The relationship between December haze pollution in the Sichuan Basin and preceding climate factors

Abstract

AbstractHaze pollution (HP) is one of the most serious disasters in the Sichuan Basin (SCB), adversely affecting human health, transportation, tourism and agriculture. HP in December is severe and differs from the haze days in January and February in terms of their temporal variations. To improve the understanding of December haze days in the SCB (DHDSCB), this study not only shows the atmospheric circulations and local meteorological circumstances related with the haze variation, but also analyses its relationship with the prior atmospheric apparent heat source over the Tibetan Plateau (TP) and the sea surface temperature (SST). The key circulation system associated with the interannual variation of the DHDSCB is that the SCB is controlled by the positive geopotential height anomalies and anomalous anticyclonic circulations with weak southwestward water vapour transport. Moreover, unfavourable local meteorological circumstances limit the vertical (horizontal) dispersion of pollutants. In addition, the DHDSCB during 1981–2022 is also found to have significant relationships with two preceding climate factors, which are the atmospheric apparent heat source (Q1) over the western TP in preceding November and the SST difference between the western Maritime Continent and western Australia in preceding autumn. The enhancement of Q1 over the western TP in preceding November is closely related to the midlatitude North Atlantic–southern Mediterranean Middle East–Arabian Sea–TP and its downstream region teleconnection pattern. Consequently, the anticyclonic circulation prevails over the SCB, and SCB is with less precipitation and more haze days in December. The western Maritime Continent and western Australia SST pattern in preceding Autumn is correlated with the Bay of Bengal–eastern TP and its downstream–Japan–Bering Sea teleconnection pattern, providing unfavourable moisture condition for the precipitation over the SCB and leading to the onset, development and maintenance of static weather in December. Therefore, the Q1 over the western TP and the SST pattern over the western Maritime Continent and western Australia may be potential indicators for the subseasonal prediction of HP in the SCB in December.