This collection of data forms the Permafrost Climate Research Data Package (CRDP v2), which comprises the Version 3.0 Permafrost data products from the European Space Agency's (ESA) Climate Change Initiative (CCI) Permafrost project. Data products include Ground Temperature, Active Layer Thickness and Permafrost Extent for the Northern Hemisphere (north of 30°) for the period 1997-2019. They are derived from a thermal model driven and constrained by satellite data. Gridded products are released in annual files, covering the start to the end of the Julian year. This corresponds to average annual ground temperatures, as well as the maximum depth of seasonal thaw, which corresponds to the active layer thickness.

This dataset contains v4.0 permafrost ground temperature data produced as part of the European Space Agency's (ESA) Climate Change Initiative (CCI) Permafrost project. It forms part of the third version of their Climate Research Data Package (CRDP v3). It is derived from a thermal model driven and constrained by satellite data. CRDPv3 covers the years from 1997 to 2021. Grid products of CDRP v3 are released in annual files, covering the start to the end of the Julian year. This corresponds to average annual ground temperatures and is provided for specific depths (surface, 1m, 2m, 5m , 10m). Case A: It covers the Northern Hemisphere (north of 30°) for the period 2003-2021 based on MODIS Land Surface temperature merged with downscaled ERA5 reanalysis near-surface air temperature data. Case B: It covers the Northern Hemisphere (north of 30°) for the period 1997-2002 based on downscaled ERA5 reanalysis near-surface air temperature data which are bias-corrected with the Case A product for the overlap period 2003-2021 using a pixel-specific statistics for each day of the year.

This dataset contains the output of three fully coupled seasonal forecast experiments performed as a case study of summer 2022, using the same model setup as ECWMF seasonal forecast system 5 (SEAS5), as presented in the paper Patterson, M., Befort, D., O'Reilly, C., Weisheimer, A. "The ECMWF SEAS5 seasonal forecast of the hot and dry European summer of 2022" Quarterly Journal of the Royal Meteorological Society, https://doi.org/10.1002/qj.4851 ​ ​The three experiments are: 1) CONTROL A coupled hindcast ensemble with perturbed initial conditions for the 2022 summer, identical to the operational hindcast with the start date 1st May, but for 200 members rather than 51. 2) ATMOS-IC-2022 Similar to the CONTROL with 2022 initial conditions for the atmosphere and land surface and 2022 concentrations of carbon dioxide, but with ocean initial conditions taken from a year in 1981-2021. Five perturbed initial condition states taken for each year hence, 41 x 5 = 205 members. 3) OCEAN-IC-2022 Similar to CONTROL with 2022 initial conditions for the ocean, but with initial atmosphere, land surface and carbon dioxide conditions taken from a year in 1981-2021. Like ATMOS-IC-2022, 41 x 5 = 205 members. ​ The OCEAN-IC-2022 experiments were performed by taking the setup for hindcasts 1981-2021 and swapping the ocean initial conditions for 2022. The time dimension therefore corresponds to the time of the base hindcast taken from 1981-2021. Conversely, the ATMOS-IC-2022 were performed by running the 2022 hindcast and swapping the ocean initial conditions for other years. The time dimension for ATMOS-IC-2022 therefore is identical for all members. Hindcasts are all started on 1st May and run for four months. The data stored is monthly-mean output from the experiments with the following directory structure for variables on pressure levels: [experiment_name]/pl/[experiment_name]_[ensemble_member_number]_pl_[level]hPa.nc and for those on a single level or at the surface: [experiment_name]/sfc/[experiment_name]_[ensemble_member_number]_sfc.nc The files each contain multiple variables. Variables on pressure levels are stored at 700hPa,500hPa and 250hPa levels. Pressure level variables stored are: u (zonal wind), v (meridional wind), t (air temperature), z (geopotential), q (specific humidity) Surface variables stored are: sst (sea surface temperature), swvl1 (Volumetric soil water layer 1), swvl2 (Volumetric soil water layer 2), swvl3 (Volumetric soil water layer 3), swvl4 (Volumetric soil water layer 4), msl (air pressure at mean sea level), t2m (2m temperature), tprate (mean total precipitation rate).

The UK daily weather observation data contain meteorological values measured on a 24 hour time scale. The measurements of sunshine duration, concrete state, snow depth, fresh snow depth, and days of snow, hail, thunder and gail were attained by observation stations operated by the Met Office across the UK operated and transmitted within DLY3208, NCM, AWSDLY and SYNOP messages. The data span from 1887 to 2023. For details of observations see the relevant sections of the MIDAS User Guide linked from this record for the various message types. This version supersedes the previous version of this dataset and a change log is available in the archive, and in the linked documentation for this record, detailing the differences between this version and the previous version. The change logs detail new, replaced and removed data. These include the addition of data for calendar year 2023. This dataset is part of the Midas-open dataset collection made available by the Met Office under the UK Open Government Licence, containing only UK mainland land surface observations owned or operated by the Met Office. It is a subset of the fuller, restricted Met Office Integrated Data Archive System (MIDAS) Land and Marine Surface Stations dataset, also available through the Centre for Environmental Data Analysis - see the related dataset section on this record. Currently this represents approximately 95% of available daily weather observations within the full MIDAS collection.

Aerosol number-size distribution data collected by the University of Manchester at the Kiva-2 site at Langmuir ground station in the Magdalena Mountains, New Mexico, between July and August 2022 as part of the Deep Convective Microphysics Experiment (DCMEX) project. Instrument supplied by the National Centre for Atmospheric Science - Atmospheric Measurement and Observation Facility (NCAS-AMOF). This version 1.0 dataset contains the aerosol size distribution data from the Kiva-2 site at Langmuir Laboratory. A GRIMM Optical Particle Counter (OPC) model 1.108 was installed at the Langmuir Laboratory Kiva-2 site (33.97495N, 107.18100W, ~3255 m). The GRIMM OPC was supported by AMOF and the University of Manchester scientists.

