Chemical evidence of inter-hemispheric air mass intrusion into the Northern Hemisphere mid-latitudes

Abstract

The East Asian Summer Monsoon driven by temperature and moisture gradients between the Asian continent and the Pacific Ocean, leads to approximately 50% of the annual rainfall in the region across 20–40°N. Due to its increasing scientific and social importance, there have been several previous studies on identification of moisture sources for summer monsoon rainfall over East Asia mainly using Lagrangian or Eulerian atmospheric water vapor models. The major source regions for EASM previously proposed include the North Indian Ocean, South China Sea and North western Pacific. Based on high-precision and high-frequency 6-year measurement records of hydrofluorocarbons (HFCs), here we report a direct evidence of rapid intrusion of warm and moist tropical air mass from the Southern Hemisphere (SH) reaching within a couple of days up to 33°N into East Asia. We further suggest that the combination of direct chemical tracer record and a back-trajectory model with physical meteorological variables helps pave the way to identify moisture sources for monsoon rainfall. A case study for Gosan station (33.25°N, 126.19°E) indicates that the meridional transport of precipitable water from the SH accompanying the southerly/southwesterly flow contributes most significantly to its summer rainfall.

Emissions of Tetrafluoromethane (CF4) and Hexafluoroethane (C2F6) From East Asia: 2008 to 2019

“…The uncertainty of our background is defined as the variability (standard deviation) of the concentrations in the monthly binned background, and linearly extrapolated from month to month similarly to the background concentrations. Note that our background uncertainty typically increases during summer when southern transport tends to increase the background concentration variability (Figure 3, UNC bkg ; Li et al, 2018). This background uncertainty defined here contributes to the total measurement uncertainty used in our model, as further discussed in Section 5.2.…”

Climate factors and the East Asian summer monsoon may drive large outbreaks of dengue in China

“…Monsoons are the main determinant of climatic variability over much of Asia and affect the most densely populated region on Earth. The East Asian Summer Monsoon (EASM) is driven by moisture and temperature gradients between the Pacific Ocean and the Asian continent (Li, Park et al 2018). The regions influenced by EASM include eastern China and the South China Sea, Korea, Japan, and the adjacent marginal seas (Yihui and Chan 2005).…”

Epidemiological and clinical analysis of the outbreak of dengue fever in Zhangshu City, Jiangxi Province, in 2019

“…With the geographical expansion of DENV and the virus vectors Aedes over the recent decades, the incidence of DF has increased 30 times [5]. In Asia, monsoon is the major decisive factor leading to the variation of local climate, and the East Asian Summer Monsoon (EASN) is the main driver for climate change in East China, Korea, Japan, and other countries [19]. Jiangxi Province in the southeast of China is a typical sub-tropical zone with plentiful rainfall throughout the year.…”