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  • This dataset comprises of model output from 25 runs (5 case studies, with 5 runs in each case study) of the Met Office Unified Model (MetUM) in realistic limited-area one-way nesting mode. The output data include values for model fields (e.g. temperature, humidity, winds, pressure) at model grid points over regularly spaced time intervals. These runs were used in a paper on convective aggregation: Holloway (2017, Journal of Advances in Modeling Earth Systems). All runs use the ""New Dynamics"" dynamical core, MetUM version 7.5, as described in Holloway (2017). The simulations are run with 4-km horizontal grid spacing. They all have a horizontal domain size of 20 degrees latitude X 20 degrees longitude (or 574 X 574 grid points, although the grid points in the outer 8 points on all sides, the ""rim"", should be discarded before analysis), with 70 vertical levels. All runs are initialised from operational analyses from the European Centre for Medium-Range Weather Forecasting (ECMWF) taken from actual cases. Lateral boundary conditions are comprised of 6-hourly ECMWF analyses, and the model is relaxed to these conditions in and near the outer rim as described in Holloway (2017). Sea surface temperatures (SST) are taken from the initial ECMWF analysis and are held constant in time for the 15 days (but are not constant in space). There are small land regions in four of the case studies which include an interactive land surface model. Each simulation was run for 15 days. The model output includes hourly model-level prognostic variables (temperature, specific humidity, pressure, wind components, liquid water, ice water) as well as some model-level increments to temperature and specific humidity. There are also many fields containing surface variables and fluxes (averaged over each hour or every 15 minutes). Note that the ""control"" simulations have slightly more available data than the other four runs in each of the five case studies. The five case studies are centred on the equator and occur between 2008 and 2010. See Holloway (2017) for further details: For each case, there are five runs: 1) control (interactive radiation, interactive surface fluxes) 2) constant radiative cooling run (radiative cooling over sea points is prescribed from domain-time mean of control run) 3) constant surface flux run (surface latent and sensible heat fluxes over sea points are prescribed from domain-time mean of control run) 4) constant radiative cooling and constant surface flux run (combination of 2 and 3 above) 5) no rain evaporation run (rain is prevented from evaporating in the atmosphere)"

  • High-resolution hindcasts (1979-2019) of summer climate over Antarctica using the UK Met Office Unified Model (MetUM) and HIRHAM5 were conducted at the British Antarctic Survey and Danish Meteorological Institute, respectively. The hindcasts are conducted for summer 1979-2018, i.e., from December 1979 to February 2019, for December, January, February (DJF). This dataset consists of near-surface temperature output from these hindcasts at a temporal resolution of every 3 hrs. The hindcasts are contributions to the COordinated Regional Downscaling EXperiment (CORDEX) project. Both models are run over Antarctic CORDEX domains, which encompass all of Antarctica and some of the surrounding ocean, at a horizontal grid spacing of around 12 km. The near-surface temperatures are used to estimate regional surface melt "potential" over Antarctic ice shelves as a function of summertime temperature extremes and identify regions of potentially enhanced "hotspots" of melt potential based on the occurrence (and magnitude) of various temperatures. Funding was provided by the European Union''s Horizon 2020 research and innovation framework programme under Grant agreement no. 101003590 (PolarRES)

  • Firstly, simulations of surface pressure, 10 m zonal wind speed, 10 m meridional wind speed, 1.5 m air temperature, and 1.5 m specific humidity over the Larsen C Ice Shelf for the duration of the OFCAP (Orographic Flows and the Climate of the Antarctic Peninsula) field campaign from 8 January 2011 to 8 February 2011 were conducted using the regional atmosphere-only configuration of the Met Office Unified Model (MetUM) at 4 km grid spacing by the British Antarctic Survey, Cambridge, UK. The datasets produced were necessary to compare with corresponding measurements derived from five Automatic Weather Stations (AWSs) distributed across the Larsen C Ice Shelf to evaluate the main biases in the simulations. Secondly, further MetUM simulations at grid spacings of 1.5 and 0.5 km of a foehn wind event that occurred on 27 January 2011 were conducted, with the datasets produced used to compare results at 4, 1.5 and 0.5 km grid spacing and examine whether the added benefit of sub-kilometre scale grid spacing improves the model representation of foehn winds. Thirdly, a simulation of the foehn wind event on 27 January 2011 using the MetUM at 4 km grid spacing but replacing the ''sharp'' stability function used by the boundary layer scheme with the ''long-tail'' stability function were also conducted, with the dataset produced used to examine the impact of stronger turbulent mixing for statically stable conditions on the model representation of foehn winds. Funding was provided by NERC grant NE/G014124/1.

  • High-resolution simulations of extreme warm temperature events over South Georgia Islands using the UK Met Office Unified Model (MetUM) were conducted at the British Antarctic Survey. The simulations are conducted for the period 1 to 17 January 1991, which included an event in which the temperature at Signy station peaked at 17.4 degrees Celsius on 13 January 1991, as well as a series of consecutive warm events preceding this. The dataset consists of 1) 10 m zonal wind, 10 m meridional wind, 1.5 m temperature, 1.5 m dew point temperature, 1.5 m relative humidity, and mean sea level pressure at a temporal resolution of every 1 hr for the period 1 to 17 January, 2) zonal wind, meridional wind, vertical wind, and potential temperature on model levels at 00UTC 13 January, and 3) rainfall rate at 00 UTC 13 January (averaged over a 3-hr period). The MetUM is run over a domain that includes South Orkney Islands and the surrounding ocean, which comprises 120 x 120 grid points at a grid spacing of 1 km. The model output is used to investigate the detailed influence of South Orkney Islands orography on temperature, precipitation, and winds, and in particular the importance of foehn events in producing extreme warm temperatures at Signy station. Funding: 1) Core funding from the Natural Environment Research Council (NERC) to the Atmosphere, Ice and Climate Programme of British Antarctic Survey (BAS). 2) NERC National Capability International grant SURface FluxEs In AnTarctica (NE/X009319/1). 3) European Union''s Horizon 2020 research and innovation framework programme under Grant agreement no. 101003590 (PolarRES).