ENSO Events Research Articles

Can Stomach Content and Microbiomes of Tuna Provide Near Real-Time Detection of Ecosystem Composition in the Pacific Ocean?

This preliminary study used DNA metabarcoding to test whether the stomach content and gut microbiome of tuna could be a viable near real-time monitoring tool for detecting composition and change in oceanic ecosystems. The gut content of skipjack (Katsuwonus pelamis, n=55) and yellowfin tuna (Thunnus albacares, n=46) captured in the Pacific Ocean during El Niño Southern Oscillation events (ENSO) between 2015-2017 were examined by high throughput sequencing and complemented by morphological assessments to identify fishes, crustaceans and cephalopods in the stomach content. Gut microbiome was examined solely by high throughput sequencing. Stomach content and gut microbiome were compared between tuna species, ENSO events and capture location using generalised linear models. The full model (tuna species, capture location and interaction with ENSO) best explained fish prey composition, while capture location and ENSO weakly explained the composition of crustaceans and cephalopods. Skipjack and yellowfin tuna captured near coastal areas (Longitude<170°W) showed a greater diversity of prey compared to fish captured in oceanic regions of the Pacific, while Thunnus albacares showed a much more diverse stomach content than K. pelamis (21 fish, eight cephalopods and six crustaceans). Fish captured during La Niña events showed higher prey diversity compared to fish captured during El Niño. Tuna species best explained differences in gut microbiome to the Phylum level, while no model explained gut microbiome differences to the Order or Family level. This preliminary study shows that capture location and ENSO events explained differences in stomach content of K. pelamis and T. albacares, while tuna species best explained gut microbiome assemblages to the Phylum level.

Possible Impact of Boreal Winter Siberian High on ENSO Development in the Following Year

Siberian High (SH) is the dominant pressure system located in the mid-high latitudes of Eurasia during boreal wintertime. This study reveals a triggering impact of SH variation in preceding winter on the following ENSO events, and gives a possible explanation via diagnosing the SH-associated air-sea response over the tropical Pacific and North Pacific. When SH is anomalously enhanced (suppressed) during boreal winter, an Aleutian Low enhanced (suppressed) response will occur over the downstream North Pacific. The Aleutian Low response gradually evolves into a meridional dipole structure similar to the negative (positive) phase of the North Pacific Oscillation (NPO) during the following spring and early summer. Correspondingly, the oceanic response in the North Pacific features a pattern similar to the negative (positive) phase of the Victoria mode. These SH-associated air-sea responses over the subtropical North Pacific will be maintained and further delivered into the tropical Pacific through the so-called seasonal footprinting mechanism, which favors the Bjerknes feedback established around boreal summer and finally grows into a La Niña (El Niño).

Possible impacts of spring subtropical Indian Ocean Dipole on the summer tropical cyclone genesis frequency over the western North Pacific

AbstractThe linkage between the spring subtropical Indian Ocean Dipole (SIOD) events and tropical cyclone genesis frequency over the western North Pacific (WNP) in the following summer is investigated in this study. It is found that their correlation is positive and statistically significant with a greater number of TCs genesis over the WNP in summer of a positive SIOD year. After removing the ENSO effects, diagnostic analysis reveals that under positive SIOD conditions the summertime WNP monsoon trough becomes intensified. Correspondingly, there are enhanced lower‐level vorticity, reduced vertical zonal wind shear, increased middle‐level relative humidity and vertical velocity over the WNP, conductive to generation of more TCs. Further examination indicates that the Mascarene high and Australian high are strengthened successively from spring to subsequent summer in a positive SIOD year, contributing to the maintenance of SIOD‐related SST dipole anomalies in southern Indian Ocean due to SST–wind–evaporation feedback mechanism. The resulting cyclonic anomaly is formed at lower troposphere over the WNP induced by the prominently enhanced cross‐equator airflows and the related Ekman upwelling. At upper troposphere, there tend to be remarkably WNP divergence anomalies of the interhemispheric vertical circulation forced by the summertime SST patterns closely associated with positive SIOD cases. By contrast, the monsoon trough is weakened and the dynamic and thermodynamic conditions are unfavourable for the WNP TC genesis in summer of a negative SIOD year, in agreement with a lower‐level anticyclonic anomaly and suppressed deep convection over the WNP forced by the SIOD‐related SST anomalies.

