Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, Jan 28, 2016
Here, we analyse high-frequency (1 min) surface air temperature, mean sea-level pressure (MSLP), ... more Here, we analyse high-frequency (1 min) surface air temperature, mean sea-level pressure (MSLP), wind speed and direction and cloud-cover data acquired during the solar eclipse of 20 March 2015 from 76 UK Met Office weather stations, and compare the results with those from 30 weather stations in the Faroe Islands and 148 stations in Iceland. There was a statistically significant mean UK temperature drop of 0.83±0.63°C, which occurred over 39 min on average, and the minimum temperature lagged the peak of the eclipse by about 10 min. For a subset of 14 (16) relatively clear (cloudy) stations, the mean temperature drop was 0.91±0.78 (0.31±0.40)°C but the mean temperature drops for relatively calm and windy stations were almost identical. Mean wind speed dropped significantly by 9% on average during the first half of the eclipse. There was no discernible effect of the eclipse on the wind-direction or MSLP time series, and therefore we can discount any localized eclipse cyclone effect ov...
this report is to publish the hours of bright sunshine observed in Denmarksince 1961, including t... more this report is to publish the hours of bright sunshine observed in Denmarksince 1961, including the climatological standard normals from the period 1961-90, which isthe latest standard normal period defined by the World Meteorological Organisation (WMO).WMO Technical Regulations define climatological standard normals as "averages of climatologicaldata computed for the following consecutive periods of 30 years: 1 January 1901 to31 December
The Danish Meteorological Institute (DMI) is improving the knowledge of future climate problems t... more The Danish Meteorological Institute (DMI) is improving the knowledge of future climate problems through scientific cooperation with Zambia, Ghana and Tanzania. Collaboration with Zambia on Climate Change The Danish Meteorological Institute has established a twinning project with the Zambia Meteorological Department (ZMD) with a focus on enhancing ZMD's competence in the fields of climate variability and change in Zambia. By strengthening ZMD's capacity in climate monitoring and modelling as well as in the production and dissemination of weather and climate products, ZMD will be better prepared for providing weather and climate related information and services to the public as well as governmental and non-governmental stakeholders. The project, which covers the period 2009-2012, was initiated by the Royal Danish Embassy in Lusaka, Zambia. This project is one of a number of similar initiatives, both ongoing and concluded, with the main goal of providing developing countries wi...
The adaptation to a changing future climate, e.g. with more extreme precipitation events, present... more The adaptation to a changing future climate, e.g. with more extreme precipitation events, presents a major challenge for society. Without proper handling of larger water flows, it is probable that an increase in the strength and frequency of extreme precipitation events in Denmark will lead to more frequent floodings within both urban and rural areas, causing serious societal and economic damage. Expected change in precipitation patterns will furthermore lead to more frequent and longer dry periods in summer and increased amounts of precipitation in winter. Global observations of precipitation for the last 100 years show general geographical patterns in the change of total precipitation. Local and regional temporal variations are generally so large, however, that it is not possible to attribute such changes to anthropogenic climate change. This report provides a brief review of current knowledge with respect to observed and expected future precipitation change in Denmark, based on D...
ABSTRACT We use observed air temperature data series from fourteen meteorological stations in coa... more ABSTRACT We use observed air temperature data series from fourteen meteorological stations in coastal Greenland (located all around the Greenland Ice Sheet (GrIS)) for 1960-2010, where long-term records for five of the stations extend back to 1890, to illustrate the annual and monthly temporal and spatial distribution of temperature extremes. We find that the 2000s (2001-2010) had the highest number of mean annual air temperature (MAAT) warm extremes, and the 1890s (1891-1900) the highest number of cold extremes. For the 2000s the number of warm extremes was significantly higher by around 50% than the number in the 1940s (the Early Twentieth Century Warm Period): the decade with the second highest occurrence of MAAT warm extremes. Since 1960, based on MAAT the number of cold extremes has decreased on the decadal timescale, while warm extremes have increased leading to a higher occurrence of extremes (cold plus warm extremes): an almost similar pattern occurred on mean monthly and on monthly mean daily maximum and minimum scales. Further, a division of Greenland into east and west sectors shows that the occurrence of cold (warm) extremes was more pronounced in the East than in the West in the 1960s and 1970s (mid-1980s to the 2000s).
The freshwater input to the Godthåbsfjord (SW Greenland) is analyzed in a HIRHAM5 regional climat... more The freshwater input to the Godthåbsfjord (SW Greenland) is analyzed in a HIRHAM5 regional climate model experiment with special emphasis on the melt and runoff from the part of the ice sheet that drains into the fjord. The regional model covers all of Greenland and is forced by the ERA-Interim reanalysis on the lateral boundaries over the period 1989-2012. During this period, the lower to middle parts of the ice sheet experience increasing energy input from the surface turbulent heat exchange and the middle to high parts experience increasing energy input due to shortwave radiation. These effects are related to an overall increase in atmospheric pressure over North Greenland, southerly wind anomalies and decreased cloudiness. These factors contribute to increased summer melt which dominates over changes in annual accumulation, resulting in a decline in surface mass balance and an upward migration of the equilibrium line. The increased summer melt from the ice sheet draining into the Godthåbsfjord dominates over significantly smaller changes in precipitation directly over the fjord waters and surface runoff from non-glacier land areas. The high horizontal resolution of the model (about 5.5 km) allows great detail in the representation of topography and surface types. This makes the model particularly suited for this kind of local catchment-scale analysis. The model output is compared to a range of different hydro-meteorological observations both on and off the ice sheet and is found to represent even day-to-day weather variability well.
Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, Jan 28, 2016
Here, we analyse high-frequency (1 min) surface air temperature, mean sea-level pressure (MSLP), ... more Here, we analyse high-frequency (1 min) surface air temperature, mean sea-level pressure (MSLP), wind speed and direction and cloud-cover data acquired during the solar eclipse of 20 March 2015 from 76 UK Met Office weather stations, and compare the results with those from 30 weather stations in the Faroe Islands and 148 stations in Iceland. There was a statistically significant mean UK temperature drop of 0.83±0.63°C, which occurred over 39 min on average, and the minimum temperature lagged the peak of the eclipse by about 10 min. For a subset of 14 (16) relatively clear (cloudy) stations, the mean temperature drop was 0.91±0.78 (0.31±0.40)°C but the mean temperature drops for relatively calm and windy stations were almost identical. Mean wind speed dropped significantly by 9% on average during the first half of the eclipse. There was no discernible effect of the eclipse on the wind-direction or MSLP time series, and therefore we can discount any localized eclipse cyclone effect ov...
this report is to publish the hours of bright sunshine observed in Denmarksince 1961, including t... more this report is to publish the hours of bright sunshine observed in Denmarksince 1961, including the climatological standard normals from the period 1961-90, which isthe latest standard normal period defined by the World Meteorological Organisation (WMO).WMO Technical Regulations define climatological standard normals as "averages of climatologicaldata computed for the following consecutive periods of 30 years: 1 January 1901 to31 December
The Danish Meteorological Institute (DMI) is improving the knowledge of future climate problems t... more The Danish Meteorological Institute (DMI) is improving the knowledge of future climate problems through scientific cooperation with Zambia, Ghana and Tanzania. Collaboration with Zambia on Climate Change The Danish Meteorological Institute has established a twinning project with the Zambia Meteorological Department (ZMD) with a focus on enhancing ZMD's competence in the fields of climate variability and change in Zambia. By strengthening ZMD's capacity in climate monitoring and modelling as well as in the production and dissemination of weather and climate products, ZMD will be better prepared for providing weather and climate related information and services to the public as well as governmental and non-governmental stakeholders. The project, which covers the period 2009-2012, was initiated by the Royal Danish Embassy in Lusaka, Zambia. This project is one of a number of similar initiatives, both ongoing and concluded, with the main goal of providing developing countries wi...
The adaptation to a changing future climate, e.g. with more extreme precipitation events, present... more The adaptation to a changing future climate, e.g. with more extreme precipitation events, presents a major challenge for society. Without proper handling of larger water flows, it is probable that an increase in the strength and frequency of extreme precipitation events in Denmark will lead to more frequent floodings within both urban and rural areas, causing serious societal and economic damage. Expected change in precipitation patterns will furthermore lead to more frequent and longer dry periods in summer and increased amounts of precipitation in winter. Global observations of precipitation for the last 100 years show general geographical patterns in the change of total precipitation. Local and regional temporal variations are generally so large, however, that it is not possible to attribute such changes to anthropogenic climate change. This report provides a brief review of current knowledge with respect to observed and expected future precipitation change in Denmark, based on D...
ABSTRACT We use observed air temperature data series from fourteen meteorological stations in coa... more ABSTRACT We use observed air temperature data series from fourteen meteorological stations in coastal Greenland (located all around the Greenland Ice Sheet (GrIS)) for 1960-2010, where long-term records for five of the stations extend back to 1890, to illustrate the annual and monthly temporal and spatial distribution of temperature extremes. We find that the 2000s (2001-2010) had the highest number of mean annual air temperature (MAAT) warm extremes, and the 1890s (1891-1900) the highest number of cold extremes. For the 2000s the number of warm extremes was significantly higher by around 50% than the number in the 1940s (the Early Twentieth Century Warm Period): the decade with the second highest occurrence of MAAT warm extremes. Since 1960, based on MAAT the number of cold extremes has decreased on the decadal timescale, while warm extremes have increased leading to a higher occurrence of extremes (cold plus warm extremes): an almost similar pattern occurred on mean monthly and on monthly mean daily maximum and minimum scales. Further, a division of Greenland into east and west sectors shows that the occurrence of cold (warm) extremes was more pronounced in the East than in the West in the 1960s and 1970s (mid-1980s to the 2000s).
The freshwater input to the Godthåbsfjord (SW Greenland) is analyzed in a HIRHAM5 regional climat... more The freshwater input to the Godthåbsfjord (SW Greenland) is analyzed in a HIRHAM5 regional climate model experiment with special emphasis on the melt and runoff from the part of the ice sheet that drains into the fjord. The regional model covers all of Greenland and is forced by the ERA-Interim reanalysis on the lateral boundaries over the period 1989-2012. During this period, the lower to middle parts of the ice sheet experience increasing energy input from the surface turbulent heat exchange and the middle to high parts experience increasing energy input due to shortwave radiation. These effects are related to an overall increase in atmospheric pressure over North Greenland, southerly wind anomalies and decreased cloudiness. These factors contribute to increased summer melt which dominates over changes in annual accumulation, resulting in a decline in surface mass balance and an upward migration of the equilibrium line. The increased summer melt from the ice sheet draining into the Godthåbsfjord dominates over significantly smaller changes in precipitation directly over the fjord waters and surface runoff from non-glacier land areas. The high horizontal resolution of the model (about 5.5 km) allows great detail in the representation of topography and surface types. This makes the model particularly suited for this kind of local catchment-scale analysis. The model output is compared to a range of different hydro-meteorological observations both on and off the ice sheet and is found to represent even day-to-day weather variability well.
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