Combined Effects of Blocking and AO on a Prolonged Snowstorm in Jeju Island

et al. 2023

Sci Rep

Although 2020 was the fourth warmest year on record in northern Asia, the cold condition in April 2020 caused severe damage to the agricultural and marine ecosystems in northeastern Asia. Previous studies have indicated that the dipole atmospheric circulation over Siberia and the East Sea (Japan Sea) produced this cold environment with strong northwesterly wind. However, the potential causes of the dipole circulation over northeastern Asia remain unclear. In this study, we found that the East Atlantic/Western Russia (EAWR) pattern and blocking combined to produce the atmospheric structure. The wave train originated from the vorticity forcing of northwestern/central Russia and propagated from Western Europe to the East Sea via the background westerly and northerly winds. In addition, the Siberian blocking days increased eleven times in April 2020 relative to the climatological average, and an easterly (westerly) anomaly was observed over Mongolia–northeastern China (northern Russia). The strong blocking and EAWR pattern led to the robust atmospheric dipole structure with a prevailing northerly flow in April 2020, thereby causing the extreme cold condition over northeastern Asia. Our results provide novel insights into the cause of extreme cold condition in April over northeastern Asia.

Section: Summary and Discussionmentioning

confidence: 99%

Causes for an extreme cold condition over Northeast Asia during April 2020

et al. 2023

Sci Rep

What caused the cold condition over northeast Asia during April 2020?

et al. 2022

Preprint

Northeast Asia has experienced severe damage to agricultural and marine ecosystems due to the cold condition in April 2020, despite the fourth warmest year in northern Asia on record. Previous studies have indicated that the dipole atmospheric circulation over Siberia and the East Sea (Japan Sea) rendered this cold environment, although the cause of atmospheric circulation affecting the cold condition over northeast Asia remains nebulous. Herein we found that the atmospheric structure was a mixed result of the East Atlantic/Western Russia (EAWR) pattern and blocking. The wave train was originated from the vorticity forcing of northwest/central Russia and propagated from western Europe to the East Sea via the background westerly and northerly winds. Besides, the Siberian blocking days increased ten times in April 2020 than climatology along with the easterly anomaly over Mongolia–northeast China. The blocking occurrence was linked to wavy westerly at the high latitudes. The strong blocking and EAWR pattern led to the robust dipole atmospheric structure with the prevailing northerly flow in April 2020, thereby causing the cold over northeast Asia. Our results provide novel insights into the cause of the cold condition in April over northeast Asia and its impact on the land-ocean ecosystems.

Record-Breaking Slow Temperature Evolution of Spring Water During 2020 and Its Impacts on Spring Bloom in the Yellow Sea

Lee

et al. 2022

Front. Mar. Sci.

Unprecedented retardation of spring water temperature rising during the 2020 pandemic year was identified in the Socheongcho Ocean Research Station within the northeastern basin of the Yellow Sea: an exceptionally high water temperature anomaly in March and a contrasted low-temperature anomaly in May. The slowest temperature evolution was principally caused by the significant increase in latent heat releases in April (117% higher than the climatology of 1982–2019). Strong northwesterly winds generated these exceptional heat fluxes associated with the dipole-like atmospheric circulation pattern over Siberia and the East Sea (Japan Sea). Besides, warm winter water facilitated the enhanced release of latent heat fluxes as a precondition. The oceanic heat redistribution partially supported the cold anomaly in the surface layer up to the middle of May through positive feedback between the low surface temperature and the active entrainment associated with tidal turbulent mixing. The resultant low temperature at the surface weakened the vertical stratification, both impeding the activation of phytoplankton’s photosynthesis albeit under the eutrophic surface layer, consequently resulting in the delayed and suppressed spring bloom during 2020. Since such extreme events are anticipated to occur more frequently under global warming, our results highlight the importance of continuously monitoring multi-disciplinary environmental conditions, climate extremes, and their impact on the Yellow Sea marine ecosystem.