Temperature
Project summary
In this project, we identified and examined the 50 coldest extreme temperature events in North America and the 50 hottest extreme temperature events in southwestern Europe during winter. Our objective was to investigate the co-occurrence of those events, namely the (near)-simioutaniously occurence in remote regions. The findings revealed a clear connection between these occurrences. When Europe experienced unusually warm temperatures, parts of the US faced exceptionally cold conditions, and vice versa. The study also identified specific weather patterns that contributed to these extreme events. Understanding these connections can enhance our ability to prepare for and comprehend extreme weather phenomena.
The temperature-related results in high resolution can be found below. Please click on the figures to enlarge them.
Temperature, sea level pressure and geopotential height anomalies during cold extremes in North America (CENA)
Figure 1: Mean temperature anomaly, sea level pressure anomaly (SLP) and 500hPa geopotenial height (Z500) anomaly during the WEEU. The first row depicts 5 days prior the event, the second on the day of the event and the last row 5 days after the event. Areas with 5% significance level are marked by symbols.
Temperature, sea level pressure (slp) and geopotential height (Z500) anomalies during warm extremes in western and southern Europe (WEEU)
Figure 2: Mean temperature (Tanom), sea level pressure anomaly(SLP) and 500hPa geopotenial height (Z500) anomaly during the WEEU. The first row depicts 5 days prior the event, the second on the day of the event and the last row 5 days after the event. Areas with 5% significance level are marked by symbols.
Percentage of days with same-sign anomalies (either positive or negative)
Let’s take a look at the percentage of days with similar temperature anomalies during the CENA and WEEU events.
In Panel (a), we see the percentage of days with positive anomalies in Europe during the CENA events. This tells us how often temperatures were higher than normal during these extreme events.
In Panel (b), we observe the percentage of days with negative anomalies in Europe during the CENA events. This shows us how frequently temperatures were lower than normal during these events.
Moving on to Panels (c) and (d), we have the percentage of days with positive and negative anomalies, respectively, in North America during the WEEU events. These panels reveal the frequency of temperature deviations from the normal range in different parts of North America during these extreme events.
The red boxes indicate the areas that were studied in North America and Europe. Additionally, areas with statistically significant negative or positive anomalies are marked with “∗” and “▲”, respectively.
By examining these percentages, we can gain insights into how often temperatures deviated from the norm during these extreme events in different regions.
Figure 3:
Temperature anomaly +-10 days of the extreme cold in North America
Now let’s explore the mean temperature anomalies during the 50 warm extremes in Europe (WEEU) at different time lags.
In Panel (a), we have the mean temperature anomalies at lag -5, showing the deviations from normal temperatures five days before the warm extremes.
Panel (b) displays the mean temperature anomalies at lag 0, indicating the peak of the warm extremes.
Moving to Panel (c), we observe the mean temperature anomalies at lag +5, which represent the deviations from normal temperatures five days after the warm extremes.
The red boxes highlight the studied areas in North America and Europe. Additionally, areas with statistically significant negative or positive anomalies are marked with “∗” and “▲”, respectively, indicating the significance of these temperature deviations.
By examining these mean temperature anomalies at different time lags, we can understand the patterns and changes in temperature during the warm extremes in Europe, providing valuable insights into the characteristics of these events.
Figure 4: Mean temperature anomalies (°C) during the 50 cold extremes in Europe (CENA) at different lags. Panel a) at lag -5, panel b) at lag 0, and panel c) at lag +5. The two studied domains over North America and Europe are marked by red boxes. Areas of 5% significance level are highlighted using symbols, negative anomalies are marked with “∗“, while positive anomalies with “▲“.
Temperature anomaly +-10 days of the extreme warm in Europe
Figure 5: Mean temperature anomalies (°C) during the 50 warm extremes in Europe (WEEU) at different lags. Panel a) at lag -5, panel b) at lag 0, and panel c) at lag +5. The two studied domains over North America and Europe are marked by red boxes. Areas of 5% significance level are highlighted using symbols, negative anomalies are marked with “∗“, while positive anomalies with “▲“.
