Eirik Førland - Profile on Academia.edu (original) (raw)
Papers by Eirik Førland
Hydrology Research
Based on observation data the spatial variability and long-term trends of snow depth, snow water ... more Based on observation data the spatial variability and long-term trends of snow depth, snow water equivalent and number of days with snow coverage ≥50% for Northern Eurasia are estimated. The significance of continental snow cover variability over Northern Eurasia is illustrated by comparison with snow cover variability of the northern part of North America (Canada). The fundamental scientific problem of our investigations is revealing spatial and temporal changes of snow cover under the present climate conditions. The snow cover depends on a climate on the one hand and appreciably defines a hydrological regime on the other hand and, thus, the snow cover is a good indicator of changes in the condition of an environment. In this case the condition of the snow cover of the Northern hemisphere on an example of Northern Eurasia within the boundaries of the NIS and the northern part of North America within the boundaries of Canada is investigated. The novelty of the work, in particular, c...
Hydrology Research
Although the sensitivity of river ice processes to climatic inputs is well known, there is very l... more Although the sensitivity of river ice processes to climatic inputs is well known, there is very little information on how a changing climate can affect the severity and frequency of ice jam events and their numerous ecological and socio-economic impacts. The present study adds to this information by examining the ice regime of the Southwest Miramichi River, New Brunswick, and identifying recent trends that may be linked to concomitant climatic variations. The timing of freeze-up and breakup, as well as the thickness of the winter ice cover, do not exhibit significant temporal trends. However, spring ice jamming is becoming more severe, and there is increasing potential for devastating mid-winter breakup events. These findings are consistent with increasing rainfall and snowfall amounts, as well as increasing river flows, during the winter and early spring. Unlike in most parts of Canada, slight cooling during the winter months was detected, consistent with cooling trends found elsew...
Estimating Regional Precipitation Trends Comparison of two Methods
Hydrology Research
Two different methods were applied to estimate long-term precipitation trends representative for ... more Two different methods were applied to estimate long-term precipitation trends representative for regions in Norway. A new method, comparative trend analysis (CTA), was applied on 142 homogeneous precipitation series of 70-100 years. In this way 12 precipitation trend regions were identified. Principal component analysis (PCA) was applied on a subset of 30 series during the period 1896-1994 The results from both analyses were used to estimate precipitation trend series at several locations. The estimates based upon the PCA were of same quality as the estimates based upon the CTA. However, by CTA it is possible to visualize the trend in a distinct region by using just one trend curve, while trend curves based on PCA are composed of contributions from 5 principal components. The resulting trend curves document that the annual precipitation level has increased by 8-14% throughout this century in most Norwegian regions. The increase occurred not simultaneously all over the country. The r...
Utviklingen av naturulykker som f�lge av klimaendringer
Long-term climate trends of the Yamalo-Nenets AO, Russia
... T ARKO-SALE - 1953.-.06 23330 SALEKHARD 1973 - 1956.-.02 23032 MARE-SALE - 1951 29.08 23445 N... more ... T ARKO-SALE - 1953.-.06 23330 SALEKHARD 1973 - 1956.-.02 23032 MARE-SALE - 1951 29.08 23445 NAD YM - - T able 2: Relocation of the meteorological stations at the Y amal p eninsula (Svyashchennikov, 2010). WMO num b er Station name Jan Feb Mar Apr May Jun ...
