Many applications in Earth sciences require spatial prediction, that is, obtaining a continuous scalar field from a set of discrete scalar data points on the Earth's surface. Such applications ...include model‐data comparisons and derivation of continuous scalar fields as input for Earth system models. The advantage of kriging as an interpolation method is that it provides predictions with confidence intervals for data sets of irregularly distributed points in space. However, the theory of kriging for non‐Euclidean domains such as oblate spheroids (e.g., the Earth's surface) is poorly developed, and existing kriging algorithms for global interpolation oftentimes cannot guarantee the validity of their predictions. Here, we present Global‐Krigger, a new kriging interpolation algorithm adapted for local to global applications that (a) incorporates a numerical check to guarantee that the necessary conditions for the kriging system of linear equations are met, and (b) derives a combined uncertainty field due both to spatial variations in data density and measurement error. The robustness of the method is demonstrated by cross‐validating predictions against reanalysis fields of traditional climatological scalar variables. We also show an example application in paleoclimatology for Holocene mineral dust deposition fluxes. The toolbox includes a user‐friendly graphical user interface that guides users through a range of choices during data pre‐interpolation analysis, kriging, and post‐processing.
Plain Language Summary
Many climatic variables such as temperature and precipitation are measured by monitoring stations on the Earth's surface at irregularly distributed locations. Similarly, paleoclimatic proxy variables are available at specific locations where paleoclimatic archives such as marine sediment cores have been retrieved. Such data sets can be used to guide Earth system simulations, but this works best when they are available as a regular grid. Kriging is an interpolation method that produces regular grids from irregularly distributed measurements. However, while kriging theory is well‐developed for measurements on a plane surface, its application on curved surfaces is problematic. To improve this, we have developed Global‐Krigger, a user‐friendly kriging interpolation toolbox for the surface of the Earth. It incorporates new tests to check the validity of kriging results on curved surfaces. The toolbox also provides a quantification of the interpolation uncertainty, taking into account both the uncertainty of the measurements and the spatial distribution of the measurement sites. We show that our algorithm gives robust results by applying it to a sub‐sample of known modern climatology fields, and also provides a paleoclimatic application for Holocene mineral dust deposition fluxes. Finally, we develop a graphical user interface to guide users in the process of kriging.
Key Points
A new kriging algorithm is introduced for the interpolation of irregularly distributed scalar data sets on the Earth's surface
The algorithm is validated against reanalysis data, and an example application to Holocene dust deposition is presented
An easy‐to‐use, versatile and open access graphical user interface is included
Dry lakebeds exposed by shrinking water bodies in arid regions constitute sodium (Na)‐rich mineral dust emission hotspots that may potentially affect agriculture through soil sodification. However, ...no soluble Na mass balance has so far been attempted. We modeled 13 years (2005–2017) of dust emission from Mar Chiquita (MC), the most extensive shrinking saline lake in South America. Based on a chemical characterization of dust, we found that a mean ∼15–150 mg m−2 of soluble Na was deposited 300 km from the source during the season of strongest dust emissions. We estimated the impact of this atmospheric input on 13 agricultural soils, with different rainfall regimes and water holding capacities. At most sites, dust‐equilibrated infiltrated rainfall water had a Na concentration 8–7,000 times lower than the lowest concentration threshold proposed to trigger sodification. Additionally, this rainfall water is diluted ∼2–20 times as it infiltrates in saturated soils, and its sodium adsorption ratio is probably reduced due to the abundance of soluble calcium and magnesium in the soil solution. Thus, there is no risk of short‐term, seasonal sodification, except possibly at two sites and in close proximity to the dust source (<50 km), where dust deposition is maximum. At these sites, we estimated potential dust‐related rises in the proportion of soil exchangeable Na. Under scenarios of enhanced salt‐rich dust emissions from shrinking lakes in the twenty‐first century, agricultural soils close to salt‐rich dust sources worldwide should be monitored for potential Na enrichment related to Na‐rich dust.
Plain Language Summary
When lakes rich in dissolved salts shrink, the lakes' bed becomes exposed, and upon drying, these areas may emit salt‐rich dust to the atmosphere. This dust may be deposited on soils used for agriculture in the surrounding areas, and depending on the dust chemistry it may affect soil productivity, with sodium‐rich dust posing the highest potential threat. In this study, we analyzed dust emission from Mar Chiquita lake, the most extensive shrinking saline lake in South America, and its potential effect on agricultural soils in the region. To do this, we sampled dust, characterized its chemistry, modeled dust emission, transport in the atmosphere and final deposition to the soils, sampled soils at sites located at different distances from the lake, and finally compared the inputs of dust‐derived sodium, magnesium, and calcium with preexisting concentrations of these elements in the soils. We found that the short‐term input of sodium to the soils derived from dust is comparatively low, except close to the lake. However, the long‐term effect remains uncertain. Given that more intense dust emissions from shrinking lakes are projected globally in the twenty‐first century, agricultural soils exposed to salt‐rich dust deposition should be monitored to gauge threats to food production.
