China Spring Research Articles

Inter-Model Spread in Representing the Impacts of ENSO on the South China Spring Rainfall in CMIP6 Models

A major challenge for climate system models in simulating the impacts of El Niño–Southern Oscillation (ENSO) on the interannual variations of East Asian rainfall anomalies is the wide inter-model spread of outputs, which causes considerable uncertainty in physical mechanism understanding and short-term climate prediction. This study investigates the fidelity of 40 models from Phase 6 of the Coupled Model Intercomparison Project (CMIP6) in representing the impacts of ENSO on South China Spring Rainfall (SCSR) during the ENSO decaying spring. The response of SCSR to ENSO, as well as the sea surface temperature anomalies (SSTAs) over the tropical Indian Ocean (TIO), is quite different among the models; some models even simulate opposite SCSR anomalies compared to the observations. However, the models capturing the ENSO-related warm SSTAs over TIO tend to simulate a better SCSR-ENSO relationship, which is much closer to observation. Therefore, models are grouped based on the simulated TIO SSTAs to explore the modulating processes of the TIO SSTAs in ENSO affecting SCSR anomalies. Comparing analysis suggests that the warm TIO SSTA can force the equatorial north–south antisymmetric circulation in the lower troposphere, which is conducive to the westward extension and maintenance of the western North Pacific anticyclone (WNPAC). In addition, the TIO SSTA enhances the upper tropospheric East Asian subtropical westerly jet, leading to anomalous divergence over South China. Thus, the westward extension and strengthening of WNPAC can transport sufficient water vapor for South China, which is associated with the ascending motion caused by the upper tropospheric divergence, leading to the abnormal SCSR.

Bias of ENSO-like SST breaks the connection between the North Atlantic SST and Northeast China spring precipitation in the NCEP CFSv2

Bias of ENSO-like SST breaks the connection between the North Atlantic SST and Northeast China spring precipitation in the NCEP CFSv2

Heavy Southern China Spring Rainfall Promoted by Multi‐Year El Niño Events

AbstractSouthern China spring rainfall (SCSR) is significant for agricultural sowing and soil moisture accumulation before the rainy summer. A better prediction of the rainfall improves our ability to risk response to natural disasters. It is found that the SCSR can be promoted by multi‐year El Niño events through the high‐latitude pathway (HP) and low‐latitude pathway (LP). The long‐lasting El Niño warming heats the tropical troposphere persistently until the decaying spring, which strengthens the Arctic polar vortex and the mid‐latitude blockings. This HP is in favor of more southward transport of Rossby wave energy and cold air, resulting in strong ascending motions over southern China (SC) in spring. The multi‐year El Niño also induces an enhanced western North Pacific anticyclone and a secondary circulation transporting moisture to SC through the LP. The HP is more important in the early spring, while the LP dominates the heavy SCSR in the late spring.

Physiological and Transcriptome Analysis Reveals the Differences in Genes of Antioxidative Defense Components and Cold-Related Proteins in Winter and Spring Wheat during Cold Acclimation

Recent findings suggest that cold acclimation can enhance cold resistance in wheat. Dongnongdongmai 1 (DM1) is a winter wheat variety that can overwinter at −30 °C; however, its cold acclimation mechanism is yet to be fully elucidated. Here, we elucidated the potential mechanisms of cold acclimation in DM1 and the China Spring (CS) variety, especially the role of the antioxidant system, using transcriptome and physiological analyses. Cold stress increased H2O2 and O2− production in both varieties; however, CS had higher contents of H2O2 and O2− than DM1. Moreover, cold significantly increased ROS-scavenging activities in DM1, especially at 30 days after exposure. Gene ontology (GO) analysis showed that differentially expressed peroxidase (POD) genes were enriched in antioxidant activity, with most POD genes being significantly upregulated in DM1 under cold acclimation. Additionally, cold acclimation increased the expression of cold acclimation protein (CAP), late embryogenesis abundant protein (LEA), and cold-responsive genes in both varieties, with higher expression levels in DM1. Overall, the results showed that DM1 exhibited a higher cold tolerance than CS during cold acclimation by increasing the expression of POD genes, LEA, CAP, and cold-responsive proteins, improving the understanding of the mechanism of cold resistance in DM1.

