77 research outputs found
The importance of vegetation in understanding terrestrial water storage variations
Funding Information: The article processing charges for this openaccess publication were covered by the Max Planck Society. Publisher Copyright: © 2022 Tina Trautmann et al.So far, various studies have aimed at decomposing the integrated terrestrial water storage variations observed by satellite gravimetry (GRACE, GRACE-FO) with the help of large-scale hydrological models. While the results of the storage decomposition depend on model structure, little attention has been given to the impact of the way that vegetation is represented in these models. Although vegetation structure and activity represent the crucial link between water, carbon, and energy cycles, their representation in large-scale hydrological models remains a major source of uncertainty. At the same time, the increasing availability and quality of Earth-observation-based vegetation data provide valuable information with good prospects for improving model simulations and gaining better insights into the role of vegetation within the global water cycle. In this study, we use observation-based vegetation information such as vegetation indices and rooting depths for spatializing the parameters of a simple global hydrological model to define infiltration, root water uptake, and transpiration processes. The parameters are further constrained by considering observations of terrestrial water storage anomalies (TWS), soil moisture, evapotranspiration (ET) and gridded runoff (Q) estimates in a multi-criteria calibration approach. We assess the implications of including varying vegetation characteristics on the simulation results, with a particular focus on the partitioning between water storage components. To isolate the effect of vegetation, we compare a model experiment in which vegetation parameters vary in space and time to a baseline experiment in which all parameters are calibrated as static, globally uniform values. Both experiments show good overall performance, but explicitly including varying vegetation data leads to even better performance and more physically plausible parameter values. The largest improvements regarding TWS and ET are seen in supply-limited (semi-arid) regions and in the tropics, whereas Q simulations improve mainly in northern latitudes. While the total fluxes and storages are similar, accounting for vegetation substantially changes the contributions of different soil water storage components to the TWS variations. This suggests an important role of the representation of vegetation in hydrological models for interpreting TWS variations. Our simulations further indicate a major effect of deeper moisture storages and groundwater-soil moisture-vegetation interactions as a key to understanding TWS variations. We highlight the need for further observations to identify the adequate model structure rather than only model parameters for a reasonable representation and interpretation of vegetation-water interactions.publishersversionpublishe
A change in perspective: downhole cosmic-ray neutron sensing for the estimation of soil moisture
Above-ground cosmic-ray neutron sensing (CRNS) allows for the non-invasive estimation of the field-scale soil moisture content in the upper
decimetres of the soil. However, large parts of the deeper vadose zone remain outside of its observational window. Retrieving soil moisture
information from these deeper layers requires extrapolation, modelling or other methods, all of which come with methodological challenges. Against
this background, we investigate CRNS for downhole soil moisture measurements in deeper layers of the vadose zone. To render calibration with in situ
soil moisture measurements unnecessary, we rescaled neutron intensities observed below the terrain surface with intensities measured above a waterbody.
An experimental set-up with a CRNS sensor deployed at different depths of up to 10 m below the surface in a groundwater observation well
combined with particle transport simulations revealed the response of downhole thermal neutron intensities to changes in the soil moisture content at
the depth of the downhole neutron detector as well as in the layers above it. The simulation results suggest that the sensitive measurement radius
of several decimetres, which depends on soil moisture and soil bulk density, exceeds that of a standard active neutron probe (which is only about
30 cm). We derived transfer functions to estimate downhole neutron signals from soil moisture information, and we describe approaches for
using these transfer functions in an inverse way to derive soil moisture from the observed neutron signals. The in situ neutron and soil moisture
observations confirm the applicability of these functions and prove the concept of passive downhole soil moisture estimation, even at larger depths,
using cosmic-ray neutron sensing.</p
Modelling sediment export, retention and reservoir sedimentation in drylands with the WASA-SED model
Monitoring of selected skin- and breath-borne volatile organic compounds emitted from the human body using gas chromatography ion mobility spectrometry (GC-IMS)
ISSN:1873-376XISSN:1570-0232ISSN:1572-6495ISSN:1387-227
Mass-change And Geosciences International Constellation (MAGIC) expected impact on science and applications
Summary
The joint ESA/NASA Mass-change And Geosciences International Constellation (MAGIC) has the objective to extend time series from previous gravity missions, including an improvement of accuracy and spatio-temporal resolution. The long-term monitoring of Earth’s gravity field carries information on mass-change induced by water cycle, climate change, and mass transport processes between atmosphere, cryosphere, oceans and solid Earth. MAGIC will be composed of two satellite pairs flying in different orbit planes. The NASA/DLR–led first pair (P1) is expected to be in a near-polar orbit around 500 km of altitude; while the second ESA–led pair (P2) is expected to be in an inclined orbit of 65–70 degrees at approximately 400 km altitude. The ESA–led pair P2 Next Generation Gravity Mission (NGGM) shall be launched after P1 in a staggered manner to form the MAGIC constellation. The addition of an inclined pair shall lead to reduction of temporal aliasing effects and consequently of reliance on de-aliasing models and post-processing. The main novelty of the MAGIC constellation is the delivery of mass-change products at higher spatial resolution, temporal (i.e. sub–weekly) resolution, shorter latency, and higher accuracy than GRACE and GRACE-FO. This will pave the way to new science