Climate Drivers of the Recent Springtime Cooling Pattern in Northern North America
Labe, Z.M., N.C. Johnson, and T.L. Delworth. Climate drivers of the recent springtime cooling pattern in northern North America, 36th Conference on Climate Variability and Change, Virtual Attendance (Jan 2023). https://ams.confex.com/ams/103ANNUAL/meetingapp.cgi/Paper/415409 While much of the Northern Hemisphere has observed widespread warming over the last several decades, an area stretching across the northern United States to central Canada has experienced weak cooling in early spring from 1979 to present. It remains unclear whether this regional lack of surface warming is driven by external forcing or a reflection of internal climate variability. To understand the variability and drivers of this regional temperature pattern, we compare observations with combinations of AMIP-style counterfactual simulations and a collection of coupled climate model large ensemble experiments from the recently developed Seamless System for Prediction and EArth System Research (SPEAR) at GFDL. Although a few individual ensemble members capture a similar spatial pattern of temperature anomalies, we find that the mean observed regional trend is generally near or outside the ensemble spread of trends from each of the different climate model experiments. This suggests that this temperature pattern may correspond to an unusual realization of atmospheric internal variability. We further identify the potential modes of Pacific climate variability, land surface feedbacks from anomalous snow cover, and connections to springtime variability in the stratosphere polar vortex that may have contributed to this recent regional temperature trend.
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Climate Drivers of the Recent Springtime Cooling Pattern in Northern North America
- 1. CLIMATE DRIVERS OF THE RECENT SPRINGTIME COOLING PATTERN IN NORTHERN NORTH AMERICA @ZLabe Zachary M. Labe1,2 with Nathaniel C. Johnson2 and Thomas L. Delworth2 1Princeton University; Atmospheric and Oceanic Sciences Program 2 NOAA Geophysical Fluid Dynamics Laboratory 10 January 2023 36th Conference on Climate Variability and Change 103rd AMS Annual Meeting in Denver, CO
- 2. 2021 brought changes to our 30-year climatological normals ERA5
- 3. ERA5
- 4. ERA5
- 5. ERA5
- 6. ERA5
- 7. ERA5
- 8. ERA5
- 9. ERA5
- 10. ERA5
- 11. ERA5
- 12. ERA5
- 13. ERA5
- 14. ERA5
- 15. ERA5 February to April temperature trends 1979-2022
- 17. IS IT ROBUST IN OBS?
- 18. Comparing April temperature trends in other observational datasets…
- 19. Berkeley Earth
- 20. WAIT. WHAT ABOUT THE ARCTIC?
- 21. Observed April trends in ERA5 T2M SLP Near-surface temperature
- 22. Observed April trends in ERA5 T2M SLP Sea level pressure
- 23. Observed April trends in ERA5 T2M SLP Sea level pressure Near-surface temperature
- 24. Arctic near-surface temperature trends ERA5 compared to SPEAR-AMIP
- 25. Arctic climate trends from 1979 to 2022 Sea-Ice Concentration Near-Surface Temperature
- 26. Arctic climate trends from 1979 to 2022 Sea-Ice Concentration Near-Surface Temperature
- 27. Deserving of its own study – Arctic warming in April AMIP simulations Mean Arctic trends from 1979 to 2019
- 28. How well do climate models capture this trend? Observed Temperature
- 29. How well do climate models capture this trend? Prescribed SST/sea ice Observed Temperature
- 30. How well do climate models capture this trend? Coupled GFDL SPEAR Observed Temperature
- 31. How well do climate models capture this trend? Coupled GFDL FLOR Observed Temperature
- 32. How well do climate models capture this trend? Coupled GFDL FLOR Observed Prescribed SST/sea ice Coupled GFDL SPEAR Sea Level Pressure
- 33. Distribution of April temperature trends between multi-model large ensembles
- 34. TRENDS
- 35. Range of variability in the large ensembles… Closest matches for T2M trends April
- 39. IS IT THE STRATOSPHERE?
- 40. Related to the stratospheric final warming? GFDL SPEAR hindcast simulations – initialized in January (1992-2021) Stratosphere Experiment Control
- 41. IS IT ENSO?
- 42. SPEAR AMIP ERA5 ENSO teleconnection too strong in SPEAR! ERA5
- 43. SPEAR AMIP ERA5 ENSO teleconnection too strong in SPEAR! ERA5
- 44. SPEAR AMIP ERA5 ENSO teleconnection too strong in SPEAR!
- 45. IS IT THE LAND SURFACE?
- 46. Related to Northern Hemisphere snow cover?
- 47. IS IT THE NORTH PACIFIC?
- 48. The North Pacific Oscillation! Z500 correlation map with a standardized index of temperature over North America ERA5
- 49. The North Pacific Oscillation! OUR INDEX
- 50. The North Pacific Oscillation! TELECONNECTION
- 51. The North Pacific Oscillation! T2M regression map with our custom NPO index ERA5
- 52. ERA5 (obs) SPEAR-AMIP Shift in the NPO centers of action in springtime Not simulated by AMIP or coupled historical simulations with SPEAR
- 53. ERA5 (obs) SPEAR-AMIP Shift in the NPO centers of action in springtime Not simulated by AMIP or coupled historical simulations with SPEAR
- 54. ERA5 (obs) Recent North Pacific SST and precipitation trends
- 55. KEY POINTS 1. While observed trends are well below the multi-model ensemble mean, a few individual ensemble members simulate a similar warming hole spatial pattern 2. Trends in springtime snow cover and the stratospheric polar vortex do not fully explain this pattern of cooling in North America 3. Temperature variability is predominately driven by the North Pacific Oscillation (NPO), and observed shifts in its pattern may be related to this anomalous cooling Zachary Labe zachary.labe@noaa.gov @ZLabe