Contextual, Taphonomic, and Paleoecological Insights from Anurans on Tiwanaku Sites in Southern Peru

We examine the processes that resulted in the deposition of bones of at least three anuran genera on four archaeological sites associated with the Tiwanaku culture occupied between 700–1100 CE in the Moquegua Valley of far southern Peru. We review archaeological data and ethnographic accounts of Andean peoples using frogs and toads for food and in rain-quest rituals. Anuran bones are common in prehispanic cemeteries, but far less common in habitational and ceremonial sites. The quantity of anuran remains in certain cemeteries is anomalous in comparison to other archaeological sites in the valley and to Tiwanaku sites in other geographic settings. We conclude that anurans are most common where abandoned below-ground rock-covered tombs are likely to have been reused by nesting owls, and propose that most anuran remains in archaeological contexts in Moquegua are the result of predation. We consider environmental, cultural and taphonomic explanations and posit that the abundance of anuran remains relates to the 14th-century Miraflores ENSO event. This event generated increased rainfall in the desert, creating conditions favorable for frogs and toads, and predation by owls. We also advocate for the use of fine-screening to recover small-sized animal remains, such as anurans, that can be used to understand taphonomic processes and paleoenvironmental conditions.

Evaluation of the contraction and expansion of lentic water systems under the influence of the ENSO phenomenon (case study. Department of Córdoba, Colombia)

The sustainability of ecosystems and economic activities depend significantly on the availability of water, which can be affected by its temporal variability. Colombia is one of the countries that suffers high temporal variability of the water resource because of global, regional, and local phenomena. One of the macro-climatic events that alter the water regime is ENSO. Its impact on lotic water bodies is well known, while the effects on lentic systems are unknown. In this study, a methodology, which integrates climatic analyses with remote sensing studies, was designed to evaluate the relationship between the expansion and contraction of lotic bodies under the ENSO event, verified in four welt lands (ciénagas) in the department of Córdoba. The results showed that the dynamics depend up to 60 % on this macro-climatic event. The methodology developed can be considered as a tool for environmental planning of the territory around the lagoon systems, since it allows estimating buffer zones.

Extreme precipitation events in the Austral Chaco region of Argentina

AbstractThis study assesses the intensity, spatial distribution and temporal variability of extreme precipitation events (EPEs) on different time scales relevant to agriculture and water resources during the 1901–2016 period over Argentina's Austral Chaco (ACh). EPEs were identified using a nonparametric approach for the Standardized Precipitation Index (SPI). The leading modes of SPI's variability were detected using the Singular Spectrum Analysis. We also compile and control the quality of precipitation observations in a scarcely monitored region. The limited number of stations conditions the interpolation of the GPCC v2018 database here used, mainly during the early twentieth century. The EPEs characterized by SPI at a 24‐month time scale, which favour long‐lasting water excesses or deficits with hydrological impacts, underwent two differentiated long‐term periods: a dry one before 1960 and a wet one from 1960 to 2005. Consistently, seasonal wet EPEs were more frequent during the wet period while seasonal droughts were more frequent and with larger spatial extent during the dry period. Seasonal EPEs, represented by the SPI at 3‐month time scale, can impact agriculture during the crops' critical growth period. Since 2006, the long‐term wetting trend has been reversed. If this behaviour continues into the coming decades, more droughts and less wetness might be expected. The EPEs present a large interannual variability with 6.3‐ and 9‐year significant cycles that, combined with long‐term trends, favoured extremely wet/dry EPEs. Most of the wet/dry EPEs occurred during El Niño/La Niña events. Although this relationship is not straightforward, we found a discriminant ENSO signal between October of the year when an ENSO event starts and February of the next year. Finally, severely dry/wet EPEs tend to have large spatial extent in the ACh region. The central‐eastern ACh region experiences the most extreme wet and dry conditions, which makes this area more prone to extreme EPEs.

