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Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol–cloud interactions

Remotely piloted aircraft systems (RPAS), commonly called UAVs, are used in atmospheric science for in situ measurements. The presented work shows wind measurements from a five-hole probe on an RPAS. Comparisons with other instruments (sonic anemometer and cloud radar) show good agreement, validating the RPAS measurements. In situ vertical wind measurements at cloud base are highlighted because they are a major parameter needed for simulating aerosol–cloud interactions, though rarely collected.

Brief communication: Unabated wastage of the Juneau and Stikine icefields (southeast Alaska) in the early 21^st century

Two recent studies suggested a slowdown in mass loss after 2000 of the Juneau and Stikine icefields, accounting for 10% of the total ice cover in Alaska. Here, the ASTER-based geodetic mass balances are revisited, carefully avoiding the use of the SRTM DEM, because of the unknown penetration depth of the SRTM C-band radar signal. We find strongly negative mass balances from 2000 to 2016 for both icefields, in agreement with airborne laser altimetry. Mass losses are thus continuing unabated.

A new method, with application, for analysis of the impacts on flood risk of widely distributed enhanced hillslope storage

Flooding is a significant hazard and extreme events in recent years have focused attention on effective means of reducing its risk. An approach known as natural flood management (NFM) seeks to increase flood resilience by a range of measures that work with natural processes. The paper develops a modelling approach to assess one type NFM of intervention – distributed additional hillslope storage features – and demonstrates that more strategic placement is required than has hitherto been applied.

Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

A compact array spectroradiometer technology that enables precise and robust measurements of UV spectral irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range, is physically reduced so that no other stray-light reduction methods are needed. During an international total ozone measurement intercomparison, the high quality was verified.

Global evaluation and calibration of a passive air sampler for gaseous mercury

A new passive air sampler for gaseous mercury was tested at 20 sites on four continents. These sites have in common that they use the state-of-the-art active air sampling technique for gaseous mercury on a continuous basis and therefore allow for an evaluation and calibration of the passive sampler. The sampler proved to work exceptionally well, with a precision and accuracy on par with the active instrument and better than what has previously been achieved with passive samplers.

Novel pathway of SO₂ oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol

Synergistic effects between SOA formation and SO₂ oxidation through Criegee chemistry and reactive uptake by organic peroxides were observed. The relative importance of these two pathways (Criegee vs. peroxide) varies with relative humidity. The latter SO₂ loss mechanism to organic peroxides in SOA has not previously been identified. Our results suggest a new pathway of atmospheric SO₂ oxidation, which may contribute to the missing mechanisms of high-sulfate production in the polluted areas.

Using satellite measurements of N₂O to remove dynamical variability from HCl measurements

Detecting trends in short data sets of stratospheric molecules is difficult because of variability due to dynamical fluctuations. We suggest that one way around this difficulty is using the measurements of one molecule to remove dynamical variability from the measurements of another molecule. We illustrate this using Aura MLS measurements of N₂O to help us sort out issues in the determination of trends in HCl. This shows that HCl is decreasing throughout the middle stratosphere as expected.

The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation

Coupled climate–ice sheet simulations have been growing in popularity in recent years. Experiments of this type are however challenging as ice sheets evolve over multi-millennial timescales, which is beyond the practical integration limit of most Earth system models. A common method to increase model throughput is to trade resolution for computational efficiency (compromise accuracy for speed). Here we analyze how the resolution of an atmospheric general circulation model (AGCM) influences the simulation quality in a stand-alone ice sheet model. Four identical AGCM simulations of the Last Glacial Maximum (LGM) were run at different horizontal resolutions: T85 (1.4∘), T42 (2.8∘), T31 (3.8∘), and T21 (5.6∘). These simulations were subsequently used as forcing of an ice sheet model.

Considering the future of anthropogenic gas-phase organic compound emissions and the increasing influence of non-combustion sources on urban air quality

Following decades of successful regulatory policies focused on combustion-related sources (e.g. motor vehicles), emissions from non-combustion sources have become increasingly important for urban air quality. Using multiple approaches, we demonstrate that emissions from consumer, commercial, and industrial products and materials have become prominent contributors to the formation of photochemical smog (i.e. secondary organic particulate matter and ozone) and its associated health effects.

Moving beyond the age–depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera

Palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid climate change, but only a small proportion of the ocean is suitable for such reconstructions using the existing state of the art, i.e. the age–depth approach. We use dual radiocarbon (¹⁴C) and stable isotope analysis on single foraminifera to bypass the long-standing age–depth approach, thus facilitating past ocean chemistry reconstructions from vast, previously untapped ocean areas.

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