Reply to: A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation.
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ABSTRACT:
SUBMITTER: Mamalakis A
PROVIDER: S-EPMC6597566 | biostudies-literature | 2019 Jun
REPOSITORIES: biostudies-literature
Publications
Reply to: A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation.
Mamalakis Antonios A Yu Jin-Yi JY Randerson James T JT AghaKouchak Amir A Foufoula-Georgiou Efi E
Nature communications 20190627 1
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Project description: Not available
| S-EPMC6584695 | biostudies-literature
Project description:Reliable prediction of seasonal precipitation in the southwestern US (SWUS) remains a challenge with significant implications for the economy, water security and ecosystem management of the region. Winter precipitation in the SWUS has been linked to several climate modes, including the El Niño-Southern Oscillation (ENSO), with limited predictive ability. Here we report evidence that late-summer sea surface temperature and geopotential height anomalies close to New Zealand exhibit higher correlation with SWUS winter precipitation than ENSO, enhancing the potential for earlier and more accurate prediction. The teleconnection depends on a western Pacific ocean-atmosphere pathway, whereby sea surface temperature anomalies propagate from the southern to the northern hemisphere during boreal summer. Analysis also shows an amplification of this new teleconnection over the past four decades. Our work highlights the need to understand the dynamic nature of the coupled ocean-atmosphere system in a changing climate for improving future predictions of regional precipitation.
| S-EPMC5997984 | biostudies-literature
Project description:Future California (CA) precipitation projections, including those from the most recent Climate Model Intercomparison Project (CMIP5), remain uncertain. This uncertainty is related to several factors, including relatively large internal climate variability, model shortcomings, and because CA lies within a transition zone, where mid-latitude regions are expected to become wetter and subtropical regions drier. Here, we use a multitude of models to show CA may receive more precipitation in the future under a business-as-usual scenario. The boreal winter season-when most of the CA precipitation increase occurs-is associated with robust changes in the mean circulation reminiscent of an El Niño teleconnection. Using idealized simulations with two different models, we further show that warming of tropical Pacific sea surface temperatures accounts for these changes. Models that better simulate the observed El Niño-CA precipitation teleconnection yield larger, and more consistent increases in CA precipitation through the twenty-first century.
| S-EPMC5504297 | biostudies-literature
Project description:Tropical South American hydroclimate sustains the world's highest biodiversity and hundreds of millions of people. Whitin this region, Amazonia and northeastern Brazil have attracted much attention due to their high biological and social vulnerabilities to climate change (i.e. considered climate change hotspots). Still, their future response to climate change remains uncertain. On precession timescale, it has been suggested that periods of decreased western Amazonian precipitation were accompanied by increased northeastern Brazilian precipitation and vice-versa, setting an east-west tropical South American precipitation dipole. However, the very existence of this precession-driven precipitation dipole remains unsettled given the scarcity of long and appropriate northeastern Brazilian records. Here we show that the precession-driven South American precipitation dipole has persisted over the last 113 ka as revealed by a northern northeastern Brazilian precipitation record obtained from quartz thermoluminescence sensitivity measured in marine sediment cores. Precession-induced austral summer insolation changes drove the precipitation dipole through the interhemispheric temperature gradient control over the regional Walker circulation and the Intertropical Convergence Zone seasonal migration range. Since modern global warming affects the interhemispheric temperature gradient, our study provides insights about possible future tropical South American hydroclimate responses.
