Southern East Asia Research Articles

Source Contributions to Carbon Monoxide Concentrations During KORUS‐AQ Based on CAM‐chem Model Applications

AbstractWe investigate regional sources contributing to CO during the Korea United States Air Quality (KORUS‐AQ) campaign conducted over Korea (1 May to 10 June 2016) using 17 tagged CO simulations from the Community Atmosphere Model with chemistry (CAM‐chem). The simulations use three spatial resolutions, three anthropogenic emission inventories, two meteorological fields, and nine emission scenarios. These simulations are evaluated against measurements from the DC‐8 aircraft and Measurements Of Pollution In The Troposphere (MOPITT). Results show that simulations using bottom‐up emissions are consistently lower (bias: −34 to −39%) and poorer performing (Taylor skill: 0.38–0.61) than simulations using alternative anthropogenic emissions (bias: −6 to −33%; Taylor skill: 0.48–0.86), particularly for enhanced Asian CO and volatile organic compound (VOC) emission scenarios, suggesting underestimation in modeled CO background and emissions in the region. The ranges of source contributions to modeled CO along DC‐8 aircraft from Korea and southern (90°E to 123°E, 20°N to 29°N), middle (90°E to 123°E, 29°N to 38.5°N), and northern (90°E to 131.5°E, 38.5°N to 45°N) East Asia (EA) are 6–13%, ~5%, 16–28%, and 9–18%, respectively. CO emissions from middle and northern EA can reach Korea via transport within the boundary layer, whereas those from southern EA are transported to Korea mainly through the free troposphere. Emission contributions from middle EA dominate during continental outflow events (29–51%), while Korean emissions play an overall more important role for ground sites (up to 25–49%) and plumes within the boundary layer (up to 25–44%) in Korea. Finally, comparisons with four other source contribution approaches (FLEXPART 9.1 back trajectory calculations driven by Weather Research and Forecasting (WRF) WRF inert tracer, China signature VOCs, and CO to CO2 enhancement ratios) show general consistency with CAM‐chem.

Linear respective roles of El Niño–Southern Oscillation and East Asian winter monsoon in the formation of the western North Pacific anticyclone

Based on reanalysis data, we investigate the respective roles of the East Asian winter monsoon (EAWM) and El Niño–Southern Oscillation (ENSO) in building an anomalous western North Pacific anticyclone (WNPAC) in winter to the succeeding summer. The isolated ENSO and EAWM parts (termed ENSOres and EAWMres, respectively) are acquired by removing the ENSO–EAWM interdependent part through linear regression. The results suggest that both ENSOres and EAWMres can produce a WNPAC in winter. The ENSOres‐related WNPAC dominantly covers the southern part of the western North Pacific, whereas the EAWMres‐related WNPAC over the northern part of the western North Pacific. In the subsequent spring and summer, only ENSOres yields a WNPAC, while EAWMres has no effect on the atmospheric circulation over the western North Pacific. Additionally, the Pacific Decadal Oscillation (PDO) can modulate the influence of ENSOres and EAWMres on the WNPAC. There tends to be a much stronger WNPAC associated with ENSOres (EAWMres) during positive (negative) PDO phases than during negative (positive) ones.

Modeling the contributions of Northern Hemisphere dust sources to dust outflow from East Asia

Mineral dust aerosols can substantially influence the Earth's climate by altering the radiation budget and modifying cloud microphysical and radiative properties. Through long-range transport, dust aerosols could have a global impact. Here, using a fully coupled meteorology-chemistry model (WRF-Chem) and the tracer-tagging technique, we conduct quasi-global simulations to investigate the characteristics of dust intercontinental transport in the Northern Hemisphere and the source contributions to dust outflow from East Asia. Model results show that total dust emission from the main deserts (i.e., North Africa desert (NFD), Middle East desert (MED) and East Asia desert (EAD)) is about 4531 Tg yr−1, in which 66% is from NFD, 24% is from MED and 10% is from EAD. During long-range transport, the NFD and MED dust plumes are separated into two branches by the Tibetan Plateau, with higher dust concentration of 4 μg m−3 in the northern branch (37° N-60° N). The imported dust mass from NFD and MED to East Asia is 16.0 Tg yr−1 and 33.8 Tg yr−1, respectively; the local dust mass emitted from EAD can circumnavigate and import about 0.41 Tg yr−1 of dust into East Asia. As part of the “Asian outflow”, the MED and NFD dust is transported above 600 hPa with concentration of 2 μg m−3, while the EAD dust is mainly transported below 600 hPa with concentration of 3 μg m−3. The total outflow dust mass from East Asia is 12.0, 9.7 and 7.7 Tg yr−1 from EAD, NFD and MED, respectively. Dust particles dominate the aerosol mass concentration with a fraction of 56.5% in southern East Asia and 75.4% in northern East Asia. Moreover, dust number from EAD dominates the total aerosol number north of 37oN below 600 hPa, with a size range of 0.156–0.625 μm, but the NFD dust number is mainly above 600 hPa. MED dust number dominates the total column aerosol number south of 37 oN, with a size range of 0.312–0.625 μm. Quantifying dust source contributions and the associated dust number loading and size distribution over East Asia is important for understanding the role of East Asian dust outflow in climate and hydrological cycle.