Snow water equivalent mapping in Norway
In high latitude area snow covers the ground large parts of the year. Information about the water... more In high latitude area snow covers the ground large parts of the year. Information about the water volume as snow is of major importance in many respects. Flood forecasters at NVE need it in order to assess possible flood risks. Hydropower producers need it to plan the most efficient production of the water in their reservoirs, traders to estimate the
Environmental Research Letters, 2016
Freezing rain and freezing drizzle events represent a critical feature of many regions of the wor... more Freezing rain and freezing drizzle events represent a critical feature of many regions of the world. Even at low intensities, these events often result in natural hazards that cause damage to housing, communication lines, and other man-made infrastructure. These events usually occur near the 0°C isotherm. In a changing climate, this isotherm will not disappear, but its position in space and time will likely change as will the geography of freezing precipitation. A larger influx of water vapor into the continents from the oceans may also increase the amount and frequency of freezing precipitation events. This paper assesses our current understanding of recent changes in freezing precipitation for the United States, Canada, Norway, and Russia. The research is part of a larger GEWEX Cross-Cut Project addressing 'cold/shoulder season precipitation near 0°C'. Using an archive of 874 long-term time series (40 years of data) of synoptic observations for these four countries, we document the climatology of daily freezing rain and freezing drizzle occurrences as well as trends therein. The regions with the highest frequency of freezing rains (from 3 to 8 days per year) reside in the northeastern quadrant of the conterminous United States and adjacent areas of southeastern Canada south of 50°N and over the south and southwest parts of the Great East European Plain. The frequency of freezing drizzle exceeds the frequency of freezing rain occurrence in all areas. During the past decade, the frequency of freezing rain events somewhat decreased over the southeastern US. In North America north of the Arctic Circle, it increased by about 1 day yr −1. Over Norway, freezing rain occurrences increased substantially, especially in the Norwegian Arctic. In European Russia and western Siberia, the frequency of freezing rain somewhat increased (except the southernmost steppe regions and the Arctic regions) while freezing drizzle frequency decreased over entire Russia.
Climatic Change, Aug 31, 2000
Results from the WMO Solid Precipitation Measurement Intercomparison and parallel precipitation m... more Results from the WMO Solid Precipitation Measurement Intercomparison and parallel precipitation measurements from Svalbard are used to evaluate and adjust models for estimating true precipitation under Arctic conditions. The conclusion is that true precipitation in the Arctic may be estimated reasonably well when the wind speed at gauge height is less than 7 m/s. It is possible to give good estimates of true annual and seasonal precipitation at Svalbard, as only a small part of the precipitation is falling at wind speeds above 7 m/s. For rough calculations, the correction factors for liquid precipitation is estimated to be 1.15 and for solid precipitation 1.85. The developed correction models are used to estimate amounts and trends of true precipitation for two sites in the Norwegian Arctic. In Ny-Ålesund the true annual precipitation is more than 50% higher than the measured amount. As the aerodynamic effects leading to precipitation undercatch are dependent on precipitation type and temperature, the observed and projected increase in the air temperature in the Arctic would also affect the measured precipitation, even if the true precipitation was unchanged. Since the mid 1960s the temperature at Svalbard Airport has increased by 0.5 • C per decade, resulting in a reduced fraction of annual precipitation falling as snow. In the same period, the measured precipitation has increased by 2.9% per decade and the 'true' by 1.7% per decade. Estimates are made of the fictitious precipitation increase that would result from a general temperature increase of 2, 4 and 6 • C. The increase in the measured annual precipitation would be 6, 10 and 13%, respectively. The expected fictitious precipitation increase is thus of the same magnitude as the real precipitation increase which according to recent GCM projections may be expected in Northern Europe as a result of a doubling of the atmospheric CO 2 content.
Egu General Assembly Conference Abstracts, May 1, 2010
Estimates of extreme values of precipitation represented as return period values and Probable Max... more Estimates of extreme values of precipitation represented as return period values and Probable Maximum Precipitation (PMP) are frequently used in flood evaluation as well as dimensioning of hydro power dams. The estimates are also of interest for infrastructure constructions (e.g. urban runoff). The estimates establish a reference to how rare a heavy rainfall event at a location is. This study presents present-day and future return period values and PMP estimates for several catchments in Norway. Daily precipitation values are extracted from grids covering the Norwegian mainland, spatial resolution 1 x 1 km2, for the time period 1957-2009. The grids are interpolated from observations at all available rain gage stations operated by the Norwegian Meteorolgoical Institute in Norway. The maps can be seen at http://senorge.no (Mohr, 2009; Jansson et al., 2007). The rain gauge network in the high mountain region is sparse, leading to reduced quality in these regions. A rough correction of