CLIMATE PREDICTION EXPERIMENT FOR TROPICAL CYCLONE GENESIS FREQUENCY USING THE LARGE-SCALE CIRCULATION FORECAST BY A COUPLED GLOBAL CIRCULATION MODEL

Based on an analysis of the relationship between the tropical cyclone genesis frequency and large-scale circulation anomaly in NCEP reanalysis, large-scale atmosphere circulation information forecast by the JAMSTEC SINTEX-F coupled model is used to build a statistical model to predict the cyclogenesis frequency over the South China Sea and the western North Pacific. The SINTEX-F coupled model has relatively good prediction skill for some circulation features associated with the cyclogenesis frequency including sea level pressure, wind vertical shear, Intertropical Convergence Zone and cross-equatorial air flows. Predictors derived from these large-scale circulations have good relationships with the cyclogenesis frequency over the South China Sea and the western North Pacific. A multivariate linear regression(MLR) model is further designed using these predictors. This model shows good prediction skill with the anomaly correlation coefficient reaching, based on the cross validation, 0.71 between the observed and predicted cyclogenesis frequency. However, it also shows relatively large prediction errors in extreme tropical cyclone years(1994 and 1998, for example).

Large-scale circulation features associated with the heat wave over Northeast China in summer 2018

In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP–NCAR reanalysis data.The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China,and the related downward motions were directly responsible for the extreme high-temperature anomalies.The northwestward shift of the western Pacific subtropical high(WPSH)and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China.In addition,an anomalous Pacific–Japan pattern in the lower troposphere led to the northwestward shift of the WPSH,jointly favoring the anomalous geopotential height over Northeast China.Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes,respectively,and converged over Northeast China,leading to the enhancement of the geopotential height anomalies.

Drought variability and its connection with large-scale atmospheric circulations in Haihe River Basin

Drought is one of the most widespread and devastating extreme climate events when water availability is significantly below normal levels for a long period.In recent years,the Haihe River Basin has been threatened by intensified droughts.Therefore,characterization of droughts in the basin is of great importance for sustainable water resources management.In this study,two multi-scalar drought indices,the standardized precipitation evapotranspiration index(SPEI)with potential evapotranspiration calculated by the PenmaneMonteith equation and the standardized precipitation index(SPI),were used to evaluate the spatiotemporal variations of drought characteristics from 1961 to 2017 in the Haihe River Basin.In addition,the large-scale atmospheric circulation patterns were used to further explore the potential links between drought trends and climatic anomalies.An increasing tendency in drought duration was detected over the Haihe River Basin with frequent drought events occurring in the period from 1997 to 2003.The results derived from both SPEI and SPI demonstrated that summer droughts were significantly intensified.The analysis of large-scale atmospheric circulation patterns indicated that the intensified summer droughts could be attributed to the positive geopotential height anomalies in Asian mid-high latitudes and the insufficient water vapor fluxes transported from the south.©2021 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Interannual Variation of Tropical Night Frequency in Beijing and Associated Large-Scale Circulation Background

This study examined the variability in frequency of tropical night occurrence （i.e., minimum air tem- perature 25℃） in Beijing, using a homogenized daily temperature dataset during the period 1960–2008. Our results show that tropical nights occur most frequently in late July and early August, which is consis- tent with relatively high air humidity associated with the rainy season in Beijing. In addition, year-to-year variation of tropical night occurrence indicates that the tropical nights have appeared much more frequently since 1994, which can be illustrated by the yearly days of tropical nights averaged over two periods： 9.2 days of tropical nights per year during 1994–2008 versus 3.15 days during 1960–1993. These features of tropical night variations suggest a distinction between tropical nights and extreme heat in Beijing. We further investigated the large-scale circulations associated with the year-to-year variation of tropical night occurrence in July and August, when tropical nights appear most frequently and occupy 95% of the annual sum. After comparing the results in the two reanalysis datasets （NCEP/NCAR and ERA-40） and considering the possible effects of decadal change in the frequency of tropical nights that occurred around 1993/94, we conclude that on the interannual time scale, the cyclonic anomaly with a barotropic structure centered over Beijing is responsible for less frequent tropical nights, and the anticyclonic anomaly is responsible for more frequent occurrence of tropical nights over Beijing.

