EGU22-1507
https://doi.org/10.5194/egusphere-egu22-1507
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Predictable Patterns of Wintertime Surface Air Temperature in Northern Hemisphere and Their Predictability Sources in the SEAS5

Hongdou Fan1,2, Lin Wang3, Yang Zhang4, Youmin Tang5, Wansuo Duan6, and Lei Wang3
Hongdou Fan et al.
  • 1Institute of Oceanography, Center for Earth System Research and Sustainability (CEN), Universität Hamburg,Hamburg, Germany
  • 2International Max Planck Research School on Earth System Modelling, Max Planck Institute for Meteorology, Hamburg, Germany (hongdou.fan@mpimet.mpg.de)
  • 3Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China (wanglin@mail.iap.ac.cn)
  • 4School of Atmospheric Sciences, Nanjing University, Nanjing, China
  • 5Environmental Science and Engineering, University of Northern British Columbia, Prince George, British Columbia, Canada
  • 6State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

Slow-varying atmospheric boundaries are the main sources of seasonal climate predictions, and their footprints on climate variables may be captured as predictable patterns. Based on 36-yr hindcasts from the fifth-generation seasonal forecast system of the European Centre for Medium-Range Weather Forecasts (SEAS5), the most predictable patterns of the wintertime 2-m air temperature (T2m) in the extratropical Northern Hemisphere are extracted via the maximum signal-to-noise (MSN) empirical orthogonal function (EOF) analysis, and their associated predictability sources are identified. The main findings of this study are as following:

  • The MSN EOF1 captures the warming trend that amplifies over the Arctic but misses the associated warm Arctic–cold continent pattern. The MSN EOF2 delineates a wavelike T2m pattern over the Pacific–North America region, which is rooted in the tropical forcing of the eastern Pacific-type El Niño–Southern Oscillation (ENSO). The MSN EOF3 shows a wavelike T2m pattern over the Pacific–North America region, which has an approximately 90° phase difference from that associated with MSN EOF2, and a loading center over midlatitude Eurasia. Its sources of predictability include the central Pacific-type ENSO and Eurasian snow cover. The MSN EOF4 reflects T2m variability surrounding the Tibetan Plateau, which is plausibly linked to the remote forcing of the Arctic sea ice.
  • The information on the leading predictable patterns and their sources of predictability is further used to develop a calibration scheme to improve the prediction skill of T2m. The calibrated prediction skill in terms of the anomaly correlation coefficient improves significantly over midlatitude Eurasia in a leave-one-out cross-validation, implying a possible way to improve the wintertime T2m prediction in the SEAS5.

How to cite: Fan, H., Wang, L., Zhang, Y., Tang, Y., Duan, W., and Wang, L.: Predictable Patterns of Wintertime Surface Air Temperature in Northern Hemisphere and Their Predictability Sources in the SEAS5, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1507, https://doi.org/10.5194/egusphere-egu22-1507, 2022.

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