QTL Mapping for Important Agronomic Traits Using a Wheat55K SNP Array-Based Genetic Map in Tetraploid Wheat

Wheat yield is highly correlated with plant height, heading date, spike characteristics, and kernel traits. In this study, we used the wheat55K single nucleotide polymorphism array to genotype a recombinant inbred line population of 165 lines constructed by crossing two tetraploid wheat materials, Icaro and Y4. A genetic linkage map with a total length of 6244.51 cM was constructed, covering 14 chromosomes of tetraploid wheat. QTLs for 12 important agronomic traits, including plant height (PH), heading date (HD), awn color (AC), spike-branching (SB), and related traits of spike and kernel, were mapped in multiple environments, while combined QTL-by-environment interactions and epistatic effects were analyzed for each trait. A total of 52 major or stable QTLs were identified, among which may be some novel loci controlling PH, SB, and kernel length-width ratio (LWR), etc., with LOD values ranging from 2.51 to 54.49, thereby explaining 2.40-66.27% of the phenotypic variation. Based on the 'China Spring' and durum wheat reference genome annotations, candidate genes were predicted for four stable QTLs, QPH.nwafu-2B.2 (165.67-166.99 cM), QAC.nwafu-3A.1 (419.89-420.52 cM), QAC.nwafu-4A.1 (424.31-447.4 cM), and QLWR.nwafu-7A.1 (166.66-175.46 cM). Thirty-one QTL clusters and 44 segregation distortion regions were also detected, and 38 and 18 major or stable QTLs were included in these clusters and segregation distortion regions, respectively. These results provide QTLs with breeding application potential in tetraploid wheat that broadens the genetic basis of important agronomic traits such as PH, HD, AC, SB, etc., and benefits wheat breeding.

Snow depth alteration and its relation with climate variability in China

AbstractVarious climatic factors and their interactions affect China's snow depth alterations. However, a measure of the relative importance of climatic factors regarding the variance in snow depth is lacking. Here, we use a heretofore largest dataset, quality‐controlled daily observations from 1,665 meteorological stations, and statistical analyses to identify proxy drivers and their contributions regarding regional variability and trends in China's snow depth and snow depth‐climate relationships from 1951 to 2019. Results show that seasonal snow depth alterations are substantial in China and caused by various climatic drivers. In winter, observed positive trends in the northwest and northeast of China mainly respond to augmentation in solid precipitation and snow accumulation in fall. For the Tibetan Plateau, the negative snow depth anomaly seems to respond to the rising air temperature below the freezing point along with some secular changes in solid precipitation and shallower fall snowpacks. All these trends in winter snow depth over the northwest, northeast, and Tibetan Plateau of China account approximately for 30% of the total interannual variance in spring snow depth in these regions. In the milder central north and south of China, snow accumulation is not evident. Besides solid precipitation and rising air temperature below the freezing point, atmospheric humidity is also notable for its effect on the interannual variance in winter snow depth in these regions. In spring and fall, however, the negative effect of warming climate on snow depth becomes remarkably more important. It seems that about 13–33% (12–50%) of the total interannual variance in the widespread decrease (insignificant perturbation), except for some weak increases in the northeast region (decreases in the Tibetan Plateau), of China's spring (fall) snow depth are caused by the rising air temperature below the freezing point.

North China Spring Rainfall and Its Linkage with SST and Atmospheric Circulation

Abstract Spring rainfall is important for agriculture and economics in North China (NC). Thus, there is an imperative need for accurate seasonal prediction of the spring precipitation. This study implements a novel rainfall framework to improve understanding of NC spring rainfall. The framework is built based on a three-cluster normal mixture model. Distribution parameters are sampled using Bayesian inference and a Markov chain Monte Carlo algorithm. The probability behaviors of light, moderate, and heavy rainfall events can be reflected by the three rainfall clusters, respectively. Analysis of 61-yr data indicates that moderate rainfall makes the largest contribution (67%) to the total rainfall amount. The moderate rainfall intensity is mainly influenced by the sea surface temperature anomaly (SSTA) in the previous season over the equatorial eastern Pacific, and rainfall frequency is influenced by geopotential height anomaly in the mid- to high latitudes in spring. It is also found that more extreme precipitation events can be observed in the spring following an eastern Pacific El Niño event in the previous autumn and winter. Based on these relationships, we develop a multiple linear regression model. Hindcasts for spring precipitation using the model indicates that its anomaly correlation is 0.48, significant at the 99% confidence level. The result suggests that the newly developed model can well predict spring rainfall amount in NC.