Influencing Factors of Rural Land Internal Circulation Market in Guangdong Province

The circulation of rural land is helpful to improving the allocation efficiency of land resources,increasing farmers'income and promoting the development of modern agriculture.In this paper,we used the social economy,the main participants and the market environment of rural land circulation to make a qualitative analysis for the factor of rural land internal circulation.With the aid of principal component analysis,grey correlation model,and other methods to make a quantitative analysis for the factor of rural land internal circulation.The results show that the grey correlation degrees of the output value of secondary and tertiary industries as a proportion of GDP,the expenditure on science and education per capita,the expenditure on financial support for agriculture,the proportion of non-agricultural population and the standardization of rural land circulation contracts are 0.8988,0.8382,0.7632 and 0.7576 respectively,indicating that these factors are significantly related to the rural internal land circulation market.

Correlation of serum platelet activating factor level with inflammatory response indexes and blood lipid metabolism in patients with posterior circulation cerebral infarction

Objective:To study the correlation of serum platelet activating factor (PAF) level with inflammatory response indexes and blood lipid metabolism in patients with posterior circulation cerebral infarction.Methods: Patients who were hospitalized and diagnosed with posterior circulation cerebral infarction in Neurology Department of Foshan Second People's Hospital between October 2016 and October 2017 were selected as the cerebral infarction group of the research, and healthy volunteers who received physical examination in the hospital during the same period were selected as control group. Serum was collected to determine the contents of PAF, inflammatory response indexes and lipid metabolism indexes.Results:Serum PAF, HMGB1, FKN, CD40L, IL-18, HCY, DKK1, LDL-C, Vaspin and Resistin levels of cerebral infarction group were greatly higher than those of control group whereas Visfatin level was greatly lower than that of control group;serum HMGB1, FKN, CD40L, IL-18, HCY, DKK1, LDL-C, Vaspin and Resistin levels of cerebral infarction group of patients with high PAF level were greatly higher than those of patients with low PAF level whereas Visfatin level was greatly lower than that of patients with low PAF level.Conclusion: The increase of PAF content in serum of patients with posterior circulation cerebral infarction is closely related to the inflammatory response activation and lipid metabolism disorder.

An Eddy-Permitting Oceanic General Circulation Model and Its Preliminary Evaluation

An eddy-permitting, quasi-global oceanic general circulation model, LICOM (LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics) Climate System Ocean Model), with a uniform grid of 0.5? × 0.5? is established. Forced by wind stresses from Hellerman and Rosenstain (1983), a 40-yr integration is conducted with sea surface temperature and salinity being restored to the Levitus 94 datasets. The evaluation of the annual mean climatology of the LICOM control run shows that the large-scale circulation can be well reproduced. A comparison between the LICOM control run and a parallel integration of L30T63, which has the same framework but a coarse resolution, is also made to con?rm the impact of resolution on the model performance. On account of the reduction of horizontal viscosity with the enhancement of the horizontal resolution, LICOM improves the simulation with respect to not only the intensity of the large scale circulations, but also the magnitude and structure of the Equatorial Undercurrent and South Equatorial Current. Taking advantage of the ?ne grid size, the pathway of the Indonesian Through?ow (ITF) is better represented in LICOM than in L30T63. The transport of ITF in LICOM is more convergent in the upper layer. As a consequence, the Indian Ocean tends to get warmer in LICOM. The poleward heat transports for both the global and individual basins are also signi?cantly improved in LICOM. A decomposed analysis indicates that the transport due to the barotropic gyre, which primarily stands for the barotropic e?ect of the western boundary currents, plays a crucial role in making the di?erence.

