DOI: 10.5285/9536f22e-37dd-4f37-948b-e19c70e15292
title: Polar Weather Research and Forecasting (WRF) simulation of West Antarctic climate, summer 1980-2015

description: High-resolution simulation of summer climate over West Antarctica using the Polar-optimised version of the Weather Research and Forecasting (WRF) model conducted at British Antarctic Survey, Cambridge, UK. Runs are conducted for summer (January-centred) 1980-2015, i.e. from December 1979 to February 2015, for December, January and February (DJF). Experiments were carried out for the NERC West Antarctic Grant (NE/K00445X/1) during 2014-2017. The project is aimed at understanding the variability and climatology over the West Antarctic ice sheet and ice shelves as well as to project the future change over the twenty-first century.
The model outer domain encompasses the West Antarctic ice sheet and a large part of the surrounding ocean at 45 km horizontal grid spacing, and the nested (one-way) inner domain covers the Amundsen Sea Embayment at 15 km grid spacing. The model uses vertical eta coordinates with both domains have a model top of 50 hPa, and 30 vertical levels.
description: The model uses the recommended configuration of version 3.5.1 of the polar modified Weather Research and Forecasting model (known as "Polar WRF"; Bromwich et al., 2013) for West Antarctica described by Deb et al. (2016). The model physics employed are - the WRF Single Moment 5-Class (WSM5) cloud microphysics scheme, the Mellor-Yamada-Janjic (MYJ) boundary layer scheme, the Rapid Radiative Transfer Model for General Circulation Models (RRTMG), and the Noah land surface model. 
	The model outer domain encompasses the West Antarctic ice sheet and a large part of the surrounding ocean at 45 km horizontal grid spacing, and the nested (one-way) inner domain covers the Amundsen Sea Embayment at 15 km grid spacing. The model uses a model top of 50 hPa, and 30 vertical levels for both domains. The model employs spectral nudging (outer domain and wave numbers 1-5 only, from approximately 1.5 km to the model top), high-resolution orography based on the Bedmap2 dataset (Fretwell et al., 2013), and meteorological forcing from ERA-Interim reanalysis (Dee et al., 2011). Additionally, the surface boundary forcing of the model includes daily satellite observations of sea ice concentration (based on the 25 km resolution Bootstrap data set; Comiso, 2000) and sea surface temperature (based on the 0.25° Advanced Very High Resolution Radiometer (AVHRR) data set; Casey et al., 2010). The hindcast was produced by running separate simulations for each of the summer months from December 1979 to February 2015 (with 24 hr spin up). 
	Python 2.7.3 version was used for post-processing. The netCDF4 library was used to extract the hourly model data and produce the monthly means (using the NumPy Python library). The monthly means were stored in binary npz format which can be easily loaded on Python.
The monthly mean of 2 m temperature (T2), 10 m wind (grid X directed (U10) and grid Y directed (V10) wind), surface pressure (PSFC) and total precipitation (RAINNC) are stored in files with extension *_monthly_mean_DJF_1980_2015_dom02.npz. The variables vDec, vJan and vFeb store monthly means for December (1979-2014), January (1980-2015) and February (1980-2015) respectively.

List of files:
T2_monthly_mean_DJF_1980_2015_dom02.npz (2 m temperature, unit: K)
RAINNC_monthly_mean_DJF_1980_2015_dom02.npz (total precipitation, unit: mm)
V10_monthly_mean_DJF_1980_2015_dom02.npz (10 m grid Y directed wind, unit: m/s)
U10_monthly_mean_DJF_1980_2015_dom02.npz (10 m grid X directed wind, unit: m/s)
PSFC_monthly_mean_DJF_1980_2015_dom02.npz (surface pressure, unit: Pa)
The variable 'u10asld' in file 'SAMpos_exclStrENSO_dailyOP_DJF_1980_2015_dom02.npz' contains the daily grid X directed wind (unit: m/s) for summer months of all SAM positive years. Similarly, the variable 't2maxasld' in file 'SAMpos_exclStrENSO_dailyOP_DJF_1980_2015_dom02.npz' contains the daily 2 m temperature maximum (unit: K) for summer months of all SAM positive years excluding strong ENSO years.
Domain configuration:
The netCDF3 file 'WRF_domain_d02_metadata.nc' contains the coordinate variables xlong (longitude) and xlat (latitude) for the inner domain grid points. The file also contains global attributes containing the projection, grid configuration and model configuration metadata for the inner (15 km) model domain. This file was created by extracting the first time step of variables XLONG and XLAT, and all the global attributes, from WRF output file wrfout_d02_1998-01-31_00:00:00 using Python 2.7.12 with Iris 1.11.0 (http://scitools.org.uk/iris/docs/v1.11.0/index.html). Similarly, 'WRF_domain_d01_metadata.nc' contains the domain data for the outer domain.
description: The model outer domain encompasses the West Antarctic ice sheet and a large part of the surrounding ocean with 64 x 61 grid points at 45 km horizontal grid spacing centred on the point 72.7°S, 118.5°W, and the nested (one-way) inner domain covers the Amundsen Sea Embayment with 132 x 111 grid points at 15 km grid spacing centred on the point 73.5°S, 118.4°W. Both grids are defined on a polar stereographic projection with straight vertical longitude 120.5°W and latitude of true scale 70°S. The inner domain has longitude extremes at 164.1°W and 73.1°W, and latitude extremes at 81.1°S and 64.3°S (though the grid, being rectangular in polar stereographic space, does not completely fill this extent). In the vertical, both domains extend from the surface to 50 hPa, with 30 vertical levels.
        Runs are conducted for summer (January-centred) 1980-2015 i.e., for December (1979-2014), January (1980-2015) and February (1980-2015).
        Model output for the inner domain (15 km horizontal resolution) are processed and stored in npz format which can be easily loaded on Python. The dataset includes a README.txt file that includes example Python/NumPy code illustrating how the data can be read.
        NPZ is a file format by numpy that provides storage of array data using gzip compression. This format supports data of any shape. However, the npz format does not provide streaming; all data is read/written at once. Further, there is no support for metadata (data is described below and in the dataset's README.txt file).