The Lagging Effect of Precipitation on NAIs Concentrations on Rainy Days in Wuyi Mountain National Park, China

Abstract

Precipitation (PRE) is an essential factor that affects the negative air ions (NAIs) concentrations. However, the mechanism of NAIs concentrations and their influencing factors on rainy and non-rainy days remains unclear. Here, we used hourly data of NAIs concentrations and meteorological data in 2019 to analyze the distribution of NAIs concentrations and its influencing factors on rainy and non-rainy days in the Wuyi Mountain National Park (WMNP) of China, which was listed as a World Cultural and Natural Heritage Site in 1999. The results indicated that the NAIs concentrations on rainy days were significantly higher than on non-rainy days. However, the NAIs concentrations on rainy days were slightly higher than on the first and second days after rainy days. Then, the NAIs concentrations were significantly reduced on the third day and after that. Thus, rainy days lead to a 2-day lag in the smooth reduction of NAIs on non-rainy days after rainy days. NAIs concentrations were significantly correlated with the relative humidity (RHU) on both rainy and non-rainy days. By analyzing the meteorological factors on NAIs for ranking the feature importance scores on rainy and non-rainy days, PRE was ranked first on rainy days, and sea level pressure (PRS_Sea) and temperature (TEM) were ranked first and second on non-rainy days, respectively. Based on the univariate linear regression model (ULRM), NAIs concentrations responded strongly (higher absolute slope values) to RHU on rainy days and to pressure (PRS), visibility (VIS), water vapor pressure (VAP), TEM, and ground surface temperature (GST) on non-rainy days. The results highlight the importance of PRE in the lag time of NAIs concentrations on rainy and non-rainy days.

Dominant Tree Species and Their Age Groups Drive Forest Carbon Storage in Wuyi Mountain National Park, China

“…WMNP located in the northern part of Fujian Province, China, ranges from 117°24′13″ to 117°59′19″ longitude and 27°31′20″ to 27°55′49″ latitude [20], and was listed as a World Cultural and Natural Heritage Site by the United Nations Educational, Scientific, and Cultural Organization (UNESCO) in 1999. Wuyi Mountain contains the largest and most representative forest types with higher diversity of the subtropical forest of China.…”

“…WMNP belongs to the subtropical evergreen broad-leaf forest region, characterized by diverse natural environments and vegetation types. It is the largest subtropical forest ecosystem at the same latitude globally [20]. Studies have revealed that biodiversity and complex forest structures can maximize carbon storage in subtropical forests [11].…”

“…WMNP possesses abundant forest resources, including subtropical native evergreen broad-leaved forests and native vegetation communities in China, which present enormous potential for the development of forest carbon sinks [20]. Leveraging its favorable forest resources, robust development of forest carbon sinks, and the carbon storage function of forest ecosystems are crucial for increasing carbon sink increments.…”

“…As one of the first five national parks in China in 2021, WMNP is not only a protected zone located in a World Heritage-Mixed Property in China but also the most complete, typical, and largest subtropical forest ecosystem in China [19]. This national park has high plant diversity, which is mainly composed of mature forests [20]. Similarly, mature forests have a high carbon density and relatively stable carbon storage [14,21,22].…”

Temporal Dynamics of Negative Air Ion Concentrations in Nanjing Tulou Scenic Area

“…The influencing factors of NAIs primarily include meteorological conditions (air temperature, relative humidity, etc.) [14,15], environmental factors (atmospheric pollution, air quality index, etc.) [3,11,16], and vegetation types (species richness and abundance, etc.)…”