ALBERT

Description: The tectonic activity and potential for linkage of adjacent active faults are crucial for seismic assessment. As the two largest faults that bound the Weihe Graben (central China), the Qinling Northern Piedmont Fault (QNF, ~200 km) and the Huashan Piedmont Fault (HPF, ~150 km) are mainly responsible for seismic risk in this densely-populated area, where the 1556 M 8.5 Huaxian earthquake occurred with 830,000 fatalities. However, their tectonic activity and the degree of interaction remain poorly constrained, hampering an adequate seismic risk assessment of the Weihe Graben. Here, we integrate 23 new 10Be-derived catchment-averaged denudation rates of ~0.06–0.32 mm/yr with topographic metrics to evaluate the seismic risk. The results demonstrate that the landscape of the Qinling and Huashan Mountains is in transient state in response to the tectonic perturbations of the QNF and the HPF, with tectonic knickpoints formed along main streams and tributaries, and widespread unstable drainage divides. These two faults have comparable tectonic activity, and are potentially capable of generating earthquakes with the maximum magnitude of Mw ~7.7–7.9. Moreover, they have likely started linking, posing a greater seismic risk than previously estimated.

Description: The GFZ German Research Centre for Geosciences as part of the GRACE Science Data System (SDS) is currently reprocessing the complete GRACE mission data. This new Level-2 data release (RL06 in the SDS nomenclature) will be based on reprocessed Level-1B instrument data (RL03), updated processing standards and background models and will take care of limitations known from previous RL05. Examples are the application of the latest RL06 Atmosphere and Ocean Dealiasing Model, update of the ocean tide model, implementation of the most recent IERS conventions or improvements in GFZ´s GPS data processing. This 15+ year time series of monthly Level-2 spherical harmonics and underlying processing standards will then serve for the continuation with GRACE-FO (Follow-on) data expected for early 2018. In parallel a team of GFZ, the Alfred-Wegener-Institute Bremerhaven and TU Dresden has developed and implemented a portal at GFZ where users can download dedicated Level-3 products for hydrological, oceanic and polar research activities. This portal is expected to be made public by the end of 2017. The presentation will show the status and examples of these new RL06 Level-2 products and prototype Level-3 products based on GFZ’s RL05a Level-2 monthly solutions.

Description: The following authors were omitted from the original version of this Data Descriptor: Markus Reichstein and Nicolas Vuichard. Both contributed to the code development and N. Vuichard contributed to the processing of the ERA-Interim data downscaling. Furthermore, the contribution of the co-author Frank Tiedemann was re-evaluated relative to the colleague Corinna Rebmann, both working at the same sites, and based on this re-evaluation a substitution in the co-author list is implemented (with Rebmann replacing Tiedemann). Finally, two affiliations were listed incorrectly and are corrected here (entries 190 and 193). The author list and affiliations have been amended to address these omissions in both the HTML and PDF versions. © 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.

Description: Since its launch in 2002, the Gravity Recovery and Climate Experiment (GRACE) mission provides as a unique way to monitor the terrestrial water storage (TWS) variations at large spatial scale (〉300km) by measuring month-to-month changes of the Earth’s gravity field. We apply TWS variations estimated from GRACE to assess the accuracy of four hydrological model realizations that simulate the continental branch of the global water cycle. All four model experiments are consistently forced with atmospheric data from the WFDEI data-set derived from the ERA-Interim re-analysis. Four different validation metrics are applied to focus both on seasonal signals and year-to-year variability of the TWS from the models. Actual evapotranspiration and runoff rates calculated with the different models are also analyzed. Considering the diversity of the performance of the models, we focus on time series of TWS variations in two regions which are characterized by different climate regimes, i.e. the snow-dominated catchments and the dry catchments, by looking into the TWS variation time series from models and GRACE. Besides, snow, surface water and subsurface water including root zone or/and deep layer storage from the models are also compared in order to analyze the contribution of different storage compartments to the total water storage. By investigating the relative performance of these different models, we attempt to trigger subsequent further development of global numerical models in the areas of large-scale hydrology and land-atmosphere interactions.

Description: The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.

Description: To expand the newly developed ARM glasses as reference materials for in situ microanalysis of isotope ratios and iron oxidation state by a variety of techniques such as SIMS, LA-MC-ICP-MS and EPMA, we report Li-B-Si-O-Mg-Sr-Nd-Hf-Pb isotope data and Fe2+/ΣFe ratios for these glasses. The data were mainly obtained by TIMS, MC-ICP-MS, IR-MS and wet-chemistry colorimetric techniques. The quality of these data was cross-checked by comparing different techniques or by comparing the results from different laboratories using the same technique. All three glasses appear to be homogeneous with respect to the investigated isotope ratios (except for B in ARM-3) and Fe2+/ΣFe ratios at the scale of sampling volume and level of the analytical precision of each technique. The homogeneity of Li-B-O-Nd-Pb isotope ratios at the microscale (30–120 μm) was estimated using LA-MC-ICP-MS and SIMS techniques. We also present new EPMA major element data obtained using three different instruments for the glasses. The determination of reference values for the major elements and their uncertainties at the 95% confidence level closely followed ISO guidelines and the Certification Protocol of the International Association of Geoanalysts. The ARM glasses may be particularly useful as reference materials for in situ isotope ratio analysis.