Upper vertical thermal contrast over the western Tibetan Plateau and its impact on convection over the Mediterranean region during ENSO events

Upper vertical thermal contrast over the western Tibetan Plateau and its impact on convection over the Mediterranean region during ENSO events

Spatiotemporal Rainfall Variability and Drought Assessment during Past Five Decades in South Korea Using SPI and SPEI

About 41% of the earth is drought-affected, which has impacted nearly 2 billion people, and it is expected that more than 90% of terrestrial areas will be degraded by 2050. To evade and mitigate the harmful impacts of drought, it is necessary to study the rainfall variability and assess the drought trend at a global and regional level. This study utilized 70 meteorological stations in South Korea to evaluate the rainfall variability, drought, and its trend during the past five decades using the standardized precipitation evapotranspiration index (SPEI) and the standardized precipitation index (SPI). Rainfall data normality was assessed with mean, standard deviation, skewness, and kurtosis. The highest amount of rainfall was observed in the months of June, July, and August. The SPI and SPEI 12-month results revealed that 1982, 1988, 2008, 2015, and 2017 were dry years throughout the country, while from 2013 to 2017 mixed drought events were observed for the 6-month time series. The Mann-Kendall trend test was applied to the 1- and 12-month time series, and the results revealed that the months of January, March, April, May, June, and August had a significant negative trend, which means drought is increasing in these months, while the months of September, October, and December had a significant positive trend, which means wetter conditions prevailed in these months during the study period. It was observed in the 12-month time series that only two met stations had a significant negative trend, while only one had a significant positive trend. It was found that January and March were the driest months, and October was the wettest month. The detected drought events in this research are consistent with ENSO events. We have observed differences in drought characteristics (duration and frequency) for both indices. Climatic data revealed that South Korea has faced drought conditions (rainfall deficit) due to a shortened monsoon season. This study can provide guidance on water management strategies under the changing pattern of drought in South Korea.

Enhanced risk of concurrent regional droughts with increased ENSO variability and warming

Spatially compounding extremes pose substantial threats to globally interconnected socio-economic systems. Here we use multiple large ensemble simulations of the high-emissions scenario to show increased risk of compound droughts during the boreal summer over ten global regions. Relative to the late twentieth century, the probability of compound droughts increases by ~40% and ~60% by the middle and late twenty-first century, respectively, with a disproportionate increase in risk across North America and the Amazon. These changes contribute to an approximately ninefold increase in agricultural area and population exposure to severe compound droughts with continued fossil-fuel dependence. ENSO is the predominant large-scale driver of compound droughts with 68% of historical events occurring during El Niño or La Niña conditions. With ENSO teleconnections remaining largely stationary in the future, a ~22% increase in frequency of ENSO events combined with projected warming drives the elevated risk of compound droughts. The co-occurrence of drought across different regions will have far-reaching effects on global agriculture and food supply. Model projections show an increased likelihood of these compound droughts under a high-emissions scenario, with a ninefold increase of farm land and population exposure.

Risk Management and Adaptation for Extremes and Abrupt Changes in Climate and Oceans: Current Knowledge Gaps

Perspectives for risk management and adaptation have received ample attention in the recent IPCC Special Report on Changes in the Oceans and Cryosphere (SROCC). However, several knowledge gaps on the impacts of abrupt changes, cascading effects and compound extreme climatic events have been identified, and need further research. We focus on specific climate change risks identified in the SROCC report, namely: changes in tropical and extratropical cyclones; marine heatwaves; extreme ENSO events; and abrupt changes in the Atlantic Meridional Overturning Circulation. Several of the socioeconomic impacts from these events are not yet well-understood, and the literature is also sparse on specific recommendations for integrated risk management and adaptation options to reduce such risks. Also, past research has mostly focussed on concepts that have seen little application to real-world cases. We discuss relevant research needs and priorities for improved social-ecological impact assessment related to these major physical changes in the climate and oceans. For example, harmonised approaches are needed to better understand impacts from compound events, and cascading impacts across systems. Such information is essential to inform options for adaptation, governance and decision-making. Finally, we highlight research needs for developing transformative adaptation options and their governance.

