Study on the propagation characteristics of Rossby wave and its influence mechanism on weather at the initial section of the Northeast Passage in the Arctic

The initial section of the Arctic Northeast Passage is located in the Yellow Sea and Bohai Sea of China. The severe weather types that may threaten the safety of shipping in this area are mainly strong winds and heavy precipitation. Among them the cold air gale accompanied by the cold wave process, as well as the disastrous weather such as strong wind and heavy precipitation caused by weather systems such as tropical cyclones and extratropical cyclones, have a great impact on shipping safety in this area. Based on the National Centers for Environmental Prediction (NCEP) global daily reanalysis data from 1991 to 2020, we analyze the energy propagation characteristics of the Rossby wave along the upper-level jet stream during the seaworthiness period (July to October) of the Arctic Northeast Passage and its impact on the weather in the initial section of the Arctic Northeast Passage, especially on heavy precipitation. The results are as follows. (1) The meridional wind along the 250 hPa westerly jet axis in the subtropical region of the Northern Hemisphere shows a zonal three-wave quasi-stationary Rossby wave pattern. (2) The atmospheric quasi-stationary Rossby wave source at 250 hPa is located in the Mediterranean region. The wave is excited here and propagates eastward along the jet stream. Although the wave energy is dissipated during the propagation process, continuous input of energy from the Mediterranean region maintains and strengthens the wave. (3) The absolute value of the correlation coefficient between the key area of the wave action flux divergence and the precipitation and wind speed in the initial section of the Arctic Northeast Passage is greater than 0.5. While the absolute value of the correlation coefficient between the key area wave action flux index and the precipitation and wind speed is close to 0.9, indicating a strong correlation, it shows that the energy of the Rossby wave is concentrated and strengthened when it propagates along the upper jet stream, significantly influencing the precipitation and wind speed in the initial section of the Northeast Passage of the Arctic, thus triggering disastrous weather such as heavy precipitation and strong winds. (4) When the Rossby wave disturbance is stronger, the downstream propagation energy is also stronger. The westerly jet is then strengthened, and the vertical upward motion is enhanced. This results in an abnormal increase in precipitation in the initial section of the Arctic Northeast Passage.