Key Points
Mar Chiquita, the largest South American shrinking saline lake, has emitted ∼0.5 Tg of dust in August plus September of each year since 2004
Despite a marked dust enrichment in soluble sodium, dust inputs are low compared to agricultural soil sodium stocks at most studied sites
While short‐term soil sodification risk is low, potential long‐term effects and projected stronger dust emissions merit soil monitoring
The high elevation of the onshore fore‐arc platform in northern Chile cannot be accounted for by previously proposed tectonic mechanisms such as coastal underplating and coseismic deformation, whose ...topographic effects are restricted to the coastal zone. Subduction channels have been recognized both in modern and fossil noncollisional convergent margins, yet their role on fore‐arc surface elevation has not been sufficiently explored. Long‐term viscoelastic flow in a strengthened, finite‐thickness subduction channel promotes coupled offshore fore‐arc subsidence and onshore fore‐arc platform uplift. We propose that the onset of protracted hyperaridity in the coastal zone of northern Chile starved the trench of sediments, inducing a rise in shear stress at the top of the subduction channel sufficient to trigger hundreds of meters of uplift of the onshore fore‐arc basin surface, most of which took place by the middle Miocene. This is consistent with latitudinal correlations between coastal precipitation, trench sediment thickness and onshore fore‐arc topography along the Chilean margin, and with available paleoclimatic and paleotopographic evidence in northern Chile.
Key Points
Trench fill sediments have been proposed to influence plate interface rheology and fore‐arc elevation
Strengthening the subduction channel promotes coupled long‐wavelength onshore uplift and offshore subsidence in the fore arc
Hyperaridity‐induced sediment starvation in the trench may explain the highly elevated onshore fore‐arc basin surface in northern Chile
An elevation‐dependent relationship of the 87Sr/86Sr ratio of Holocene surface accumulations of sulfate salts is demonstrated for a continental margin hyperarid setting. In the Atacama Desert of ...northern Chile, gypsum and anhydrite of multiple origins exist widely on superficial materials that originated during the last 10,000 years. An important source of calcium sulfate is from offshore‐generated stratocumulus clouds that are advected onto the continent, where they generate fog that transfers water droplets to the ground surface which, upon evaporation, leaves calcium sulfate crystals. Meteorological measurements of the cloud base and top altitudes average ∼400 m and ∼1100 m above sea level (masl), respectively. The seawater ratio of 87Sr/86Sr (0.70917) is distinctively higher than that reported for weathered mean Andean rock (less than 0.70750). Samples of 28 modern surface salt accumulations for locations between 200 and 2950 masl and between ∼19°30′ and ∼21°30′S verify that 87Sr/86Sr varies as a function of site altitude. Sites below 1075 masl and above 225 masl display calcium sulfate 87Sr/86Sr of mean value 0.70807 ± 0.00004, while the ratio outside this altitudinal domain is 0.70746 ± 0.00010. Thus, the 87Sr/86Sr ratio of Holocene salt accumulations differentiates two altitudinal domains.
Key Points:
A modern altitude proxy is proposed for the Atacama Desert based on 87Sr/86Sr of Holocene surficial accumulations of gypsum
The proxy's bimodal, single‐threshold nature derives from the dynamics of marine aerosols
Dealing with the safety assessment of existing buildings engineers often have to face the diagnosis of old timber structures. The current standards framework does not provide clear prescriptions ...about the evaluation of these kinds of structures, so the principal aim of this work is to outline an alternative methodology that leaves the concept of “Knowledge Level” and “Confidence Factor”, usually applied for existing buildings. An experimental campaign carried out on old timber joists supplied a sample of homogeneous data that were the support to the theoretical reasoning.
Mineral aerosols may affect global climate indirectly by enhancing net primary productivity (NPP) upon deposition to the oceans and associated atmosphere‐to‐ocean CO2 flux. This mechanism is ...hypothesized to have contributed significantly to the last interglacial‐to‐glacial climatic transition. However, the dust‐NPP connection remains contentious for the present‐day climate system. We analyze the impact of southernmost Patagonian dust emissions on southwestern Atlantic Ocean continental shelf and proximal open ocean satellite chlorophyll‐a concentration. We use the first decadal time series of surface dust mass flux in southern Patagonia, along with in situ visibility data, to model dust emission, transport, and deposition to the ocean. We then perform a dust event‐based analysis of chlorophyll‐a time series, using a novel approach by which time series are corrected for post‐depositional particle advection due to ocean currents. Finally, we performed chemical analysis of iron in dust samples, a key micronutrient limiting phytoplankton biomass in high‐nutrient, low‐chlorophyll oceans such as offshore of the 200‐m isobath off Patagonia. We find no compelling evidence for an influence of dust as an enhancer of phytoplankton biomass either on shelf or proximal open ocean waters of the southwestern Atlantic Ocean. For open ocean waters this is consistent with a lack of source‐inherited bioavailable iron in dust samples. Future case studies addressing similar questions should concentrate on dust sources with identified high contents of bioavailable iron, particularly in the Southern Hemisphere where atmospheric processing of iron is weak.