Uniparental Genetic Analyses Reveal the Major Origin of Fujian Tanka from Ancient Indigenous Daic Populations.

The Fujian Tanka people are officially classified as a southern Han ethnic group, whereas they have customs similar to Daic and Austronesion people. Whether they originated in Han or Daic people, there is no consensus. Three hypotheses have been proposed to explain the origin of this group: (1) the Han Chinese origin, (2) the ancient Daic origin, (3) and the admixture between Daic and Han. This study addressed this issue by analyzing the paternal Y chromosome and maternal mtDNA variation of 62 Fujian Tanka and 25 neighboring Han in Fujian. The southern East Asian predominant haplogroups (e.g., Y-chromosome O1a1a-P203 and O1b1a1a-M95, and mtDNA F2a, M7c1, and F1a1) had relatively high frequencies in Tanka. The interpopulation comparison revealed that the Tanka have a closer affinity with Daic populations than with Han Chinese in paternal lineages but are closely clustered with southern Han populations such as Hakka and Chaoshanese in maternal lineages. Network and haplotype-sharing analyses also support the admixture hypothesis. The Fujian Tanka mainly originate from the ancient indigenous Daic people and have only limited gene flows from Han Chinese populations. Notably, the divergence time inferred by the Tanka-specific haplotypes indicates that the formation of Fujian Tanka was a least 1033.8-1050.6 years before present (the early Northern Song dynasty), indicating that they are an indigenous population, not late Daic migrants from southwestern China.

Potential impacts of enhanced tropical cyclone activity on the El Niño–Southern Oscillation and East Asian monsoon in the mid-Piacenzian warm period

Tropical cyclones (TCs) not only passively respond to climate change, but also play an important role in vertical mixing of the upper ocean and in driving oceanic heat transport. Using a fully coup...

Food Security as a Water Grand Challenge

AbstractPerhaps the biggest challenge the world faces is providing sufficient, nutritious, and safe food at the right time for its ever‐increasing population. Considering current world population growth trends, it is estimated that the global population will be about 10 billion by the year 2050. Therefore, food production should at least double in the same period if food security is to be satisfied. Water and land resources play a pivotal role in agriculture and directly connect to food security. At the same time, the capacity to produce food is constrained by global climate changes and increased pressure on land resources. These challenges are more severe in Southern Asia, Sub‐Saharan Africa, and East Asia, where conflict and lack of capacity to fund agricultural research and food production are common. Strategies that simultaneously increase food production and reduce threats to food security are therefore needed. The objectives of this paper are to review the grand challenges of global food security and to propose strategies for mitigating food insecurity, with an emphasis on the link between water resources and food production.

Reconstruction of the Little Ice Age glaciers and equilibrium line altitudes in the Kodar Range, southeast Siberia

