This dataset contains hourly averaged 4-pi filter radiometer measurements of the rate constant of NO2 photolysis, j(JNO2) from both downwelling radiation (direct and diffuse radiation from the above atmosphere) and upwelling (diffuse radiation from the atmosphere below). Data are reported in s^-1. Measurements made at Auchencorth Moss (55ᵒ47’36” N, 3°14’41” W), for more information see http://www.auchencorth.ceh.ac.uk/. The instrument was situated in a clear section of the site, 3 m above ground level. The surface cover consisted of long grasses (~15 cm), often covered by frost/snow in the winter months (December - February). Data were collected between 2018/11/21 12:00 - 2019/11/20 23:00, using a j(NO2) 4-pi filter radiometer manufactured by Meteorologie Consult GmbH (MetCon) measuring broadband actinic flux between ~310-420 nm. The instrument was operated and data were collected by staff at the UK Centre for Ecology & Hydrology. Most of the missing data are between 2019/06/13-25, due to the instrument being relocated for calibration. Other incidences of missing data occur due to power cuts at the site and problems with the data collection. This data comprises the start of a long-term time series of filter radiometer measurements at Auchencorth Moss, in order to provide data access to evaluate j-values in current radiation models and parameterisations. The ongoing operation of the j(NO2) filter radiometer is supported by the UK Natural Environment Research Council award number NE/R016429/1 as part of the UK-SCAPE programme delivering National Capability.

The Auchencorth Moss Atmospheric Observatory was setup in 1995 to measure meteorology, trace gases, aerosols and their fluxes. It is (55ᵒ47’36” N, 3°14’41” W) an ombrotrophic peatland with an extensive fetch at an elevation of 270 m, lying 18 km SSW of Edinburgh, UK, and can be categorised as a transitional lowland raised bog. The site is grazed with < 1 sheep ha^-1. During 2000s the site activity has increased and was established in 2006 as EMEP (European Monitoring and Evaluation Program, Level 2/3) supersite for the UK. Long term monitoring is led by NERC CEH with contributions from other organisations/research institutes including Ricardo AEA, BureauVeritas, NPL, the University of Birmingham and University of Edinburgh. In April 2014 the site was awarded WMO GAW regional station (World Meteorological Orgamisation Global Atmospheric Watch). In 2017 the site joined the ICOS network (Integrated Carbon Observation System). Similar measurements are also made at nearby Easter Bush Field site by the same team. The meteorological measurements were initially made to assist with interpretation of the fluxes and as such weren't installed with the intention of providing WMO standard measurements.

The site was setup in 1995 to measure meteorology, trace gases, aerosols and their fluxes. It is (55ᵒ47’36” N, 3°14’41” W) an ombrotrophic peatland with an extensive fetch at an elevation of 270 m, lying 18 km SSW of Edinburgh, and can be categorised as a transitional lowland raised bog. The site is grazed with < 1 sheep ha^-1. During 2000s the site activity has increased and was established in 2006 as EMEP (European Monitoring and Evaluation Program, Level 2/3) supersite for the UK. Long term monitoring is led by NERC CEH with contributions from other organisations/research institutes including Ricardo AEA, BureauVeritas, NPL, the University of Birmingham and University of Edinburgh. In April 2014 the site was awarded WMO GAW regional station (World Meteorological Orgamisation Global Atmospheric Watch). In 2017 the site joined the ICOS network (Integrated Carbon Observation System). The meteorological measurements were initially made to assist with interpretation of the fluxes and as such weren't installed with the intention of providing WMO standard measurements but since 2014 we have been moving towards these standards as well as enhancing instrumentation. The dataset includes the following parameters at half hourly intervals, although not every variable is available from 1995 to 2016: -T_upper_Avg - initially used to estimate senisble heat fluxes, fine wire type-E thermocouple. -T_lower_Avg - initially used to estimate senisble heat fluxes, fine wire type-E thermocouple. -T_RHT_Avg - Temperature measured by a Vailsala relative humidity and temperature probe. -RH_RHT_Avg - Relative humidity measured by a Vailsala relative humidity and temperature probe. -P_Avg - atmospheric pressure at the sites elevation. -Tot_Solar_Avg - Total solar radiation measured by a Skye SKS1110. -PAR_Avg - Photosynthetically Averaged Radiation measured by a Skye SKP215. -NetRad_Avg - Net radiation, Kipp & Zonen NrLite. -Rainfall - tipping bucket rainfall. -SoilTavg - Average soil temperature from four type-E thermocouple probes. -Soil Heat Flux - calculated from two measurements of soil heat flux with Hukseflux HFP01 plates, corrected to surface flux using the standard formula. -Cs = Bd(Cd+fSWC.Cw) -SC = DTs.Cs.d/Dtime -SHF = Plate Average + SC -DTs = change in average soil temperature from start to end of measurement period (first and last two minutes); d = plate depth 0.2 m; Bd = soil bulk density, 100 kg m-3; cd = Specific Heat Dry Soil, 840J kg-1 K-1; fSWC = fractional soil water content, measured or 0.9; cw = Specific Capacilty Heat of Water, 4190 J kg-1 K-1; Dtime = measurement period, 1800 s -Soil Moisture - soil water content measured with TDR probes, campbell CS616 -WindSpd (measured) - measured by a Gill R3 then Windmaster sonic anemometer at 3.6 m -WindSpd 10 m - for most of the time period this is estimated from the turbulence measurements and 3.6 m windspeed but from 22/06/2016 a Gill Windsonic 2D anemeometer measures at 10 m -Wind Dir - measured by the sonic anemometer at 3.6 m -snow_depth_Avg - Campbell Scientific SR50A-L Sonic Ranging Sensor -Present Weather - Vaisala FD12P Present Weather Sensor -1 hr Past Weather - Vaisala FD12P Present Weather Sensor -Visibility - Vaisala FD12P Present Weather Sensor -Evaporation - to be estimated from the water-vapout flux measurements For modelling purposes gapfilled (variables with _gf suffixes) times series will be included, they are created by linearly initially interpolating across upto an hours missing data, filling with colocated measurements (adjusted by linear interpolation with the core data), filling with measurements from nearby sites (adjusted by linear interpolation with the core data). Ta_gf P_gf RH_gf Total_Solar_gf Rainfall_gf Windspd 10m_gf Wind Dir_gf