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Fine particulate matter (PM2.5) has been reported to be an important risk factor for asthma. This study was designed to evaluate the relationship between PM2.5 and lung function among children with asthma in Shanghai, China. From 2016 to 2019, a total of 70 Chinese children aged 4 to 14 in Shanghai were recruited for this panel study. The questionnaire was used to collect baseline information, and the lung function covering forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were carried out for each child more than twice during follow-up. Meanwhile, the simultaneous daily air atmospheric pollutants and meteorological data were collected. The linear mixed effect (LME) model was used to assess the relationship between air pollutants and lung function. A significantly negative association was found between PM2.5 and lung function in children with asthma. In the single-pollutant model, the largest effects of PM2.5 on lung function were found for lag 0–2, with FVC and FEV1 decreasing by 0.91% [95% confidence interval (CI): −1.75, −0.07] and 1.05% (95% CI: −2.09, 0.00), respectively, for each 10 μg/m3 increase in PM2.5. In the multi-pollution model (adjusted PM2.5 + SO2 + O3), the maximum effects of PM2.5 on FVC and FEV1 also appeared for lag 0–2, with FVC and FEV1 decreasing by 1.57% (95% CI: −2.69, −0.44) and 1.67% (95% CI: −3.05, −0.26), respectively, for each 10 μg/m3 increase in PM2.5. In the subgroup analysis, boys, preschoolers (

The potential of mitigation actions to limit global warming within 2 degrees C (ref.(1)) might rely on the abundant supply of biomass for large-scale bioenergy with carbon capture and storage (BECCS) that is assumed to scale up markedly in the future(2-5). However, the detrimental effects of climate change on crop yields may reduce the capacity of BECCS and threaten food security(6-8), thus creating an unrecognized positive feedback loop on global warming. We quantified the strength of this feedback by implementing the responses of crop yields to increases in growing season temperature, atmospheric CO2 concentration and intensity of nitrogen (N) fertilization in a compact Earth system model(9). Exceeding a threshold of climate change would cause transformative changes in social-ecological systems by jeopardizing climate stability and threatening food security. If global mitigation alongside large-scale BECCS is delayed to 2060 when global warming exceeds about 2.5 degrees C, then the yields of agricultural residues for BECCS would be too low to meet the Paris goal of 2 degrees C by 2200. This risk of failure is amplified by the sustained demand for food, leading to an expansion of cropland or intensification of N fertilization to compensate for climate-induced yield losses. Our findings there by reinforce the urgency of early mitigation, preferably by 2040, to avoid irreversible climate change and serious food crises unless other negative-emission technologies become available in the near future to compensate for the reduced capacity of BECCS.

An unprecedented cold event occurred in Central and eastern Eurasia during the 2020/21 winter, including five episodes of consecutive cold spells (EP1–5). Through analysis of both observational and simulations, we show that the concurrent Arctic sea-ice loss and extratropical Pacific decadal oscillation (EPDO) warming are potential drivers for the cold event. Their relative contributions to the intraseasonal evolutions of atmospheric circulation and concomitant cold surges are thoroughly investigated. The circulation anomalies highlight the gradual development of the negative Arctic oscillation, accompanied by strengthened Siberian high and deepened Aleutian low. Stratospheric pathways were integrally involved in the dynamical response and the timing of episodes. Our results suggest that the sea-ice, irrespective of seasonality, and autumn EPDO experiments can generally capture the spatial patterns of atmospheric circulation and temperature in observation, albeit weaker in magnitude. Autumn (winter) sea-ice loss led to the EP1–3 (EP2–3) cold spells, and autumn EPDO led to the EP1–3 cold surges; whereas the EP4–5 cold spells induced by autumn SIC and PDO were not statistically robust. The Eurasian cooling response to winter PDO is weak due to the extensive warming over southern China and Eurasian highlatitudes that offsets the midlatitude cooling. The largest coolings were found in SIC and EPDO combined experiments, suggesting their synergic importance in driving such cold events. Our results have implications for the potential predictability of winter extreme events over Eurasia in the context of ongoing sea-ice decline and a recent shift to the positive PDO phase.

An approach of broadband mode separation in shallow water is proposed using phase speed extracted from one hydrophone and solved with sparse Bayesian learning (SBL). The approximate modal dispersion relation, connecting the horizontal wavenumbers (phase velocities) for multiple frequencies, is used to build the dictionary matrix for SBL. Given a multi-frequency pressure vector on one hydrophone, SBL estimates a set of sparse coefficients for a large number of atoms in the dictionary. With the estimated coefficients and corresponding atoms, the separated normal modes are retrieved. The presented method can be used for impulsive or known-form signals in a shallow-water environment while no bottom information is required. The simulation results demonstrate that the proposed approach is adapted to the environment where both the reflected and refracted modes coexist, whereas the performance of the time warping transformation degrades significantly in this scenario.