Little Ice Age (LIA), a time of global cooling widely manifested in the 14th-19th centuries, was characterized by worldwide expansion of mountain glaciers. Unfortunately, little is known about the LIA glacier changes in remote areas of continental Siberia. In this work we studied the evolution of the glaciers of the Kodar Range, southeast Siberia. These glaciers are mainly of small size (<0.5 km2), cirque and cirque-valley, with predominant northern and north-eastern aspects, located at elevations of 1900–2800 m a.s.l. Using field and satellite imagery data over the 2001–2013 period (Landsat ETM+, Cartosat-1, WorldView-2) we mapped the glaciers, equilibrium line altitudes (ELAs) and the LIA moraines. Modern ELAs vary from 1945 to 2615 m a.s.l. (mean value is 2286 ± 162 m) and demonstrate NNW to SSE increasing regional trend (from 2060 to 2430 m a.s.l.) with local ELA variability due to orography of ±114 m. The extents of the LIA glaciers were reconstructed from terminal moraines, located in front of the glacier termini. These moraines are of fresh morphology, non-vegetated, and locally dated by lichenometry at the mid-18th century. Since the LIA the total glacier area decreased from 19 km2 to 9 km2 (by 53%) and glacier termini retreated, on average, by 440 m. South and south-west facing glaciers shrunk 1.5–2 times stronger than those with northern and north-eastern aspects. Using the toe-to-headwall altitude ratio (THAR) and toe-to-summit altitude method (TSAM), the LIA ELAs were calculated. The LIA ELAs lowered, on average, by 40–60 m, while the ELA changes on south and south-west facing glaciers (mean value of 80–100 m) was 2–2.5 times greater than of the northern. ELA depression during the LIA corresponded to decrease in mean summer temperature of 0.9–1.1 °C (if precipitation was equal to the present). Temperature increase was mainly responsible for ELA rising since the LIA, however, the response of small glaciers could be modulated by other factors (e.g. local insolation or precipitation). Stronger reduction of the south and south-west facing Kodar glaciers can be explained by their greater sensitivity to both solar radiation and snow nourishment with southern cyclones and East Asian monsoon.

The role of anthropogenic aerosols in future precipitation extremes over the Asian Monsoon Region

The role of anthropogenic aerosols in future projections (up to 2100) of summertime precipitation and precipitation extremes over the Asian monsoon region is investigated, by comparing two sets of the Community Earth System Model (CESM1) large ensemble simulations under the Representative Concentration Pathway 8.5 scenario (RCP8.5) and the corresponding scenario with aerosol fixed at 2005 levels (RCP8.5_FixA). The model is verified to be performing well in capturing present-day (1986–2005) climate and precipitation extremes. Our results suggest that the Asian monsoon region would become progressively warmer and wetter in the future under RCP8.5, while precipitation extremes will be significantly aggravated due to anthropogenic aerosol mitigation, particularly over East Asia. Specifically, aerosol reductions are found to shift the distribution of precipitation mean and extremes to larger values. For example, aerosol reductions would result in an increased likelihood of extreme precipitation (e.g. the maximum consecutive 5-day precipitation amount) and related disasters. Sensitivities of changes in precipitation mean and extremes to local warming from aerosol reductions are much larger than that from greenhouse gas increases. This is particularly important over East Asia in accordance with larger magnitudes of aerosol reductions compared to South Asia. Finally, by investigating the response of the climate system to aerosol changes, our findings demonstrate that aerosol induced precipitation changes would be dominated by aerosol–radiation–cloud forcing over northern East Asia and aerosol forcing induced large-scale circulation anomalies over southern East and South Asia.

The origin and evolution history of East Asian populations from genetic perspectives

East Asia is widely concerned as one of the important places for the dispersal and evolution of the Anatomically Modern Human (AMH). How the diverse ethnic groups in East Asia originated and diversified is also widely focused by different disciplines of Anthropology. The adoption of genetic data had provided new clues for reconstructing the genetic history of East Asian populations. Genetic studies supported the hypothesis that the AMHs originated from Africa's Homo sapiens at about 200 kilo years ago (kya) and then migrated out of Africa at ~100 kya, followed by expansions into the whole East Asia since their arrival in Southern East Asia at 5~6 kya along the coastal route. Early Homo Sapiens might have genetic contribution to the non-African AMHs. Early settlement, cultural assimilation, population migration and genetic exchanges are crucial in the origination and evolution of East Asia populations. Previous studies made detailed analysis for the genetic history of East Asian populations, which largely resolved the longstanding divergence between archaeology and history. However, this needs further verification by whole-genome sequencing and ancient DNA studies. Here we briefly reviewed the progresses of genetic studies in exploring the population origin, dispersal and diversification in East Asia, which improved understanding of the evolution of East Asian populations. We also prospected the future of genetic studies in revealing the prehistory of East Asians.

