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    2023,46(4): 481-490, DOI: 10.13878/j.cnki.dqkxxb.20230517001
    [Abstract] (181) [HTML] (672) [PDF 10.20 M] (423)
    The investigation of climate change in arid and semiarid regions has long been a prominent scientific issue of extensive interest,particularly concerning the patterns and future trends of dry and wet climatic variations.Previous research has made significant advancements in unraveling the facts and mechanisms underlying these climatic changes across diverse arid and semiarid regions worldwide.Although the 6th IPCC evaluation report indicates a projected exacerbation of global aridity trends in the future,several contentious issues persist.This paper provides a comprehensive review of studies focusing on interdecadal changes in dry and wet conditions,particularly interdecadal drought,in arid and semiarid regions within the context of global warming.The current state of related research is systematically analyzed,and key scientific challenges faced by arid and semiarid region studies are identified.
    2023,46(4): 491-498, DOI: 10.13878/j.cnki.dqkxxb.20220921001
    Short-lived Climate Forcers (SLCFs) have a significant impact on air pollution and climate change.The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) pays a special attention on SLCFs,which includes an assessment of natural emissions of SLCFs in addition to the anthropogenic SLCFs.The understanding of natural emissions of SLCFs and their climate feedbacks would be more important in the future with the reduction of anthropogenic SLCFs under climate warming.In this paper,the latest findings from IPCC AR6 are introduced in terms of natural emissions of SLCFs,changes in emissions under historical and future climate scenarios,and their climate feedbacks.Under climate warming,future emissions of lighting NOx,biogenic VOCs,and biomass burning will likely increase,and the sensitivity in emissions of soil NOx,dust,sea salt,and dimethyl sulfide (DMS) to climate change is uncertain.Meanwhile,due to changes in emissions,atmospheric burden,or lifetime of SLCFs in response to climate warming,the overall effect will likely result in a negative feedback of -0.20 W/m2/℃ (-0.41~+0.01 W/m2/℃),which may slightly mitigate climate warming.
    2023,46(4): 499-516, DOI: 10.13878/j.cnki.dqkxxb.20221118007
    Based on the observation and a set of downscaling bias corrected model (NEX-GDDP-CMIP6) data,this study has investigated the model performance in simulating precipitation extremes over Southwest China using Taylor diagram and GEV fitting methods.Furthermore,the future changes of precipitation extremes that with different return intervals and their associated population exposure are also explored.Results show that NEX-GDDP-CMIP6 models and the multi-model ensemble (N-CMIP6-MME) can reasonably capture the spatial-temporal characteristics of changes in precipitation extremes over Southwest China,and N-CMIP6-MME out performs most of individual models.In the future,the precipitation extremes are expected to significant increases over most regions of Southwest China,including the extreme events that occurring once in 10 or 20 years,which will further increase the risk of population exposure to these extremes.Additionally,for the more extreme events (once in 20-year),the increasing magnitude of its occurring probability would be much greater and it would also exert a larger increase of its associated population exposure,when compared to the events of once in 10-year.Around the year of 2050,the occurring probabilities of the RX1day (RX5day) extremes that occurring once in 20-year are expected to increase by 175.2%(148.9%),216.0%(162.4%),210.9%(156.8%),and 274.3%(207.1%) under SSP1-2.6,SSP2-4.5,SSP3-7.0and SSP5-8.5 scenario,respectively.Correspondingly,thepopulation exposuresare projected to respective increase by 129.1%(118.8%),177.7% (135.1%),182.4%(143.2%),and 237.5%(161.5%).Further analyses indicate that the increase of population exposure to the precipitation extreme over Southwest China is mainly due to the significant increase of precipitation extremes,and the changes in populations and their interaction generally present a negative contribution.
