“It is the first time annual N deposition data has been released at this resolution over this number of years in the UK, using a consistent methodology throughout. The consistent methodology means that the latest knowledge for emission distributions across the whole period can be used, with the latest emission factors used to back cast the entire time series at a high spatial resolution. In addition, model parameters and calibrations for each time step use the same most up-to-date model version. It is envisaged that studying the effects of N deposition on the environment can be aided by such an increase in detail, as suggested by Hallsworth et al. (2010)” 

 2. The authors have added the following text to the paragraph that ends on L38;  

The following text was added to L48 to clarify this point, also covering comments made by Reviewer #1 on the same topic: 

“It is the first time annual N deposition data has been released at this resolution over this number of years in the UK, using a consistent methodology throughout. The consistent methodology means that the latest knowledge for emission distributions across the whole period can be used, with the latest emission factors used to back cast the entire time series at a high spatial resolution. In addition, model parameters and calibrations for each time step use the same most up-to-date model version. It is envisaged that studying the effects of N deposition on the environment can be aided by such an increase in detail, as suggested by Hallsworth et al. (2010)” 

Re contrastive analyses, the authors agree some context regarding the performance of the correlations is important, and the following text has been added after L260; 

We agree, and our changes also respond to similar queries from Reviewer #1. 

 For context, Carslaw (2011) undertook a model inter-comparison exercise for the UK Department for Environment, Food & Rural Affairs (Defra), with a specific focus on deposition from the CMAQ, EMEP4UK, FRAME, HARM and NAME models. Respectively, those models (at the time) were run at resolutions of 12 km, 5 km, 5 km, 10 km and 12 km. The models reviewed by Carslaw (2011) performed with a similar correlation coefficient (‘r’) for all N compounds, aside from NH4 and NO3 in precipitation, for which the 2017 model run in this study had a weaker correlation (0.51 – 0.61 compared to 0.7 – 0.88). 

There may be some misunderstanding by the reviewer, but Table 4 displays evaluations for the latest modelled year, 2017, while Table 5 displays the exact same evaluation but for 3 other selected years (1990, 1999 and 2008) in an attempt to draw out some statistical conclusions for the model performance across the time series, instead of just the latest year. In table 5, the amount of data points for the N form has been added.  

 “From the perspective of model sensitivity and/or uncertainty, there were no further model runs made with adjusted emissions inputs or adjusted deposition parameters within this study. However, Aleksankina et al. (2018) employed statistical techniques to obtain uncertainty estimates of the FRAME model, representing model runs with a ±40 % variation range for the UK emissions of SO2, NOx, and NH3. They found that the sensitivity of concentrations of primary precursors NOx and NH3, plus the deposition of N, were dominated by emissions. However, concentrations of secondary species such as particulate NO−3 and NH+4 were more geographically dependent.”  

 […]“, while Fig 3. shows the spatial distribution of the observation sites with measurements in 1990, 1999, 2008 and 2017 (the first year of measurements for each observation network is noted in Table 3). It is believed that this is the first time model evaluation for gases, aerosols and concentration in precipitation has been done across a long time series at multiple points in time on the same dataset.” 

“The two wet deposition surfaces in Fig. 7 exhibit smoother spatial distributions and less heterogeneity (compared to dry deposition), a reflection of the precipitation surface across the UK, and constitute ~67% of the total deposition. Wet deposition is nearly always of a longer range than dry deposition, due to the transport in more elevated atmospheric layers, but some enhanced local washout around strong sources is also represented. This longer range transport acts as a smoothing effect on the deposition field due to the increased distance from the emission source.” 

Would appreciate help here, Fig 6 (now fig 8) shows total N in kt across the years across all 4 types, while Fig 8 (now Fig 10) is the % of total N dep that each of the four forms is.  

A new figure, Figure 1, has been produced to show the data created in the European context with lines of latitude and longitude. However, the mapped figures are produced in British National Grid, a projected coordinate system specific to the United Kingdom, which differs to the World Geodetic geographic coordinate system (commonly known as ‘Lat-Long’) in that it projects latitude and longitude onto a two-dimensional surface. We feel that it is correct to show the results in the coordinate system in which they were made and in which they are going to be most useful for further analysis, and which are relevant to the study area. 

The following text is appended to L58; 

“Fig. 1 shows the 1km x 1km UK model domain - which captures both the UK and the Republic of Ireland to allow for high resolution modelling of the closest neighbouring territory - in the European context. Further figures in this work di not show lines of latitude or longitude.”