Alternation of the Atmospheric Teleconnections Associated with the Northeast China Spring Rainfall during a Recent 60-Year Period

Alternation of the Atmospheric Teleconnections Associated with the Northeast China Spring Rainfall during a Recent 60-Year Period

Spatiotemporal characteristics of spring rainfall over Southwest China and their relationships with sea surface temperature during 1961–2017

The spatiotemporal variability of southwest China (SWC) spring (March–April–May) rainfall (SWCSR) during 1961–2017 is investigated using rainfall data from 75 meteorological stations over SWC in this study. It is found that (1) SWC can be divided into four subregions using the rotated empirical orthogonal function (REOF) method: southern Yunnan province (SY), northwestern Yunnan province (NWY), eastern Guizhou province (EG), and northeastern Sichuan province (NES). (2) All subregions show significant 2–8-year periodicity on the interannual timescale. However, only SY rainfall shows significant interdecadal periodicity. (3) The spring La Nina has a significant impact on the simultaneous rainfall over SY. The sea surface temperature anomalies (SSTAs) in the central North Pacific during late winter can be an important oceanic signal for the prediction of spring rainfall variability over NWY. The southern Indian Ocean dipole (SIOD)–like SSTA pattern during late autumn (early winter) can be an important predictor of rainfall variability over EG (NES) during the following spring. Moreover, the impact of the late autumn SIOD-like pattern on the following spring rainfall over EG is stronger than the impact of the early winter SIOD-like pattern on the NES rainfall during the following spring.

Evolution of Air Transport Networks under Different Airline Business Models: The Case of Three Chinese Airlines

This study was conducted to compare the evolution process of air transport networks (ATNs) under different airline business models, and empirically analyzed the causes of evolution differences combining with airline market behaviors. Three representative Chinese airlines (China Southern Airlines, Spring Airlines, and Lucky Air) that belong to three business models (full-service, low-cost, and regional) were examined. Based on mathematical statistics and complex network theory, from spatial pattern, topological feature and central city, the result showed that the airlines have their own unique evolution characteristics of ATNs driven by different business models. China southern airlines as state-owned full-service network carrier, its ATN is easily affected by national policy. Spring Airlines has more flexible and diverse choice in choosing target markets and the ATN had a transformation from a mono-centric divergence network to a two-centric regional one. Lucky Air as a regional feeder carrier, whether navigable airports or navigable routes increasingly concentrated within the southwest of China. This information is important for government to improve the national ATN by developing targeted airlines.

Analysis of factors affecting the impurity rate of mechanically-harvested maize grain in China

The grain impurity rate is an important index for assessing the quality of mechanical maize harvesting. Therefore, it is of great significance to clarify the current situation of maize impurity rate and study the factors that affect the impurity rate in order to promote the development of mechanical maize harvesting technology. From 2012 to 2019, a total of 2504 maize impurity rate measurements were obtained. The results showed that the average impurity rate at maize harvest was 1.18% in China, in which the Huang-Huai-Hai summer maize area was 1.68%, which was significantly higher than the 0.65% in the Northwest spring maize area and 0.77% in the North China spring maize area. There was a significant positive correlation between the impurity rate and the moisture content of the maize harvest. The average moisture content of maize at harvest in Huang-Huai-Hai summer maize area was the highest at 27.55%, which was the main reason for the high impurity rate in this area. When harvesting different varieties with the same moisture content, there were significant differences in the impurity rate between different varieties. The cob hardness of the variety may also affect the impurity rate of maize. Different harvesters and weather conditions during harvesting are also important factors affecting the impurity rate. Therefore, by breeding fast dehydrated varieties and harvesting maize in time, the impurity rate of maize during mechanical harvesting can be effectively reduced. Keywords: mechanically-harvested maize grain, impurity rate, factors, analysis DOI: 10.25165/j.ijabe.20201305.6038 Citation: Huang Z F, Xue J, Ming B, Wang K R, Xie R Z, Hou P, et al. Analysis of factors affecting the impurity rate of mechanically-harvested maize grain in China. Int J Agric & Biol Eng, 2020; 13(5): 17–22.

