The Methane and other greenhouse gases in the Artic - Measurements, process studies and Modelling (MAMM) project was a consortium as part of the NERC Artic Research Programme. This project used a range of expertise, from measurements of methane and its isotopes, and other greenhouse gases, through flux measurements to numerical analysis and modelling. Analysis of gas mixing ratios (concentrations), isotopic character, and source fluxes, both from the ground and aircraft. Both past and new measurements were modelled using a suite of techniques. Fluxes were implemented into the JULES land surface model. Atmospheric modelling, including trajectory and inverse modelling will improve understanding on the local/regional scale, placing the role of Arctic emissions in large scale global atmospheric change. The project was led by the University of Cambridge, and in association with the University of Manchester, University of East Anglia, Royal Holloway, University of London, Centre for Ecology and Hydrology and UK and International partners (Met Office, NILU, NOAA, etc).

How feasible is it to predict Arctic climate at seasonal-to-interannual timescales? As part of the APPOSITE project a multi-model ensemble prediction experiment was conducted in order to answer this question. The main goal of APPOSITE was to quantify the timescales on which Arctic climate is predictable. In order to achieve this, a coordinated set of idealised initial condition predictability experiments with seven general circulation models was conducted. This was the first intercomparison project designed to quantify the predictability of Arctic climate on seasonal to interannual timescales. Several different coupled climate models performed simulations for APPOSITE (see Doc below for Details of simulations submitted to the APPOSITE database). Six of these models followed the same experimental protocol (see Doc below for Control Simulations details and for Ensemble Predictions). One model, CanCM4 followed a slightly different protocol. The Model data output from the APPOSITE project are now archived at CEDA. The collection of model outputs (control and prediction) include data from: - Canadian Centre for Climate Modelling and Analysis (CanCM4) - ECHAM6-FESOM (E6F), run and developed by the Alfred Wegener Institute. - EC-Earth consortium (ec-earth_v2_3) - Geophysical Fluid Dynamics Laboratory (gfdlcm3) - Met Office (hadgem1-2) - Model for Interdisciplinary Research on Climate (MIROC5-2) - Max-Planck-Institut for Meteorologie (mpiesm) Although designed to address Arctic predictability, this data set could also be used to assess the predictability of other regions and modes of climate variability on these timescales, such as the El Nino Southern Oscillation. A paper describing the simulations for APPOSITE is in preparation to be submitted to the Geoscientific Model Development Journal. Note: These data do not correspond to a particular time period since the studies are all conducted in the model world. They are not predictions or attempts to simulate a particular period of time. So the dates in the files are completely arbitrary.

The AAST L3S Combined Surface Temperature (CST) products here primarily provide data on surface temperatures in the Arctic, across all Arctic surfaces, and their associated uncertainties. This dataset consists of CSTs with uncertainty estimates produced from the ATSR-2 and AATSR instruments on ESA's ERS-2 and Enivsat satellite respectively. The CSTs in this dataset are surface temperatures across ocean, snow/ice and land surfaces in the Arctic region, where the Arctic is defined as the area at, or north of, 60°N. Please note, the data here provide daily temperature data, not daily mean data as indicated by the dataset title. For more information see the paper linked under the details tab The data were produced for ATSR Satellite Dataset project, which was funded by The UK Dept. for Business, Energy & Industrial Strategy. Ice (and snow) Surface Temperatures (ISTs) and Land Surface Temperatures (LSTs) used to produce this dataset are sourced from the GlobTemperature Level 2 LST V2.1 product. Sea Surface Temperature (SSTs) are from the ATSR SST L2P V3.0 product. This version of the CST dataset is v2.1, with an earlier version previously provided via the GlobTemperature data portal. ATSR data was sourced from the GlobTemperature data portal and the CEDA archive. It consists of a complete set of CST and accompanying auxiliary (AUX) datafiles for the ATSR-2 and AATSR instruments separately. ATSR-2 data are available for 01/08/1995 - 22/06/2003 while AATSR data are available for 20/05/2002 – 08/04/2012.

This dataset contains lidar radial velocity and backscatter data for vertical stare mode from the NCAS AMF Halo Doppler lidar mounted on a motion stabilised platform on board the Swedish Icebreaker Oden during the joint Arctic Climate Across Scales (ACAS) and Microbiology-Ocean-Cloud Coupling in the High Arctic (MOCCHA) projects. Both projects are part of the Arctic Ocean 2018 (AO2018) expedition to the High Arctic. AO2018 took place in the Arctic from 1 August until 21 September 2018. These measurements were used to complement a suite of other observations taken during the expedition. Those of the UK contribution, as well as selected other data, are available within the associated data collection in the Centre for Environmental Data Analysis (CEDA) archives. Other cruise data may be available in the Bolin Centre for Climate Research MOCCHA/AO2018 holdings. Data were corrected for ship motion. The raw data and detailed instrument information can be obtained from the AMF archive at CEDA. The UK participation of MOCCHA was funded by the Natural Environment Research Council (NERC, grant: NE/R009686/1) and involved instrumentation from the Atmospheric Measurement Facility (AMF) of the UK's National Centre for Atmospheric Science (NCAS AMF).