AIM To investigate the value of computed tomography (CT) texture analysis (TA) and imaging features for evaluating suspected surgical superior mesenteric–portal vein (SMPV) invasion in patients with pancreatic ductal adenocarcinoma (PDAC). MATERIALS AND METHODS Fifty-four patients with PDAC in the pancreatic head or uncinate process with suspected SMPV involvement were analysed retrospectively. SMPV invasion status was identified by surgical exploration. For each patient, 396 texture features were extracted on pretreatment CT. Non-parametric tests and minimum redundancy maximum relevance were used for feature selection. A CTTA model was constructed using multivariate logistic regression, and the area under the receiver operating characteristic (AUROC) of the model was calculated. Two reviewers evaluated qualitative imaging features independently for SMPV invasion and interobserver agreement was investigated. The diagnostic performance of the imaging features and the CTTA model for SMPV invasion was compared using the McNemar test. RESULTS Of the 54 patients with PDAC, SMPV invasion was detected in 23 (42.6%). The CTTA model yielded an AUROC of 0.88 (95% confidence interval, 0.76–0.97) and achieved significantly higher specificity (0.90) than the two reviewers (0.61 and 0.65; p=0.027 and 0.043). Interobserver agreement was moderate between the two reviewers (κ = 0.517). Of the 13 cases with disagreement between the two reviewers, 11 cases were predicted accurately by the CTTA model. CONCLUSION CTTA can predict suspected SMPV invasion in PDAC and may be a beneficial addition for qualitative imaging evaluation.

Tibetan Plateau vortices (TPVs) are important rainfall producers over the Tibetan Plateau in summer and can also influence wide areas east of the Tibetan Plateau when emigrating from the plateau. The Effects of the variations in air temperature over the Tibetan Plateau on the genesis frequency of TPVs at interannual timescales is explored in this work to understand the interannual variations in TPVs and the resultant precipitation. The results indicate that the interannual variations in the genesis frequency of TPVs are significantly related to that in the air temperature at 250 hPa over the Tibetan Plateau. The upper-level air temperature affects the genesis of TPVs by modulating the large-scale circulations at 200 hPa. In warm (cold) years, an anomalous high (low) at 200 hPa is observed over the eastern Tibetan Plateau and central China, and a strong (weak) westerly jet is found north of the Tibetan Plateau. The upper-level westerly jet is considered to have a direct influence on TPVs. Impact of 250-hPa air temperature over the Tibetan Plateau on the westerly jet is further explained from two perspectives. First, the air temperature at 250 hPa regulates the thermal wind between 250 and 200 hPa, thereby affecting the wind at 200 hPa. Second, the air temperature at 250 hPa changes the geopotential height gradient at 200 hPa north of the Tibetan Plateau, which results in variations in the westerly jet there. Consequently, more TPVs are generated over the Tibetan Plateau in warm years, and vice versa for cold years.

The variation in the concentrations of ambient PM2.5 (particles with an aerodynamic diameter less than 2.5 µm ) generally forms a continuous sawtooth cycle with a recurring smooth increase followed by a sharp decrease. The episode of abrupt decay of pollution is mostly meteorological in origin and is controlled by the passage of synoptic systems. One affordable and effective measure for quickly reducing PM2.5 concentrations in northern China is to wait for a strong wind to arrive. However, it is still unclear how strong the wind needs to be and exactly what kind of synoptic system most effectively results in the rapid decay of air pollution episodes. PM2.5 variations over the 28 pollution channel cities of the Beijing region are investigated to determine the mechanisms by which synoptic patterns affect the decay processes of pollution episodes. This work shows more obvious day-to-day variations in PM2.5 concentration in winter than in summer, which implies that wintertime PM2.5 variations are more sensitive to meteorological factors. There were 365 decay processes from January 2014 to March 2020, and 97 of them were related to the effective wet deposition. In total, 26 % – 43 % of PM2.5 pollutant is removed by the wet deposition in different seasons. Two dominant circulation patterns are identified in summer. All the other three seasons have three circulation types (CTs), respectively. The three CTs in spring show the same patterns as those in autumn and winter. The circulation patterns beneficial to the decay processes all exhibit a higher-than-normal surface wind speed, a negative relative humidity anomaly and net outflow of PM2.5 from the domain. In addition, CT1 in spring, autumn and winter is controlled by northeasterly wind and features the most significant horizontal net outflow of air pollutants and effective upward spread of air pollutants to the free atmosphere. CT2 is the most frequent CT in autumn and winter, with the highest wind speed from the northwest, highest boundary layer height (BLH) and lowest relative humidity among the three CTs, all of which are favorable for the reduction of PM2.5 concentrations. In CT3, strong vertical wind shear within the boundary layer enhances the mixing of surface air pollutants, which is the extra cleaning mechanism besides dry and clean air mass inflow. PM2.5 concentrations show significant decreases of more than 37 %, 41 % and 27 % after the passage of CT1, CT2 and CT3, respectively. A dry airflow with a positive BLH anomaly and the effective horizontal outflow of air pollutants are the main reasons for the abrupt decay phase in summer. PM2.5 concentrations after the decay process show a significant decreasing trend from 2014 to 2020, reflecting successful emission mitigation. Emission reductions have led to a 4.3–5.7 µ g m - 3 yr - 1 decrease in PM2.5 concentrations in the 28 pollution channel cities of the Beijing region.