Epidermal growth factor receptor-targeted immune magnetic liposomes capture circulating colorectal tumor cells efficiently

AIM To compare the capacity of newly developed epidermal growth factor receptor(EGFR)-targeted immune magnetic liposomes(EILs) vs epithelial cell adhesion molecule(Ep CAM) immunomagnetic beads to capture colorectal circulating tumor cells(CTCs).METHODS EILs were prepared using a two-step method, and the magnetic and surface characteristics were confirmed. The efficiency of capturing colorectal CTCs as well as the specificity were compared between EILs and Ep CAM magnetic beads. RESULTS The obtained EILs had a lipid nanoparticle structure similar to cell membrane. Improved binding with cancer cells was seen in EILs compared with the method of coupling nano/microspheres with antibody. The binding increased as the contact time extended. Compared with Ep CAM immunomagnetic beads, EILs captured more CTCs in peripheral blood from colorectal cancer patients. The captured cells showed consistency with clinical diagnosis and pathology. Mutation analysis showed same results between captured CTCs and cancer tissues. CONCLUSION EGFR antibody-coated magnetic liposomes show high efficiency and specificity in capturing colorectal CTCs.

Relationships between the Oxygen Isotopes in East Asian Stalagmites and Large-Scale Atmospheric and Oceanic Modes

The stalagmite δ18O record is known to be associated with the climate, but the specifics of the relationship remain unclear. It may not represent variation in air temperature or precipitation, but instead reflect integral changes of monsoon circulation, especially water vapor sources(the so-called "circulation effect"). Since large-scale atmospheric-oceanic modes such as the Atlantic Multidecadal Oscillation(AMO), Pacific Decadal Oscillation(PDO), and North Atlantic Oscillation(NAO) exert significant effects on Asian monsoon, in this paper the authors investigate the relationships of the East Asian stalagmite δ18O record with these modes. The last three centuries form the focus of our study, for which the authors use reconstructed as well as instrumental data. Considering the impacts of human activity, our analysis is conducted with respect to two periods—the pre- and post-industrial periods. The results show significant lead-lag connections: a positive correlation peaks when the PDO leads East Asian stalagmite δ18O by 3 years, which is persistent over the past 300 years; while the relationships of the AMO and NAO with the East Asian stalagmite δ18O record show significant differences in the post-industrial relative to the pre-industrial period. This implies that the East Asian stalagmite δ18O record may primarily reflect the PDO signal.

