Decreasing trends of ammonia emissions over Europe seen from remote sensing and inverse modelling

The set consists of 5 files that constitute the main calculations of ammonia emissions over Europe for the years 2013-2020. 
The detailed description of variables follows:

1) PriorEmission.nc
- Pall: tensor of the size 240 x 200 x 12 x 8 (lat x lon x months x years) with ammonia prior emissions used in the study [ng/m2/s]

2) PosteriorEmission.nc
- Xall: tensor of the size 240 x 200 x 12 x 8 (lat x lon x months x years) with ammonia posterior emissions [ng/m2/s]

3) UncertaintyEmission.nc
- Uall: tensor of the size 240 x 200 x 12 x 8 (lat x lon x months x years) with uncertainty of posterior emissions [ng/m2/s]

4) FLEXPART.tar.gz
FLEXPART source-receptor relationships (SRRs) for ammonia. The directory contains respective directories for each year between 2013 and 2020. For each year, 365 or 366 (leap years) subdirectories are listed named as OUT_001, OUT_002 etc. which represent daily runs. In each of the directories, the classic FLEXPART output is found as explained in detail in Pisso et al. (2019), https://doi.org/10.5194/gmd-12-4955-2019. The file grid_time_**************.nc contains the FLEXPART SRRs named with the variable spec001_mr with size 1 x 72000 x 8 x 1 x 200 x 240 (nageclass x pointspec x time x height x latitude x longitude). Pointspec is 72000 because we release from -10E to 50E and from 25N to 75N to cover Europe every 0.5 degrees for 6 vertical levels that match the first 6 levels of the averaging kernel of the satellite product. This gives 100*120*6=72000. Time = 8 is the days that we go backward in time to account for all sources of ammonia given an average lifetime 12-24 hours. Longitude = 240 and latitude = 200 are the grid size defined for Europe as the emissions, namely from -10E to 50E and from 25N to 75N with a resolution of 0.25 degrees.

5) stations_vmodVSobs.mat 
- st_list: list of stations identifiers, 53 stations in total
- st_coord: stations coordinates [lot,lat]
- st_OBSdays: matrix of the size 53 x (366*8) with observations in daily resolution [ug/m3]
- st_ind_obs: logical matrix of the size 53 x (366*8) with indicators when each station provides observation (1) and when not (0)
- st_prior_vmod_days: matrix of the size 53 x (366*8) with calculated concentrations using model with prior emission [ug/m3]
- st_post_vmod_days: matrix of the size 53 x (366*8) with calculated concentrations using model with posterior emission [ug/m3]