According to the corresponding historical averages of air quality during each month of BF, AF1, and AF2 period (in Fig In general, it shows more notable variations in air quality during the AF1 period than that of the AF2 period [ ]we will go through some detailed air quality variation in the AF1 period here According to the low normalized concentration in the BF period, SO2 concentration shows significant decrease throughout China in recent years, especially over northern China, indicating the importance of coal desulfurization and nationwide emission reduction Considering O3, the concentration of which is driven by two major classes of directly emitted precursors, i e , NOx and volatile organic compounds (VOCs), except for the Guangxi Province, O3 over the other provinces and areas increased significantly with the outbreak of coronavirus

Despite the fact that great efforts have been made to improve the prediction of El Niño events, it remains challenging because of limited understanding of El Niño and its precursors. This research focuses on the influence of South Pacific atmospheric variability on the development of the sea surface temperature anomaly (SSTA) in the tropical Pacific. It is found that as early as in the boreal spring of El Niño years, the sea level pressure anomaly (SLPA) shows a configuration characterized by two significant negative anomaly centers in the north and a positive anomaly center in the south between the subtropics and high latitudes in South Pacific. Such an anomalous SLPA pattern becomes stronger in the following late boreal spring and summer associated with the strengthening of westerly anomalies in the tropical Pacific, weakening the southeasterly trade winds and promoting the warming of tropical eastern Pacific, which is conducive to the development of El Niño events. It is demonstrated that the SLPA pattern in boreal spring revealed in this study is closely associated with boreal summer South Pacific Oscillation (SPO) and South Pacific meridional mode (SPMM). As a precursor in boreal spring, the prediction skill of the South Pacific SLPA in boreal spring for the SSTA in the eastern equatorial Pacific is better than that of the SPMM. This study is helpful to deepen our understanding of the contribution of South Pacific extratropical atmospheric variability to El Niño occurrence.

The Chinese government has made many efforts to mitigate fine particulate matter pollution in recent years by taking strict measures on air pollutant reduction, which has generated the nationwide improvements in air quality since 2013. However, under the stringent air pollution controls, how the wintertime PM2.5 concentration (i.e., the mass concentration of atmospheric particles with diameters less than 2.5 µm) varies and how much the meteorological conditions contribute to the interannual variations in PM2.5 concentrations are still unclear, and these very important for the local government to assess the emission reduction of the previous year and adjust mitigation strategies for the next year. The effects of atmospheric circulation on the interannual variation in wintertime PM2.5 concentrations over the Beijing–Tianjin–Hebei (BTH) region in the period of 2013–2018 are evaluated in this study. Generally, the transport of clean and dry air masses and an unstable boundary layer in combination with the effective near-surface horizontal divergence or pumping action at the top of the boundary layer benefits the horizontal or vertical diffusion of surface air pollutants. Instead, the co-occurrence of a stable boundary layer, frequent air stagnation, positive water vapor advection and deep near-surface horizontal convergence exacerbate the wintertime air pollution. Favorable circulation conditions lasting for 2–4 d are beneficial for the diffusion of air pollutants, and 3–7 d of unfavorable circulation events exacerbates the accumulation of air pollutants. The occurrence frequency of favorable circulation events is consistent with the interannual variation in seasonal mean PM2.5 concentrations. There is better diffusion ability in the winters of 2014 and 2017 than in other years. A 59.9 % observed decrease in PM2.5 concentrations in 2017 over the BTH region could be attributed to the improvement in atmospheric diffusion conditions. It is essential to exclude the contribution of meteorological conditions to the variation in interannual air pollutants when making a quantitative evaluation of emission reduction measurements.

s Background The SIAMESE (SIM) locus is a cell-cycle kinase inhibitor (CKI) gene that has to date been identified only in plants; it encodes a protein that promotes transformation from mitosis to endoreplication. Members of the SIAMESE-RELATED (SMR) family have similar functions, and some are related to cell-cycle responses and abiotic stresses. However, the functions of SMRs are poorly understood in maize (Zea mays L.). Results In the present study, 12 putative SMRs were identified throughout the entire genome of maize, and these were clustered into six groups together with the SMRs from seven other plant species. Members of the ZmSMR family were divided into four groups according to their protein sequences. Various cis-acting elements in the upstream sequences of ZmSMRs responded to abiotic stresses. Expression analyses revealed that all ZmSMRs were upregulated at 5, 20, 25, and 35 days after pollination. In addition, we found that ZmSMR9/11/12 may have regulated the initiation of endoreplication in endosperm central cells. Additionally, ZmSMR2/10 may have been primarily responsible for the endoreplication regulation of outer endosperm or aleurone cells. The relatively high expression levels of almost all ZmSMRs in the ears and tassels also implied that these genes may function in seed development. The effects of treatments with ABA, heat, cold, salt, and drought on maize seedlings and expression of ZmSMR genes suggested that ZmSMRs were strongly associated with response to abiotic stresses. Conclusion The present study is the first to conduct a genome-wide analysis of members of the ZmSMR family by investigating their locations in chromosomes, identifying regulatory elements in their promoter regions, and examining motifs in their protein sequences. Expression analysis of different endosperm developmental periods, tissues, abiotic stresses, and hormonal treatments suggests that ZmSMR genes may function in endoreplication and regulate the development of reproductive organs. These results may provide valuable information for future studies of the functions of the SMR family in maize.