Infarction Patterns in Posterior Cerebral Circulation: Etiology and Prognosis

Study Objectives: About a quarter of strokes and transient ischemic attacks occur in the vertebrobasilar distribution. Vertebrobasilar stroke is particularly prone to devastating consequences especially brain stem infarctions due to damage of the regional brain tissues that contain vital centers, and is associated with high rates of death and disability. Study Design: This was across sectional observational prospective hospital-based study conducted on 60 patients with first-ever acute posterior circulation ischemic stroke. The aim of the current study was to determine the relationship between different risk factors and different infarction patterns in posterior circulation;single small lacunar lesion, single large lesion, or multiple scattered lesions. Diagnosis of ischemic stroke and stroke subtypes were defined using the Trial of ORG 10,172 in Acute Stroke Treatment (TOAST) criteria as well as clinical and brain imaging features. Stroke severity using National Institutes of Health Stroke Scale (NIHSS) score was done on admission, after 24 hours from admission, and at 7 days from onset of symptoms. The patients functional status was assessed by modified Rankin scale (mRS) done on admission and on discharge from hospital and at 7-day follow up from onset of symptoms. Patients were classified according to infarction patterns into a single small lacunar lesion (group I), a single large lesion (group II), and multiple scattered lesions (group III) 20 patients in each group. Results: There was no significant difference between the three groups as regard the presence of vascular risk factors and the only significant difference as regard vascular risk factors was atrial fibrillation (AF). There was significant difference between the three groups as regard the occurrence of previous transient ischemic attacks (TIA). There was significant difference between the three groups as regard NIHSS score on admission, after 24 hours, and at 7 days from admission. There were significant differences between the three groups as regard mRS score at discharge and at 7-day follow up from the onset of symptoms and the degree of improvement from admission to discharge. There was significant difference between the three groups as regard volume of infarction in Brain magnetic resonance imaging (MRI). Group II and group III patients had larger volumes of infarction when compared to group I patients. There was no significant difference between the three groups as regard presence of significant intracranial stenosis in magnetic resonance angiography (MRA). There was significant difference between the three groups as regard stroke etiology. It was found that largeartery atherosclerosis (LAA) was the most common stroke etiology in posterior circulation being present in (53.3%) of the patient group and was common in group II and III in contrast to group I patients. Conclusions: Different vascular risk factors such as hypertension, diabetes, dyslipidemia, and smoking are present in all infarction patterns of posterior circulation ischemic stroke either single or multiple infarctions. However, AF and significant vertebrobasilar stenosis were mostly associated with large and multiple infarct lesion patterns. Small vessel disease was the most common stroke etiology for single small lacunar lesion while large artery atherosclerosis was associated with single large lesion and multiple lesions in the posterior circulation. Early MRI and MRA help in define type and prognosis of posterior circulation infarcts. Early diagnosis and control of potentially modifiable risk factors and comorbid conditions are an important aspect in the early management of patients with infarction in the posterior circulation.

Circulation-Enhanced Tank Heating Using Shallow Profile Coil Bundles

Heavy fuel oils require heated tanks to facilitate their transportation and processing.This paper proposes and investigates threeand four-level heating coil bundles.Numerical study revealed that powerful large-scale circulation of the heated fluid enhances heat transfer,delivering 16.7%and 23%improvements to the average heat transfer coefficient for the three-and four-level bundles,respectively.Furthermore,this circulation improves oil mixing and limits the variation in bulk oil temperature to-0.3 to+1.3°C from the average.The study also quantified oil flow velocity near the bottom of the tank.The time-averaged horizontal components of velocity,estimated 25 mm and 50 mm above the bottom of the tank,exceed 2 mm/s and 4 mm/s,respectively.The proposed heating coil bundles feature a compact design that reduces the material and labor costs of construction and that,by occupying only a small portion of the bottom of the tank,improves accessibility,maintenance,and cleaning.

Evolving Perspectives on Abrupt Seasonal Changes of the General Circulation

Professor Duzheng YE（Tu-cheng YEH） was decades ahead of his time in proposing a model experiment to investigate whether abrupt seasonal changes of the general circulation can arise through circulation feedbacks alone, unrelated to underlying inhomogeneities at the lower boundary. Here, we introduce Professor YEH＇s ideas during the 1950 s and 1960 s on the general circulation and summarize the results and suggestions of Yeh et al.（1959） on abrupt seasonal changes. We then review recent advances in understanding abrupt seasonal changes arising from model experiments like those proposed by Yeh et al.（1959）. The model experiments show that circulation feedbacks can indeed give rise to abrupt seasonal transitions.In these transitions, large-scale eddies that originate in midlatitudes and interact with the zonal mean flow and meridional overturning circulations in the tropics play central roles.

Algorithms for Finding the Inverses of Factor Block Circulant Matrices

In this paper,algorithms for finding the inverse of a factor block circulant matrix, a factor block retrocirculant matrix and partitioned matrix with factor block circulant blocks over the complex field are presented respectively.In addition,two algorithms for the inverse of a factor block circulant matrix over the quaternion division algebra are proposed.