Greater maize yield improvements in low/unstable yield zones through recommended nutrient and water inputs in the main cropping regions, China

Maize (Zea mays L.) is an important cereal crop grown worldwide. With the increase in human food demand but limited land and water resources, precise spatially explicit knowledge about the maize production capacity through agricultural management practices (e.g., using recommended nutrient and water inputs, RNWI, by local agronomists) is essential to guide the future policy, research, development, and investment. Here, we used a well-validated crop model (APSIM-Maize) for 1981–2010 combined with actual climatic and soil data to estimate maize yield improvements under RNWI in three main cropping regions in China (the North China Spring Maize Region, NCS; the Huanghuaihai Summer Maize region, HS; and the Southwest China Mountain Maize Region, SCM). Compared with the county-level maize actual yield in the three main cropping regions, the average maize yield could be increased by 33 % (4 Mg ha−1) through RNWI, while the improvements in the coefficients of variation (CVs) of grain yield and reliable grain production (RGP) were 0.11 and 32 % (69 million Mg), respectively. Except for RNWI, the average yield, CVs of yield, and RGP could still be increased by 28 % (3 Mg ha−1), 0.10, and 36 % (80 million Mg) through other management and technologies (OMT). Further analysis in four types of yield level-stability zones (high-stable, low-stable, high-unstable, and low-unstable zones) showed that greater contributions of using RNWI and OMT to improve maize grain yield, yield stability, and RGP were found in zones with low/unstable yield across the three regions. The findings highlighted the focus on increasing maize yield in low/unstable-yield zones could provide a greater return.

Analysis of factors affecting the impurity rate of mechanically-harvested maize grain in China

The grain impurity rate is an important index for assessing the quality of mechanical maize harvesting. Therefore, it is of great significance to clarify the current situation of maize impurity rate and study the factors that affect the impurity rate in order to promote the development of mechanical maize harvesting technology. From 2012 to 2019, a total of 2504 maize impurity rate measurements were obtained. The results showed that the average impurity rate at maize harvest was 1.18% in China, in which the Huang-Huai-Hai summer maize area was 1.68%, which was significantly higher than the 0.65% in the Northwest spring maize area and 0.77% in the North China spring maize area. There was a significant positive correlation between the impurity rate and the moisture content of the maize harvest. The average moisture content of maize at harvest in Huang-Huai-Hai summer maize area was the highest at 27.55%, which was the main reason for the high impurity rate in this area. When harvesting different varieties with the same moisture content, there were significant differences in the impurity rate between different varieties. The cob hardness of the variety may also affect the impurity rate of maize. Different harvesters and weather conditions during harvesting are also important factors affecting the impurity rate. Therefore, by breeding fast dehydrated varieties and harvesting maize in time, the impurity rate of maize during mechanical harvesting can be effectively reduced. Keywords: mechanically-harvested maize grain, impurity rate, factors, analysis DOI: 10.25165/j.ijabe.20201305.6038 Citation: Huang Z F, Xue J, Ming B, Wang K R, Xie R Z, Hou P, et al. Analysis of factors affecting the impurity rate of mechanically-harvested maize grain in China. Int J Agric & Biol Eng, 2020; 13(5): 17–22.

Legacy effect of spring phenology on vegetation growth in temperate China

Spring vegetation phenology is one of the most sensitive bio-indicators of the ongoing climate warming. Climate warming has substantially advanced spring phenological development and increased productivity of terrestrial ecosystems. However, the relative importance of spring phenology and climatic factors on vegetation growth has not yet been thoroughly investigated. We extracted Start of Season (SOS) dates using five standard methods from satellite-derived Normalized Difference Vegetation Index (NDVI) data in temperate China from 1982 to 2015 and explored the spatio-temporal variation in vegetation growth and its linkages to spring phenology and climatic factors. In line with previous studies, we found that in temperate China spring phenology was significantly advanced on the average by −1.16 ± 0.25d per decade during 1982–2015. Spring and summer vegetation growth, that was defined as mean value of NDVI over spring and summer respectively, were significantly increased on the average by 2.6 × 10−3 and 4.8 × 10−3, respectively, per decade over the same period. Interestingly, we found that SOS, rather than climatic factors, was the main determinant of spring vegetation growth across the forests and grasslands. However, phenology effect on summer vegetation growth was weaker in all vegetation types, and in grasslands precipitation was the main determinant of summer growth. Our study confirms that spring phenology plays a key role in vegetation growth but further highlighted that its role diminishes as the growing season progresses from spring to summer.