Enhanced Linkage between Eurasian Winter and Spring Dominant Modes of Atmospheric Interannual Variability since the Early 1990s

The present study reveals a marked enhancement in the relationship between Eurasian winter and spring atmospheric interannual variability since the early 1990s. Specifically, the dominant mode of winter Eurasian 500-hPa geopotential height anomalies, with same-sign anomalies over southern Europe and East Asia and opposite-sign anomalies over north-central Eurasia, is largely maintained to the following spring after the early 1990s, but not before the early 1990s. The maintenance of the dominant atmospheric circulation anomaly pattern after the early 1990s is associated with a triple sea surface temperature (SST) anomaly pattern in the North Atlantic that is sustained from winter to the subsequent spring. This triple SST anomaly pattern triggers an atmospheric wave train over the North Atlantic through Eurasia during winter through spring. Atmospheric model experiments verify the role of the triple SST anomaly in maintaining the Eurasian atmospheric circulation anomalies. By contrast, before the early 1990s, marked SST anomalies related to the winter dominant mode only occur in the tropical North Atlantic during winter and they disappear during the following spring. The triple SST anomaly pattern after the early 1990s forms in response to a meridional atmospheric dipole over the North Atlantic induced by a La Niña–like cooling over tropical Pacific, and its maintenance into the following spring may be via a positive air–sea interaction process over the North Atlantic. Results of this analysis suggest a potential source for the seasonal prediction of the Eurasian spring climate.

Out of Southern East Asia of the Brown Rat Revealed by Large-Scale Genome Sequencing.

The geographic origin and migration of the brown rat (Rattus norvegicus) remain subjects of considerable debate. In this study, we sequenced whole genomes of 110 wild brown rats with a diverse world-wide representation. We reveal that brown rats migrated out of southern East Asia, rather than northern Asia as formerly suggested, into the Middle East and then to Europe and Africa, thousands of years ago. Comparison of genomes from different geographical populations reveals that many genes involved in the immune system experienced positive selection in the wild brown rat.

Whole genome sequencing analysis of Salmonella enterica serovar Weltevreden isolated from human stool and contaminated food samples collected from the Southern coastal area of China

Salmonella enterica serovar Weltevreden is the most common non-typhoid Salmonella found in South and Southeast Asia. It causes zoonoses worldwide through the consumption of contaminated foods and seafood, and is considered as an important food-borne pathogen in China, especially in the Southern coastal area. We compared the whole genomes of 44 S. Weltevreden strains isolated from human stool and contaminated food samples from Southern Coastal China, in order to investigate their phylogenetic relationships and establish their genetic relatedness to known international strains. ResFinder analysis of the draft genomes of isolated strains detected antimicrobial resistance (AMR) genes in only eight isolates, equivalent to minimum inhibitory concentration assay, and only a few isolates showed resistance to tetracycline, ciprofloxacin or ampicillin. In silico MLST analysis revealed that 43 out of 44 S. Weltevreden strains belonged to sequence type 365 (CC205), the most common sequence type of the serovars. Phylogenetic analysis of the 44 domestic and 26 international isolates suggested that the population of S. Weltevreden could be segregated into six phylogenetic clusters. Cluster I included two strains from food and strains of the “Island Cluster”, indicating potential inter-transmission between different countries and regions through foods. The predominant S. Weltevreden isolates obtained from the samples from Southern coastal China were found to be phylogenetically related to strains from Southern East Asia, and formed clusters II–VI. The study has demonstrated that WGS-based analysis may be used to improve our understanding of the epidemiology of this bacterium as part of a food-borne disease surveillance program. The methods used are also more widely applicable to other geographical regions and areas and could therefore be useful for improving our understanding of the international spread of S. Weltevreden on a global scale.

Transient simulation of the Tibetan Plateau modulated distinct orbital-scale precipitation variation in East and South Asia