daily gauge precipitation for undercatch because of wind exposure is performed before interpolation. Six climate projections downscaled with different Regional Climate Models (RCMs) are adjusted to be representative locally for the Norwegian mainland (Engen-Skaugen, 2007). Daily precipitation projections are established for the same grid extent as for observations. Time series of daily precipitation are then extracted from these grids representing the same catchments as the historic data. The estimates of extreme precipitation are based on daily precipitation values (Førland, 1992; Alfnes, 2007). Instead of producing area estimates based on site values adjusted by an Area Reduction Factor (ARF), area estimates in the present study is based on time series of daily precipitation representing the actual catchments extracted from the high resolution grids. Alfnes (2007) found that the five-year return value estimates (M5) for these two methods were similar, with exceptions for catchments located in southwestern Norway. In these regions the M5 estimates based on daily grids lead to larger estimates. A reason for this may be that the wind correction factor is too large. However, there is also a possibility that the traditional method underestimates the return period values and PMP estimates. To study future changes in extreme design values, estimates are obtained for four time periods:
Long-term climate trends of Finnmarksvidda, Northern-Norway
The combination of dry autumns and low temperatures in the succeeding winter may lead to high pri... more The combination of dry autumns and low temperatures in the succeeding winter may lead to high prices on electricity and problems with energy supply in Norway. Heating Degree-Days (HDD) are commonly used as an indicator for energy demand for heating buildings. HDD sum anomalies for the latest 50-100 years are in this report presented together with the frequency of years with high demand for heating in combination with low hydro power potential and vice versa. Three scenarios for the period 2071-2100 are also analysed. The main conclusion is that the demand for heating buildings has decreased during the latest decades and the hydro power potential has been high. Precipitation is projected to increase in Norway during the 21 st century. The analyses show that winters with high HDD-values have a tendency to occur simultaneously in all regions in Norway. The scenario results indicate that dry autumns and relatively cold winters may occur in the future as well. The demand for heating buildings will however continue to decrease in the future ( ~30% for the period 2071-2100 relative to .
This report presents projected changes in snow conditions in Norway. Possible changes from presen... more This report presents projected changes in snow conditions in Norway. Possible changes from present climate (1961-1990) to future climate (2071-2100) are described. Projected air temperature and precipitation data from two climate models (HadAm3 and ECHAM4/OPYC3) run with the B2 emission scenario were dynamically downscaled using the regional climate model HIRHAM, and also locally adjusted to stations in Norway. The Gridded Water Balance model was run using these daily data sets. Snow water equivalent, which is reported in this study, is one of the output variables. It is found that both the mean annual maximum snow water equivalent and the duration of the snow season are projected to decrease almost everywhere in Norway. Generally, the decrease gets smaller with increasing altitude and distance from the coast. The start of the snow accumulation season is projected approximately 3-4 weeks later than in the present climate. The snow melt season starts earlier, leading to an earlier end of the snow season (approximately 1-7 weeks earlier). Maximum amounts of snow is projected to shift from April/May to March/April. In extreme years the maximum snow water equivalent might be higher than today in a few high altitude or northern drainage basins.
Local Climate Scenarios for Norway Based on MPI’s ECHAM/OPYC3, a New DNMI Data Analysis, and the Common EOF Method
Detecting and Modelling Regional Climate Change, 2001
This study is part of a collaboration between met.no and AARI on the Norwegian Research Council p... more This study is part of a collaboration between met.no and AARI on the Norwegian Research Council projects «EALÁT-Research: Reindeer herders vulnerability network study: Reindeer pastoralism in a changing climate» and "CAVIAR: Community Adaptation and Vulnerability in Arctic Regions"
Trends and frequencies of extreme precipitation have been studied for long observation series in ... more Trends and frequencies of extreme precipitation have been studied for long observation series in Norway. The annual maximum 1-day precipitation shows an increasing tendency during the 20 th century, although significant trends were found only at four locations. The frequency of extreme precipitation values was highest in the 1920's-1930's and in the 1980's-1990's. The occurrence of the most extreme events seems to have decreased during the 20 th century, whereas the number of slightly smaller precipitation events has increased in the same period. Design values used for flood predictions and dam constructions were investigated for possible changes during the last decades. A 5% increase in the 5-years return period value was found on a regional scale in the south western and the northernmost regions of Norway since the standard normal period 1961-1990. In the remaining Norwegian regions the picture was more scattered with both increases and decreases. Large local and regional gradients exist in both annual and 1-day maximum precipitation. These gradients are also reflected in the absolute and relative changes in the return values.
