This dataset contains 12 files with radiative kernels generated from the HadGEM2-ES climate model.

The radiative kernels describe the differential change in either top of atmosphere (TOA) or surface radiation to a small perturbation in a climate state variable at a particular layer in the atmosphere. Kernels are produced for net fluxes, and also for shortwave (SW) and longwave (LW) fluxes.

The units of all 4-dimensional (time, height, latitude, longitude) kernels are watts per metre squared per kelvin per 100 hPa. Units of 3-dimensional variables are watts per metre squared per kelvin for surface temperature and watts per metre squared per percent for surface albedo.

In all cases, the time dimension is length 12 (one entry for each month), latitude is 145 grid points and longitude 192 grid points, matching the HadGEM2 native grid.

38-level kernels are output on native HadGEM2 model levels and contain a p_mean and p_thickness variable describing the pressure at the centre of each level, and the thickness of the level (in pressure coordinates). 17-level kernels are derived from climate model output on standard CMIP5 pressure levels (10, 20, 30, 50, 70, 100, 150, 200, 250, 300, 400, 500, 600, 700, 850, 925 and 1000 hPa). 17-level kernels contain regions of zero contribution near the surface, as the surface pressure is less than the lowest CMIP5 pressure levels. To apply to model output, the kernel needs to be un-normalised, by multiplying each layer's radiative effect by 10000/p_thickness. For 17-level kernels, the layer thickness is constant and is not supplied.

Surface albedo and surface temperature kernels are contained in the 38-level kernel files.

Files are named HadGEM2_<spectrum>_<location>_L<nn>.nc and are in netCDF format.
  spectrum: net, lw or sw
  location: TOA or surf (surface)
  nn: 17 or 38, number of levels in the kernel

Variable names (for <net> files):
tsurf          Radiative flux change for a 1 K perturbation in surface temperature.
tsurf_cs:      Radiative flux change for a 1 K perturbation in surface temperature assuming cloud-free skies.
ta:            Radiative flux change for a 1 K perturbation in a level.
ta_cs:         Radiative flux change for a 1 K perturbation in a level assuming cloud-free skies.
q:             Radiative flux change for an increase in specific humidity that preserves relative humidity for a 1 K perturbation in a level.
q_cs:          Radiative flux change for an increase in specific humidity that preserves relative humidity for a 1 K perturbation in a level assuming cloud-free skies.
albedo:        Radiative flux change for a 1 % perturbation (absolute) in surface albedo.
albedo_cs:     Radiative flux change for a 1 % perturbation (absolute) in surface albedo assuming cloud-free skies.
p_mean:        Pressure at layer centres in L38 kernels.
p_thickness:   Thickness of layers in L38 kernels.

In SW and LW kernel files, the variables are named, for example,
q_sw (for SW specific humidity),
q_sw_cs (for SW specific humidity assuming cloud-free skies),
q_lw (for LW specific humidity),
q_lw_cs (for LW specific humidity assuming cloud-free skies),
and so on.