High-amylose maize starch has great potential for widespread industrial use due to its ability to form strong gels and film and in the food processing field, thus serving as a resistant starch source. However, there is still a substantial shortage of high-amylose maize due to the limitation of natural germplasm resources, although the well-known amylose extender (ae) gene mutants have been found to produce high-amylose maize lines since 1948. In this context, high-amylose maize lines (13 inbreds and 18 hybrids) originating from a natural amylose mutant in our testing field were utilized to study the correlation between amylose content (AC) and phenotypic traits (kernel morphology and endosperm glossiness), grain filling characteristics, gene expression, and amylose inheritance. Our results showed that AC was negatively correlated with total starch content but was not correlated with grain phenotypes, such as kernel fullness, kernel morphology and endosperm glossiness. Maize lines with higher amylose had a greater grain filling rate than that of the control (B73) during the first 20 days after pollination (DAP). Both starch debranching enzyme (DBE) groups and starch branching enzyme IIb (SBEIIb) groups showed a greater abundance in the control (B73) than in the high-amylose maize lines. Male parents directly predicted AC of F1, which was moderately positively correlated with the F2 generation.

Analyses of in situ and reanalysis output are performed to examine linkages between surface sensible heat fluxes over the central and eastern Tibetan Plateau (CETP) and indices of the East Asian winter monsoon (EAWM) and wintertime near-surface air temperatures over China. The results demonstrate that the sensible heat fluxes over CETP exhibit substantial decadal variability with positive, negative and positive phase during 1980–1987, 1988–2002 and 2003–2014, respectively. This decadal variability exhibits statistically significant associations with sub-components of EAWM and surface temperature anomalies over eastern China. The recovery of decadal change in wintertime sensible heat fluxes from negative to positive phase over CETP over the past decade (since 2003) has been associated with intensification and northward displacement of the East Asian subtropical jet (EASJ), enhanced and westward displacement of East Asian trough and strengthening of the Siberian High. Such processes are associated with the strengthening of EAWM, as well as cold air advection from high latitudes towards the south. Increased wintertime sensible heat fluxes over CETP is associated with markedly changes in the meridional temperature gradient that in term intensifies upper-level zone flow in the EASJ region, which provides a key physical factor linking the anomalies of sensible heat fluxes and EAWM.

The National Natural Science Foundation of China (NSFC) launched the Reform Initiatives, and defined three major reform tasks under the guidance of the overall goal of building a national natural science funding system in the new era. One of the three tasks under this goal is to optimize the funding layout in order to support convergence between knowledge and application according to the inherent logic and landscape of the knowledge systems. The application code system of NSFC is of vital importance to its funding strategy and provides strong guidelines for the disciplinary layout. In 2019, the discipline of atmospheric sciences (DAS) was selected as a reform pilot in the Department of Earth Sciences (DOE) of NSFC. Based on “problem orientation”, the application code system was reviewed and significantly revised according to the top-level strategy of “Habitable Earth”, initiated by DOE. The “Habitable Earth” strategy is dedicated to promote the geosciences within the frame of Earth System Sciences, with emphasis on “deep earth”, “deep sea”, and “deep space”. In this study, the background for the code system adjustment is addressed, the reform idea and measurements are illustrated, and the structures of the new code system are set up, which are helpful for the applicants to select the appropriate codes in their proposals, and beneficial to the scientific community to better understand the future funding layout of DAS. After in-depth analysis of previous application code system, several key drawbacks are pointed out. They are but not limited to: (1) Lack of self-consistency in logical structures, (2) incomplete coverage of sub-disciplines, and (3) disconnection with the strategy of “Habitable Earth”. To address these issues, this paper proposes a new classification strategy for the application codes according to three coordinated aspects: (1) Branch disciplines, (2) supporting technologies, and (3) social development services. The effective promotion of the integration of atmospheric sciences within “Habitable Earth” is proposed by establishing cross-disciplinary codes for interdisciplinary sciences. The proposed new code system in DAS consists of 15 sub-codes, i.e., “D0501 Synoptic Meteorology”, “D0502 Climate and Climate System”, “D0503 Paleoclimatology”, “D0504 Atmospheric Dynamics”, “D0505 Atmospheric Physics”, “D0506 Atmospheric Chemistry”, “D0507 Ecological Meteorology”, “D0508 Planetary Atmosphere”, “D0509 Atmospheric Observation Techniques”, “D0510 Atmospheric Data and Information Science”, “D0511 Atmospheric Numerical Model Development”, “D0512 Earth System Model Development”, “D0513 Climate Change, its Impacts and Countermeasures”, “D0514 Atmospheric Environment and Medical Meteorology”, and “D0515 Applied Meteorology”. The first eight items (D0501 to D0508), the next four items (D0509 to D0512), and the last three items (D0513 to D0515) are categorized as “branch disciplines”, “supporting technologies”, and “social development services”, respectively. Based on the adjusted application code system, the “research directions” for each code as well as “keywords” for each direction are determined. Finally, a complete information chain for the discipline of atmospheric sciences is formed, consisting of “application codes”, “research directions”, and “keywords”. The expert information in the DAS database has begun to be updated according to the new chain. The information in the new chain will be also conducive to the application of artificial intelligence technology in assigning the proposals to appropriate reviewers and classifying the research achievements in DAS. The efforts to adjust the application codes reflect the consensus of the broad atmospheric sciences community on the development of atmospheric sciences from “traditional meteorology” to the concept of “Habitable Earth”, as well as embody NSFC’s funding orientation in the new era of China.