| S-EPMC9217799 | biostudies-literature
Project description:Uncertainty about the influence of anthropogenic radiative forcing on the position and strength of convective rainfall in the Intertropical Convergence Zone (ITCZ) inhibits our ability to project future tropical hydroclimate change in a warmer world. Paleoclimatic and modeling data inform on the timescales and mechanisms of ITCZ variability; yet a comprehensive, long-term perspective remains elusive. Here, we quantify the evolution of neotropical hydroclimate over the preindustrial past millennium (850 to 1850 CE) using a synthesis of 48 paleo-records, accounting for uncertainties in paleo-archive age models. We show that an interhemispheric pattern of precipitation antiphasing occurred on multicentury timescales in response to changes in natural radiative forcing. The conventionally defined “Little Ice Age” (1450 to 1850 CE) was marked by a clear shift toward wetter conditions in the southern neotropics and a less distinct and spatiotemporally complex transition toward drier conditions in the northern neotropics. This pattern of hydroclimatic change is consistent with results from climate model simulations indicating that a relative cooling of the Northern Hemisphere caused a southward shift in the thermal equator across the Atlantic basin and a southerly displacement of the ITCZ in the tropical Americas, with volcanic forcing as the principal driver. These findings are at odds with proxy-based reconstructions of ITCZ behavior in the western Pacific basin, where changes in ITCZ width and intensity, rather than mean position, appear to have driven hydroclimate transitions over the last millennium. This reinforces the idea that ITCZ responses to external forcing are region specific, complicating projections of the tropical precipitation response to global warming.
| S-EPMC9169948 | biostudies-literature
Project description:BackgroundLow-density lipoprotein cholesterol is an important marker highly associated with cardiovascular disease. Since the direct measurement of it is inefficient in terms of cost and time, it is common to estimate through the Friedewald equation developed about 50 years ago. However, various limitations exist since the Friedewald equation was not designed for Koreans. This study proposes a new low-density lipoprotein cholesterol estimation equation for South Koreans using nationally approved statistical data.MethodsThis study used data from the Korean National Health and Nutrition Examination Survey from 2009 to 2019. The 18,837 subjects were used to develop the equation for estimating low-density lipoprotein cholesterol. The subjects included individuals with low-density lipoprotein cholesterol levels directly measured among those with high-density lipoprotein cholesterol, triglycerides, and total cholesterol measured. We compared twelve equations developed in the previous studies and the newly proposed equation (model 1) developed in this study with the actual low-density lipoprotein cholesterol value in various ways.ResultsThe low-density lipoprotein cholesterol value estimated using the estimation formula and the actual low-density lipoprotein cholesterol value were compared using the root mean squared error. When the triglyceride level was less than 400 mg/dL, the root mean squared of the model 1 was 7.96, the lowest compared to other equations, and the model 2 was 7.82. The degree of misclassification was checked according to the NECP ATP III 6 categories. As a result, the misclassification rate of the model 1 was the lowest at 18.9%, and Weighted Kappa was the highest at 0.919 (0.003), which means it significantly reduced the underestimation rate shown in other existing estimation equations. Root mean square error was also compared according to the change in triglycerides level. As the triglycerides level increased, the root mean square error showed an increasing trend in all equations, but it was confirmed that the model 1 was the lowest compared to other equations.ConclusionThe newly proposed low-density lipoprotein cholesterol estimation equation showed significantly improved performance compared to the 12 existing estimation equations. The use of representative samples and external verification is required for more sophisticated estimates in the future.
| S-EPMC10186074 | biostudies-literature
Project description:Multiple paleoclimate proxies are required for robust assessment of past hydroclimatic conditions. Currently, estimates of drought variability over the past several thousand years are based largely on tree-ring records. We produced a 1,500-y record of winter precipitation in the Pacific Northwest using a physical model-based analysis of lake sediment oxygen isotope data. Our results indicate that during the Medieval Climate Anomaly (MCA) (900-1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450-1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). These findings are somewhat discordant with drought records from tree rings, suggesting that differences in seasonal sensitivity between the two proxies allow a more compete understanding of the climate system and likely explain disparities in inferred climate trends over centennial timescales.
