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Doescher, Ralf
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Publications (10 of 34) Show all publications
Caian, M., Koenigk, T., Doescher, R. & Devasthale, A. (2018). An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation. Climate Dynamics, 50(1-2), 423-441
Open this publication in new window or tab >>An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation
2018 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, no 1-2, p. 423-441Article in journal (Refereed) Published
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-4490 (URN)10.1007/s00382-017-3618-9 (DOI)000422908700026 ()
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-02-06Bibliographically approved
Caian, M., Koenigk, T., Doescher, R. & Devasthale, A. (2018). An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation (vol 50, pg 423, 2017). Climate Dynamics, 50(1-2), 443-443
Open this publication in new window or tab >>An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation (vol 50, pg 423, 2017)
2018 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, no 1-2, p. 443-443Article in journal (Refereed) Published
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-4491 (URN)10.1007/s00382-017-3684-z (DOI)000422908700027 ()
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-02-06Bibliographically approved
Smith, D. M., Scaife, A. A., Hawkins, E., Bilbao, R., Boer, G. J., Caian, M., . . . Yeager, S. (2018). Predicted Chance That Global Warming Will Temporarily Exceed 1.5 degrees C. Geophysical Research Letters, 45(21), 11895-11903
Open this publication in new window or tab >>Predicted Chance That Global Warming Will Temporarily Exceed 1.5 degrees C
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2018 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 21, p. 11895-11903Article in journal (Refereed) Published
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-5022 (URN)10.1029/2018GL079362 (DOI)000451832600042 ()
Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2018-12-19Bibliographically approved
Berg, P., Doescher, R. & Koenigk, T. (2016). On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model. Climate Dynamics, 46(11-12), 3499-3515
Open this publication in new window or tab >>On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model
2016 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 11-12, p. 3499-3515Article in journal (Refereed) Published
National Category
Climate Research
Identifiers
urn:nbn:se:smhi:diva-3202 (URN)10.1007/s00382-015-2783-y (DOI)000381108600009 ()
Available from: 2016-09-27 Created: 2016-09-27 Last updated: 2018-05-08Bibliographically approved
Koenigk, T., Berg, P. & Doescher, R. (2015). Arctic climate change in an ensemble of regional CORDEX simulations. Polar Research, 34, Article ID 24603.
Open this publication in new window or tab >>Arctic climate change in an ensemble of regional CORDEX simulations
2015 (English)In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, article id 24603Article in journal (Refereed) Published
Abstract [en]

Fifth phase Climate Model Intercomparison Project historical and scenario simulations from four global climate models (GCMs) using the Representative Concentration Pathways greenhouse gas concentration trajectories RCP4.5 and RCP8.5 are downscaled over the Arctic with the regional Rossby Centre Atmosphere model (RCA). The regional model simulations largely reflect the circulation bias patterns of the driving global models in the historical period, indicating the importance of lateral and lower boundary conditions. However, local differences occur as a reduced winter 2-m air temperature bias over the Arctic Ocean and increased cold biases over land areas in RCA. The projected changes are dominated by a strong warming in the Arctic, exceeding 15 degrees K in autumn and winter over the Arctic Ocean in RCP8.5, strongly increased precipitation and reduced sea-level pressure. Near-surface temperature and precipitation are linearly related in the Arctic. The wintertime inversion strength is reduced, leading to a less stable stratification of the Arctic atmosphere. The diurnal temperature range is reduced in all seasons. The large-scale change patterns are dominated by the surface and lateral boundary conditions so future response is similar in RCA and the driving global models. However, the warming over the Arctic Ocean is smaller in RCA; the warming over land is larger in winter and spring but smaller in summer. The future response of winter cloud cover is opposite in RCA and the GCMs. Precipitation changes in RCA are much larger during summer than in the global models and more small-scale change patterns occur.