The insolation change caused by the Earth's orbital forcing is known to play an important role in regulating variations of the Asian monsoon at various time scales. Geological records and numerical simulation revealed that the climate change in the Asian monsoon region was in-phase or out-of-phase with the boreal summer insolation at the orbital scale. Using the Community Climate System model version 3 and the orbital acceleration technique, we conducted two long-term transient simulations with and without the Tibetan Plateau (TP) orography (TP1 and TP0 experiments). The main objective of this study was to examine the influence of the TP uplift on the orbital-scale precipitation in East and South Asia, and the anti-phase relationship between southern and northern East Asia (SEA and NEA), during the past 150kyr. The results further confirm that the uplift of the TP significantly affects the Asian atmospheric circulation and precipitation, and is an amplifier of the Asian summer monsoon at the precessional scale. In general, the presence of the TP causes the rain belt and atmospheric circulation front to shift northward. In particular, we found that the anti-phase relationship of precipitation between NEA and SEA at the precessional band is also controlled by the uplift of the TP. Simulations in TP1 and TP0 experiments show that the inverse variations in atmospheric circulation, including the 850hPa wind field and vertical pressure velocity caused by the uplift of the TP, can directly lead to the out-of-phase JJA precipitation at the precessional scale between NEA and SEA. Future research to collect various climatic proxies with high spatial and temporal resolutions, at least since the Cenozoic, is required to support the simulation results of this study.

Effect of the tropical Pacific and Indian Ocean warming since the late 1970s on wintertime Northern Hemispheric atmospheric circulation and East Asian climate interdecadal changes

Observation reveals that the tropical Pacific-Indian Ocean (TPIO) has experienced a pronounced interdecadal warming since the end of the 1970s. Meanwhile, the wintertime midlatitude Northern Hemispheric atmospheric circulation and East Asian climate have also undergone substantial interdecadal changes. The effect of the TPIO warming on these interdecadal changes are identified by a suite of AMIP-type atmospheric general circulation model experiments in which the model is integrated from September 1948 to December 1999 with prescribed historical, observed realistic sea surface temperature (SST) in a specific region and climatological SST elsewhere. Results show that the TPIO warming reproduces quite well the observed Northern Hemispheric wintertime interdecadal changes, suggesting that these interdecadal changes primarily originate from the TPIO warming. However, each sub-region of TPIO has its own distinct contribution. Comparatively, the tropical central-eastern Pacific (TCEP) and tropical western Pacific (TWP) warming makes dominant contributions to the observed positive-phase PNA-like interdecadal anomaly over the North Pacific sector, while the tropical Indian Ocean (TIO) warming tends to cancel these contributions. Meanwhile, the TIO and TWP warming makes dominant contributions to the observed positive NAO-like interdecadal anomaly over the North Atlantic sector as well as the interdecadal anomalies over the Eurasian sector, although the TWP warming’s contribution is relatively small. These remote responses are directly attributed to the TPIO warming-induced tropical convection, rainfall and diabatic heating increases, in which the TIO warming has the most significant effect. Moreover, the TPIO warming excites a Gill-type pattern anomaly over the tropical western Pacific, with a low-level anticyclonic circulation anomaly over the Philippine Sea. Of three sub-regions, the TIO warming dominates such a pattern, although the TWP warming tends to cancel this effect. The anticyclonic circulation anomaly intensifies the southwesterly flow that transfers more moisture from the Bay of Bengal to East Asia and considerably increases the winter precipitation over the southern East Asia. This is strongly supported by the observational fact that there has been a significant interdecadal increase of winter precipitation over the southern China since the end of the 1970s.

Anthropogenic aerosol effects on East Asian winter monsoon: The role of black carbon‐induced Tibetan Plateau warming

AbstractThis study investigates anthropogenic aerosol effects on East Asian winter monsoon (EAWM) with Community Atmospheric Model version 5. In winter, the anthropogenic aerosol optical depth is the largest over southern East Asia and adjacent oceans. The associated EAWM change, however, is the most significant in northern East Asia, which is characterized by a significant surface cooling in northern East Asia and an acceleration of the jet stream around 40°N, indicating an intensification of the EAWM northern mode. Such an intensification is attributed to anthropogenic black carbon (BC)‐induced Tibetan Plateau (TP) warming. The BC is mostly transported from northern South Asia by wintertime westerly and southwesterly and then deposited on snow, giving rise to a reduction of surface albedo and an increase of surface air temperature via the snow‐albedo feedback. The TP warming increases meridional temperature gradient and lower tropospheric baroclinicity over northern East Asia, leading to the jet stream acceleration around 40°N and the westward shift of East Asian major trough via the transient eddy‐mean flow feedback. Such upper tropospheric pattern favors more cold air outbreak, leading to a large surface cooling in northern East Asia. In southern East Asia, the effect of nonabsorbing aerosols is dominant. The solar flux at surface is significantly reduced directly by scattering of nonabsorbing aerosols and indirectly by intensification of short wave cloud forcing. Accordingly, the surface air temperature in southern East Asia is reduced. The precipitation is also significantly reduced in South China and Indo‐China Peninsula, where the aerosol indirect effect is the largest.