    2023,46(4): 517-531, DOI: 10.13878/j.cnki.dqkxxb.20220701001
    Based on reanalysis datasets of land precipitation,circulation,radiation,and indices representing atmospheric waves,anomalies of the East-Asian circulation and the summer precipitation in North China of the years in which El Niño decayed fast in spring are compared with those of El Niño slow decaying years between 1951—2020;And the reason why El Niño decayed fast in spring in some years was discussed from the perspective of atmospheric wave intensity.Results show that,compared with the other years without El Niño decaying,the precipitation in North China in July and August of the fast decaying years are significantly greater,especially in August.In contrast,the summer precipitation in North China are not significantly greater in the slow decaying years.There was an anomalous anticyclone at 850 hPa over the Philippines to the South China Sea from June to August in the fast decaying years,which was much stronger than that in the slow decaying years.The western Pacific subtropical high (WPSH) at 500 hPa was significantly northward-displaced in August in the fast decaying years,while the WPSH in the slow decaying years was more westward rather than northward.The 200 hPa subtropical westerly jet in August of the fast decaying years was significantly northward,while the corresponding westerly jet in the slow decaying years was slightly southward.And the Walker Circulation from June to August in the fast decaying years was much stronger than that in the slow decaying years.These circulation anomalies in the fast decaying years provided favorable conditions for more precipitation in North China from July to August.According to the composite analysis of near-surface wind,the outbreak of anomalous equatorial easterly wind occurred around the month in which El Niño decayed fast over the Western and Central Pacific.However,in the slow decaying years,the anomalous equatorial easterly wind was much weaker and unsignificant.The convection over the Indian Ocean remained active and spread to the Maritime continent during the fast decay of El Niño.Such continuous active convection very likely induced the outbreak of anomalous near-surface easterly wind by triggering atmospheric waves,and consequently resulted in the fast decay of El Niño.
    2023,46(4): 532-548, DOI: 10.13878/j.cnki.dqkxxb.20221025001
    This study investigates the characteristics and underlying processes of the month-to-month reversal of air temperature anomalies in Northeast Asia during early summer (May to June) on the interannual timescales,focusing on the influences of soil moisture anomalies in eastern Europe.Utilizing observational and reanalysis data spanning from 1979 to 2020,the results reveal that the dominant mode of intermonthly variation in air temperature anomalies exhibits a reversal pattern,with warmer (colder) conditions in May and colder (warmer) conditions in June.This reversal mode is directly linked to circulation anomalies over Northeast Asia.Further analysis demonstrates that reduced soil moisture in eastern Europe during May contributes to a warmer May and a colder June in Northeast Asia.The potential physical processes driving these effects are explored.Lower soil moisture in May leads to local soil warming and subsequent warming of the lower troposphere.This,in turn,weakens (enhances) the lower tropospheric meridional temperature gradient and baroclinicity in the Mediterranean region (northern Europe).Consequently,high-frequency transient wave activity weakens (enhances),facilitating the formation of an anomalous high-pressure system over central and eastern Europe,thereby generating Rossby wave sources through transient vorticity forcing.These associated Rossby waves propagates eastward along the polar front jet,resulting in the formation of a barotropic anomalous high-pressure system over Northeast Asia and inducing surface warming.While the soil moisture anomalies persist until June,their intensity weakens.Similarly,this favors the formation of an anomalous high-pressure system and Rossby wave source;however,their centers shift westward towards western Europe.The associated Rossby wave activity leads to the formation of a barotropic anomalous low-pressure system,causing cooling over Northeast Asia.Notably,the activity characteristics of Rossby waves (wave source,activity centers,and propagation pathway) associated with the soil moisture anomalies in eastern Europe exhibit distinct differences between May and June,closely tied to the atmospheric climatology over northern Eurasia.When soil moisture is high in May,the aforementioned physical processes exhibit reverse tendencies.
    2023,46(4): 549-560, DOI: 10.13878/j.cnki.dqkxxb.20220303001
    The Tibetan Plateau exhibits complex train,resulting in significant variability in soil conditions across different regions.Gravel and soil organic matter have a substantial influence on soil thermal and hydraulic properties.In this study,we employ the regional climate model RegCM4.7 coupled with CLM4.5 to modify the surface data and implement a corresponding soil thermal and hydraulic parameterization scheme.We conduct two tests:one considering the influence of gravel (test2)and another considering the combined influence of gravel and organic matter (test3).Our results indicate that test2 significantly improves the simulation accuracy for the western part of the Plateau by incorporating gravel effects but exhibits poor performance for the eastern part.Test3 further enhances the simulation of shallow soil properties in the central and eastern regions based on test2.The regional average root mean square error of shallow soil temperature decreases from 2.11 ℃ to 0.47 ℃,and the regional average root mean square error of shallow soil moisture decreases from 0.05 mm3·mm-3 to 0.01 mm3·mm-3 when transitioning from test1 to test3.Furthermore,all three schemes successfully simulate the surface temperature of the Tibetan Plateau,with test3 exhibiting the smallest error.The root mean square error of the regional average decreases from 2.18 ℃ to 0.74 ℃,bringing it closer to the reanalysis data.