| S-EPMC3406856 | biostudies-literature
Project description:This study characterizes the spatial and temporal patterns of aerosol and precipitation composition at six sites across the United States Southwest between 1995 and 2010. Precipitation accumulation occurs mostly during the wintertime (December-February) and during the monsoon season (July-September). Rain and snow pH levels are usually between 5-6, with crustal-derived species playing a major role in acid neutralization. These species (Ca2+, Mg2+, K+, Na+) exhibit their highest concentrations between March and June in both PM2.5 and precipitation due mostly to dust. Crustal-derived species concentrations in precipitation exhibit positive relationships with [Formula: see text], [Formula: see text], and Cl-, suggesting that acidic gases likely react with and partition to either crustal particles or hydrometeors enriched with crustal constituents. Concentrations of particulate [Formula: see text] show a statistically significant correlation with rain [Formula: see text] unlike snow [Formula: see text], which may be related to some combination of the vertical distribution of [Formula: see text] (and precursors) and the varying degree to which [Formula: see text]-enriched particles act as cloud condensation nuclei versus ice nuclei in the region. The coarse : fine aerosol mass ratio was correlated with crustal species concentrations in snow unlike rain, suggestive of a preferential role of coarse particles (mainly dust) as ice nuclei in the region. Precipitation [Formula: see text] : [Formula: see text] ratios exhibit the following features with potential explanations discussed: (i) they are higher in precipitation as compared to PM2.5; (ii) they exhibit the opposite annual cycle compared to particulate [Formula: see text] : [Formula: see text] ratios; and (iii) they are higher in snow relative to rain during the wintertime. Long-term trend analysis for the monsoon season shows that the [Formula: see text] : [Formula: see text] ratio in rain increased at the majority of sites due mostly to air pollution regulations of [Formula: see text] precursors.
| S-EPMC3890361 | biostudies-literature
Project description:Precipitation is the major cause of yield variation in rainfed agriculture production on the Loess Plateau. Overfertilization is economically and environmentally undesirable. Optimizing nitrogen management based on fallow season precipitation is crucial for enhancing crop water use efficiency and achieving high yields in dryland/rainfed farming systems, considering the economic and environmental drawbacks of overfertilization and the uncertainty of crop yield and N input returns under high rainfall variability. Therefore, this study establishes a reference range that characterizes different wheat cultivation year types based on 37 years of fallow season precipitation data. The reference range for describing years as normal (220.7-346.2 mm), dry (< 220.7 mm), or wet (> 346.2 mm) is based on a 37-year precipitation record. At the same time, an 8 year field experiment (A randomized block design) was conducted using 7 N rates(0, 90, 120, 150, 180, 210, 240 kg N ha-1 to explore the prediction of PF on optimal N input for higher yield and water use efficiency (WUE). Optimum nitrogen (N) rates varied with the precipitation factor, being 150, 150-180, and 210 kg ha- 1 during dry, normal, and wet years respectively. Maximizing yield and water use efficiency (WUE) through optimized N input was primarily attributed to an increase in spike number per hectare. A non-linear regression analysis revealed a positive correlation between yield and precipitation frequency (PF), with an increase in yield ranging from 1.6 to 15 kg ha-1 for every mm increment in PF. Furthermore, the study demonstrated that an increase of 1% in the ratio of PF to total precipitation resulted in a significant yield gain of 46 kg ha-1.And as "drought at sowing" effects on yield were more adverse than "drought in growing season" effects in dryland systems, our results indicate that adjusting N fertilizer inputs based on summer rainfall variation could enhance wheat yield and WUE in the rainfed farming system. Thus, our results indicate that adjusting N fertilizer inputs based on seasonal variation in summer rainfall could enhance wheat yield and WUE in the rain-fed farming system.
| S-EPMC11842855 | biostudies-literature
Project description:Previous studies reported that boreal winter precipitation in southeastern China (SEC) tends to increase during El Niño. In this study, however, we find that most weak El Niño events are accompanied by below-normal precipitation in SEC, although strong El Niño events are accompanied by above-normal precipitation in SEC for both eastern Pacific El Niño and central Pacific El Niño. Both the cold SST anomalies in the western North Pacific (WNP) and the warm SST anomalies in the central tropical Pacific are important for the formation of anomalous anticyclone over the WNP, which favors above-normal precipitation over SEC by transporting more water vapor to SEC. The cold SST anomalies in the WNP only excite a weak anomalous anticyclone locally when the weak warm SST anomalies in the central tropical Pacific are accompanied by weak enhanced convection anomalies. In such condition, El Niño does not affect precipitation in SEC apparently.
| S-EPMC6874680 | biostudies-literature