Characteristics of fragmented aurora-like emissions (FAEs) observed on Svalbard Annales Geophysicae DOI 10.5194/angeo-39-277-2021 26 March 2021 This study analyses the observations of a new type of small-scale aurora-like feature, which is further referred to as fragmented aurora-like emission(s) (FAEs). One possible explanation for this is Farley–Buneman instabilities of strong local currents. In the present study, we provide an overview of the observations and discuss their characteristics and potential generation mechanisms. Read more
Model physics and chemistry causing intermodel disagreement within the VolMIP-Tambora Interactive Stratospheric Aerosol ensemble Atmospheric Chemistry and Physics DOI 10.5194/acp-21-3317-2021 25 March 2021 As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), several climate modeling centers performed a coordinated pre-study experiment with interactive stratospheric aerosol models simulating the volcanic aerosol cloud from an eruption resembling the 1815 Mt. Tambora eruption (VolMIP-Tambora ISA ensemble). Read more
Comparison of ozone measurement methods in biomass burning smoke: anevaluation under field and laboratory conditions Atmospheric Measurement Techniques DOI 10.5194/amt-14-1783-2021 24 March 2021 In recent years wildland fires in the United States have had significant impacts on local and regional air quality and negative human health outcomes. Although the primary health concerns from wildland fires come from fine particulate matter (PM2.5), large increases in ozone (O3 have been observed downwind of wildland fire plumes. The chemiluminescence FRM method is highly recommended for accurate measurements of O3 in wildland fire plume studies and at regulatory ambient monitoring sites frequently impacted by wildland firesmoke. Read more
Cryptotephra from the Icelandic Veiðivötn 1477 CE eruption in a Greenland ice core: confirming the dating of volcanic events in the 1450s CE and assessing the eruption’s climatic impact Climate of the Past DOI 10.5194/cp-17-565-2021 23 March 2021 Volcanic eruptions are a key source of climatic variability, and reconstructing their past impact can improve our understanding of the operation of the climate system and increase the accuracy of future climate projections. While many chronological mismatches have been resolved, the precise timing and climatic impact of two major sulfate-emitting volcanic eruptions during the 1450s CE, including the largest atmospheric sulfate-loading event in the last 700 years, have not been constrained. Here we explore this issue through a combination of tephrochronological evidence and high-resolution ice-core chemistry measurements from a Greenland ice core, the TUNU2013 record. Read more
The case of a southern European glacier which survived Roman and medieval warm periods but is disappearing under recent warming The Cryosphere DOI 10.5194/tc-15-1157-2021 22 March 2021 We present here the first chronological study of a glacier located in the Central Pyrenees (NE Spain), Monte Perdido Glacier (MPG),carried out by different radiochronological techniques and a comparison with geochemical proxies from neighbouring palaeoclimate records. The chronological model evidences that the glacier persisted during the Roman period and the Medieval Climate Anomaly. The apparent absence of ice in the past∼ 600 years suggests that any ice accumulated during the Little Ice Age has since ablated. Read more
Diverging responses of high-latitude CO2 and CH4 emissions in idealized climate change scenarios The Cryosphere DOI 10.5194/tc-15-1097-2021 19 March 2021 The present study investigates the response of the high-latitude carbon cycle to changes in atmospheric greenhouse gas (GHG) concentrations in idealized climate change scenarios. We find that at a global mean temperature of roughly 1.75 K (±0.5 K) above pre-industrial levels the high-latitude ecosystem turns from a CO2 sink into a source of atmospheric carbon, with the net fluxes into the atmosphere increasing substantially with rising atmospheric GHG concentrations. This is very different from scenario simulations with the standard version of the MPI-ESM, in which the region continues to take up atmospheric CO2 throughout the entire 21st century. Read more
A dynamical systems characterization of atmospheric jet regimes Earth System Dynamics DOI 10.5194/esd-12-233-2021 18 March 2021 Atmospheric jet streams are typically separated into primarily “eddy-driven” (or polar-front) jets and primarily “thermally driven” (or subtropical) jets. Here, we link the current understanding of dynamical jet maintenance mechanisms, mostly arising from conceptual or idealized models, to the phenomena observed in reanalysis data. Read more
Lower oceanic δ13C during the last interglacial period compared to the Holocene Climate of the Past DOI 10.5194/cp-17-507-2021 17 March 2021 The last time in Earth’s history when high latitudes were warmer than during pre-industrial times was the last interglacial period (LIG, 129–116 ka BP). Since the LIG is the most recent and best documented interglacial, it can provide insights into climate processes in a warmer world. However, some key features of the LIG are not well constrained, notably the oceanic circulation and the global carbon cycle. Here, we use a new database of LIG benthic δ13C to investigate these two aspects. Read more
Mapping avalanches with satellites – evaluation of performance andcompleteness The Cryosphere DOI 10.5194/tc-15-983-2021 16 March 2021 The spatial distribution and size of avalanches are essential parameters for avalanche warning, avalanche documentation, mitigation measure design and hazard zonation. Despite its importance, this information is incomplete today and only available for limited areas and limited time periods. Read more
