This dataset collection contains a number of observational datasets (mainly from the NERC funded contribution, but others too) of surface and boundary layer meteorological measurements collected on board the Icebreaker Oden during its voyage for the Arctic Cloud Summer Expedition (ACSE). ACSE was a collaboration between the University of Leeds, the University of Stockholm, and NOAA-CIRES (the Cooperative Institute for Research In Environmental Sciences). ACSE aimed to study the response of Arctic boundary layer cloud to changes in surface conditions in the Arctic Ocean as a working package of the larger Swedish-Russian-US Investigation of Climate, Cryosphere and Carbon interaction (SWERUS-C3) Expedition in Summer 2014. This expedition was a core component to the overall SWERUS-C3 programme and was supported by the Swedish Polar Research Secretariat. ACSE took place during a 3-month cruise of the Swedish Icebreaker Oden from Tromso, Norway to Barrow, Alaska and back over the summer of 2014. During this cruise ACSE scientists measured surface turbulent exchange, boundary layer structure, and cloud properties. Many of the measurements used remote sensing approaches - radar, lidar, and microwave radiometers - to retrieve vertical profiles of the dynamic and microphysical properties of the lower atmosphere and cloud. The UK participation of ACSE was funded by the Natural Environment Research Council (NERC, grant: NE/K011820/1) and involved instrumentation from the Atmospheric Measurement Facility of the UK's National Centre for Atmospheric Science (NCAS AMF). This dataset collection contains data mainy from the UK contribution with some additional data from other institutes also archived to complement the suite of meteorological measurements.

Atmosphere and Ocean components; Frequency: daily and monthly Variables Atmosphere daily: tas uas vas zg500 Variables Atmosphere monthly: cl clt evspsbl hfss hus prc prw rlds rlut rsds rsdt rsuscs rsutcs ta tauu ua va wap cli clw hfls hurs pr prsn psl rlus rlutcs rsdscs rsus rsut sfcWind tas tauv uas vas zg500 Variables Ocean daily: rsdssi sic sit snc snd snw tsice usi vsi Variables Ocean monthly: htovovrt mlotst msftmyz rsdssi sic sit sltovovrt snd so sos thetao tos tsice uo vo

ACCACIA was part of the NERC Arctic research programme. (NERC Reference: NE/I028858/1). ACCACIA aimed to improve our understanding of aerosol-cloud interactions in the Arctic, and the potential changes and feedbacks that may result from decreasing Arctic sea ice cover in the future. In situ measurements have been made during two field campaigns utilising ship-based measurements of surface aerosol sources and airborne measurements of aerosol and cloud microphysical properties, boundary layer dynamics, and radiative forcing. The observations have been complemented by modelling studies on a range of scales: from explicit aerosol and cloud microphysics process modelling, through large eddy simulation and mesoscale models, up to global climate models. This dataset contains sulphate and organic measurements from instruments onboard RRS James Clark Ross ship cruise identifier JR20130713 (JR288).

Reference state data derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis for the nudging experiments of the Stratospheric Nudging And Predictable Surface Impacts (SNAPSI) project. These reference states are used to nudge the stratosphere towards a specified evolution in the ensemble forecasts carried out by the SNAPSI project. The data contain: (a) lightly processed horizontal winds and temperatures from ERA5 spanning three case studies of sudden stratospheric warmings from 2018 to 2019 and (b) climatological horizontal winds and temperatures.