Decreased aviation leads to increased ice crystal number and a positive radiative effect

This is the dataset to support our paper titled of "Decreased aviation leads to increased ice crystal number and a positive radiative effect". Travel restrictions in the wake of the COVID-19 pandemic resulted in an unprecedented decrease of 73% in global flight mileage in April-May 2020 compared to 2019. Here we examine the CALIPSO satellite observations and find a significant increase in ice crystal number concentrations (Ni) in cirrus clouds in the mid-latitudes of the Northern Hemisphere, which we attribute to an increase in homogeneous freezing when soot from aircraft emissions is reduced. A relatively small positive radiative effect of 21 mWm^-2 is estimated if a decrease in aircraft traffic continues. We infer from this analysis that the worldwide adoption of biofuel blending in aircraft fuels that lead to smaller soot emissions could lead to a significant change in the microphysical properties of cirrus clouds but a rather small positive radiative effect.

This dataset including three sections. The data are model output or input from climate simulations conducted with Community Earth System Model (CESM) version 1.2.2 with IMPACT aerosol module. The input files are default in the component set of "FC5" in the CESM model. The files in the dataset are described below:

Model code.zip: This tar file contains the sources code of the IMPACT aerosol module that we implemented as additional aerosol module embedded in the CESM model which is publicly available from NCAR repository. This code is used to create model output list in this dataset.

2020_act.rar: This tar file contains NetCDF out file of daily mean meteorological and aerosol fields during January and May in 2020 from the model based on the actual aviation activity in 2020.

2020_yes.rar: This tar file contains NetCDF out file of daily mean meteorological and aerosol fields during January and May in 2020 from the model assuming the aviation activity in 2020 is same as 2019.

Year_act.zip: This tar file contains NetCDF out file of annual mean meteorological and aerosol fields in the next five years from the model assuming the aviation restriction in 2020 last for the next five years.

Year_yes.zip: This tar file contains NetCDF out file of annual mean meteorological and aerosol fields in the next five years from the model assuming the aviation activity keeping same as 2019 in the next five years.

filght.zip: The FlightRadar24 commercial database of flight mileages from January 2019 to May 2020 at 1°x1° resolution, which were used as input file in our model.