The World Climate Research Program (WCRP) Coupled Model Intercomparison Project, Phase 6 Plus (CMIP6Plus) data from the Met Office Hadley Centre (MOHC) HadGEM3-GC31-LL model output for the "historical forcing, but with pre-industrial aerosol emissions" (hist-piAer) experiment. These are available at the following frequency: APday. The runs included the ensemble member: f2023-r1i1p1f3.

The UK hourly rainfall data contain the rainfall amount (and duration from tilting syphon gauges) during the hour (or hours) ending at the specified time. The data also contains precipitation amounts, however precipitation measured over 24 hours are not stored. Over time a range of rain gauges have been used - see the linked MIDAS User Guide for further details. This version supersedes the previous version of this dataset and a change log is available in the archive, and in the linked documentation for this record, detailing the differences between this version and the previous version. The change logs detail new, replaced and removed data. The data were collected by observation stations operated by the Met Office across the UK and transmitted within the following message types: NCM, AWSHRLY, DLY3208, SREW and SSER. The data spans from 1915 to 2023. This dataset is part of the Midas-open dataset collection made available by the Met Office under the UK Open Government Licence, containing only UK mainland land surface observations owned or operated by the Met Office. It is a subset of the fuller, restricted Met Office Integrated Data Archive System (MIDAS) Land and Marine Surface Stations dataset, also available through the Centre for Environmental Data Analysis - see the related dataset section on this record. A large proportion of the UK raingauge observing network (associated with WAHRAIN, WADRAIN and WAMRAIN for hourly, daily and monthly rainfall measurements respectively) is operated by other agencies beyond the Met Office, and are consequently currently excluded from the Midas-open dataset.

The UK hourly weather observation data contain meteorological values measured on an hourly time scale. The measurements of the concrete state, wind speed and direction, cloud type and amount, visibility, and temperature were recorded by observation stations operated by the Met Office across the UK and transmitted within SYNOP, DLY3208, AWSHRLY and NCM messages. The sunshine duration measurements were transmitted in the HSUN3445 message. The data spans from 1875 to 2023. This version supersedes the previous version of this dataset and a change log is available in the archive, and in the linked documentation for this record, detailing the differences between this version and the previous version. The change logs detail new, replaced and removed data. These include the addition of data for calendar year 2023. For details on observing practice see the message type information in the MIDAS User Guide linked from this record and relevant sections for parameter types. This dataset is part of the Midas-open dataset collection made available by the Met Office under the UK Open Government Licence, containing only UK mainland land surface observations owned or operated by Met Office. It is a subset of the fuller, restricted Met Office Integrated Data Archive System (MIDAS) Land and Marine Surface Stations dataset, also available through the Centre for Environmental Data Analysis - see the related dataset section on this record. Note, METAR message types are not included in the Open version of this dataset. Those data may be accessed via the full MIDAS hourly weather data.

The UK daily temperature data contain maximum and minimum temperatures (air, grass and concrete slab) measured over a period of up to 24 hours. The measurements were recorded by observation stations operated by the Met Office across the UK and transmitted within NCM, DLY3208 or AWSDLY messages. The data span from 1853 to 2023. For details on measurement techniques, including calibration information and changes in measurements, see section 5.2 of the MIDAS User Guide linked to from this record. Soil temperature data may be found in the UK soil temperature datasets linked from this record. This version supersedes the previous version of this dataset and a change log is available in the archive, and in the linked documentation for this record, detailing the differences between this version and the previous version. The change logs detail new, replaced and removed data. These include the addition of data for calendar year 2023. This dataset is part of the Midas-open dataset collection made available by the Met Office under the UK Open Government Licence, containing only UK mainland land surface observations owned or operated by the Met Office. It is a subset of the fuller, restricted Met Office Integrated Data Archive System (MIDAS) Land and Marine Surface Stations dataset, also available through the Centre for Environmental Data Analysis - see the related dataset section on this record. Currently this represents approximately 95% of available daily temperature observations within the full MIDAS collection.

The UK daily rainfall data contain rainfall accumulation and precipitation amounts over a 24 hour period. The data were collected by observation stations operated by the Met Office across the UK and transmitted within the following message types: NCM, AWSDLY, DLY3208 and SSER. The data spans from 1853 to 2023. Over time a range of rain gauges have been used - see section 5.6 and the relevant message type information in the linked MIDAS User Guide for further details. This version supersedes the previous version (202308) of this dataset and a change log is available in the archive, and in the linked documentation for this record, detailing the differences between this version and the previous version. The change logs detail new, replaced and removed data. These include the addition of data for calendar year 2023. This dataset is part of the Midas-open dataset collection made available by the Met Office under the UK Open Government Licence, containing only UK mainland land surface observations owned or operated by Met Office. It is a subset of the fuller, restricted Met Office Integrated Data Archive System (MIDAS) Land and Marine Surface Stations dataset, also available through the Centre for Environmental Data Analysis - see the related dataset section on this record. A large proportion of the UK raingauge observing network (associated with WAHRAIN, WADRAIN and WAMRAIN for hourly, daily and monthly rainfall measurements respectively) is operated by other agencies beyond the Met Office, and are consequently currently excluded from the Midas-open dataset. Currently this represents approximately 13% of available daily rainfall observations within the full MIDAS collection.