Sea surface temperature trend analysis by Mann-Kendall test and sen’s slope estimator: a study of the Hai Phong coastal area (Vietnam) for the period 1995-2020

Based on the Mann-Kendall test and Sen’s slope method, this study investigates the monthly, seasonal, and annual sea surface temperature (SST) trends in the coastal area of Hai Phong (West of Tonkin Gulf) based on the measurements at Hon Dau Station from 1995 to 2020. The results show a sea surface warming trend of 0.02°C/year for the period 1995-2020 (significant level α = 0.1) and of 0.093°C/year for the period 2008-2020 (significant level α = 0.05). The monthly SSTs in June and September increased by 0.027°C/year and 0.036°C/year, respectively, for the period 1995-2020, and by 0.080°C/year and 0.047°C/year, respectively, for the period 2008-2020. SST trends in winter, summer, and other months were either different for the two periods or not significant enough. This may be due to the impact of ENSO, which caused interannual SST variability in the Hai Phong coastal with two intrinsic mode functions (IMF) signals a period of ~2 (IMF3) and ~5.2 years cycle (IMF4). A combination of these signals had a maximum correlation of 0.22 with ONI (Oceanic Niño Index) delayed by 8 months. ENSO events took ~8 months to affect SST at Hai Phong coastal area for 1995-2020 and caused a variation of SST within 1.2°C.

CHARACTERISTICS AND IMPACTS OF EXTREME PRECIPITATION UNDER CLIMATE CHANGE: BASED ON CNKI LITERATURE INVESTIGATION

Extreme precipitation event is one of the most extensive and harmful meteorological disasters in China and even the world. Discussing the research situation of extreme precipitation under the background of climate change can grasp the research status and hot spots in this field from a macro perspective and provide a reference for in-depth understanding of the causes and trends of extreme precipitation. Since 1992, the research on extreme precipitation has been gradually carried out, so this study systematically counts and analyzes the scientific literature from the CNKI database from 1992 to 2022 by bibliometric. It shows that the frequency and intensity of extreme precipitation events increase in the China monsoon region, and the regional differences are obvious. It also has a great impact on agricultural production and vegetation coverage. In addition, in recent years, scholars have gradually carried out research on the relationship between extreme precipitation and atmospheric circulation, especially the relationship between the spatial and temporal characteristics of extreme precipitation and ENSO events, which has become a new research hotspot. It is suggested that future studies should comprehensively analyze various influencing factors, quantitatively analyze the impact of extreme precipitation on agricultural production and vegetation coverage, and put forward corresponding solutions.

International Satellite Cloud Climatology Project: Extending the Record

AbstractISCCP continues to quantify the global distribution and diurnal-to-interannual variations of cloud properties in a revised version. This paper summarizes assessments of the previous version, describes refinements of the analysis and enhanced features of the product design, discusses the few notable changes in the results, and illustrates the long-term variations of global mean cloud properties and differing high cloud changes associated with ENSO. The new product design includes a global, pixel-level product on a 0.1° grid, all other gridded products at 1.0°-equivalent equal area, separate satellite products with ancillary data for regional studies, more detailed, embedded quality information, and all gridded products in netCDF format. All the data products including all input data, expanded documentation, the processing code, and an operations guide are available online. Notable changes are 1) a lowered ice–liquid temperature threshold, 2) a treatment of the radiative effects of aerosols and surface temperature inversions, 3) refined specification of the assumed cloud microphysics, and 4) interpolation of the main daytime cloud information overnight. The changes very slightly increase the global monthly mean cloud amount with a little more high cloud and a little less middle and low cloud. Over the whole period, total cloud amount slowly decreases caused by decreases in cumulus/altocumulus; consequently, average cloud-top temperature and optical thickness have increased. The diurnal and seasonal cloud variations are very similar to earlier versions. Analysis of the whole record shows that high cloud variations, but not low clouds, exhibit different patterns in different ENSO events.