Impacts of Central Pacific El Niño on Southern China Spring Precipitation Controlled by its Longitudinal Position

ABSTRACT Here we investigate the response of boreal spring precipitation over southern China (SPSC) to central Pacific (CP) El Niño based on observational datasets. While there is enhanced precipitation over southern China during the decaying boreal spring of eastern Pacific (EP) El Niño events, so far no clear precipitation response has been detected during the same decaying stage for CP El Niño composites. Here we show that around half of the CP El Niño events coincide with enhanced SPSC (wet CP El Niño), while the other half are accompanied by reduced SPSC (dry CP El Niño). These two types of CP El Niño events bear dramatically different evolution features in their respective tropical sea surface temperature anomaly (SSTA) patterns. Wet CP El Niño events are characterized by an SSTA longitudinal position confined to the tropical central-eastern Pacific. In contrast, dry CP El Niño events exhibit a clear westward propagation of SSTAs during their evolution, with maximum SSTAs located to the west of the date line after their mature phase. These different longitudinal positions of positive SSTAs during their decaying phase result in distinct meridional structures of the tropical Pacific convection anomalies as well as the ENSO combination mode (C-mode) response. An anomalous low-level anticyclone is evident over the western North Pacific during wet CP El Niño events during their decaying phase, while an anomalous cyclonic circulation is found for dry CP El Niño events. We emphasize that the impacts of CP El Niño on the SPSC depend crucially on the simultaneous zonal location of warm SSTAs in the tropical Pacific.

A comparative study of airline efficiency in China and India: A dynamic network DEA approach

Using a dynamic network DEA approach, this research examines the efficiency performance of major Chinese and Indian air carriers with a consideration of the airline's internal processes and links as well as the carry-over items that connect consecutive time periods. It is found that two low-cost carriers (LCCs), namely, China's Spring and India's SpiceJet were the most efficient carriers during the period between 2008 and 2015. China's three state-owned airlines performed poorly in both the capacity generation and service stages, particularly the latter. The second-stage regression results confirm that the LCC model and private ownership are significantly associated with better airline efficiency performance. This paper thus calls for continual reforms in China's air transport including further privatisation and policy support for LCCs and private carriers to improve the overall efficiency of this industry.

Spatial patterns of yield-based cropping suitability and its driving factors in the three main maize-growing regions in China.

Reasonable crop planting division is important for farmers to grow suitable plants and for decision makers to make short- and long-term plans. In this study, we assessed the cropping suitability for maize in the three main growing regions in China, including the North China Spring Maize Region (NCS), the Huanghuaihai Summer Maize Region (HS), and the Southwest China Mountain Maize Region (SCM). We determined the spatial patterns of cropping suitability for maize and the dominant climate and soil drivers by assessing both yield level and yield stability (high-stable index (HSI)) under four production input levels (simulated yield potential (Yp), water-limited yield (Ypw), and water-limited-soil-constrained yield (Ypws) by APSIM-Maize model and actual yield (Ya)) during the period of 1981-2010. According to the HSI of Yp for maize, optimal and suitable areas for maize production were focused in NCS and HS. In SCM, the percentages of subtotal optimal and suitable areas for both simulated Ypw and Ypws to total regional area were higher than those in NCS and HS. Yield level of Ya was significantly higher in NCS and HS than in SCM, while yield stability of Ya in NCS was significantly lower than that in the other two study regions. Based on Ya, HS (SCM) showed the largest (smallest) optimal and suitable areas for maize production. In addition, the percentage of subtotal optimal and suitable area to total regional area is the highest in HS. Under the Yp level, solar radiation was the dominant factor for cropping suitability in the three study regions. Under the Ypw and Ypws levels, precipitation was the driving factor for cropping suitability in NCS and HS, while solar radiation and soil water properties were the driving factors for cropping suitability in SCM. These results can be used to assist local policy makers in dividing maize-growing regions in China. Hence, local farmers could choose the most suitable varieties accordingly in order to maximize the yield production while maintaining a relatively high yield stability.

