Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin Atmospheric Chemistry and Physics DOI 10.5194/acp-18-921-2018 25 January 2018 We made airborne measurements of aerosol particle concentrations and properties over the Amazon Basin. We found extremely high concentrations of very small particles in the region between 8 and 14 km altitude all across the basin, which had been recently formed by gas-to-particle conversion at these altitudes. This makes the upper troposphere a very important source region of atmospheric particles with significant implications for the Earth’s climate system. Read more
On the link between stress field and small-scale hydraulic fracture growth in anisotropic rock derived from microseismicity Solid Earth DOI 10.5194/se-9-39-2018 25 January 2018 To characterize the stress field at the Grimsel Test Site (GTS) underground rock laboratory, a series of hydrofracturing and overcoring tests were performed. Our study demonstrates that microseismicity monitoring along with high-resolution event locations provides valuable information for interpreting stress characterization measurements. Read more
Minimum forest cover required for sustainable water flow regulation of a watershed: a case study in Jambi Province, Indonesia Hydrology and Earth System Sciences DOI 10.5194/hess-22-581-2018 24 January 2018 This study is the first to describe the quantitative association between forest and plantation areas and the flow indicators (surface runoff and baseflow) in a watershed; this understanding is required by spatial planners if they are to balance the ecology and socioeconomic functions of a landscape with the rapid expansion of plantation crops. In addition, our study provides data regarding how SWAT input parameters related to tropical plantations such as oil palm and rubber should be adjusted. Read more
Reviews and syntheses: to the bottom of carbon processing at the seafloor Biogeosciences DOI 10.5194/bg-15-413-2018 19 January 2018 Organic carbon processing at the seafloor is studied by geologists to better understand the sedimentary record, by biogeochemists to quantify burial and respiration, by organic geochemists to elucidate compositional changes, and by ecologists to follow carbon transfers within food webs. These disciplinary approaches have their strengths and weaknesses. This award talk provides a synthesis, highlights the role of animals in sediment carbon processing and presents some new concepts. Read more
Response to marine cloud brightening in a multi-model ensemble Atmospheric Chemistry and Physics DOI 10.5194/acp-18-621-2018 19 January 2018 Marine cloud brightening (MCB) has been proposed to help limit global warming. We present here the first multi-model assessment of idealized MCB simulations from the Geoengineering Model Intercomparison Project. While all models predict a global cooling as intended, there is considerable spread between the models both in terms of radiative forcing and the climate response, largely linked to the substantial differences in the models’ representation of clouds. Read more
Can riparian vegetation shade mitigate the expected rise in stream temperatures due to climate change during heat waves in a human-impacted pre-alpine river? Hydrology and Earth System Sciences DOI 10.5194/hess-22-437-2018 18 January 2018 In eastern Austria, where air temperature rise is double that recorded globally, stream temperatures of a human-impacted river were simulated during heat waves, as calculated by regional climate models until 2100. An increase of up to 3 °C was predicted – thus exceeding thresholds of resident cold-adapted species. Vegetation management scenarios showed that adding vegetation can reduce both absolute temperatures and its rate of increase but is not able to fully mitigate the expected rise. Read more
On the similarity and apparent cycles of isotopic variations in East Antarctic snow pits The Cryosphere DOI 10.5194/tc-12-169-2018 17 January 2018 We explain why snow pits across different sites in East Antarctica show visually similar isotopic variations. We argue that the similarity and the apparent cycles of around 20 cm in the δD and δ18O variations are the result of a seasonal cycle in isotopes, noise, for example from precipitation intermittency, and diffusion. The near constancy of the diffusion length across many ice-coring sites explains why the structure and cycle length is largely independent of the accumulation conditions. Read more
A machine learning calibration model using random forests to improve sensor performance for lower-cost air quality monitoring Atmospheric Measurement Techniques DOI 10.5194/amt-11-291-2018 15 January 2018 Low-cost sensors promise neighborhood-scale air quality monitoring but have been plagued by inconsistent performance for precision, accuracy, and drift. CMU and SenSevere collaborated to develop the RAMP, which uses electrochemical sensors. We present a machine learning algorithm that overcomes previous performance issues and meets US EPA’s data quality recommendations for personal exposure for NO2and tougher “supplemental monitoring” standards for CO&ozone across 19 RAMPs for several months. Read more
Agricultural ammonia emissions in China: reconciling bottom-up and top-down estimates Atmospheric Chemistry and Physics DOI 10.5194/acp-18-339-2018 12 January 2018 Substantial differences exist in current estimates of agricultural ammonia emissions in China, hindering understanding of their environmental consequences. This study applies both bottom-up and top-down methods to better quantify agricultural ammonia sources in China using observations from satellite and surface networks interpreted by a chemical transport model. Our estimate of annual Chinese anthropogenic ammonia emission is 11.7 tg (teragram) for 2008 with a strong seasonality peak in summer. Read more
Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding Atmospheric Chemistry and Physics DOI 10.5194/acp-18-371-2018 12 January 2018 Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth’s atmosphere. The temporal variation of these waves is studied using a record long 10-day continuous Rayleigh–Mie–Raman lidar sounding at midlatitudes. This data set shows a large variability of these waves on timescales of a few days and therefore provides new insights into wave intermittency phenomena, which can help to improve model simulations. Read more
