluxes in the net heat loss to the atmosphere are the sensible heat flux, the latent heat Aux and the net long wave radiation. The heat flux from water to ice also needs to be included in the modeling efforts. Heat flows associated with precipitation in the form of rain and snow can, as annual means, be neglected as well as the heat fluxes associated with river runoff, solar radiation through the ice and ice advecting out through the Baltic Sea entrance area. The total annual mean heat loss from the water body is in close balance with the annual change of heat storage in the water and the net heat exchange through the Baltic Sea entrance area is small. This illustrates that the Baltic Sea thermodynamically responds as a closed ocean basin.

National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-1518 (URN)000087016800008 ()
Conference
2nd Study Conference on Baltic Sea Experiment (BALTEX), MAY 25-29, 1998, JULIUSRUH, GERMANY
Available from: 2015-08-18 Created: 2015-08-17 Last updated: 2018-05-22Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4971-9441

Search in DiVA

Show all publications
v. 2.35.4
|