    2023,46(4): 561-574, DOI: 10.13878/j.cnki.dqkxxb.20210519001
    This study analyzes the spatiotemporal variation of heat discomfort days characterized by Humidex and cold discomfort days represented by Wind Chill Index in different latitudes (high latitudes,middle latitudes,and low latitudes) of the northern hemisphere during 1961—2014,using NCEP/NCAR reanalysis data and simulations from six CMIP6 models.The investigation focuses on the attribution of these discomfort days.The results show a significant increase in the frequency of heat discomfort in the middle and low latitudes,and a significant decrease in the frequency of cold discomfort in the middle and high latitudes of the northern hemisphere.Furthermore,using the optimal fingerprint method,we find that the increased frequency of heat discomfort in middle latitude and the decreased frequency of cold discomfort in high latitude can be attributed to ALL,ANT,and GHG forcings,with GHG forcing dominating changes in the frequency of heat discomfort in mid-latitude areas and the frequency of cold discomfort in high-latitude areas.In the low latitudes,the significant increase in the frequency of heat discomfort can be attributed to anthropogenic greenhouse gas forcing,while AER has the opposite effect.The frequency of cold discomfort may be attributed to the internal variability of the climate system.In the future,the frequency of heat (cold) discomfort in the middle and low latitudes (middle and high latitudes) is expected to increase (decrease) under the uncoordinated and rapid development with higher radiative forcing.However,low radiative forcing and sustainable development can ensure a stable level of human comfort.
    2023,46(4): 575-586, DOI: 10.13878/j.cnki.dqkxxb.20220614001
    Two moderate La Niña and El Niño events occurred in early 2008 and early 2016,respectively.During these two distinct El Niño/Southern Oscillation (ENSO) events,Yunnan experienced low temperatures and snowstorms.This study investigates the causes of these two extreme cold events during different ENSO events using statistical methods based on atmospheric circulation data,sea surface temperature (SST),and monthly temperature records from 124 observation stations in Yunnan.The findings are as follows:1) The extremely cold events in Yunnan were more pronounced in February for both 2008 and 2016.2) During the two different ENSO events in February,the variations in atmospheric circulation and temperature exhibited notable differences.In La Niña (El Niño) years,the Siberian high strengthened (weakened),with high geopotential height in the north (west) and low geopotential height in the south (east).The western Pacific subtropical high weakened (strengthened),and anomalous northerly (southerly) winds intensified on the northwest side of the Philippine anomalous cyclone (anticyclone).Additionally,the East Asian winter Monsoon was strong (weak),resulting in low (high) temperatures in the eastern region of Yunnan.3) The atmospheric circulation over the northeast Pacific responded to SST anomalies in the central and eastern equatorial Pacific in 2008 and 2016.Furthermore,the northerly current in the west of the Philippine cyclone triggered by the cold SST in the central and east of the equatorial Middle East Pacific significantly impacted the strengthening and southward activity of the East Asian winter monsoon in 2008,while the warm SST had no significant impact on the atmospheric circulation over the Philippines region in 2006.4) The effects of the Arctic Oscillation (AO) and Arctic Sea ice on the strengthening of the Siberian high in February 2008 and 2016 exhibited different characteristics.The positive phase of AO had a greater impact on the strengthening of the Siberian high in February 2008,whereas the reduction in Arctic Sea ice had a significant impact on the strengthening of the Siberian high in February 2016.
    2023,46(4): 587-599, DOI: 10.13878/j.cnki.dqkxxb.20220715002
    [Abstract] (147) [HTML] (107) [PDF 33.90 M] (274)
    To enhance our understanding of the causes behind interannual summer precipitation anomalies in North China and improve climate monitoring and prediction technologies,this study examines the relationship between the East Asian subtropical summer monsoon index (EAMI),the North China atmospheric dynamic rise index (HBDRI),and the summer precipitation in North China.Correlation analysis,synthesis,and circulation anomaly regression reconstruction methods are employed using summer precipitation data in North China and NCEP/NCAR reanalysis circulation data.The main findings are as follows:1) The EAMI and HBDRI exhibit a significant correspondence with summer precipitation in North China.Stronger values of both indices are associated with above-average summer precipitation in North China,while weaker values are associated with below-average summer precipitation.In cases where the strength of the two indices is inconsistent,regional precipitation in North China may be above average,but the overall precipitation in the entire region remains relatively normal.2) Anomalies in summer precipitation in North China result from the combined effects of the East Asian subtropical summer monsoon and the upward motion of atmospheric dynamics in North China.In years with stronger EAMI and HDBRI values,the Baikal Lake trough deepens at the 500 hPa level during summer,the Northwest Pacific subtropical high shifts northward,and North China falls under influence of a circulation pattern characterized by a high-pressure system in the east and a low-pressure system in the west.Consequently,the movement of the western low trough eastward is hindered,leading to a sustained upward motion of the atmosphere over North China.This pattern is accompanied by an increased intensity of the Indian summer monsoon and the East Asian subtropical summer monsoon at the 850 hPa level.During this period,the westerly wind water vapor transport from the tropical Indian Ocean,the southerly wind water vapor transport from the East Asian subtropical region,or the southeast wind water vapor transport strengthens,ensuring an ample supply of water vapor to North China.Such a configuration of high-and low-level circulations is highly conducive to generating increased summer precipitation in North China.Conversely,unusually below-average summer precipitation occurs when the aforementioned conditions are not met.3) The stronger values of the EAMI and HBDRI during the early April-May period can serve as climate monitoring and prediction indicators for abnormally high summer precipitation in North China.