Calophyllum inophyllum methyl ester biodiesel blend as an alternate fuel for diesel engine applications

Calophyllum inophyllum oil is non-edible in nature could be used as a source for biodiesel esterification in India and it is also available in abundant quantities in places such as Southern east and East Asia and Australia. The present research work examines the suitability of Calophyllum inophyllum as promising feedstock for biodiesel production and its employability in diesel engine operation. The Calophyllum trees are found in abundance in India and can reduce the dependency of petroleum imports to a certain extent. The biodiesel Calophyllum inophyllum Methyl Ester (CIME100) and its blends CIME30 and CIME60 are used in engine testing. The experimental parameters such as brake thermal efficiency, brake specific energy consumption, unburned hydrocarbon, carbon monoxide, and NOx emissions are evaluated with CIME100 biodiesel and the results are compared with conventional fuel. It is observed that the CIME biodiesel resulted in slight decrease in brake thermal efficiency. The hydrocarbon and carbon monoxide emissions are reduced with the use of biodiesel with significant penalty in oxides of nitrogen emissions. In addition, the combustion parameters such as cylinder gas pressure, ignition delay period, and heat release rate of CIME100 are discussed in detailed and compared to conventional diesel fuel under various loading conditions.

Statistical–Dynamical Seasonal Forecast of Western North Pacific and East Asia Landfalling Tropical Cyclones using the GFDL FLOR Coupled Climate Model

Abstract This study attempts to improve the prediction of western North Pacific (WNP) and East Asia (EA) landfalling tropical cyclones (TCs) using modes of large-scale climate variability [e.g., the Pacific meridional mode (PMM), the Atlantic meridional mode (AMM), and North Atlantic sea surface temperature anomalies (NASST)] as predictors in a hybrid statistical–dynamical scheme, based on dynamical model forecasts with the GFDL Forecast-Oriented Low Ocean Resolution version of CM2.5 with flux adjustments (FLOR-FA). Overall, the predictive skill of the hybrid model for the WNP TC frequency increases from lead month 5 (initialized in January) to lead month 0 (initialized in June) in terms of correlation coefficient and root-mean-square error (RMSE). The hybrid model outperforms FLOR-FA in predicting WNP TC frequency for all lead months. The predictive skill of the hybrid model improves as the forecast lead time decreases, with values of the correlation coefficient increasing from 0.56 for forecasts initialized in January to 0.69 in June. The hybrid models for landfalling TCs over the entire East Asian (EEA) coast and its three subregions [i.e., southern EA (SEA), middle EA (MEA), and northern EA (NEA)] dramatically outperform FLOR-FA. The correlation coefficient between predicted and observed TC landfall over SEA increases from 0.52 for forecasts initialized in January to 0.64 in June. The hybrid models substantially reduce the RMSE of landfalling TCs over SEA and EEA compared with FLOR-FA. This study suggests that the PMM and NASST/AMM can be used to improve statistical/hybrid forecast models for the frequencies of WNP or East Asia landfalling TCs.

Increased trapping efficiency for the peach fruit moth Carposina sasakii (Matsumura) with synthetic sex pheromone

Abstract Carposina sasakii Matsumura is one of the most serious fruit‐damaging pests in Southern East Asia. The management of C. sasakii using sex pheromones has proven to be simple, effective and environmentally friendly with respect to monitoring and controlling this pest. To apply sex pheromone‐based pest control techniques effectively, we characterized a range of application parameters, as well as the effects of synthetic sex pheromones, in jujube orchards. Trapping radius was determined by comparing the mean number of trapped individuals at different inter‐trap distances, and mating disruption parameters were inferred by comparing the rate of trapping efficiency reduction and the infestation ratio of fruits in the experimental fields by uniformly placing different number/types of lures/100 m2. These studies revealed capture rates with significant differences across 10–50‐m inter‐trap distances: for example, a 30‐m or greater inter‐trap distance was suitable for monitoring and mass trapping, whereas distances &lt;20 m significantly decreased the trapping efficiency in the testing area. The studies lay the foundation for the implementation of these technologies within the context of a well‐conceived control strategy against this significant agricultural pest.