Key Points
We present the first decadal time series of surface dust mass flux in Patagonia
The first event‐based study in the southwestern Atlantic Ocean shows no evidence for an influence of dust on chlorophyll‐a concentrations
Source‐inherited low concentrations of bioavailable iron preclude enhancement of primary producers' biomass in proximal open ocean waters
Abstract
Background
Patients older than 90 years are less likely to receive percutaneous coronary intervention (PCI) for treatment of acute myocardial infarction (AMI). This is due to the lack of ...evidence derived from randomized trials, multimorbidity, and possible futility. We investigated the prognostic impact of PCI in a large population of patients hospitalized with AMI in the period 2003-2018, by using the Lombardy Health Database (Italy).
Methods
We analyzed data of all patients >90 years hospitalized with AMI (both STEMI and NSTEMI) in Lombardy. Patients were grouped according to whether they were treated or not with PCI during index hospitalization. The primary outcome was in-hospital mortality. One-year mortality and 1-year re-hospitalization for acute heart failure (AHF) or AMI were considered as secondary endpoints.
Results
During the study period, 15,954 patients (median age 92 91-94 years); 50% STEMI) were hospitalized with a primary diagnosis of AMI. Twelve percent of them (n=1,954) were treated with PCI. The in-hospital mortality rate in the entire cohort was 22% (29% in STEMI and 15% in NSTEMI). It was significantly lower in patients treated with PCI than in those not treated with PCI (15% vs. 23%; P<0.0001). In the overall population, 1-year mortality was 56% and 1-year re-hospitalization for AHF/AMI was 19%. Both these endpoints were less frequent in PCI-treated (37% vs. 58% and 16% vs. 21%, respectively; P<0.0001). The adjusted risk of the study endpoints was significantly lower in patients treated with PCI: OR 0.61 (95% CI 0.54-0.69) for in-hospital mortality; HR 0.53 (95% CI 0.49-0.57) for 1-year mortality; HR 0.68 (95% CI 0.66-0.70) for 1-year re-hospitalization for AHF/AMI. The figure shows the 1-year survival curves of AMI patients treated or not treated with PCI. Similar results were found in STEMI and NSTEMI patients considered separately.
Conclusions
Our real-world data showed that in patients with AMI older than 90 years of age, PCI use is associated with a significant in-hospital and 1-year clinical benefit.
Abstract
Background
Glucagon-like peptide-1 receptor agonists (GLP-1 RA) and sodium glucose cotransporter-2 inhibitors (SGLT-2i) demonstrated cardiovascular and renal protection in addition to their ...glucose-lowering effect. Whether their benefits occur also in patients with diabetes mellitus (DM) during hospitalisation with acute myocardial infarction (AMI) has not been investigated yet.
Purpose
We evaluated in-hospital outcomes of patients hospitalised with AMI according to their chronic use (before hospitalisation) of GLP-1 RA and SGLT-2i therapy.
Methods
Using administrative healthcare databases, we analysed patients hospitalised with a primary diagnosis of AMI from 2010 to 2019 in the Lombardy region, Italy. Patients were stratified according to their DM status, then divided into three cohorts: Group 1 (non-DM patients); Group 2 (DM patients taking GLP-1 RA or SGLT-2i); and Group 3 (DM patients not taking GLP-1 RA and/or SGLT-2i). Patients were matched in a 1:1:1 ratio using a propensity score including all available variables. The primary endpoint of the study was the composite of in-hospital mortality, acute heart failure, and acute kidney injury requiring renal replacement therapy.
Results
We identified 146,800 patients hospitalised with AMI (26% of them with DM). After propensity score matching, 1,030 patients were included in each group. The primary endpoint rate in the overall population was 16% (n=502) and it significantly increased going from Group 1 to Group 3 (13%, 16%, and 20% respectively; p for trend <0.0001). The risk of the composite endpoint significantly increased from Group 1 to Group 3 (P for trend <0.0001). In comparison with Group 2, Group 3 had a significant higher risk of the composite endpoint (OR 1.40 95% CI 1.11–1.77).
Conclusions
Our study shows that DM patients hospitalised with AMI and on chronic GLP-1 RA and/or SGLT-2i therapy have a better in-hospital clinical outcome than DM patients without them.
Funding Acknowledgement
Type of funding sources: None.
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