    2023,46(4): 600-614, DOI: 10.13878/j.cnki.dqkxxb.20220727001
    This study analyzes the frontogenesis characteristics of rainstorms during the Meiyu period in 2020 using ERA5 reanalysis data and the precipitation data from automatic stations in Jiangsu Province.The main results are as follows:1) The characteristics of frontogenesis during the Meiyu period in 2020 are significant.Heavy rain is associated with middle-low frontogenesis,with deformation frontogenesis being the main contributor.2) Heavy rainfall during the Meiyu period can be categorized into two types.Severe convective rainstorms exhibit a larger frontogenesis range,higher development,greater intensity,and more overlap between total frontogenesis and decomposition terms.However,stable rainfall shows opposite characteristics.3) Two typical cases,namely the strong convective rainfall event on “6.28” and the stable rainfall event on “7.11” are selected.Frontogenesis occurs along shear lines and in regions of significant pseudo-equivalent potential temperature gradient.Strong convective rainfall is observed near the main frontal zone and in high-energy zones of pseudo-equivalent potential temperature,indicating the presence of multiple secondary frontogenesis centers.Stable heavy precipitation,on the other hand,is concentrated near the main frontal zone.These different rainfall distributions arise from variations in triggering mechanism and precipitation properties.4) The vertical front zone in both processes tilts northward from low to high.In the “6.28” process,a notable transport of warm and moist airflow is observed on the south side of the frontal zone,with strong upward motion within the frontal zone.In contrast,the “7.11” process exhibits less pronounced features and weaker convection.The magnitude and impact of frontogenesis differ across various precipitation processes and stages.Rainstorms are primarily generated by divergence and deformation frontogenesis,while the tilting term frontolysis in convective precipitation and frontogenesis in stable precipitation.Quantitative analysis of each decomposition term reveals that low-level divergence and deformation frontogenesis initially increase and then decrease in both processes.Deformation and divergence frontogenesis below 700 hPa are the main contributors,while the middle-high atmosphere experiences frontolysis.
    2023,46(4): 615-629, DOI: 10.13878/j.cnki.dqkxxb.20210130001
    This study evaluates the performance of several existing tropical cyclone (TC) genesis potential indices (GPIs) in reproducing the observed TC genesis frequency (TCGF) in the North Atlantic and western North Pacific (WNP) from 1979 to 2017.The results demonstrate that the existing GPIs can reasonably replicate the climatological distribution,annual cycle,and interannual variability of TCGF in the North Atlantic.However,they fail to reproduce the interannual variability of TCGF in the WNP.To address this limitation,a modified GPI is developed for the WNP,utilizing best-track TC data and ERA-Interim reanalysis data spanning 1979—2017.The modified GPI incorporates earth vorticity (the Coriolis parameter) and relative vorticity separately instead of absolute vorticity and excludes relative humidity,which is commonly used in existing GPIs.Compared with the existing GPIs,the modified GPI can reproduce not only the climatological distribution and annual cycle but also the interannual variability of TCGF in the WNP,particularly in the southeastern region.Additionally,the modified GPI is evaluated using NCEP/NCAR,JRA-55,and ERA5 reanalysis datasets,demonstrating consistent and improved performance in reproducing the interannual variability of TCGF,especially when employing JRA-55 or NCEP/NCAR reanalysis datasets.