A-Train estimates of the sensitivity of the cloud-to-rainwater ratio to cloud size, relative humidity, and aerosols Atmospheric Chemistry and Physics DOI 10.5194/acp-21-2765-2021 15 March 2021 Precipitation efficiency has been found to play an important role in constraining the sensitivity of the climate through its role in controlling cloud cover, yet its controls are not fully understood. Here we use CloudSat observations to identify individual contiguous shallow cumulus cloud objects and compute the ratio of cloud water path to rainwater (WRR) path as a proxy for warm-rain efficiency. Read more
Development of a MetUM (v 11.1) and NEMO (v 3.6) coupled operational forecastmodel for the Maritime Continent – Part 1: Evaluation of ocean forecasts Geoscientific Model Development DOI 10.5194/gmd-14-1081-2021 12 March 2021 This article describes the development and ocean forecast evaluation of an atmosphere–ocean coupled prediction system for the Maritime Continent (MC) domain, which includes the eastern Indian and western Pacific oceans. Overall, the model forecast deviation of SST, SSH, and subsurface temperature and salinity fields relative to observation is within acceptable error limits of operational forecast models. Read more
Long-term global ground heat flux and continental heat storage from geothermal data Climate of the Past DOI 10.5194/cp-17-451-2021 11 March 2021 Here, we provide new global estimates of changes in ground surface temperature, ground surface heat flux, and continental heat storage derived from geothermal data using an expanded database and new techniques. Read more
Radar-based assessment of hail frequency in Europe Natural Hazards and Earth System Sciences DOI 10.5194/nhess-21-683-2021 10 March 2021 In this study we present a unique 10 year climatology of severe convective storm tracks for a large European area covering Germany, France, Belgium and Luxembourg. For the period 2005–2014, a high-resolution hail potential composite of 1×1 km2 is produced from two-dimensional radar reflectivity and lightning data. Read more
In situ cosmogenic 10Be–14C–26Al measurements from recently deglaciated bedrock as a new tool to decipher changes in Greenland Ice Sheet size Climate of the Past DOI 10.5194/cp-17-419-2021 9 March 2021 Sometime during the middle to late Holocene (8.2 ka to ∼ 1850–1900 CE), the Greenland Ice Sheet (GrIS) was smaller than its current configuration. Contemporary retreat of the GrIS from its historical maximum extent in southwestern Greenland is exposing a landscape that holds clues regarding the configuration and timing of past ice-sheet minima. Read more
Reviews and syntheses: Impacts of plant-silica–herbivore interactions onterrestrial biogeochemical cycling Biogeosciences DOI 10.5194/bg-18-1259-2021 8 March 2021 Researchers have known for decades that silicon plays a major role in biogeochemical and plant–soil processes in terrestrial systems. We review and synthesize 119 available studies directly investigating silicon and herbivory to summarize key trends and highlight research gaps and opportunities. Read more
Response of tidal flow regime and sediment transport in North Malé Atoll, Maldives, to coastal modification and sea level rise Ocean Science DOI 10.5194/os-17-319-2021 5 March 2021 Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport processes, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago, which has undergone significant land reclamation in recent years and decades and is also particularly exposed to sea level rise. Read more
Assessment of a full-field initialized decadal climate prediction system with the CMIP6 version of EC-Earth Earth System Dynamics DOI 10.5194/esd-12-173-2021 4 March 2021 In this paper, we present and evaluate the skill of an EC-Earth 3.3 decadal prediction system contributing to the Decadal Climate Prediction Project – Component A (DCPP-A). This prediction system is capable of skilfully simulating past global mean surface temperature variations at interannual and decadal forecast times as well as the local surface temperature in regions such as the tropical Atlantic, the Indian Ocean and most of the continental areas, although most of the skill comes from the representation of the external radiative forcings. Read more
Vapor plumes in a tropical wet forest: spotting the invisible evaporation Hydrology and Earth System Sciences DOI 10.5194/hess-25-619-2021 3 March 2021 Forest evaporation exports a vast amount of water vapor from land ecosystems into the atmosphere. This work describes the formation process of vapor plumes in a tropical wet forest as evidence of evaporation processes happening during rain events. Read more
Low-NO atmospheric oxidation pathways in a polluted megacity Atmospheric Chemistry and Physics DOI 10.5194/acp-21-1613-2021 2 March 2021 The impact of emissions of volatile organic compounds (VOCs) to the atmosphere on the production of secondary pollutants, such as ozone and secondary organic aerosol (SOA), is mediated by the concentration of nitric oxide (NO). Polluted urban atmospheres are typically considered to be high-NO” environments, while remote regions such as rainforests, with minimal anthropogenic influences, are considered to be “low NO”. However, our observations from central Beijing show that this simplistic separation of regimes is flawed. Read more
A limited effect of sub-tropical typhoons on phytoplankton dynamics Biogeosciences DOI 10.5194/bg-18-849-2021 1 March 2021 Typhoons are assumed to stimulate primary ocean production through the upward mixing of nutrients into the ocean surface. This assumption is based largely on observations of increased surface chlorophyll concentrations following the passage of typhoons. This surface chlorophyll enhancement, occasionally detected by satellites, is often undetected due to intense cloud coverage. Read more