National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-2009 (URN)10.3402/polar.v34.24603 (DOI)000350806300001 ()
Available from: 2016-04-06 Created: 2016-03-03 Last updated: 2018-05-08Bibliographically approved
Wang, S., Dieterich, C., Doescher, R., Höglund, A., Hordoir, R., Meier, M., . . . Schimanke, S. (2015). Development and evaluation of a new regional coupled atmosphere-ocean model in the North Sea and Baltic Sea. Tellus. Series A, Dynamic meteorology and oceanography, 67, Article ID 24284.
Open this publication in new window or tab >>Development and evaluation of a new regional coupled atmosphere-ocean model in the North Sea and Baltic Sea
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2015 (English)In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, article id 24284Article in journal (Refereed) Published
Abstract [en]

A new regional coupled model system for the North Sea and the Baltic Sea is developed, which is composed of the regional setup of ocean model NEMO, the Rossby Centre regional climate model RCA4, the sea ice model LIM3 and the river routing model CaMa-Flood. The performance of this coupled model system is assessed using a simulation forced with ERA-Interim reanalysis data at the lateral boundaries during the period 1979-2010. Compared to observations, this coupled model system can realistically simulate the present climate. Since the active coupling area covers the North Sea and Baltic Sea only, the impact of the ocean on the atmosphere over Europe is small. However, we found some local, statistically significant impacts on surface parameters like 2m air temperature and sea surface temperature (SST). A precipitation-SST correlation analysis indicates that both coupled and uncoupled models can reproduce the air-sea relationship reasonably well. However, the coupled simulation gives slightly better correlations even when all seasons are taken into account. The seasonal correlation analysis shows that the air-sea interaction has a strong seasonal dependence. Strongest discrepancies between the coupled and the uncoupled simulations occur during summer. Due to lack of air-sea interaction, in the Baltic Sea in the uncoupled atmosphere-standalone run the correlation between precipitation and SST is too small compared to observations, whereas the coupled run is more realistic. Further, the correlation analysis between heat flux components and SST tendency suggests that the coupled model has a stronger correlation. Our analyses show that this coupled model system is stable and suitable for different climate change studies.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Oceanography
Identifiers
urn:nbn:se:smhi:diva-1928 (URN)10.3402/tellusa.v67.24284 (DOI)000369824300001 ()
Available from: 2016-05-02 Created: 2016-03-03 Last updated: 2018-01-10Bibliographically approved
Gascard, J.-C. -., Vihma, T. & Doescher, R. (2015). General introduction to the DAMOCLES special issue. Atmospheric Chemistry And Physics, 15(10), 5377-5379
Open this publication in new window or tab >>General introduction to the DAMOCLES special issue
2015 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 10, p. 5377-5379Article in journal (Refereed) Published
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-1979 (URN)10.5194/acp-15-5377-2015 (DOI)000355289200003 ()
Available from: 2016-04-26 Created: 2016-03-03 Last updated: 2017-11-30Bibliographically approved
Doescher, R., Vihma, T. & Maksimovich, E. (2014). Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review. Atmospheric Chemistry And Physics, 14(24), 13571-13600
Open this publication in new window or tab >>Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review
2014 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 24, p. 13571-13600Article in journal (Refereed) Published
Abstract [en]

Sea ice is the central component and most sensitive indicator of the Arctic climate system. Both the depletion and areal decline of the Arctic sea ice cover, observed since the 1970s, have accelerated since the millennium. While the relationship of global warming to sea ice reduction is evident and underpinned statistically, it is the connecting mechanisms that are explored in detail in this review. Sea ice erodes both from the top and the bottom. Atmospheric, oceanic and sea ice processes interact in non-linear ways on various scales. Feedback mechanisms lead to an Arctic amplification of the global warming system: the amplification is both supported by the ice depletion and, at the same time, accelerates ice reduction. Knowledge of the mechanisms of sea ice decline grew during the 1990s and deepened when the acceleration became clear in the early 2000s. Record minimum summer sea ice extents in 2002, 2005, 2007 and 2012 provide additional information on the mechanisms. This article reviews recent progress in understanding the sea ice decline. Processes are revisited from atmospheric, oceanic and sea ice perspectives. There is strong evidence that decisive atmospheric changes are the major driver of sea ice change. Feedbacks due to reduced ice concentration, surface albedo, and ice thickness allow for additional local atmospheric and oceanic influences and self-supporting feedbacks. Large-scale ocean influences on Arctic Ocean hydrology and circulation are highly evident. Northward heat fluxes in the ocean are clearly impacting the ice margins, especially in the Atlantic sector of the Arctic. There is little indication of a direct and decisive influence of the warming ocean on the overall sea ice cover, due to an isolating layer of cold and fresh water underneath the sea ice.