The gender division of labor and second births: Labor market institutions and fertility in Japan

1. IntroductionVery low fertility rates in Southern Europe, Eastern Europe, and East Asia have been a source of great interest for demographers in recent years (Kohler, Billari, and Ortega 2002; Lesthaeghe 2010). Among the theories proposed to explain the emergence of what is termed 'lowest-low' fertility (total fertility rates of 1.3 or lower), theories emphasizing the unevenness of gender-role change have increasingly occupied center stage. Central among these is McDonald's gender equity framework, with its focus on the slow pace of change in men's and women's household roles compared to their increasingly equal participation in the public sphere, especially the labor market (McDonald 2000). Recent work has suggested that increases in gender equality are likely to help societies currently experiencing low fertility to move towards an equilibrium characterized by near-replacement fertility rates (Esping-Andersen and Billari 2015; Goldscheider, Bernhardt, and Lappegard 2015).This paper seeks to make both a theoretical and an empirical contribution to the analysis of how gender equality is related to fertility. First, we bring the role of labor market institutions into the analysis, theorizing the importance of considering how employment norms and work culture affect men's ability to participate in housework. In doing so we establish the connection not only between women's roles in the public and private spheres but also between men's roles in these two spheres. Second, we bring East Asia more fully into the literature on low fertility, which has been dominated by research on Europe. We utilize individual-level panel data from Japan, one of the countries that has had persistently low fertility over the past two decades, despite government policy efforts to raise the birth rate. We employ an analysis strategy that models husband's contribution to household labor in the context of Japanese labor market institutions and then models the effect of husband's household work on the transition to second birth. In demonstrating how gender-role specialization in Japanese marriages is connected to the broader labor market context, we argue that Japanese labor market structure and workplace norms have a negative impact on Japan's fertility rate.2. The household division of labor and fertility2.1 Empirical studiesFollowing McDonald's gender equity perspective and the expectation that a highly gendered household division of labor in postindustrial societies is likely to depress fertility, in recent years a number of empirical studies have endeavored to test this relationship. At the macro level, Feyrer, Sacerdote, and Stern (2008) find a positive relationship in OECD countries between the average household work share of husbands and the average number of births.3 A number of studies using micro-level data find that increased involvement of fathers in childcare and housework increases the likelihood of a second birth. For instance, Olah (2003) compares Sweden, which has had a longstanding dual-earner/dual-carer family model, with Hungary, a country that has emphasized paid work for men and women but a more traditional division of labor at home. She finds that fathers' involvement in household work increases the probability of second birth in both countries.4 Using US data, Torr and Short (2004) find a Ushaped relationship between couples' distribution of household labor and the transition to second birth, with a higher probability of second birth for couples where the wife does most of the housework (the 'traditional' model) as well as for couples where housework is shared relatively equally between spouses.Studies using micro-level data from countries with a more traditional malebreadwinner model have produced somewhat mixed results. In her comparative study of Italy and Spain, Cooke (2009) finds that fathers' share of childcare has no effect on the probability of a second birth in Spain. In Italy, fathers' childcare time has a positive effect but the strength of the effect varies by mothers' employment status. …

Variability in zonal location of winter East Asian jet stream

ABSTRACTThis study reveals that the winter East Asian jet stream (EAJS) shows a strong variability in its zonal location; this topic has received less attention compared with the EAJS intensity and meridional location variability in previous studies. We show that the mid‐to‐high latitude climate system is mainly responsible for the EAJS eastward shift and the tropical system is closely related with the EAJS westward shift. In the EAJS east‐located years, North Pacific Oscillation undergoes a positive phase, which can enhance the eastern part of the EAJS over the North Pacific, favouring the eastward shift of the EAJS. In the west‐located years, the tropical convection over the Indian Ocean is strong, which can strengthen the zonal angular momentum transport from the Tropics to subtropical westerly belt. Consequently, the western part of the EAJS enhances and the EAJS shifts westward. In addition, the east‐located EAJS is related to the intensified Aleutian Low and East Asian trough, and thus, Northeast China, Korean Peninsula, and Japan experience low temperatures. On the other hand, the west‐located EAJS is associated with the weakened mid‐Asian ridge and cold‐temperature advection over southern East Asia, and thus, regions from mid‐Asia southeastward to southern China experience cold temperatures. Therefore, the zonal location of the EAJS is a potentially good index of the northern or southern East Asian anomalous temperature pattern.