A severe flooding hit southern China along the Yangtze River in summer 2020. The floods were induced by heavy rains, and the associated dynamic and thermodynamic conditions are investigated using daily gridded rainfall data of China and NCEP-NCAR reanalysis. It is found that the summer rainfall over the Yangtze River Basin (YRB) experienced pronounced subseasonal variation in 2020, dominated by a quasi-biweekly oscillation (QBWO) mode. The southwestward-moving anomalous QBWO circulation was essentially the fluctuation of cold air mass related to the tropospheric polar vortex or trough-ridge activities over the mid-high latitude Eurasian in boreal summer. The large-scale southwestward-transport of cold air mass from mid-high latitudes and the northeastward-transport of warm and moist air by the strong anomalous anticyclone over the western North Pacific provided important circulation support for the heavy rainfall in the YRB. The quasi-biweekly anomalies of potential and divergent component of vertically integrated water vapor flux played a major role in maintaining the moisture during summer 2020. The diagnosis of moisture budget shows that the enhanced moisture associated with the quasi-biweekly fluctuation rainfall was primarily attributed to the moisture convergence. The convergence of QBWO specific humidity by the background mean flow and convergence of mean specific humidity by QBWO flow played dominant roles in contributing to the positive moisture tendency. In combination with an adiabatic ascent induced by the warm temperature advection, the boundary layer moisture convergence strengthens the upward transport of moisture from lower troposphere. The vertical moisture transport associated with boundary layer convergence was of critical importance in causing low-level tropospheric moistening, whereas the horizontal advection of moisture showed a negative effect during the anomalous quasi-biweekly summer rainfall in 2020.

BackgroundFine particulate matter with aerodynamic diameter ≤ 2.5 mm (PM2.5) has been reported to be an important risk factor for asthma. Our study was designed to evaluate the relationship between air PM2.5 and lung function among children with asthma in Shanghai, China. MethodsFrom 2016 to 2019, a total of 70 Chinese children aged 4 to 14 in Pudong, Shanghai were recruited for this panel study. Upon entry to the group, questionnaire was used to collect basic information, and the lung function covering forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and peak expiratory flow (PEF) were carried out for each child more than two times during follow-up. Meanwhile, the simultaneous daily air atmospheric pollutants and meteorological data were collected. The linear mixed effect (LME) model was used to assess the relationship between air pollutants and lung function adjusting other covariates like sex, age, season and so on. ResultsA significantly negative association was found between PM2.5 level and lung function in children with asthma. In the single-pollutant model, the largest effect of PM2.5 on lung function were found on lag 0-2, FVC and FEV1 decreased by 0.91% [95% confidence interval (CI): -1.75, -0.07] and 1.05% (95% CI: -2.09, 0.00) for every 10 mg/m3 increase of PM2.5. In the multi-pollution model (adjusted PM2.5+SO2+O3), the maximum effect of PM2.5 on FVC and FEV1 also appeared on lag 0-2, FVC and FEV1 decreased by 1.57% (95% CI: -2.69, -0.44) and 1.67% (95% CI: -3.05, -0.26) for every 10 mg/m3 increase of PM2.5, respectively. In the subgroup analysis, boys, children and hot season more were sensitive. ConclusionThe short-term exposure of ambient PM2.5 is a risk factor for the lung function of children with asthma, particularly in boys, preschoolers (

The characteristics of anomalous circulations during spring associated with the climate shift of the South China Sea summer monsoon (SCSSM) onset in 1993/1994 and its physical causes are investigated. It is found that the interdecadal shift of SCSSM onset happened in 1993/1994 is related closely to the 850 hPa zonal wind anomalies over the area around Kalimantan Island. Easterly (westerly) anomalies over Kalimantan Island enhance (weaken) subtropical high over the western North Pacific, leading to the late (early) onset of SCSSM in 1979–1993 (1994–2013). The sea surface temperature anomalies (SSTAs) in the key region 140°–150° E, 5° S–2.5° N influence the interdecadal change of zonal winds over Kalimantan Island. The positive SSTAs over this key region in 1994–2013 force convergence toward the region at low-level and form significant westerly anomalies near Kalimantan Island located to the west of the key region. The negative anomalies of meridional gradient of zonal winds over the South China Sea region increase the atmospheric vorticity over there significantly and result in the weakening and retreating eastward of the subtropical high over the western North Pacific, which is conducive to the early onset of SCSSM.