Relationship between multi-scale climate factors and performance of ecological engineering on the Loess Plateau, China

The long-term “Grain-to-Green Program” (GGP) on China’s Loess Plateau is a major global ecological engineering project which has significantly boosted vegetation renewal. Some studies have found that the rate of restoration is quite rapid during the implementation of ecological engineering, however, the influence of multi-scale climatic conditions on the performance of ecological engineering is unclear. In this study, multiple sources of remote sensing data were used to estimate the dynamics of vegetation structural and functional indicators, water-related local climatic factors, and atmospheric circulation factors. These datasets were also used to detect possible causes for vegetation restoration on the Loess Plateau over the past 20 years. The results show that widespread increases in rates of normalized difference vegetation indexes (NDVI), leaf area indexes (LAI), gross primary production (GPP), and aboveground biomass carbon (ABC) during 2000–2016 were significantly higher than before 2000. GPP was significantly correlated with rainfall and surface runoff on a monthly scale, and there were significant positive correlations between GPP and atmospheric circulation. Our results demonstrate that both vegetation structural and functional indicators rapidly increase, and ecological engineering greatly accelerated vegetation restoration after 2000. Local climatic conditions and atmospheric circulation patterns enhance vegetation growth and impact of ecological engineering.

Recognition of two dominant modes of EASM and its thermal driving factors based on 25 monsoon indexes

Based on three reanalysis datasets—ERA-Interim,NCAR–NCEP and JRA-55—the classification of25 commonly used indexes of the East Asian summer monsoon(EASM)was investigated.The physical nature of two categories of monsoon index,together with their circulation pattern,climate anomalies,and driving factors,were investigated.Results suggest that the selected 25 monsoon indexes can be classified into two typical categories(CategoryⅠandⅡ),which are dominated by interannual and decadal variabilities of the EASM,respectively.The anomalous circulation patterns and summer rainfall patterns related to the two categories of index also exhibit evident differences.CategoryⅠis closely linked to the low-latitude circulation system and the anomalous circulation pattern is a typical East Asia–Pacific teleconnection pattern.The summer rainfall anomaly exhibits a typical tripole pattern.However,CategoryⅡmainly reflects the impacts of the middle–high latitude circulation system on the summer monsoon and is closely linked to a typical Eurasian teleconnection pattern,which corresponds to a dipole of summer rainfall anomalies.Further analysis suggests that the underlying thermal driving factors of the two categories of monsoon are distinct.The main driving factors of CategoryⅠare the tropical sea surface temperature anomalies(SSTAs),especially ENSO-related SSTAs in the preceding winter and summer SSTAs in the tropical Indian Ocean.The winter signal of Category II summer monsoon anomalous activity mainly originates from the polar region and the middle and high latitudes of the Eurasian continent.CategoryⅡmonsoon activity is also associated with summer SSTAs in the equatorial central Pacific.

Effect of Epalrestat combined with Huoxue Huayu preparation on early diabetic retinopathy and its effect on serum oxidative stress and inflammatory factors

Objective:To investigate the effect of Epalrestat combined with Huoxue Huayu preparation on early diabetic retinopathy and its effect on serum oxidative stress and inflammatory factors.Methods:132 patients with early diabetic retinopathy from June 2017 to July 2019 in our hospital were randomly divided into the control group(66 cases)and the observation group(66 cases);The control group was treated with epalrestat,and the observation group was treated with epalrestat combined with ginkgo damo injection;The treatment effect,blood rheology indexes,serum oxidative stress indexes and inflammatory factor indexes of the two groups were compared.Results:The treatment efficiency of the observation group(96.96%)was significantly higher than that of the control group(84.84%)(P<0.05).After 3 months of treatment,the high-cut whole blood viscosity(3.62±0.45 mPa/s),low-cut whole blood viscosity(1.54±0.26 mPa/s),erythrocyte sedimentation rate(15.63±2.97 mm/s)of the observation group compared with the control group(4.57±0.52 mPa/s,2.91±0.30 mPa/s,22.36±3.38 mm/s)were significantly lower(P<0.05).After 3 months of treatment,the SOD(93.41±10.17 nmol/mL)and TAC(20.57±3.76 u/mL)of the observation group compared with the control group(82.26±9.45 nmol/mL,18.26±3.63 u/mL)were significantly higher(P<0.05),and the MDA of the observation group(9.22±1.98 u/mL)was significantly lower than that of the control group(12.13±1.06 u/mL)(P<0.05).After 3 months of treatment,the CRP(9.74±1.12 mg/L),IL-2(70.37±12.13 ng/L),TNF-a(11.36±2.08 ng/L)of the observation group compared with the control group(15.28±1.73 mg/L L,82.46±10.58 ng/L,16.28±2.43 ng/L)were significantly lower(P<0.05).Conclusion:Epalrestat combined with Huoxue Huayu preparation is more effective in the treatment of early diabetic retinopathy,and can significantly improve the blood rheology indexes,serum oxidative stress indexes and inflammatory factor indexes of patients.