近60年秦岭山地旱涝变化规律

PDF HTML阅读 XML下载 导出引用 引用提醒 近60年秦岭山地旱涝变化规律 DOI: 10.5846/stxb202107191951 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 陕西省国际科技合作与交流计划重点项目（2020KWZ-010）；商洛市气候适应型城市重点实验室开放研究基金项目（SLSYS2019019）；陕西省青年高校创新团队 Changes of drought and flood in the Qinling Mountains in the last 60 years Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:随着极端气候变化，山地灾害频发。基于秦岭山地32个气象站点的实测数据，以标准化降水蒸散指数（SPEI）为旱涝量化指标，研究了过去60年秦岭山地旱涝时空变化特征、频率、周期等变化规律，结果表明：（1）1960-2019年，秦岭山地年SPEI指数以0.124/10a的速度下降，其中，90.23%的面积呈显著下降趋势，1.96%的面积呈显著上升趋势，并在1990年发生干旱突变；秦岭北坡的干旱化趋势大于南坡，且高海拔地区干旱化更为明显。（2）突变前秦岭山地湿润比例平均值为36.94%，突变后下降为18.19%；干旱比例由突变前的17.64%急剧上升到突变后的38.19%；突变前30年秦岭山地极端干旱事件、严重干旱事件极少发生，发生频率几乎为0；突变后30年严重干旱和极端干旱事件发生频率增加，秦岭南北坡极端湿润和严重湿润事件近乎销声匿迹。（3）整体上，太阳黑子与秦岭山地旱涝变化以显著负相关关系为主；ENSO事件对秦岭山地的旱涝变化影响较大，在La Nina年易发生洪涝事件，在El Niño年易发生干旱事件；在不同时域范围内，海表温度距平（SSTA）对秦岭山地旱涝变化的影响不同：1990年以前，SPEI与SSTA存在显著的负相关关系；1990年后，SPEI与SSTA存在5-6年的强凝聚性共振周期，且SPEI滞后SSTA约1/4周期。 Abstract:With the global environmental change, extreme climate events occur frequently and meteorological disasters become more and more serious, and mountain disasters are frequent. Based on the long-term monitoring data from 32 meteorological stations in the Qinling Mountains, we conducted a study using the standardized precipitation evapotranspiration index (SPEI) as a quantitative indicator of drought and flooding. We haved studied the spatial and temporal characteristics, frequency, and periodicity of drought and flood in the Qinling Mountains over the past 60 years. The results showed that:(1) from 1960 to 2019, the annual SPEI index in the Qinling Mountains decreased at a rate of 0.124/10 a. Of which, 90.23% of the area showed a significant decreasing trend and 1.96% showed a significant increasing trend, and aridity mutation occurred in 1990. The aridity trend of the northern slopes of the Qinling Mountains was greater than that of the southern slopes, and the aridity was more obvious at high altitudes. (2) The average wetness ratio of the Qinling Mountains was 36.94% before the mutation, and decreased to 18.19% after the mutation. The aridity ratio increased sharply from 17.64% before the mutation to 38.19% after the mutation. The frequency of extreme drought events and severe drought events in the Qinling Mountains in the 30 years before the mutation was almost zero; the frequency of severe drought and extreme drought events increased in the 30 years after the mutation, and the extreme wetness and severe wetness events on the north and south slopes of the Qinling Mountains nearly disappeared. (3) On the whole, there is a negative correlation between sunspots and drought and flood changes in the Qinling Mountains. ENSO events had a greater impact on drought and flood changes in the Qinling Mountains, and were prone to flood events in La Nina years and drought events in El Niño years. The impact of SSTA (Sea surface temperature anomaly) on drought and flood changes in the Qinling Mountains is different in different time domains:before 1990, there was a significantly negative correlation between SPEI and SSTA; After 1990, there was a strongly cohesive resonance cycle of 5-6 a between SPEI and SSTA, and SPEI lags SSTA by about 1/4 cycle. These findings would be of important reference value for the prevention of droughts and floods on the southern and northern slopes of the Qinling Mountains, and the development of forestry and agriculture in the Qinling Mountains. 参考文献 相似文献 引证文献