Background Drought stress severely limits maize seedling growth and crop yield. Previous studies have elucidated the mechanisms by which maize acquires drought resistance and contends with water deficiency. However, the link between the physiological and molecular variations among maize cultivars are unknown. Here, physiological and proteomic analyses were conducted to compare the stress responses of two maize cultivars with contrasting drought stress tolerance. Results The physiological analysis showed that the drought-tolerant SD609 maize variety maintains relatively high photochemical efficiency by enhancing its protective cyclic electron flow (CEF) mechanism and antioxidative enzymes activities. Proteomics analysis revealed that 198 and 102 proteins were differentially expressed in SD609 and the drought-sensitive SD902 cultivar, respectively. GO and KEGG enrichments indicated that SD609 upregulated proteins associated with photosynthesis, antioxidants/detoxifying enzymes, molecular chaperones and metabolic enzymes. Upregulation of the proteins related to PSII repair and photoprotection improved photochemical capacity in SD609 subjected to moderate drought stress. In SD902, however, only the molecular chaperones and sucrose synthesis pathways were induced and they failed to protect the impaired photosystem. Further analysis demonstrated that proteins related to the electron transport chain (ETC) and redox homeostasis as well as heat shock proteins (HSPs) may be important in protecting plants from drought stress. Conclusions Our experiments explored the mechanism of drought tolerance and clarified the interconnections between the physiological and proteomic factors contributing to it. In summary, our findings aid in further understanding of the drought tolerance mechanisms in maize.

The existing ENSO indices are defined based on the sea surface temperatue anomalies (SSTAs) in different regions of the equatorial Pacific. Considering that the tropical convective activities are c...

Background: Drought is an environmental stress that adversely affects maize productivity. However, drought adaption strategies of different maize varieties are not fully clear at the transcriptomic level. In the paper, drought-sensitive SD902 and -resistant SD609 varieties were analyzed to explore transcriptional and physiological alterations to drought stress. Results: The higher SOD, CAT, GSH enzymatic antioxidants, stomatal conductance, transpiration, net photosynthesis rate suggested better performance of SD609 than SD902 variety under drought stress. In transcriptome profiling, a total of 8985 and 7305 difference expression genes (DEGs) were identified in SD902 and SD609 respectively. These genes were overall involved in antioxidation reduce, osmotic adjustment, protein modification (e.g. HSP and chaperone protein), photosynthesis, phytohormone (e.g. ABA, IAA, ethylene), transcription factors (TFs) (e.g. ERF, WRKY, NAC and bZIP) and MAPK (MAPK1/8, MKK4/9 and MKKK17) cascade. Among them, the upregulated genes significantly correlated with stress adjustment, HSPs and chaperone functions might better reduce drought-induced damage in both SD902 and especially SD609. The higher genes expression of IAA, ethylene and electron transfer in SD609 may be closely related to drought-tolerant performance than SD902 plants. Moreover, the misregulation of TFs, MAPK and ABA signaling would appear vital to explain the various sensitivity to drought in both varieties. Conclusion: The more drought-tolerant SD609 presented a beneficial and significantly higher genes expression of stress protection, IAA transduction, photosynthesis compared with drought-sensitive SD902 variety. Our findings provide vital insights into the molecular signatures underpinning drought resistance in maize.

The real-time monitoring of reductions of economic activity by containment measures and its effect on the transmission of the coronavirus (COVID-19) is a critical unanswered question. We inferred 5,642 weekly activity anomalies from the meteorology-adjusted differences in spaceborne tropospheric NO2 column concentrations after the 2020 COVID-19 outbreak relative to the baseline from 2016 to 2019. Two satellite observations reveal reincreasing economic activity associated with lifting control measures that comes together with accelerating COVID-19 cases before the winter of 2020/2021. Application of the near-real-time satellite NO2 observations produces a much better prediction of the deceleration of COVID-19 cases than applying the Oxford Government Response Tracker, the Public Health and Social Measures, or human mobility data as alternative predictors. A convergent cross-mapping suggests that economic activity reduction inferred from NO2 is a driver of case deceleration in most of the territories. This effect, however, is not linear, while further activity reductions were associated with weaker deceleration. Over the winter of 2020/2021, nearly 1 million daily COVID-19 cases could have been avoided by optimizing the timing and strength of activity reduction relative to a scenario based on the real distribution. Our study shows how satellite observations can provide surrogate data for activity reduction during the COVID-19 pandemic and monitor the effectiveness of containment to the pandemic before vaccines become widely available., This work was supported by the National Natural Science Foundation of China (41877506), the Fudan’s Wangdao Undergraduate Research Opportunities Program (18107), the Chinese Thousand Youth Talents Program, the PolEASIA-ANR project (ANR15-CE04-0005), and the Australia-China Centre for Air Quality Science and Management. J.P. and J.S. acknowledge financial support from the Catalan Government grant AGAUR-2020PANDE00117. P.C. acknowledges support from the European Space Agency Climate Change Initiative ESA-CCI RECCAP2 project (ESRIN/4000123002/18/I-NB) and the Observation-based system for monitoring and verification of greenhouse gases project (VERIFY, grant 725546).

Background: Drought stress seriously limits the seedling growth and yield of maize. Despite previous studies on drought resistance mechanisms by which maize cope with water deficient, the link between physiological and molecular variations are largely unknown. To reveal the complex regulatory mechanisms, comparative physiology and proteomic analyses were conducted to investigate the stress responses of two maize cultivars with contrasting tolerance to drought stress. Results: Physiological results showed that SD609 (drought-tolerant) maintains higher photochemical efficiency by enhancing CEF (cyclic electron flow) protective mechanism and antioxidative enzymes activities. Proteomics analysis revealed a total of 198 and 102 proteins were differentially expressed in SD609 and SD902, respectively. Further enrichment analysis indicated that drought-tolerant ‘SD609’ increased the expression of proteins related to photosynthesis, antioxidants/detoxifying enzymes, molecular chaperones and metabolic enzymes. The up-regulation proteins related to PSII repair and photoprotection mechanisms resulted in more efficient photochemical capacity in tolerant variety under moderate drought. However, the drought-sensitive ‘SD902’ only induced molecular chaperones and sucrose synthesis pathways, and failed to protect the impaired photosystem. Further analysis indicated that proteins related to the electron transport chain, redox homeostasis and heat shock proteins (HSPs) could be important in protecting plants from drought stress. Conclusions: Our experiments explored the mechanism of drought tolerance, and obtained detailed information about the interconnection of physiological research and protein research. In summary, our findings could provide new clues into further understanding of drought tolerance mechanisms in maize.

