This dataset contains data from the MODIS (Moderate Resolution Imaging Spectroradiometer) cloud product, collocated to wind-advected ship locations and shipping emissions. Most importantly, it includes effective droplet radii, calculated droplet number concentration, liquid water path, and cloud optical depth for locations where clouds have been polluted by shipping and to either side of a ship trajectory. Cloud data in the trajectory is labelled with the variable name only, data on either side additionally with [property]_1 and [property]_3 for the western and eastern side, respectively. The data is ungridded and comes in the form of csv files. It covers the period of 2014-2019. The dataset is the product of three data sources: AIS data giving ship locations, ERA5 winds used to advect the emissions up to the time of the Aqua and Terra overpasses, as well as the level-2 cloud product MOD06. This data was collected for the study of shipping aerosols' effect on marine liquid clouds, in particular when the emissions do not produce a satellite-visible ship track, which could be hand-logged.

The ship based SYNOP messages measurements describe hourly observations from sea based stations (ships, rigs, platforms and moored buoys) distributed globally. The observations cumulate in around 10,000 reports a day, giving measurements of parameters such as wind speed and direction, maximum and minimum air temperature, sunshine duration, rainfall accumulation, and cloud type. The data are collected by observation stations worldwide and transmitted within the ship SYNOP message.

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.

Southern Ocean Atmospheric Photochemistry Experiment 2 (SOAPEX-2) is primarily an experiment to study atmospheric cleansing by free radicals in extremely clean and slightly perturbed tropospheric air and focuses on a field campaign carried out at Cape Grim, Tasmania in January-February 1999. The dataset contains concentrations of atmospheric constituents such as halocarbons, hydrocarbons, methane, nitric oxide, and carbon monoxide. This dataset is public. Oxidation of almost all trace gases released into the atmosphere is initiated by hydroxyl (OH) radicals, produced mainly from the action of near-UV light on ozone in the presence of water vapour. Increasing evidence suggests that the oxidative capacity of the troposphere has been perturbed in recent years due to the emission of gases such as methane, carbon monoxide, non-methane hydrocarbons and nitrogen oxides from man-made sources. These perturbations may be causing changes in the natural atmospheric composition, for instance increasing tropospheric levels of the greenhouse gas ozone, which has important consequences for climate and human health. It is also possible that the rates of oxidation of gases such as methane, and production of sulphate aerosols from the oxidation of sulphur dioxide, have been modified. Taken together a change in the oxidative capacity of the atmosphere has many consequences for the long-term stability of the Earth's climate. SOAPEX-2 builds upon the success of the original SOAPEX-I experiment conducted at Cape Grim in January/February 1995 which resulted in the publication of several papers to the literature on the relationship between concentrations of peroxy radicals and uv light levels in different NOx concentration regimes, and the consequences for ozone production and loss in the marine boundary layer. SOAPEX-2 is a more complete experiment with the addition of atmospheric measurements of key new species including hydroxyl, hydroperoxyl, halogen oxide and nitrate radicals, non methane hydrocarbons, speciated aldehydes, PAN and halocarbons. SOAPEX-2 involves four groups of tropospheric scientists from the UK and Australia, namely the Universities of East Anglia, Leeds and Leicester along with CSIRO (Commonwealth Scientific Research Organisation), Melbourne. The clean air photochemistry experiment is an essential prerequisite for experiments carried out in more polluted atmospheres. The data obtained is allowing rigorous testing of basic mechanisms which describe the behaviour of free radical concentrations at differing light levels, water vapour and nitrogen oxide concentrations, etc. The measurements performed in this project are expected to yield valuable information on chemical changes that are affecting the oxidative capacity of the global troposphere and, therefore, the rate at which the global atmosphere can cleanse itself of pollutants. The measurements are also highly relevant to the situation in more polluted atmospheres, where increased levels of confidence in our understanding of atmospheric chemistry is an essential prerequisite to any legislation designed to reduce regional and global pollution. The specific objectives of SOAPEX-2 are: * To quantitatively test fast photochemical theory in clean air. * To examine perturbations from the baseline situation in polluted continental air containing more complex mixtures of free radical sources and sinks * Investigation of the balance between tropospheric O3 production and destruction in differing NOx regimes * A test of instrumental performance * Testing of models used to simulate chemical processes in the lower atmosphere which are deficient in their description of boundary layer processes

This dataset contains methane, carbon dioxide and meteorological observations taken onboard the commercial freight ferry Finlandia Seaways on route between Rosyth (Scotland, UK: 56°1'21.611''N 3°26'21.558'' W) and Zeebrugge (Belgium : 51°21'16.96''N 3°10'34.645''E) 2015-2017 by the Centre for Ecology and hydrology (CEH). The measurements were taken using a Picarro CRDS model G1301, Vaisala WXT510 weather station and Garmin GPS. This data was collected as part of the Natural Environment Research Council (NERC) Greenhouse gAs Uk and Global Emissions (GAUGE) project (NE/K002449/1NERC) and NERC UK-SCAPE programme delivering National Capability (NE/R016429/1). The GAUGE project aimed to determine the magnitude, spatial distribution, and uncertainties of the UK's Greenhouse Gas budget using new and existing measurement networks and modelling approaches at a range of scales.