National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-132 (URN)10.5194/acp-14-13571-2014 (DOI)000347957100009 ()
Available from: 2015-04-09 Created: 2015-03-26 Last updated: 2017-12-04Bibliographically approved
Doescher, R. & Koenigk, T. (2013). Arctic rapid sea ice loss events in regional coupled climate scenario experiments. Ocean Science, 9(2), 217-248
Open this publication in new window or tab >>Arctic rapid sea ice loss events in regional coupled climate scenario experiments
2013 (English)In: Ocean Science, ISSN 1812-0784, E-ISSN 1812-0792, Vol. 9, no 2, p. 217-248Article in journal (Refereed) Published
Abstract [en]

Rapid sea ice loss events (RILEs) in a mini-ensemble of regional Arctic coupled climate model scenario experiments are analyzed. Mechanisms of sudden ice loss are strongly related to atmospheric circulation conditions and preconditioning by sea ice thinning during the seasons and years before the event. Clustering of events in time suggests a strong control by large-scale atmospheric circulation. Anomalous atmospheric circulation is providing warm air anomalies of up to 5 K and is forcing ice flow, affecting winter ice growth. Even without a seasonal preconditioning during winter, ice drop events can be initiated by anomalous inflow of warm air during summer. It is shown that RILEs can be generated based on atmospheric circulation changes as a major driving force without major competing mechanisms, other than occasional longwave effects during spring and summer. Other anomalous seasonal radiative forcing or short-lived forcers (e.g., soot) play minor roles or no role at all in our model. RILEs initiated by ocean forcing do not occur in the model, although cannot be ruled out due to model limitations. Mechanisms found are qualitatively in line with observations of the 2007 RILE.

National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-409 (URN)10.5194/os-9-217-2013 (DOI)000320348700002 ()
Available from: 2015-04-01 Created: 2015-03-31 Last updated: 2017-12-04Bibliographically approved
Paquin, J.-P., Doescher, R., Sushama, L. & Koenigk, T. (2013). Causes and consequences of mid-21st-century rapid ice loss events simulated by the Rossby centre regional atmosphere-ocean model. Tellus. Series A, Dynamic meteorology and oceanography, 65, Article ID 19110.
Open this publication in new window or tab >>Causes and consequences of mid-21st-century rapid ice loss events simulated by the Rossby centre regional atmosphere-ocean model
2013 (English)In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 65, article id 19110Article in journal (Refereed) Published
Abstract [en]

Recent observations and modelling studies suggest that the Arctic climate is undergoing important transition. One manifestation of this change is seen in the rapid sea-ice cover decrease as experienced in 2007 and 2012. Although most numerical climate models cannot adequately reproduce the recent changes, some models produce similar Rapid Ice Loss Events (RILEs) during the mid-21st-century. This study presents an analysis of four specific RILEs clustered around 2040 in three transient climate projections performed with the coupled Rossby Centre regional Atmosphere-Ocean model (RCAO). The analysis shows that long-term thinning causes increased vulnerability of the Arctic Ocean sea-ice cover. In the Atlantic sector, pre-conditioning (thinning of sea ice) combined with anomalous atmospheric and oceanic heat transport causes large ice loss, while in the Pacific sector of the Arctic Ocean sea-ice albedo feedback appears important, particularly along the retreating sea-ice margin. Although maximum sea-ice loss occurs in the autumn, response in surface air temperature occurs in early winter, caused by strong increase in ocean-atmosphere surface energy fluxes, mainly the turbulent fluxes. Synchronicity of the events around 2040 in the projections is caused by a strong large-scale atmospheric circulation anomaly at the Atlantic lateral boundary of the regional model. The limited impact on land is caused by vertical propagation of the surface heat anomaly rather than horizontal, caused by the absence of low-level temperature inversion over the ocean.

Keywords
coupled regional climate model, rapid ice loss events, Arctic, climate scenarios, sea-ice
National Category
Climate Research
Research subject
Climate
Identifiers
urn:nbn:se:smhi:diva-402 (URN)10.3402/tellusa.v65i0.19110 (DOI)000323764700001 ()
Available from: 2015-04-01 Created: 2015-03-31 Last updated: 2017-12-04Bibliographically approved
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