MERRA-2 developed by the National Aeronautics and Space Administration (NASA) provides the long-term record of surface PM

We used the APSIM-Maize model to simulate maize potential yield (Yp) and rain-fed yield (Yw) when adaptation options of sowing date and planting density were adopted under Representative Concentration Pathway (RCP) 4.5 and 8.5 in the Guanzhong Plain of China. The results showed that Yp would decrease by 10.6–14.9% and 15.0–31.4% under RCP4.5 and RCP8.5 for summer maize, and 13.9–19.7% and 18.5–36.3% for spring maize, respectively. The Yw would decrease by 17.1–19.0% and 23.6–41.1% under RCP4.5 and RCP8.5 for summer maize, and 20.9–24.5% and 27.8–45.5% for spring maize, respectively. The loss of Yp and Yw could be reduced by 2.6–9.7% and 0–9.9%, respectively, under future climate for summer maize through countermeasures. For spring maize, the loss of Yp was mitigated by 14.0–25.0% and 2.0–21.8% for Yw. The contribution of changing sowing date and plant density on spring maize yield was more than summer maize, and the optimal adaptation options were more effective for spring maize. Additionally, the influences of changing sowing date and planting density on yields become weak as climate changes become more severe. Therefore, it is important to investigate the potential of other adaptation measures to cope with climate change in the Guanzhong Plain of China.

Warm and cold phases of El Nino–Southern Oscillation (ENSO) exhibit a significant asymmetry in their decay speed. To explore the physical mechanism responsible for this asymmetric decay speed, the asymmetric features of anomalous sea surface temperature (SST) and atmospheric circulation over the tropical Western Pacific (WP) in El Nino and La Nina mature-to-decay phases are analyzed. It is found that the interannual standard deviations of outgoing longwave radiation and 850 hPa zonal wind anomalies over the equatorial WP during El Nino (La Nina) mature-to-decay phases are much stronger (weaker) than the intraseasonal standard deviations. It seems that the weakened (enhanced) intraseasonal oscillation during El Nino (La Nina) tends to favor a stronger (weaker) interannual variation of the atmospheric wind, resulting in asymmetric equatorial WP zonal wind anomalies in El Nino and La Nina decay phases. Numerical experiments demonstrate that such asymmetric zonal wind stress anomalies during El Nino and La Nina decay phases can lead to an asymmetric decay speed of SST anomalies in the central-eastern equatorial Pacific through stimulating different equatorial Kelvin waves. The largest negative anomaly over the Nino3 region caused by the zonal wind stress anomalies during El Nino can be threefold greater than the positive Nino3 SSTA anomalies during La Nina, indicating that the stronger zonal wind stress anomalies over the equatorial WP play an important role in the faster decay speed during El Nino.

The ‘westerlies-dominated climatic regime’ (WDCR) in the present interglacial period was proposed because precipitation/moisture variations between arid central Asia and mid-latitude monsoonal Asia are out-of-phase or anti-phased on different timescales during the Holocene. In this study. we first review the development of the theoretical framework of the WDCR, and then outline the boundary of its core area: from the Caspian Sea in the west to the western Hexi Corridor in the east, with the northern and southern limits coinciding with the domain of arid central Asia. Next, we present a synthesis of multiple lines of evidence for the occurrence of the WDCR on multi-millennial (‘sub-orbital’ herein) to decadal timescales during the Holocene. Finally, we examine the possible physical mechanisms responsible for the WDCR. We find that external factors (insolation changes induced by orbital factors) generated the WDCR on a sub-orbital timescale, whereas a circum-global teleconnection/Silk Road pattern was the most significant factor responsible for the WDCR on centennial and decadal timescales. The study provides a comprehensive summary of the development of our knowledge of the WDCR over the past several decades, together with a tentative theoretical framework for understanding climatic and environmental changes within its region of influence. In addition, it forms a scientific basis for environmental management and ecological restoration in this arid region in the context of global warming.