The Relationships between Serum Concentration of IGF-I and Left Ventricular Function as well as Coronary Collateral Circulation in Patients with Coronary Artery Disease

Objective To investigate therelationships between serum concentration of insulin -like growth factor - I (IGF-I) and left ventricular function as well as coronary collateral circulation in patients with coronary artery disease (CAD) . Methods In 41 patients with CAD and 15 control subjects without CAD, the concentrations of serum IGF - I were measured using radioimmunoassay. The relationships between the concentration of serum IGF - I and Leaman coronary artery score, Rentrop grade of coronary collateral circulation, left ventricular ejection fraction (LVEF) as well as left ventricular wall motion Cortina score were assessed. Results 1. There was no significant difference in the mean level of serum IGF -I between the CAD group and the control group (107. 92±44.74 ng/ml vs 113.05 ±33. 65 ng/ml, P> 0. 05), but the IGF - I concentrations in the subgroup with collateral circulation were significantly greater than that in the control group (147. 33 ±29. 92 ng/ml vs 113. 05±33. 65 ng/ml, P < 0. 01) or in the subgroup without collateral circulation (147. 33 ±29. 92 ng/ml vs 80. 01±29. 75 ng/ml , P < 0. 01). 2. The serum concentration of IGF -I had no significant correlation to the Leaman coronary artery score. 3. The serum level of IGF -I had significantly positive correlation to both LVEF ( r = 0. 45, P < 0. 001) and the Rentrop grade of coronary collateral circulation ( r = 0. 74, P < 0. 001), and was negatively related to the left ventricular wall motion Cortina score (r = -0. 53, P < 0. 001). 4. The Leaman coronary artery score had no significant correlation to the Rentrop grade of coronary collateral circulation. 5. The Leaman coronary artery score was related to neither the LVEF nor the Cortina score in the whole CAD group. In the subgroup without coronary collateral circulation, however, the Leaman score had significantly negative correlation to LVEF ( r = - 0. 46, P < 0. 05) and positive correlation to the Cortina score (r = 0. 47, P < 0. 05) . Conclusions The serum concentration of IGF -I was associated with both left ventricular function and coronary collateral circulation in patients with CAD. IGF -I may play a role in promoting coronary collateral circulation and in protecting left ventricular function in patients with coronary artery disease.

The interannual periodicity of precipitation and its links to the large-scale circulations over the Third Pole

