351 research outputs found

    Joint Sentinel-1 and SMAP data assimilation to improve soil moisture estimates

    Get PDF
    SMAP (Soil Moisture Active and Passive) radiometer observations at similar to 40 km resolution are routinely assimilated into the NASA Catchment Land Surface Model to generate the 9 km SMAP Level-4 Soil Moisture product. This study demonstrates that adding high-resolution radar observations from Sentinel-1 to the SMAP assimilation can increase the spatiotemporal accuracy of soil moisture estimates. Radar observations were assimilated either separately from or simultaneously with radiometer observations. Assimilation impact was assessed by comparing 3-hourly, 9 km surface and root-zone soil moisture simulations with in situ measurements from 9 km SMAP core validation sites and sparse networks, from May 2015 to December 2016. The Sentinel-1 assimilation consistently improved surface soil moisture, whereas root-zone impacts were mostly neutral. Relatively larger improvements were obtained from SMAP assimilation. The joint assimilation of SMAP and Sentinel-1 observations performed best, demonstrating the complementary value of radar and radiometer observations

    Performance of self-reported measures of alcohol use and of harmful drinking patterns against ethyl glucuronide hair testing among young Swiss men.

    Get PDF
    There is a need for empirical studies assessing the psychometric properties of self-reported alcohol use as measures of excessive chronic drinking (ECD) compared to those of objective measures, such as ethyl glucuronide (EtG). To test the quality of self-reported measures of alcohol use and of risky single-occasion drinking (RSOD) to detect ECD assessed by EtG. A total of 227 samples of hair from young Swiss men were used for the determination of EtG. Self-reported measures of alcohol use (previous twelve-month and previous-week alcohol use) and RSOD were assessed. Using EtG (<30 pg/mg) as the gold standard of ECD assessment, the sensitivity and specificity were computed, and the AUROC were compared for alcohol use measures and RSOD. Logistic regressions were used to test the contribution of RSOD to the understanding of ECD after controlling for alcohol use. A total of 23.3% of participants presented with ECD. Previous twelve-month alcohol use with a cut-off of >15 drinks per week (sensitivity = 75.5%, specificity = 78.7%) and weekly RSOD (sensitivity = 75.5%, specificity = 70.1%) yielded acceptable psychometric properties. No cut-off for previous-week alcohol use gave acceptable results. In the multivariate logistic regression, after controlling for the previous twelve months of alcohol use, RSOD was still significantly associated with EtG (p = .016). Self-reported measures of the previous twelve months of alcohol use and RSOD were acceptable measures of ECD for population-based screening. Self-reported RSOD appeared to be an interesting screening measure, in addition to the previous twelve months of alcohol use, to understand ECD among young people

    Assimilation of Freeze–Thaw Observations into the NASA Catchment Land Surface Model

    Get PDF
    The land surface freeze–thaw (F/T) state plays a key role in the hydrological and carbon cycles and thus affects water and energy exchanges and vegetation productivity at the land surface. In this study, an F/T assimilation algorithm was developed for the NASA Goddard Earth Observing System, version 5 (GEOS-5), modeling and assimilation framework. The algorithm includes a newly developed observation operator that diagnoses the landscape F/T state in the GEOS-5 Catchment land surface model. The F/T analysis is a rule-based approach that adjusts Catchment model state variables in response to binary F/T observations, while also considering forecast and observation errors. A regional observing system simulation experiment was conducted using synthetically generated F/T observations. The assimilation of perfect (error free) F/T observations reduced the root-mean-square errors (RMSEs) of surface temperature and soil temperature by 0.206° and 0.061°C, respectively, when compared to model estimates (equivalent to a relative RMSE reduction of 6.7% and 3.1%, respectively). For a maximum classification error CEmax of 10% in the synthetic F/T observations, the F/T assimilation reduced the RMSE of surface temperature and soil temperature by 0.178° and 0.036°C, respectively. For CEmax = 20%, the F/T assimilation still reduces the RMSE of model surface temperature estimates by 0.149°C but yields no improvement over the model soil temperature estimates. The F/T assimilation scheme is being developed to exploit planned F/T products from the NASA Soil Moisture Active Passive (SMAP) mission

    Benefits and pitfalls of GRACE data assimilation: A case study of terrestrial water storage depletion in India