Tibetan Plateau vortices (TPVs) are important synoptic systems generated over the Tibetan Plateau, triggering heavy rainfall over southwestern and eastern China when they move off the plateau. In the present work, the precipitation associated with the moving-off TPVs is explored, and two groups of TPVs are selected according to the precipitation intensity (PI) related to the TPVs. The characteristics of these two groups of TPVs and the large-scale circulations during the period after the TPVs move off the plateau are compared. The results show that the impact of TPVs is mainly found in the region to the west of 115° E between 30° N and 36° N, becoming weaker along with the longitude. Sichuan Basin is the area with the greatest influence from the TPVs. PI is attributed to both the TPVs and the large-scale background. The TPVs related to high (low) PI are stronger (weaker) and travel further eastward (travel shorter distance), and the ascending motion associated with the TPVs is stronger (weaker) and deeper (shallower). The Western Pacific subtropical high (WPSH), southwesterlies to the south of TPVs in middle and lower troposphere, the South Asia High (SAH), and upper-level jet stream are crucial systems influencing the PI. Stronger and northwestward stretching WPSH, more intensive southwesterlies and the associated water vapor transportation to the south of TPVs, and stronger upper-level jet stream, as well as the more powerful and eastward extending SAH, correspond to higher PI, and vice versa.

Tibetan Plateau vortices (TPVs) are major rainfall producers generated over the Tibetan Plateau, and the ones moving off the Tibetan Plateau can trigger heavy rainfall over eastern China. The structure characteristics of the moving-off TPVs are investigated based on the final operational global analysis data from the National Centers for Environmental Prediction. Generally, the TPVs show different dynamic and thermodynamic structures before and after they move off the Tibetan Plateau. Specifically, the structures of TPVs at the genesis and peak times before they move off the Tibetan Plateau are distinguishing, and different structure characteristics are also found at the times when the TPVs just move off the Tibetan Plateau and when the intensity reaches the peak after moving off. In addition, the moving-off TPVs are divided into two groups according to their lifespans after moving off the plateau, and the structure characteristics of these two groups of TPVs are further compared. Furthermore, on the basis of the evolution features of the moving-off TPVs, the relationship between the structures of TPVs and their intensity is discussed. It is inferred that the evolution of the TPVs is determined by the structures of TPVs themselves to some extent.

Tibetan Plateau vortices (TPVs) are major rain producer over the Tibetan Plateau, which trigger heavy rainfall in southwestern and eastern China when moving off the plateau. In this work, two groups of TPVs moving off the plateau are selected according to their eastward moving speeds. The features of the atmospheric dynamic and thermodynamic fields associated with the two groups of TPVs are compared, based on the final (FNL) operational global analysis data from the Global Forecasting System of the National Centers for Environment Prediction (NCEP). The results show that the large-scale circulations and heating fields have a close relationship with the moving speed of the TPVs. The TPVs move eastward faster when wider and stronger convergence at 500 hPa, divergence at 200 hPa and the related ascending motion are observed to the east of TPVs. In addition, the stronger and further eastward stretching unstable stratification and water vapor convergence, as well as the more intensive heating field above 500 hPa to the east of TPVs, correspond to larger eastward moving speed of TPVs. Furthermore, the crucial factors modulating the moving speed of TPVs are explored through potential vorticity (PV) budget analyses, in which the physical variables are partitioned into zonal means and disturbances. The convergence of the mean zonal winds and disturbance winds at 500 hPa, as well as the vertical distribution of disturbance heating to the east of TPVs are the crucial factors influencing the eastward moving speed of TPVs, among which the vertical distribution of disturbance heating is the most dominant.

The climatic characteristics of 260 East Asian tropical monsoon depressions (EAMDs) are investigated using the ERA-Interim reanalysis dataset and a tracking dataset of global monsoon low-pressure systems. Most EAMDs form over the South China Sea (SCS) and the western tropical Pacific Ocean in July–October and have an average lifetime of 10 days. The vertical structures of EAMDs are usually upright or tilt slightly westward with height. The warm-over-cold thermal structure is a distinctive characteristic of EAMDs and two potential vorticity (PV) centers are related to the warm core in the upper level and the specific humidity center in the lower level, respectively. We divided the EAMDs into four groups: eastward-moving, westward-moving, turning, and northwestward-moving EAMDs. Most of the eastward-moving EAMDs form over the SCS in May and June, whereas the westward-moving EAMDs form over both the SCS and the western Pacific Ocean in July–October. The turning and northwestward-moving EAMDs are mainly generated over the western Pacific Ocean and have longer lifetimes. The structures of the eastward-moving and turning EAMDs show common characteristics in each stage. Their vertical structures change from upright in the developing and peak stages to northeast tilting with height in the attenuating stage, especially for the specific humidity. By contrast, the structures of westward- and northwestward-moving EAMDs show little change during their lifetime. They are symmetrical relative to the vertical axis of the EAMDs over their whole lifetime and only vary in strength.

Year-to-year variability of surface air temperature (SAT) over central India is most pronounced in June. Climatologically over central India, SAT peaks in May, and the transition from the hot premonsoon to the cooler monsoon period takes place around 9 June, associated with the northeastward propagation of intraseasonal convective anomalies from the western equatorial Indian Ocean. Positive (negative) SAT anomalies during June correspond to a delayed (early) Indian summer monsoon onset and tend to occur during post–El Niño summers. On the interannual time scale, positive SAT anomalies of June over central India are associated with positive SST anomalies over both the equatorial eastern–central Pacific and Indian Oceans, representing El Niño effects in developing and decay years, respectively. Although El Niño peaks in winter, the correlations between winter El Niño and Indian SAT peak in the subsequent June, representing a post–El Niño summer capacitor effect associated with positive SST anomalies over the north Indian Ocean. These results have important implications for the prediction of Indian summer climate including both SAT and summer monsoon onset over central India.