Rapid growth and high cloud-forming potential of anthropogenic sulfate aerosol in a thermal power plant plume during COVID lockdown in India

The COVID lockdown presented an interesting opportunity to study the anthropogenic emissions from different sectors under relatively cleaner conditions in India. The complex interplays of power production, industry, and transport could be dissected due to the significantly reduced influence of the latter two emission sources. Here, based on measurements of cloud condensation nuclei (CCN) activity and chemical composition of atmospheric aerosols during the lockdown, we report an episodic event resulting from distinct meteorological conditions. This event was marked by rapid growth and high hygroscopicity of new aerosol particles formed in the SO2 plume from a large coal-fired power plant in Southern India. These sulfate-rich particles had high CCN activity and number concentration, indicating high cloud-forming potential. Examining the sensitivity of CCN properties under relatively clean conditions provides important new clues to delineate the contributions of different anthropogenic emission sectors and further to understand their perturbations of past and future climate forcing

Snapshots of the instantaneous phases (left panel) and the effective frequencies (right panel) for the homogeneous coupling when the intra-layer and inter-layer coupling strength are set to 0.42 and 0.5, respectively.

Snapshots of the instantaneous phases (left panel) and the effective frequencies (right panel) for the homogeneous coupling when the intra-layer and inter-layer coupling strength are set to 0.42 and 0.5, respectively.</p

Snapshots of the instantaneous phases (left panel) and the effective frequencies (right panel) for the super-linear correlation when the intra-layer and inter-layer coupling strength are set to 0.72 and 0.9, respectively.

Snapshots of the instantaneous phases (left panel) and the effective frequencies (right panel) for the super-linear correlation when the intra-layer and inter-layer coupling strength are set to 0.72 and 0.9, respectively.</p

The evolution of order parameter of the upper layer with the increase of inter-layer coupling strength for different values of <i>β</i>, (a) <i>β</i> = 0.5, (b) <i>β</i> = 2.0.

The intra-layer coupling strength μ is set to 0.8. Every data point in the two panels is the average of 2000 time steps after discarding the initial 2000 time steps.</p

Fig 12 -

The panels show the evolution of order parameters of the upper (a) and lower (b) layers with the increase of intra-layer coupling strength for a bilayer network composed of a scale-free network in the upper layer and a random network in the lower layer. The inter-layer coupling strength λ is set to 0.9. The natural frequency of each oscillator in the upper layer is randomly selected in the interval [-1, 1], and the natural frequency of oscillators with the same label in the lower layer changes synchronously.</p

Fig 9 -

(a) Synchronization and desynchronization diagrams of upper layers with different sizes. (b) Dependence of hysteresis loop width on network size. Other parameters are set to β = 1.5 and λ = 0.9.</p

Minimal data set.

This compressed file covers the data information of all pictures in the manuscript. (ZIP)</p

Fig 10 -

(a) The evolution of order parameter of the upper layer for the linear correlation. (b) and (c) show the evolutions of instantaneous frequencies and phases of the oscillators, respectively. (d) is the snapshot of instantaneous phases at λ = 1.0. The intra-layer coupling strength is set to 0.02. The red solid circles represent the oscillators with positive natural frequencies, while the oscillators with negative natural frequencies are described by blue hollow circles.</p

Order parameter of the upper layer is described by chromaticity in the λ − <i>μ</i> parameter plane.

The chromaticity ranges from 0 (black) to 1 (red). The greater its value, the higher the degree of phase coherence. The values of β in each panel are (a) β = 0, (b) β = 0.5, (c) β = 1, (d) β = 2, respectively.</p

Fig 11 -

The panels show the evolution of order parameter of the upper layer with the increase of intra-layer coupling strength for different network topologies, (a) both the upper and lower layers are random networks, (b) both the upper and lower layers are scale-free networks. The inter-layer coupling strength λ is set to 0.9. The natural frequency of each oscillator in the upper layer is randomly selected in the interval [-1, 1], and the natural frequency of oscillators with the same label in the lower layer changes synchronously. Because the upper and lower networks belong to the same type, the evolution of order parameters is almost the same. In order to avoid repetition, the evolution law of order parameter of the lower layer is omitted.</p