November 2023:
neue Veröffentlichung:
Krüger, J, Kjellsson, J, Kedzierski, RP and Claus, M. 2023. Connecting North Atlantic SST Variability to European Heat Events over the Past Decades. Tellus A: Dynamic Meteorology and Oceanography, 75(1): 358–374. DOI: https://doi.org/10.16993/tellusa.3235
Summary: "The intensity and frequency of European heat events has increased in the recent two decades, which has strengthened the interest about identifying potential driving mechanisms. This study investigates five different composites of North Atlantic sea surface temperatures. We find that events with an atmospherically-driven fall of cold North Atlantic sea surface temperatures are accompanied by a subsequent surface air temperature maximum over central Europe, indicating a higher probability for heat events. In addition to the surface temperature contrast, we identify a distinct atmospheric trough-ridge pattern in the North Atlantic-European sector. An additional composite of European heat events supports this time-lagged relationship between cold North Atlantic SSTs with a negative tendency and European heat events. "
Evolution of cold SST events with negative tendency (solid – blue), with positive tendency (dashed – blue), neutral SSTs with negative tendency (solid – orange), warm SST events with negative tendency (solid – red), with positive tendency (dashed – red) relative to the respective onset date smoothed with a 5–day running mean; the composite mean is shown for a) North Atlantic SST anomalies (15 – 40°W, 45 –60°N), b) North Atlantic Z300 anomalies (15 – 40°W, 45 –60°N), c) European T2m anomalies (0 – 20°E, 45 – 52.5°N), d) European Z300 anomalies (0 – 20°E, 45 – 52.5°N); a thicker line width indicates significance according to the 95% confidence interval based on the bootstrap method.
Oktober 2023:
neue Veröffentlichung:
Duteil, O., Park, W. Future changes in atmospheric synoptic variability slow down ocean circulation and decrease primary productivity in the tropical Pacific Ocean. npj Clim Atmos Sci6, 136 (2023). https://doi.org/10.1038/s41612-023-00459-3
Summary: "This study investigates the impact of future changes in atmospheric synoptic variability (ASV) on ocean properties and biogeochemical cycles in the tropical Pacific Ocean using coupled and forced atmosphere–ocean model experiments. Future climate projections show an annual mean decrease in ASV in subtropical gyres and an increase in the tropical band. Maintaining ASV to current values lead to a deepening of the mixed layer in subtropical regions and a shalllowing at the equator associated with a sea surface temperature decrease. The changes in ASV impact the large-scale ocean circulation and the strength of the subtropical and tropical cells, which constrain the equatorial water upwelling and the tropical net primary productivity. Ultimately, this study highlights the significance of ASV in understanding the impacts of climate change on ocean dynamics and biogeochemical processes, as half of the primary productivity decline due to climate change is caused by changes of ASV in the tropical Pacific Ocean."
Mean sea surface temperature difference (10°N–10°S) (°C) (compared to GW – Global Warming experiment) vs. Tropical Cells Index (a) and Subtropical Cells index (b). The mixed layer depth (MLD) difference (m) (10°N–10°S) is shown in color for each experiment. c, d Similar to (a, b) but net primary production (NPP) difference (percent) (compared to GW) is shown in color for each experiment.
The black square is GW, green circle GW-ASVCTL (Global Warming with control Atmospheric Synoptic Variability - ASV), green square GW-ASVCTL-FLX (Global Warming with control Atmospheric Variability only for fluxes computation), blue triangle GW-ASVM10, blue hexagon GW-ASVM20, red triangle GW-ASVP10, red hexagon GW-ASVP20 (decrease by 10 %, 20 % and increase by 10 %, 20 % of ASV respectively)