Evaluation and Analysis of the ECHAM4/OPYC3 GSDIO-Integration Temperature- and SLP-Fields over Norway and Svalbard
Detecting and Modelling Regional Climate Change, 2001
Changes in Temperature and Precipitation in the Norwegian Arctic during the 20th Century
Detecting and Modelling Regional Climate Change, 2001
Hydrological Sciences Journal, 2014
The Norwegian Railway Authority (Jernbaneverket) and The Norwegian Public Roads Administration (S... more The Norwegian Railway Authority (Jernbaneverket) and The Norwegian Public Roads Administration (Statens vegvesen). I would like to thank my supervisors Frode Stordal, Eirik Førland, and Thomas Skaugen, for their dedication and guidance throughout my PhD. They have met me with open doors and encouraging words. I am very grateful to my family, who always support me and go out of their way to help whenever they can. A special thanks to the-always-positive Mikael for showing great interest in my work, and for giving me Sanna-our amazing, sweet and funny little daughter.
Snow map system for Norway
ABSTRACT During the winter 2004 new methods are developed by NVE and met.no to produce snow maps ... more ABSTRACT During the winter 2004 new methods are developed by NVE and met.no to produce snow maps accounting for accumulation, melt, refreezing and winter rain. The maps substitute traditional snow accumulation maps, and are daily products updated on a weekly basis. Spatial estimation of temperature and precipitation is applied to observations from the Norwegian meteorological network. A snow model operating on a 1x1 km 2 and one-day resolution is used. The development of a web-and GIS-based system for producing the maps is presented. GIS technology is used for spatial estimation of weather elements, snow simulation during the winter, and presenting results as maps in order to serve Government and local authorities in early-warning of floods and hydro-electricity production and distribution shortages. A suite of 20 maps are produced daily and presented to users in web-and GIS-based interfaces. Maps of snow water equivalent (percent of normal, millimetres and rank), snow melt, runoff, snow state, fresh snow, snow age, snow depth and snow energy equivalent show daily and weekly totals or change. Web-based interfaces provide easy access and navigation in a 300,000-map archive from 1962. Snow maps combine with hydrology and energy-related data in ArcGIS and ArcIMS.
Hydrology Research
Based on observation data the spatial variability and long-term trends of snow depth, snow water ... more Based on observation data the spatial variability and long-term trends of snow depth, snow water equivalent and number of days with snow coverage ≥50% for Northern Eurasia are estimated. The significance of continental snow cover variability over Northern Eurasia is illustrated by comparison with snow cover variability of the northern part of North America (Canada). The fundamental scientific problem of our investigations is revealing spatial and temporal changes of snow cover under the present climate conditions. The snow cover depends on a climate on the one hand and appreciably defines a hydrological regime on the other hand and, thus, the snow cover is a good indicator of changes in the condition of an environment. In this case the condition of the snow cover of the Northern hemisphere on an example of Northern Eurasia within the boundaries of the NIS and the northern part of North America within the boundaries of Canada is investigated. The novelty of the work, in particular, c...
Hydrology Research
Although the sensitivity of river ice processes to climatic inputs is well known, there is very l... more Although the sensitivity of river ice processes to climatic inputs is well known, there is very little information on how a changing climate can affect the severity and frequency of ice jam events and their numerous ecological and socio-economic impacts. The present study adds to this information by examining the ice regime of the Southwest Miramichi River, New Brunswick, and identifying recent trends that may be linked to concomitant climatic variations. The timing of freeze-up and breakup, as well as the thickness of the winter ice cover, do not exhibit significant temporal trends. However, spring ice jamming is becoming more severe, and there is increasing potential for devastating mid-winter breakup events. These findings are consistent with increasing rainfall and snowfall amounts, as well as increasing river flows, during the winter and early spring. Unlike in most parts of Canada, slight cooling during the winter months was detected, consistent with cooling trends found elsew...