    Get PDF
    This study investigates some of the benefits and drawbacks of assimilating terrestrial water storage (TWS) observations from the Gravity Recovery and Climate Experiment (GRACE) into a land surface model over India. GRACE observes TWS depletion associated with anthropogenic groundwater extraction in northwest India. The model, however, does not represent anthropogenic groundwater withdrawals and is not skillful in reproducing the interannual variability of groundwater. Assimilation of GRACE TWS introduces long-term trends and improves the interannual variability in groundwater. But the assimilation also introduces a negative trend in simulated evapotranspiration, whereas in reality evapotranspiration is likely enhanced by irrigation, which is also unmodeled. Moreover, in situ measurements of shallow groundwater show no trend, suggesting that the trends are erroneously introduced by the assimilation into the modeled shallow groundwater, when in reality the groundwater is depleted in deeper aquifers. The results emphasize the importance of representing anthropogenic processes in land surface modeling and data assimilation systems

    Connecting with home, keeping in touch : physical and virtual mobility across stretched families in sub-Saharan Africa.

    Get PDF
    There is a long history of migration among low-income families in sub-Saharan Africa, in which (usually young, often male) members leave home to seek their fortune in what are perceived to be more favourable locations. While the physical and virtual mobility practices of such stretched families are often complex and contingent, maintaining contact with distantly located close kin is frequently of crucial importance for the maintenance of emotional (and possibly material) well-being, both for those who have left home and for those who remain. This article explores the ways in which these connections are being reshaped by increasing access to mobile phones in three sub-Saharan countries – Ghana, Malawi and South Africa – drawing on interdisciplinary, mixed-methods research from twenty-four sites, ranging from poor urban neighbourhoods to remote rural hamlets. Stories collected from both ends of stretched families present a world in which the connectivities now offered by the mobile phone bring a different kind of closeness and knowing, as instant sociality introduces a potential substitute for letters, cassettes and face-to-face visits, while the rapid resource mobilization opportunities identified by those still at home impose increasing pressures on migrant kin

    Improving Water Level and Soil Moisture Over Peatlands in a Global Land Modeling System

    Get PDF
    New model structure for peatlands results in improved skill metrics (without any parameter calibration) Simulated surface soil moisture strongly affected by new model, but reliable soil moisture data lacking for validation

    Nearly complete genome sequences of eight rabies virus strains obtained from domestic carnivores in the Democratic Republic of the Congo

    Get PDF
    In this report, we describe eight nearly complete genome sequences of rabies virus strains collected in the Democratic Republic of the Congo from domestic carnivores in 2017 and 2018. All of them clustered into a specific phylogroup among the Africa 1b lineage in the Cosmopolitan clade

    Conversion and degradation of [125I] labelled angiotensin I in isolated perfused porcine coronary and carotid arteries

    Get PDF
    The aims were (1) to quantitate angiotensin I to II conversion on the endothelial surface and at deeper sites in isolated arteries, (2) to assess whether the angiotensin II that is formed at deeper sites is released into the vascular lumen, and (3) to examine whether enzymes other than angiotensin converting enzyme (ACE) are involved in vascular angiotensin I to II conversion. Methods: Metabolism of [125I]-angiotensin I was studied in isolated perfused porcine coronary and carotid arteries after luminal administration of the labelled peptide (in the perfusion fluid) and after adventitial administration (in the organ bath). Measurements were made both in the presence and in the absence of captopril. Results: [125I]-angiotensin II was a major metabolite and its formation was virtually completely blocked by captopril, after both luminal and adventitial administration of [125I]-angiotensin I. In coronary arteries (n = 8), the [125I]-angiotensin I to II conversion rate after adventitial administration was about half that after luminal administration. In coronary arteries (n = 6) the conversion rate after adventitial administration was 10–20 times lower than after luminal administration. Degradation of [125I]-angiotensin I into peptides other than [125I]-angiotensin II was also observed, with both luminal and adventitial administration. No [125I]-angiotensin I or II was released into the organ bath after luminal administration of [125I]-angiotensin I, and very little [125I]-angiotensin I and II entered the lumen after adventitial administration of [125I]-angiotensin I. Conclusions: (1) Vascular angiotensin I to II conversion is not limited to the endothelial surface. (2) ACE is the most important, if not the only, enzyme responsible for vascular angiotensin I to II conversion. (3) If angiotensin I and II are formed in the adventitia or media, little of these peptides will enter the vascular lumen
    corecore