To understand the spatio-temporal variability of precipitation(P)in the Third Pole region(centered on the Tibetan Plateau-TP),it is necessary to quantify the interannual periodicity of P and its relationship with large-scale circulations.In this study,Morlet wavelet transform was used to detect significant(p<0.05)periodic characteristics in P data from meteorological stations in four climate domains in the Third Pole,and to reveal the major large-scale circulations that triggered the variability of periodic P,in addition to bringing large amounts of water vapour.The wavelet transform results were as follows.(1)Significant quasiperiodicity varied from 2 to 11 years.The high-frequency variability mode(2 to 6 years quasi-periods)was universal,and the low-frequency variability mode(7 to 11 years quasi-periods)was rare,occurring mainly in the westerlies and Indian monsoon domains.(2)The majority of periods were base periods(53%),followed by two-base periods.Almost all stations in the Third Pole(95%)showed one or two periods.(3)Periodicity was widely detected in the majority of years(84%).(4)The power spectra of P in the four domains were dominated by statistically significant high-frequency oscillations(ie.,with short periodicity).(5)Large-scale circulations directly and indirectly influenced the periodic P variability in the different domains.The mode of P variability in the different domains was influenced by interactions between large-scale circulation features and not only by the dominant circulation and its control of water vapour transport.The results of this study will contribute to better understanding of the causal mechanisms associated with P variability,which is important for hydrological science and waterresourcemanagement.

Differences in Variations of Long-Lived and Short-Lived Summer Heat Waves during 1981-2020 over Eastern China and Their Corresponding Large-Scale Circulation Anomalies

Using daily maximum temperature(Tmax)data from 516 observation stations in eastern China from 1981 to 2020,this study employed a relative threshold method to define short-and long-lived heat waves(HWs)by considering regional climate differences to investigate the spatial characteristics and evolution of large-scale circulation during summer HWs.The results demonstrated spatial disparities in the frequency distribution of HWs of different durations and differences in the magnitude of duration and intensity between short-and long-lived HWs.Empirical orthogonal function analysis revealed three dominant spatial modes for both short-and long-lived HWs.The first mode showed that short-lived HWs occur prominently in both northern and southern regions,whereas long-lived HWs mainly occur in the northern region.The second mode was characterized by a meridional dipole pattern in both cases.The third mode exhibited a quadrupole pattern for short-lived HWs and a tripole pattern for long-lived HWs.Differences in the center locations of anomalies in the 500-hPa geopotential height and 850-hPa wind fields significantly influenced the temperature and precipitation anomaly distribution of typical HWs by affecting the warm column in the lower troposphere,cloud distribution,and moisture transport.Moreover,the atmospheric circulation evolution processes of typical HWs associated with the different modes of long-and short-lived HWs were linked to distinct teleconnection patterns.During the three modes of long-lived(short-lived)HWs,there was stronger(weaker)wave flux activity with multiple(single)propagation paths.Stronger westward Atlantic wave train activity at 300 hPa triggered the synergistic action of meridional and zonal wave fluxes,favoring the strengthening and maintenance of positive anomalies in geopotential height of 500 hPa.This may have contributed to the formation of long-lived HWs.These findings provide valuable insights to enhance our understanding and prediction of summer HWs.

Interannual and Interdecadal Variations in Atmospheric Circulation Factors and Rainfall in China and Their Relationship

Wavelet analysis is used to study the interannual and interdecadal variationsof rainfall in China and atmospheric circulation factors, including the key atmosphericoscillations, W, C, E patterns and subtropical high. Regression analysis and correlation analysisare both used to study the relationship of atmospheric circulation factors and China rainfall ondifferent time scale and spatial scale. The results are as follows: (1) The variations ofatmospheric circulation and rainfall in China are characterized by interannual and interdecadalscales. The variations of atmospheric circulation and rainfall are composed of interannual andinterdecadal variations. It is necessary to separate those two time scales when climate changes andforecast are studied. (2) The variations of China rainfall are due to the interaction ofmulti-factors rather than single factors. The marked factors which influence the interannual andinterdecadal variations are various. Subtropical high is one of the marked factors which influenceinterannual variations of rainfall, while AO, NAO, and NPO are one of the marked factors whichinfluence interdecadal variations of rainfall. (3) The longer the time scale is, and the larger thespatial scale is, and the more remarkable the relationships between atmospheric circulation andrainfall are.