Increased Predictability of Spring Precipitation over Central East China around the Late 1970s

Abstract The predictability of spring (March–May) precipitation over East China is investigated, based on the February-start hindcasts of eight coupled models from DEMETER and ENSEMBLES during 1960–2001. Five out of the eight models exhibit significantly increased predictability of central East China spring precipitation (CECSP) after the late 1970s. The mechanism analysis indicates that CECSP variability is closely related to a meridional dipole vorticity pattern at 200 hPa and southerly wind at 850 hPa over East Asia, whose prediction skill increased significantly around the late 1970s, consistent with the changes in CECSP predictability. Observational analysis indicates that the sea surface temperature (SST) over the tropical Pacific and Indian Oceans experienced a notable decadal change around the late 1970s. After the decadal change, the tropical SST has an enhanced impact on the CECSP-related East Asian dipole vorticity pattern at the upper level and on the western North Pacific anticyclone at the lower level. The five models can adequately reproduce the observed enhanced connection between the tropical SST and East Asian atmospheric circulation after the late 1970s, consequently showing higher predictability of East Asian atmospheric circulation and CECSP. However, the other three models cannot reproduce the relationship between the tropical SST and East Asian atmospheric circulation; therefore, CECSP predictability in these models remains low during the entire period. The increased predictability is valuable for current dynamical seasonal prediction for central East China.

Trends In Population Flow During China's Spring Festival

Trends In Population Flow During China's Spring Festival

Constraints on maize yield and yield stability in the main cropping regions in China

Abstract Understanding the distributions of zones of high/low and stable/unstable recorded maize (Zea mays L.) yield, and identifying the constraints on yield and yield stability, is essential for optimized crop distribution and agricultural management to mitigate limitations and improve maize production under climate change. In this study, we collected recorded maize yields and simulated three levels of yield potentials (radiation-temperature yield potential Yp, climatic yield potential Ypw and soil-climatic yield potential Ypws) with the Agricultural Production Systems sIMulator (APSIM-Maize) from 1981 to 2010 in the three main cropping regions in China [the North China spring maize region (NCS), the Huanghuaihai summer maize region (HS), and the Southwest China mountain maize region (SCM)]. The distributions of four categories of maize yield and yield stability zones, and limitations by precipitation, soil and technology & management on average yield, yield stability and total production were analyzed. The county-level average recorded yields during the period under study were 4624.26 kg ha−1, 4718.32 kg ha−1 and 3880.44 kg ha−1 in NCS, HS and SCM, respectively. Coefficients of variations (CV) for recorded yields were 0.40, 0.30 and 0.27 in NCS, HS and SCM, respectively. Based on comprehensive analysis of both average yields and CV values, we divided the main maize cropping areas into four zone categories: those with high and stable yields (high-stable zone), those with high and unstable yields (high-unstable zone), those with low and stable yields (low-stable zone), and those with low and unstable yields (low-unstable zone). Comparison of Yp, Ypw, Ypws and Ya at the county level, among the three regions, revealed that precipitation was the most important limiting factor on both averages (56%, 9436.97 kg ha−1 and 53%, 8114.21 kg ha−1) and CVs (0.42 and 0.39) of yield in all four zone types in NCS and HS. On the other hand, technology & management was the most important limiting factor in SCM (39%, 3934.87 kg ha−1). Total maize productions were reduced by 47.6% and 52.7% by precipitation in NCS and HS, respectively. Nevertheless, the limiting effect of soil was lower than that of technology & management in NCS, while it was higher in HS. In SCM, technology & management was the most important limiting factor (1295.72 × 104 t and 39.3%), followed by precipitation (613.80 × 104 t and 18.6%) and soil (219.62 × 104 t and 6.7%). In the three main cropping regions, the limiting effect of each factor on total productions in high-stable zone was the highest among all four zone types. Our results could be used to provide a theoretical basis for targeted climate change adaptation policies to improve maize yield and yield stability in China. In addition, our results may serve as a reference for other maize cropping regions in the world.