Estimating Regional Precipitation Trends Comparison of two Methods
Hydrology Research
Two different methods were applied to estimate long-term precipitation trends representative for ... more Two different methods were applied to estimate long-term precipitation trends representative for regions in Norway. A new method, comparative trend analysis (CTA), was applied on 142 homogeneous precipitation series of 70-100 years. In this way 12 precipitation trend regions were identified. Principal component analysis (PCA) was applied on a subset of 30 series during the period 1896-1994 The results from both analyses were used to estimate precipitation trend series at several locations. The estimates based upon the PCA were of same quality as the estimates based upon the CTA. However, by CTA it is possible to visualize the trend in a distinct region by using just one trend curve, while trend curves based on PCA are composed of contributions from 5 principal components. The resulting trend curves document that the annual precipitation level has increased by 8-14% throughout this century in most Norwegian regions. The increase occurred not simultaneously all over the country. The r...
Utviklingen av naturulykker som f�lge av klimaendringer
Long-term climate trends of the Yamalo-Nenets AO, Russia
... T ARKO-SALE - 1953.-.06 23330 SALEKHARD 1973 - 1956.-.02 23032 MARE-SALE - 1951 29.08 23445 N... more ... T ARKO-SALE - 1953.-.06 23330 SALEKHARD 1973 - 1956.-.02 23032 MARE-SALE - 1951 29.08 23445 NAD YM - - T able 2: Relocation of the meteorological stations at the Y amal p eninsula (Svyashchennikov, 2010). WMO num b er Station name Jan Feb Mar Apr May Jun ...
Snow water equivalent mapping in Norway
In high latitude area snow covers the ground large parts of the year. Information about the water... more In high latitude area snow covers the ground large parts of the year. Information about the water volume as snow is of major importance in many respects. Flood forecasters at NVE need it in order to assess possible flood risks. Hydropower producers need it to plan the most efficient production of the water in their reservoirs, traders to estimate the
Environmental Research Letters, 2016
Freezing rain and freezing drizzle events represent a critical feature of many regions of the wor... more Freezing rain and freezing drizzle events represent a critical feature of many regions of the world. Even at low intensities, these events often result in natural hazards that cause damage to housing, communication lines, and other man-made infrastructure. These events usually occur near the 0°C isotherm. In a changing climate, this isotherm will not disappear, but its position in space and time will likely change as will the geography of freezing precipitation. A larger influx of water vapor into the continents from the oceans may also increase the amount and frequency of freezing precipitation events. This paper assesses our current understanding of recent changes in freezing precipitation for the United States, Canada, Norway, and Russia. The research is part of a larger GEWEX Cross-Cut Project addressing 'cold/shoulder season precipitation near 0°C'. Using an archive of 874 long-term time series (40 years of data) of synoptic observations for these four countries, we document the climatology of daily freezing rain and freezing drizzle occurrences as well as trends therein. The regions with the highest frequency of freezing rains (from 3 to 8 days per year) reside in the northeastern quadrant of the conterminous United States and adjacent areas of southeastern Canada south of 50°N and over the south and southwest parts of the Great East European Plain. The frequency of freezing drizzle exceeds the frequency of freezing rain occurrence in all areas. During the past decade, the frequency of freezing rain events somewhat decreased over the southeastern US. In North America north of the Arctic Circle, it increased by about 1 day yr −1. Over Norway, freezing rain occurrences increased substantially, especially in the Norwegian Arctic. In European Russia and western Siberia, the frequency of freezing rain somewhat increased (except the southernmost steppe regions and the Arctic regions) while freezing drizzle frequency decreased over entire Russia.
Climatic Change, Aug 31, 2000
Results from the WMO Solid Precipitation Measurement Intercomparison and parallel precipitation m... more Results from the WMO Solid Precipitation Measurement Intercomparison and parallel precipitation measurements from Svalbard are used to evaluate and adjust models for estimating true precipitation under Arctic conditions. The conclusion is that true precipitation in the Arctic may be estimated reasonably well when the wind speed at gauge height is less than 7 m/s. It is possible to give good estimates of true annual and seasonal precipitation at Svalbard, as only a small part of the precipitation is falling at wind speeds above 7 m/s. For rough calculations, the correction factors for liquid precipitation is estimated to be 1.15 and for solid precipitation 1.85. The developed correction models are used to estimate amounts and trends of true precipitation for two sites in the Norwegian Arctic. In Ny-Ålesund the true annual precipitation is more than 50% higher than the measured amount. As the aerodynamic effects leading to precipitation undercatch are dependent on precipitation type and temperature, the observed and projected increase in the air temperature in the Arctic would also affect the measured precipitation, even if the true precipitation was unchanged. Since the mid 1960s the temperature at Svalbard Airport has increased by 0.5 • C per decade, resulting in a reduced fraction of annual precipitation falling as snow. In the same period, the measured precipitation has increased by 2.9% per decade and the 'true' by 1.7% per decade. Estimates are made of the fictitious precipitation increase that would result from a general temperature increase of 2, 4 and 6 • C. The increase in the measured annual precipitation would be 6, 10 and 13%, respectively. The expected fictitious precipitation increase is thus of the same magnitude as the real precipitation increase which according to recent GCM projections may be expected in Northern Europe as a result of a doubling of the atmospheric CO 2 content.