ACCACIA was part of the NERC Arctic research programme. (NERC Reference: NE/I028858/1). This dataset collection contains atmospheric measurements from Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft, the British Antarctic Survey (BAS) Masin aircraft and from RRS James Clark Ross ship. This dataset collection also contains data from specially configured Met Office Unified Model runs. Data from corresponding ship measurements are also available. The climate of the Arctic is changing faster than that almost anywhere else on Earth, warming at a rate of twice the global average. This warming is accompanied by a rapid melting of the sea ice and a thinning of the ice that remains from year to year. The strong warming in the Arctic is due to several positive feedback processes, including a sea-ice albedo feedback (warmer conditions melt ice, lowering the average reflectivity of the mixed ice/ocean surface and thus absorbing more solar radiation, leading to increased ice melt and further lowering of the albedo) and several cloud feedbacks. There is a large uncertainty in models of the Arctic climate primarily because of the poor representation of physical processes within the models - particularly the representation of Arctic clouds, and due to some unique and particularly challenging conditions. A better understanding of cloud and aerosol processes in the Arctic is critical to understanding the polar atmosphere and developing more realistic climate models. To address this issue the ACCACIA project embarked on an intensive measurement campaign in the Svalbard archipelago near the margin of permanent Arctic sea ice cover resulting in a comprehensive dataset comprising of airborne in situ measurements of cloud microphysical properties, the vertical structure of the boundary layer and aerosol properties, and the fluxes of solar and infra red radiation above, below, and within cloud.

COBRA (impact of COmbined iodine and Bromine Release on the Arctic atmosphere) is a UK IPY (International Polar Year) consortium that aims to investigate the release mechanisms of iodine in the Arctic and the potential combined effects of iodine and bromine on its atmosphere. The team measured reactive inorganic halogens (BrO, IO, OIO, I2), O3, Hg, HOx, HCHO, NOx, VOCs and reactive halocarbons from temporary laboratories located on the eastern shore of Hudson Bay, north of Kuujjuarapik, during February-March 2008. Met balloons and O3 sondes were launched daily. COBRA set up an ice camp and flux chamber experiments ~500 m into the bay to directly measure halogen emissions and ozone deposition, and measured physical, chemical and biological characteristics of the sea-ice (and potentially of frost flowers) at different depths. The project is linked with OOTI, which carried out a simultaneous field experiment at Kuujjuarapik.

The dataset provides a Climate Data Record of Sea Ice Concentration (SIC) for the polar regions, derived from medium resolution passive microwave satellite data (AMSR-E and AMSR-2). It is processed with an algorithm using medium resolution (19 GHz and 37 GHz) imaging channels, and has been gridded at 25km grid spacing. This product was generated in the context of the ESA Climate Change Initiative Programme (ESA CCI) by the Sea Ice CCI (Sea_Ice_cci) project. The EUMETSAT OSI SAF contributed with access and re-use of part of its processing software and facilities. A SIC CDR at 50 km grid spacing is also available (doi:10.5285/70f611b0-ba82-48e6-9190-a62cf9f925f2) and a 12.5km product is in preparation.

The dataset provides a Climate Data Record of Sea Ice Concentration (SIC) for the polar regions, derived from medium resolution passive microwave satellite data (AMSR-E and AMSR-2). It is processed with an algorithm using coarse resolution (6 GHz and 37 GHz) imaging channels, and has been gridded at 50km grid spacing. This product was generated in the context of the ESA Climate Change Initiative Programme (ESA CCI) by the Sea_Ice_CCI project. The EUMETSAT OSI SAF contributed with access and re-use of part of its processing software and facilities. A SIC CDR at 25km grid spacing is also available (doi: 10.5285/c61bfe88-873b-44d8-9b0e-6a0ee884ad95) and a 12.5km product is in preparation.

COBRA (impact of COmbined iodine and Bromine Release on the Arctic atmosphere) is a UK IPY (International Polar Year) consortium that aims to investigate the release mechanisms of iodine in the Arctic and the potential combined effects of iodine and bromine on its atmosphere. The team measured reactive inorganic halogens (BrO, IO, OIO, I2), O3, Hg, HOx, HCHO, NOx, VOCs and reactive halocarbons from temporary laboratories located on the eastern shore of Hudson Bay, north of Kuujjuarapik, during February-March 2008. Met balloons and O3 sondes were launched daily. COBRA set up an ice camp and flux chamber experiments ~500 m into the bay to directly measure halogen emissions and ozone deposition, and measured physical, chemical and biological characteristics of the sea-ice (and potentially of frost flowers) at different depths. The project is linked with OOTI, which carried out a simultaneous field experiment at Kuujjuarapik. The dataset measurements come from the British Antartic Survey (BAS) Frost Flower Specific Surface Area (SSA) using a Brunauer-Emmett-Teller (BET) surface area measurement apparatus.

COBRA (impact of COmbined iodine and Bromine Release on the Arctic atmosphere) is a UK IPY (International Polar Year) consortium that aims to investigate the release mechanisms of iodine in the Arctic and the potential combined effects of iodine and bromine on its atmosphere. The team measured reactive inorganic halogens (BrO, IO, OIO, I2), O3, Hg, HOx, HCHO, NOx, VOCs and reactive halocarbons from temporary laboratories located on the eastern shore of Hudson Bay, north of Kuujjuarapik, during February-March 2008. Met balloons and O3 sondes were launched daily. COBRA set up an ice camp and flux chamber experiments ~500 m into the bay to directly measure halogen emissions and ozone deposition, and measured physical, chemical and biological characteristics of the sea-ice (and potentially of frost flowers) at different depths. The project is linked with OOTI, which carried out a simultaneous field experiment at Kuujjuarapik.