applications and operational services. In this article, an overview of various fields of science and service applications for hydrology, cryosphere, oceanography, solid Earth, climate change and geodesy is provided. These thematic fields and newly enabled applications and services were analysed in the frame of the initial ESA Science Support activities for MAGIC. The analyses of MAGIC scenarios for different application areas in the field of geosciences confirmed that the double-pair configuration will significantly enlarge the number of observable mass-change phenomena by resolving smaller spatial scales with an uncertainty that satisfies evolved user requirements expressed by international bodies such as IUGG. The required uncertainty levels of dedicated thematic fields met by MAGIC unfiltered Level-2 products will benefit hydrological applications by recovering more than 90% of the major river basins worldwide at 260 km spatial resolution, cryosphere applications by enabling mass change signal separation in the interior of Greenland from those in the coastal zones and by resolving small-scale mass variability in challenging regions such as the Antarctic Peninsula, oceanography applications by monitoring meridional overturning circulation changes on time scales of years and decades, climate applications by detecting amplitude and phase changes of Terrestrial Water Storage (TWS) after 30 years in 64% and 56% of the global land areas and solid Earth applications by lowering the Earthquake detection threshold from magnitude 8.8 to magnitude 7.4 with spatial resolution increased to 333 km.</jats:p
Metabolomic Plasticity in GM and Non-GM Potato Leaves in Response to Aphid Herbivory and Virus Infection
An important aspect of ecological safety of genetically
modified
(GM) plants is the evaluation of unintended effects on plant–insect
interactions. These interactions are to a large extent influenced
by the chemical composition of plants. This study uses NMR-based metabolomics
to establish a baseline of chemical variation to which differences
between a GM potato line and its parent cultivar are compared. The
effects of leaf age, virus infection, and aphid herbivory on plant
metabolomes were studied. The metabolome of the GM line differed from
its parent only in young leaves of noninfected plants. This effect
was small when compared to the baseline. Consistently, aphid performance
on excised leaves was influenced by leaf age, while no difference
in performance was found between GM and non-GM plants. The metabolomic
baseline approach is concluded to be a useful tool in ecological safety
assessment
Anthracycline rechallenge using pegylated liposomal doxorubicin in patients with metastatic breast cancer: a pooled analysis using individual data from four prospective trials
BACKGROUND: The aim of this study was to determine the activity of anthracycline rechallenge using pegylated liposomal doxorubicin (PLD) in patients with metastatic breast cancer (MBC) previously treated with conventional anthracyclines. METHODS: Pooled individual data from four prospective trials were used, and the primary end point of the pooled analysis was clinical benefit rate (CBR). The studies comprised 935 patients, of whom 274 had received PLD in the metastatic setting after prior exposure to conventional anthracyclines (rechallenge population). RESULTS: The majority of patients were heavily pretreated. Previous anthracycline therapy was administered in the adjuvant (14%) or metastatic setting (46%), or both (40%). The overall CBR from rechallenge with PLD was 37.2% (95% CI, 32.4-42.0). In univariate analyses, the CBR was significantly higher in patients with less exposure to prior chemotherapy, in taxane-naive patients, and in patients with a favourable Eastern Cooperative Group performance status of 0 vs 1 vs 2 (53.3 vs 35.5 vs 18.2%; P<0.001). In multivariate analyses, performance status proved to be the only independent predictor of the CBR achieved with PLD rechallenge (P=0.038). There was no statistically significant difference in CBR regarding the setting, cumulative dose of and/or resistance to prior anthracyclines, or time since prior anthracycline administration. CONCLUSION: Anthracycline rechallenge using PLD is effective in patients with MBC who have a favourable performance status, regardless of setting, resistance, cumulative dose or time since prior conventional anthracycline therapy. British Journal of Cancer (2010) 103, 1518-1523. doi:10.1038/sj.bjc.6605961 www.bjcancer.com Published online 26 October 2010 (C) 2010 Cancer Research U
Precision of the current methods to measure the alkenone proxy UK'37 and absolute alkenone abundance in sediments : results of an interlaboratory comparison study
Measurements of the UK'37 index and the absolute abundance of alkenones in marine sediments are increasingly used in paleoceanographic research as proxies of past sea surface temperature and haptophyte (mainly coccolith-bearing species) primary productivity, respectively. An important aspect of these studies is to be able to compare reliably data obtained by different laboratories from a wide variety of locations. Hence the intercomparability of data produced by the research community is essential. Here we report results from an anonymous interlaboratory comparison study involving 24 of the leading laboratories that carry out alkenone measurements worldwide. The majority of laboratories produce data that are intercomparable within the considered confidence limits. For the measurement of alkenone concentrations, however, there are systematic biases between laboratories, which might be related to the techniques employed to quantify the components. The maximum difference between any two laboratories for any two single measurements of UK'37 in sediments is estimated, with a probability of 95%, to be <2.18C. In addition, the overall within-laboratory precision for the UK'37 temperature estimates is estimated to be <1.68C (95% probability). Similarly, from the analyses of alkenone concentrations the interlaboratory reproducibility is estimated at 32%, and the repeatability is estimated at 24%. The former is compared to a theoretical estimate of reproducibility and found to be excessively high. Hence there is certainly scope and a demonstrable need to improve reproducibility and repeatability of UK'37 and especially alkenone quantification data across the community of scientists involved in alkenone research
Influence of molecular weight on the phase behavior and structure formation of branched side-chain hairy-rod polyfluorene in bulk phase
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