Egu General Assembly Conference Abstracts, May 1, 2010
Estimates of extreme values of precipitation represented as return period values and Probable Max... more Estimates of extreme values of precipitation represented as return period values and Probable Maximum Precipitation (PMP) are frequently used in flood evaluation as well as dimensioning of hydro power dams. The estimates are also of interest for infrastructure constructions (e.g. urban runoff). The estimates establish a reference to how rare a heavy rainfall event at a location is. This study presents present-day and future return period values and PMP estimates for several catchments in Norway. Daily precipitation values are extracted from grids covering the Norwegian mainland, spatial resolution 1 x 1 km2, for the time period 1957-2009. The grids are interpolated from observations at all available rain gage stations operated by the Norwegian Meteorolgoical Institute in Norway. The maps can be seen at http://senorge.no (Mohr, 2009; Jansson et al., 2007). The rain gauge network in the high mountain region is sparse, leading to reduced quality in these regions. A rough correction of daily gauge precipitation for undercatch because of wind exposure is performed before interpolation. Six climate projections downscaled with different Regional Climate Models (RCMs) are adjusted to be representative locally for the Norwegian mainland (Engen-Skaugen, 2007). Daily precipitation projections are established for the same grid extent as for observations. Time series of daily precipitation are then extracted from these grids representing the same catchments as the historic data. The estimates of extreme precipitation are based on daily precipitation values (Førland, 1992; Alfnes, 2007). Instead of producing area estimates based on site values adjusted by an Area Reduction Factor (ARF), area estimates in the present study is based on time series of daily precipitation representing the actual catchments extracted from the high resolution grids. Alfnes (2007) found that the five-year return value estimates (M5) for these two methods were similar, with exceptions for catchments located in southwestern Norway. In these regions the M5 estimates based on daily grids lead to larger estimates. A reason for this may be that the wind correction factor is too large. However, there is also a possibility that the traditional method underestimates the return period values and PMP estimates. To study future changes in extreme design values, estimates are obtained for four time periods:
Long-term climate trends of Finnmarksvidda, Northern-Norway
The combination of dry autumns and low temperatures in the succeeding winter may lead to high pri... more The combination of dry autumns and low temperatures in the succeeding winter may lead to high prices on electricity and problems with energy supply in Norway. Heating Degree-Days (HDD) are commonly used as an indicator for energy demand for heating buildings. HDD sum anomalies for the latest 50-100 years are in this report presented together with the frequency of years with high demand for heating in combination with low hydro power potential and vice versa. Three scenarios for the period 2071-2100 are also analysed. The main conclusion is that the demand for heating buildings has decreased during the latest decades and the hydro power potential has been high. Precipitation is projected to increase in Norway during the 21 st century. The analyses show that winters with high HDD-values have a tendency to occur simultaneously in all regions in Norway. The scenario results indicate that dry autumns and relatively cold winters may occur in the future as well. The demand for heating buildings will however continue to decrease in the future ( ~30% for the period 2071-2100 relative to .