Description: By operating for more than one decade now, the GRACE satellite provides valuable information on the total water storage (TWS) for hydrological and hydro-meteorological applications. The increasing interest in use of the GRACE-based TWS requires an in-depth assessment of the reliability of the outputs and also its uncertainties. Through years of development, different post-processing methods have been suggested for TWS estimation. However, since GRACE offers an unique way to provide high spatial and temporal scale TWS, there is no global ground truth data available to fully validate the results. In this contribution, we re-assess a number of commonly used post-processing methods using a simulated GRACE-type gravity field time-series based on realistic orbits and instrument error assumptions as well as background error assumptions out of the updated ESA Earth System Model. Three non-isotropic filter methods from Kusche (2007) and a combined filter from DDK1 and DDK3 based on the ground tracks are tested. Rescaling factors estimated from five different hydrological models and the ensemble median are applied to the post-processed simulated GRACE-type TWS estimates to correct the bias and leakage. Time variant rescaling factors as monthly scaling factors and scaling factors for seasonal and long-term variations separately are investigated as well. Since TWS anomalies out of the post-processed simulation results can be readily compared to the time-variable Earth System Model initially used as "truth" during the forward simulation step, we are able to thoroughly check the plausibility of our error estimation assessment (Zhang et al., 2016) and will subsequently recommend a processing strategy that shall also be applied for planned GRACE and GRACE-FO Level-3 products for terrestrial applications provided by GFZ.

Description: On May 22, 2021, an Mw7.4 earthquake occurred in Maduo, Qinghai, China. The epicenter was located at 34.59 degrees north latitude and 98.34 degrees east longitude. This paper uses ASF HyP3 and MintPy software to conduct time-series InSAR analysis by using the Sentinel-1 SAR images from 2018 to 2023, and then to study the temporal and spatial distribution of regional crustal deformation and the distribution of the seismic fault ruptures. The time-series InSAR analysis are taken in three groups: Pre-earthquake period from January 2018 to May 2021, Earthquake onset period from April 2021 to June 2021, and Post-earthquake period From June 2021 to January 2023. The LOS(Light of Sight) velocity results of the time series INSAR analysis in the three groups and three dimension velocity of GPS stations in this area are fused to obtain regional tectonic strain rates, co-seismic fault slips, and post-seismic displacements. The results show that crustal deformation before the earthquake is small, the range of the coseismic surface rupture of the Maduo earthquake overlaps with the abnormal area of the regional strain field obtained, and the post-seismic viscoelastic deformation is strongly correlated with Maduo earthquake fault.

Description: The observational records have shown a strengthening of the Pacific Walker circulation (PWC) since 1979. However, whether the observed change is forced by external forcing or internal variability remains inconclusive, a solid answer to more societal relevantly question of how the PWC will change in the near future is still a challenge. Here we perform a quantitative estimation on the contributions of external forcing and internal variability to the recent observed PWC strengthening using large ensemble simulations from six state-of-the-art Earth system models. We find the phase transition of the Interdecadal Pacific Oscillation (IPO), which is an internal variability mode related to the Pacific, accounts for approximately 63% (~51–72%) of the observed PWC strengthening. Models with sufficient ensemble members can reasonably capture the observed PWC and IPO changes. We further constrain the projection of PWC change by using climate models’ credit in reproducing the historical phase of IPO. The result shows a high probability of a weakened PWC in the near future.

Description: Southeast Asian monsoon region is regularly stricken by drought, but less attention is paid due to its slow-onset and less visual impact. This study investigated the observed drought changes over Southeast Asian monsoon region and impacts of anthropogenic forcing using the Coupled Model Intercomparison Project phase 6 (CMIP6) models. We revealed an increasing drought risk for 1951-2018 due to more frequent and wide-spread droughts. The influence of anthropogenic forcing is successfully detected, which has increased the likelihood of the extreme droughts in historical simulation by reducing precipitation and enhancing evapotranspiration. The time of emergence of anthropogenic forcing in extreme drought occurrence and affected area occurs around the 1960s. The future projected severe and extreme drought risks are still beyond natural only forced changes under all scenarios. Our findings demonstrate a robust impact of anthropogenic forcing on drought risk over Southeast Asia, and highlight the importance of future pathway choice.