Abstract
Using the Weather Research and Forecasting model with chemistry module (WRF-Chem), Typhoon Nida (2016) was simulated to investigate the effects of anthropogenic gaseous emissions on the vortex system. Based on the Multi-resolution Emission Inventory for China (MEIC), three certain experiments were conducted: one with base-level emission intensity (CTRL), one with one-tenth the emission of SO2 (SO2_C), and one with one-tenth the emission of NH3 (NH3_C). Results show that the simulations reasonably reproduced the typhoon’s track and intensity, which were slightly sensitive to the anthropogenic gaseous emissions. When the typhoon was located over the ocean, a prolonged duration of raindrop growth and more precipitation occurred in CTRL run. The strongest updraft in CTRL is attributed to the maximum latent heating through water vapor condensation. During the landfalling period, larger (smaller) differential reflectivities in the main-core of the vortex were produced in NH3_C (SO2_C) run. Such opposite changes of raindrop size distributions may lead to stronger (weaker) rainfall intensity, and the ice-related microphysical processes and the relative humidity in low troposphere were two possible influential factors. Moreover, additional ten-member ensemble results in which white noise perturbations were added to the potential temperature field, indicated that the uncertainty of thermodynamic field in the current numerical model should not be ignored when exploring the impacts of aerosol on the microphysics and TC precipitation.
Highlights
The effects of anthropogenic aerosols on a deep convective system have been more investigated through the theoretical and observational methods, as aerosols can act as cloud condensation nuclei (CCN) or ice nuclei (IN), changing the in-cloud microphysical properties and thermal-related processes, thence modulating the surface precipitation induced by the convective system [1,2,3,4]
Typhoon Nida (2016) is simulated using the WRF-Chem (V3.8.1) model to investigate the effects of two kinds of precursor gaseous emission on the cloud microphysical properties before and after vortex landfalling
Three certain experiments with base-level emission intensity (CTRL), one-tenth the emission intensity of SO2 (SO2_C), and one-tenth the emission intensity of NH3 (NH3_C) are conducted and integrate 36 h with the finest grid-spacing of 4 km
Summary
The effects of anthropogenic aerosols on a deep convective system have been more investigated through the theoretical and observational methods, as aerosols can act as cloud condensation nuclei (CCN) or ice nuclei (IN), changing the in-cloud microphysical properties and thermal-related processes, thence modulating the surface precipitation induced by the convective system [1,2,3,4]. The main effect of aerosols on single deep convection has been better discussed and partially understood, it becomes more complicated and controversial when involving a tropical cyclone (TC). Various factors such as when and where the aerosols intrude into the vortex jointly determine the ultimate effects of anthropogenic aerosols on the track, intensity, structure, and precipitation of TCs [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. Most of the studies indicated that aerosols may have a slight effect on TC track [14,23,24,25]
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