Dynamics of salt intrusion in the Mekong Delta: results of field observations and integrated coastal–inland modelling Earth Surface Dynamics DOI 10.5194/esurf-9-953-2021 24 September 2021 Increased salt intrusion jeopardizes freshwater supply to the Mekong Delta, and the current trends are often inaccurately associated with sea level rise. Using observations and models, we show that salinity is highly sensitive to ocean surge, tides, water demand, and upstream discharge. We show that anthropogenic riverbed incision has significantly amplified salt intrusion, exemplifying the importance of preserving sediment budget and riverbed levels to protect deltas against salt intrusion. Read more
The long-term transport and radiative impacts of the 2017 British Columbia pyrocumulonimbus smoke aerosols in the stratosphere Atmospheric Chemistry and Physics DOI 10.5194/acp-21-12069-2021 22 September 2021 Interactions of extreme fires with weather systems can produce towering smoke plumes that inject aerosols at very high altitudes (> 10 km). Three such major injections, largest at the time in terms of emitted aerosol mass, took place over British Columbia, Canada, in August 2017. We model the transport and impacts of injected aerosols on the radiation balance of the atmosphere. Our model results match the satellite-observed plume transport and residence time at these high altitudes very closely. Read more
The nano-scanning electrical mobility spectrometer (nSEMS) and its application to size distribution measurements of 1.5–25 nm particles Atmospheric Measurement Techniques DOI 10.5194/amt-14-5429-2021 20 September 2021 We present the design, modeling, and experimental characterization of the nano-scanning electrical mobility spectrometer (nSEMS), a recently developed instrument that probes particle physical properties in the 1.5–25 nm range. The nSEMS has proven to be extremely powerful in examining atmospheric nucleation and the subsequent growth of nanoparticles in the CERN CLOUD experiment, which provides a valuable asset to study atmospheric nanoparticles and to evaluate their impact on climate. Read more
Physical characteristics of frozen hydrometeors inferred with parameter estimation Atmospheric Measurement Techniques DOI 10.5194/amt-14-5369-2021 17 September 2021 Satellite observations sensitive to cloud and precipitation help improve the quality of weather forecasts. However, they are sensitive to things that models do not forecast, such as the shapes and sizes of snow and ice particles. These details can be estimated from the observations themselves and then incorporated in the satellite simulators used in weather forecasting. This approach, known as parameter estimation, will be increasingly useful to build models of poorly known physical processes. Read more
Influence of the representation of convection on the mid-Holocene West African Monsoon Climate of the Past DOI 10.5194/cp-17-1665-2021 15 September 2021 This paper investigates the impact of explicitly resolving convection on the mid-Holocene West African Monsoon rain belt by employing the ICON climate model in high resolution. While the spatial distribution and intensity of the precipitation are improved by this technique, the monsoon extents further north and the mean summer rainfall is higher in the simulation with parameterized convection. Read more
Iodide CIMS and m∕z 62: the detection of HNO3 as NO3− in the presence of PAN, peroxyacetic acid and ozone Atmospheric Measurement Techniques DOI 10.5194/amt-14-5319-2021 13 September 2021 We demonstrate in laboratory experiments that the formation of IOx anions (formed in reactions of I− with O3) or acetate anions (formed e.g. by the reaction of I− with peracetic acid) results in unexpected sensitivity of an iodide chemical ionisation mass spectrometer (I-CIMS) to HNO3 at a mass-to-charge ratio of 62. This helps explain observations of apparent high daytime levels of N2O5. Airborne measurements using I-CIMS confirm these conclusions. Read more
Recent degradation of interior Alaska permafrost mapped with ground surveys, geophysics, deep drilling, and repeat airborne lidar The Cryosphere DOI 10.5194/tc-15-3555-2021 10 September 2021 Permafrost is actively degrading across high latitudes due to climate warming. We combined thousands of end-of-summer active layer measurements, permafrost temperatures, geophysical surveys, deep borehole drilling, and repeat airborne lidar to quantify permafrost warming and thawing at sites across central Alaska. We calculate the mass of permafrost soil carbon potentially exposed to thaw over the past 7 years (0.44 Pg) is similar to the yearly carbon dioxide emissions of Australia. Read more
Spatial and temporal subsidence characteristics in Wuhan (China), during 2015–2019, inferred from Sentinel-1 synthetic aperture radar (SAR) interferometry Natural Hazards and Earth System Sciences DOI 10.5194/nhess-21-2285-2021 8 September 2021 We mapped the subsidence of Wuhan using Sentinel-1 synthetic aperture radar (SAR) images acquired during 2015–2019. Overall subsidence coincides with the distribution of engineered geological regions with soft soils, while the subsidence centers shifted with urban construction activities. Correlation between karst subsidence and concentrated rainfall was identified in Qingling–Jiangdi. Results indicate that interferometric SAR can be employed to routinely monitor and identify geohazards. Read more
Better representation of dust can improve climate models with too weak an African monsoon Atmospheric Chemistry and Physics DOI 10.5194/acp-21-11423-2021 6 September 2021 Earth system models have persistent biases that impinge on our ability to make robust future regional predictions of precipitation. For the last 15 years, there has been little improvement in these biases. This work presents an accurate representation of dust absorption based upon observed dust mineralogical composition and size distribution. The striking result is that this more accurate representation improves tropical precipitations for climate models with too weak an African monsoon. Read more
Characterization of dark current signal measurements of the ACCDs used on board the Aeolus satellite Atmospheric Measurement Techniques DOI 10.5194/amt-14-5153-2021 3 September 2021 This paper reports on dark current signal anomalies of the detectors used on board the ESA’s Earth Explorer satellite Aeolus during the first 1.5 years in orbit. After introducing sophisticated algorithms to classify dark current anomalies according to their characteristics, the impact of the different kinds of anomalies on wind measurements is discussed. In addition, mitigation approaches for the wind retrieval are presented and potential root causes are discussed. Read more
