HORAYZON v1.2: an efficient and flexible ray-tracing algorithm to compute horizon and sky view factor Geoscientific Model Development DOI 10.5194/gmd-15-6817-2022 28 November 2022 Terrain horizon and sky view factor are crucial quantities for many geoscientific applications; e.g. they are used to account for effects of terrain on surface radiation in climate and land surface models. Because typical terrain horizon algorithms are inefficient for high-resolution (< 30 m) elevation data, we developed a new algorithm based on a ray-tracing library. A comparison with two conventional methods revealed both its high performance and its accuracy for complex terrain. HORAYZON v1.2: an efficient and flexible ray-tracing algorithm to compute horizon and sky view factor">Read more
Reliability of flood marks and practical relevance for flood hazard assessment in southwestern Germany Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-2963-2022 25 November 2022 Encouraging a systematic use of flood marks for more comprehensive flood risk management, we collected a large number of marks along the Kinzig, southwestern Germany, and tested them for plausibility and temporal continuance. Despite uncertainty, the marks appeared to be an overall consistent and practical source that may also increase flood risk awareness. A wide agreement between the current flood hazard maps and the collected flood marks moreover indicated a robust local hazard assessment. Read more
South American Summer Monsoon variability over the last millennium in paleoclimate records and isotope-enabled climate models Climate of the Past DOI 10.5194/cp-18-2045-2022 23 November 2022 We evaluated the South American Summer Monsoon over the last millennium and dynamically interpreted the principal modes of variability. We find the spatial patterns of the monsoon are an intrinsic feature of the climate modulated by external forcings. Multi-centennial mean state departures during the Medieval Climate Anomaly and Little Ice Age show regionally coherent patterns of hydroclimatic change in both a multi-archive network of oxygen isotope records and isotope-enabled climate models. Read more
Ice core evidence for major volcanic eruptions at the onset of Dansgaard–Oeschger warming events Climate of the Past DOI 10.5194/cp-18-2021-2022 21 November 2022 Major volcanic eruptions are known to cause considerable short-term impacts on the global climate. Their influence on long-term climate variability and regime shifts is less well-understood. Here we show that very large, bipolar eruptions occurred more frequently than expected by chance just before abrupt climate change events in the last glacial period (Dansgaard–Oeschger events). Thus, such large eruptions may in some cases act as short-term triggers for abrupt regime shifts of the climate. Read more
Comprehensive space–time hydrometeorological simulations for estimating very rare floods at multiple sites in a large river basin Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-2891-2022 18 November 2022 Estimating the magnitude of rare to very rare floods is a challenging task due to a lack of sufficiently long observations. The challenge is even greater in large river basins, where precipitation patterns and amounts differ considerably between individual events and floods from different parts of the basin coincide. We show that a hydrometeorological model chain can provide plausible estimates in this setting and can thus inform flood risk and safety assessments for critical infrastructure. Read more
Bayesian assessment of chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC) and halon banks suggest large reservoirs still present in old equipment Atmospheric Chemistry and Physics DOI 10.5194/acp-22-11125-2022 16 November 2022 Halocarbons contained in equipment continue to be emitted after production has ceased. These “banks” must be carefully accounted for in evaluating compliance with the Montreal Protocol. We extend a Bayesian model to the suite of regulated chemicals subject to banking. We find that banks are substantially larger than previous estimates, and we identify banks by chemical and equipment type whose future emissions will contribute to global warming and delay ozone-hole recovery if left unrecovered. CFC), hydrochlorofluorocarbon (HCFC) and halon banks suggest large reservoirs still present in old equipment">Read more
The impact of climate oscillations on the surface energy budget over the Greenland Ice Sheet in a changing climate The Cryosphere DOI 10.5194/tc-16-3375-2022 14 November 2022 To overcome internal climate variability, this study uses k-means clustering to combine NAO, GBI and IWV over the Greenland Ice Sheet (GrIS) and names the approach as the North Atlantic influence on Greenland (NAG). With the support of a polar-adapted RCM, spatio-temporal changes on SEB components within NAG phases are investigated. We report atmospheric warming and moistening across all NAG phases as well as large-scale and regional-scale contributions to GrIS mass loss and their interactions. Read more
Invited perspectives: Views of 350 natural hazard community members on key challenges in natural hazards research and the Sustainable Development Goals Natural Hazards and Earth System Sciences DOI 10.5194/nhess-22-2771-2022 11 November 2022 Here we present survey responses of 350 natural hazard community members to key challenges in natural hazards research and step changes to achieve the Sustainable Development Goals. Challenges identified range from technical (e.g. model development, early warning) to governance (e.g. co-production with community members). Step changes needed are equally broad; however, the majority of answers showed a need for wider stakeholder engagement, increased risk management and interdisciplinary work. Read more
Effects of orbital forcing, greenhouse gases and ice sheets on Saharan greening in past and future multi-millennia Climate of the Past DOI 10.5194/cp-18-1897-2022 9 November 2022 Using an Earth system model of intermediate complexity, we quantify contributions of the Earth’s orbit, greenhouse gases (GHGs) and ice sheets to the strength of Saharan greening during late Quaternary African humid periods (AHPs). Orbital forcing is found as the dominant factor, having a critical threshold and accounting for most of the changes in the vegetation response. However, results suggest that GHGs may influence the orbital threshold and thus may play a pivotal role for future AHPs. Read more
TermPicks: a century of Greenland glacier terminus data for use in scientific and machine learning applications The Cryosphere DOI 10.5194/tc-16-3215-2022 7 November 2022 Terminus traces have been used to understand how Greenland’s glaciers have changed over time; however, manual digitization is time-intensive, and a lack of coordination leads to duplication of efforts. We have compiled a dataset of over 39 000 terminus traces for 278 glaciers for scientific and machine learning applications. We also provide an overview of an updated version of the Google Earth Engine Digitization Tool (GEEDiT), which has been developed specifically for the Greenland Ice Sheet. Read more