This report presents projected changes in snow conditions in Norway. Possible changes from presen... more This report presents projected changes in snow conditions in Norway. Possible changes from present climate (1961-1990) to future climate (2071-2100) are described. Projected air temperature and precipitation data from two climate models (HadAm3 and ECHAM4/OPYC3) run with the B2 emission scenario were dynamically downscaled using the regional climate model HIRHAM, and also locally adjusted to stations in Norway. The Gridded Water Balance model was run using these daily data sets. Snow water equivalent, which is reported in this study, is one of the output variables. It is found that both the mean annual maximum snow water equivalent and the duration of the snow season are projected to decrease almost everywhere in Norway. Generally, the decrease gets smaller with increasing altitude and distance from the coast. The start of the snow accumulation season is projected approximately 3-4 weeks later than in the present climate. The snow melt season starts earlier, leading to an earlier end of the snow season (approximately 1-7 weeks earlier). Maximum amounts of snow is projected to shift from April/May to March/April. In extreme years the maximum snow water equivalent might be higher than today in a few high altitude or northern drainage basins.
Local Climate Scenarios for Norway Based on MPI’s ECHAM/OPYC3, a New DNMI Data Analysis, and the Common EOF Method
Detecting and Modelling Regional Climate Change, 2001
This study is part of a collaboration between met.no and AARI on the Norwegian Research Council p... more This study is part of a collaboration between met.no and AARI on the Norwegian Research Council projects «EALÁT-Research: Reindeer herders vulnerability network study: Reindeer pastoralism in a changing climate» and "CAVIAR: Community Adaptation and Vulnerability in Arctic Regions"
Trends and frequencies of extreme precipitation have been studied for long observation series in ... more Trends and frequencies of extreme precipitation have been studied for long observation series in Norway. The annual maximum 1-day precipitation shows an increasing tendency during the 20 th century, although significant trends were found only at four locations. The frequency of extreme precipitation values was highest in the 1920's-1930's and in the 1980's-1990's. The occurrence of the most extreme events seems to have decreased during the 20 th century, whereas the number of slightly smaller precipitation events has increased in the same period. Design values used for flood predictions and dam constructions were investigated for possible changes during the last decades. A 5% increase in the 5-years return period value was found on a regional scale in the south western and the northernmost regions of Norway since the standard normal period 1961-1990. In the remaining Norwegian regions the picture was more scattered with both increases and decreases. Large local and regional gradients exist in both annual and 1-day maximum precipitation. These gradients are also reflected in the absolute and relative changes in the return values.
Evaluation and Analysis of the ECHAM4/OPYC3 GSDIO-Integration Temperature- and SLP-Fields over Norway and Svalbard
Detecting and Modelling Regional Climate Change, 2001
Changes in Temperature and Precipitation in the Norwegian Arctic during the 20th Century
Detecting and Modelling Regional Climate Change, 2001
Hydrological Sciences Journal, 2014
The Norwegian Railway Authority (Jernbaneverket) and The Norwegian Public Roads Administration (S... more The Norwegian Railway Authority (Jernbaneverket) and The Norwegian Public Roads Administration (Statens vegvesen). I would like to thank my supervisors Frode Stordal, Eirik Førland, and Thomas Skaugen, for their dedication and guidance throughout my PhD. They have met me with open doors and encouraging words. I am very grateful to my family, who always support me and go out of their way to help whenever they can. A special thanks to the-always-positive Mikael for showing great interest in my work, and for giving me Sanna-our amazing, sweet and funny little daughter.
Snow map system for Norway
ABSTRACT During the winter 2004 new methods are developed by NVE and met.no to produce snow maps ... more ABSTRACT During the winter 2004 new methods are developed by NVE and met.no to produce snow maps accounting for accumulation, melt, refreezing and winter rain. The maps substitute traditional snow accumulation maps, and are daily products updated on a weekly basis. Spatial estimation of temperature and precipitation is applied to observations from the Norwegian meteorological network. A snow model operating on a 1x1 km 2 and one-day resolution is used. The development of a web-and GIS-based system for producing the maps is presented. GIS technology is used for spatial estimation of weather elements, snow simulation during the winter, and presenting results as maps in order to serve Government and local authorities in early-warning of floods and hydro-electricity production and distribution shortages. A suite of 20 maps are produced daily and presented to users in web-and GIS-based interfaces. Maps of snow water equivalent (percent of normal, millimetres and rank), snow melt, runoff, snow state, fresh snow, snow age, snow depth and snow energy equivalent show daily and weekly totals or change. Web-based interfaces provide easy access and navigation in a 300,000-map archive from 1962. Snow maps combine with hydrology and energy-related data in ArcGIS and ArcIMS.