All cloud droplets formed in the atmosphere start with tiny particles that act as cloud condensation nuclei (CCN). These aerosols can alter cloud properties and precipitation (Albrecht, 1989;Twomey, 1977) and thereby indirectly influence the Earth's radiation budget and climate change. The radiative forcing (RF) associated with aerosolcloud interactions (aci) remains the largest source of uncertainty in climate prediction. According to the Intergovernmental Panel on Climate Change's Fifth Assessment Report (IPCC AR5, 2013), RF aci of anthropogenic aerosols was estimated to be −0.55 W•m −2 with "low" level of confidence. A number of post-IPCC AR5 global climate modeling studies still show large discrepancy in the values of RF aci , ranging from ∼ −0.35 W•m −2 (Nazarenko et al., 2017), to −0.7 W•m −2 (Rotstayn et al., 2014) to −1.08 W•m −2 (Bauer et al., 2020), to −1.28 W•m −2 (Tonttila et al., 2015), to −1.54 W•m −2 (Bauer et al., 2020), and to −2.19 W•m −2 (Zhang et al., 2016). In order to confidently interpret past and accurately project future climate change, it is essential to reduce RF aci discrepancy among different models.RF aci depends strongly on the response of number concentrations of particles that can act as CCN to anthropogenic emissions (Albrecht, 1989;Twomey, 1977). The increase in cloud drops with particle number concentration (PNC) has been confirmed by many aircraft measurements (e.g., Ramanathan et al., 2001). PNC exhibits significant spatial and temporal variability due to the non-linear dependence of new particle formation and growth