A Deep Learning Model for Sea Surface Salinity Forecast in the Eastern Tropical Pacific Ocean During Enso Events

A Deep Learning Model for Sea Surface Salinity Forecast in the Eastern Tropical Pacific Ocean During Enso Events

Evaluation of climate variability and change in ACCESS historical simulations for CMIP6

We analyse and document the historical simulations performed by two versions of the Australian Community Climate and Earth System Simulator (ACCESS-CM2 and ACCESS-ESM1.5) for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Three ensemble members from each model are used to compare the simulated seasonal-mean climate, climate variability and climate change with observations over the historical period. Where appropriate, we also compare the ACCESS model results with the results from 36 other CMIP6 models. We find that the simulations of the winter and summer mean climates (over the global domain) by the two ACCESS models are similar to or better than most of the other CMIP6 models for surface temperature, precipitation and surface specific humidity. For sea-level pressure, both ACCESS models perform worse than most other models. The spatial structures of the prominent climate variability modes (ENSO, IOD, IPO and AMO) also compare favourably with the corresponding observed structures. However, the results for the simulation of the models’ temporal variability are mixed. In particular, whereas ACCESS-ESM1.5 simulates ENSO events with ~3-year periods (that are closer to the observed periods of 3–7 years), the ACCESS-CM2 simulates ENSO events having quasi-biennial periods. However, ACCESS-CM2 has a much smaller bias (−0.1 W m−2) in present-day top-of-the-atmosphere energy balance than ACCESS-ESM1.5 (−0.6 W m−2). The ACCESS models simulate the anthropogenic climate change signal in historical global-mean surface temperature reasonably well, although the simulated signal variances are ~10% weaker than the observed signal variance (a common bias in most CMIP6 models). Both models also well simulate the major features of observed surface temperature changes, as isolated using a multiple regression model. Despite some identified biases, the two ACCESS models provide high-quality climate simulations that may be used in further analyses of climate variability and change.

Did Sunspots Cycles 19-24 Influence the Enso Events, Pdo, and Amo Indexes in the Pacific and Atlantic Oceans?

Did Sunspots Cycles 19-24 Influence the Enso Events, Pdo, and Amo Indexes in the Pacific and Atlantic Oceans?

Physical-Ecological Response of the California Current System to ENSO events in ROMS-NEMURO

Physical-Ecological Response of the California Current System to ENSO events in ROMS-NEMURO

Towards Climate Resilience in the Nile Basin: The Case of the Sudan


 
 Although Africa’s share to the causes of Climate Change is insignificant yet, the continent is the most vulnerable to the impacts of the phenomenon. The Nile Basin witnesses very high population growth rates, severe impacts of climate variability and change and severe food insecurity. About 94% of the Sudan is located in the arid and semiarid regions. Desertification, climate change and other forms of environmental degradation strongly contribute to poverty, displacement and conflicts. Separation of south Sudan imposed huge economic hardships to the country which was formerly reported to achieve economic stability due to the implementation of the Comprehensive Peace Agreement. Recent projections showed that the Sudan will witness severe water shortages of about 30 billion cubic meters by the year 2027. Different factors like the ENSO Event were found to contribute to the variability of the country’s rain fall and consequently, severe droughts, devastating floods and substantial socioeconomic impacts were incurred. Due to Climate Change the rain fall of the country showed 19% reduction and increased variability. Meanwhile, further reduction in rain fall coupled with south ward shift of agro-climatic zones and reduced crop productivity were anticipated. Climate resilience is maintained by creating conducive policy environment, strengthening relevant institutions and early warning systems and implementation of the relevant programs and projects. In addition to that basin (regional) cooperation is of vital importance especially promotion of regional trade, coordinated reservoir operation and joint research. The Higher Council for Civil Defense is the apex body to coordinate disaster management in the Sudan. The paper recommends that the efforts to craft the national water policy, other sectoral policies, the national IWRM plan and the NAP are to be urged.

Behaviors of the Tropical Pacific Barrier Layer during ENSO Events and its Mechanism

Behaviors of the Tropical Pacific Barrier Layer during ENSO Events and its Mechanism