Comparison between spring 2019 and 2020 measurements of aerosols and CCN over the Yellow Sea

Abstract:

Lack of aerosol measurement has been an obstacle to acquiring the relationship between aerosol and climate change. Despite the heavy pollution in East Asia, aerosol observation studies are insufficient. In this regard, the Yellow Sea, which is located between the mainland China and the Korean Peninsula, becomes an important region to make aerosol observations that can represent East Asia.

As an effort to increase aerosol data in this region, in spring 2019 and 2020, submicron aerosol number concentration, aerosol number size distribution, and CCN number concentration were measured over the Yellow Sea onboard the Gisang 1 research vessel with two condensation particle counters (CPC; TSI 3776 and TSI 3772), scanning mobility particle sizer (SMPS), and CCN counter (CCNC; DMT CCN-100).

In 2019, the average of N_CN10 (aerosol number concentration larger than 10 nm) and N_CCN (CCN number concentration) at 0.6% supersaturation were 7312 cm^-3 and 4565 cm^-3 and in 2020, the average value of N_CN10 and N_CCN at 0.6% supersaturation were 6415 cm^-3 and 3682 cm^-3. Average values decreased by approximately 900 cm^-3. However, it is uncertain if such decrease was affected by COVID-19 lockdown.

To distinguish the factors that influence the characteristics of aerosols, our plan is to fit aerosol number size distributions into multimodal log-normal distributions which consist of mode number concentration, geometric variance, and geometric mean diameter. We will compare them with CCN number concentration for CCN closure study. We will also try to find the relationship with the sources of aerosols by HYSPLIT back trajectories, and weather conditions such as wind direction. After classifying the theoretical distributions by hygroscopicity and sources, we will discuss the impact of continental influence in spring 2019 and 2020 to identify the effect of COVID-19 lockdown on aerosol properties. Detailed analysis results will be presented at the conference.