v1.8

• Added new tool to sample tropopause data.
• Added tropopause water vapor to meteo tools.
• Added stride for particle output.
• Added water vapor to tropo tool.
• Revised and added test for decay module.
• Added GPU code.
• Revised example.
• Added fix for polar latitudes to PV code.
• Added OpenMP parallelization to tropopause code.
• Added tool to create tropopause climatology.
• Modified calculation of lapse rate.
• Faster calculation of geopotential heights and tropopause.
• Use virtual temperature to calculate geopotential heights.
• Revised smoothing filter in met_geopot.
• Added initial check of particle position.
• Added vertical interpolation to met_prof and met_zm.
• Added split based on kernel function to atm_split.
• Removed tools smago and wind.
• Added more flexible scheme for meteo filenames.
• Changed parameters of some tools.
• Added spatial interpolation to met_map.
• Added number of particles to grid output.
• Removed calculation of tracer conservation errors from atm_dist tool.
• Added filters to atm_stat tool.
• Removed ensemble filter from atm_dist tool.
• Update air parcel statistics tool.
• Renamed some of the tools for consistency.
• Added check that meteo grids are consistent.
• Added periodic boundary conditions in met_sample.
• Update PV code.
• Update GSL and netCDF libraries.
• New control parameter MET_DT_OUT.
• New tool "invert" to estimate volcanic emissions.
• Added day2doy and doy2day utilities.
• Added code to calculate dynamical tropopause.
• Revised time step control.
• Modifications of grid and profile output.
• Revised downsampling code.
• Enabled separate calculation of horizontal and vertical diffusion.