ALBERT

Description: This study demonstrates a methodology to construct short-duration rainfall intensity–duration–frequency (IDF) curves and to quantify the variability in the rainfall intensities for different return periods with respect to the changing climate. A dynamical downscaling approach using the regional climate model (RCM) Weather Research and Forecasting (WRF) has been used to assess present and future climates using the downscaling of an ensemble of three global climate models (GCMs) (CSIRO-ACCESS1.3, MPI-ESM-MR ECHAM6 and NIES-MIROC5) under the Coupled Model Intercomparison Project phase 5 (CMIP5). Furthermore, a statistical approach using the well-known simple scaling method has been applied to extend the 6-hourly WRF precipitation output to the finer temporal scale of 10 min. The short-duration IDF curves were then constructed for the present and future climates under two representative concentration pathway (RCP) scenarios RCP4.5 and RCP8.5. A preliminary examination for this case study over Bac Ninh, an industrial area in the northern Vietnam, shows that there is a substantial increase in short-duration rainfall intensity in the future with respect to the baseline climate. The highest increase is towards the end of the century (2071–2100) ranging from 56 to 61% for a 10- and 100-year return period for 24-hr duration, respectively, while the increase is about 40–45% for the 10-min duration. These results strongly suggest that severe flooding in the future climate over the study region may be likely. The study results might be useful for policymakers and infrastructure planning and for insurance companies around the study area. Projection of simple scaling log–log-scale IDF curve for Bac Ninh using ensemble WRF: return periods (a) 10 years, (b) 25 years, (c) 50 years, (d) 100 years; (1) 2011–2040, (2) 2041–2070, (3) 2071–2100.

Description: We present an analysis of “boomerang-shaped” pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on June 7th, 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90 ∘ pitch angle electrons, the phase change of the flux modulations across energy exceeds 180 ∘ , and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wave field reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift-resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.

Description: Glacier melt is an essential source of freshwater for the arid regions surrounding the Tian Shan. However, the knowledge about glacier volume and mass changes over the last decades is limited. In the present study, glacier area, glacier dynamics and mass changes are investigated for the period ~1975–2007 for Southern Inylchek Glacier (SIG) and Northern Inylchek Glacier (NIG), the largest glacier system in Central Tian Shan separated by the regularly draining Lake Merzbacher. The area of NIG increased by 2.0 ± 0.1 km2 (~1.3%) in the period ~1975–2007. In contrast, SIG has shrunk continuously in all investigated periods since ~1975. Velocities of SIG in the central part of the ablation region reached ~100–120 m a−1 in 2002/2003, which was slightly higher than the average velocity in 2010/2011. The central part of SIG flows mainly towards Lake Merzbacher rather than towards its terminus. The measured velocities at the distal part of the terminus downstream of Lake Merzbacher were below the uncertainty, indicating very low flow with even stagnant parts. Geodetic glacier mass balances have been calculated using multi-temporal digital elevation models from KH-9 Hexagon (representing the year 1975), SRTM3 (1999), ALOS PRISM (2006) and SPOT-5 high-resolution geometrical (HRG) data (2007). In general, a continuous mass loss for both SIG and NIG could be observed between ~1975 and 2007. SIG lost mass at a rate of 0.43 ± 0.10 m w.e. a−1 and NIG at a rate of 0.25 ± 0.10 m w.e. a−1 within the period ~1975–1999. For the period 1999–2007, the highest mass loss of 0.57 ± 0.46 m w.e. a−1 was found for NIG, whilst SIG showed a potential moderate mass loss of 0.28 ± 0.46 m w.e. a−1. Both glaciers showed a small retreat during this period. Between ~1975 and 1999, we identified a thickening at the front of NIG with a maximum surface elevation increase of about 150 m as a consequence of a surge event. In contrast significant thinning (〉0.5 m a−1) and comparatively high velocities close to the dam of Lake Merzbacher were observed for SIG, indicating that Lake Merzbacher enhances glacier mass loss.