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    2022,45(2): 280-291, DOI: 10.13878/j.cnki.dqkxxb.20200719017
    [Abstract] (149) [HTML] (428) [PDF 8.14 M] (18319)
    Based on the sea surface temperature (SST) data from NOAA in USA, the asymmetric characteristics of interannual relationship between ENSO and Victoria mode (VM;EOF2 of North Pacific SST anomalies in winter (DJF)) were emphatically analyzed.Results show that the correlation between VM and ENSO is weak on the decadal scale, but strong on the interannual scale.VM has significant negative correlation with ENSO in the same year, and has strong positive correlation with ENSO in the following year.However, there is a certain asymmetry in the relationship between the positive/negative VM events and ENSO warm/cold phases on the interannual scale.The relationship between the positive VM events and the SST anomalies in the tropical central and eastern Pacific in the same winter is weak, but El Niño events often occur in the following year.In contrast, the negative VM events are usually accompanied by El Niño events in the same years, but there is no significant relationship between the negative VM events and the SST anomalies in the tropical central and eastern Pacific in the following winter and there are few ENSO events.It can be seen that the positive VM event seems to promote the occurrence and development of El Niño in the next year and can be used as one of the early prediction factors of ENSO, while the negative VM event cannot be used as the early prediction factor of ENSO.
    2014,37(5): 642-652, DOI: 10.13878/j.cnki.dqkxxb.20121017006
    [Abstract] (2928) [HTML] (0) [PDF 12.46 M] (16058)
    In this paper,the Weather Research and Forecast Model(WRF) is coupled with Surface-Layer Scheme,Single-Layer Urban Canopy Model and Mingle-Layer Urban Canopy Model respectively to evaluate the simulation effect of various parameterizations on the weather conditions on 1 August 2007 in Nanjing.The best urban parameterization scheme is coupled into WRF to study the impact of land cover change on the Urban Heat Island(UHI) effect in Nanjing.Results show that the Mingle-Layer Urban Canopy Model shows the best simulation effect for surface temperature and 10m wind field.Urbanization makes surface air temperature increase over the region,especially at night and thus intensifies the UHI effect.After urbanization,the wind speed in the downtown area decreases obviously while the Urban Heat Circulation occurs more apparently.There also exists the downstream effect of UHI in Nanjing.
    2011,34(1): 14-27, DOI:
    [Abstract] (3180) [HTML] (0) [PDF 15.30 M] (14968)
    Based on the multiple type observational data,this paper preliminarily analyses the meso scale convective systems(MCSs) and weather background producing an extremely heavy rain along the Mei yu front in Hubei and Anhui provinces during 29—30 June 2009,and investigates the multi scale structure features of the Mei yu frontal rainstorm system.Then the meso scale numerical model WRF with large domain and 9 km horizontal resolution is used to carry out a 3 domain nested fine simulation for the heavy rain process.Morlet wavelet transformation is carried out to do spatial band passing filter for the model outputs,and the meso 〖WTBX〗α, β〖WTB1〗 and 〖WTBX〗γ〖WTB1〗 scale systems are separated out,in such a way that the three dimensional spatial dynamic and thermodynamic characteristics of the meso scale systems with different scales are studied.The results are as follows.The extremely Mei yu frontal heavy rain is directly resulted from several MCSs with different scales,which are of different features on satellite cloud images and radar echoes.On meso 〖WTBX〗α, β〖WTB1〗 and 〖WTBX〗γ〖WTB1〗 scales,the Mei yu frontal heavy rain system has obvious different dynamic and thermodynamic structure features in horizontal and vertical directions.The meso 〖WTBX〗α〖WTB1〗 and 〖WTBX〗β〖WTB1〗 scale systems have obvious vertical circulation,while meso 〖WTBX〗γ〖WTB1〗 scale system has some features of inertial gravity waves and usually develops in meso 〖WTBX〗α〖WTB1〗 and 〖WTBX〗β〖WTB1〗 scale system.Lastly,a physic conceptual model is advanced for the typical Mei yu frontal rainstorm system.
    2019,42(4): 631-640, DOI: 10.13878/j.cnki.dqkxxb.20170815015
    [Abstract] (1177) [HTML] (0) [PDF 6.93 M] (14702)
    Imperative quality control methods for Doppler radar data,such as ground clutter elimination,range folding elimination and velocity dealiasing,should be adopted before being used for quantitative analyses,due to the serious impacts originating from certain non-meteorological factors.In this study,in order to precisely identify the ground clutter and precipitous echo,an automatic algorithm based on the Support Vector Machine(SVM) is performed,based on the observational CINRAD/SA Doppler weather radar data in the areas of Anqing and Changzhou from June to August,2013,and the results are compared with the recognition effect based on the Artificial Neural Networks(ANNs) method.Statistical learning theory(SLT) is favorable for small samples,which focuses on the statistical law and nature of small-sample learning.As a new machine learning based on SLT,the basic principle of the SVM is to possess an optimal separating hyperplane which is able to satisfy the requirement of the classification accuracy by introducing the largest classification intervals on either side of the hyperplane.In the first step,the dataset used in the experiment will be establised by empirically distinguishing the ground clutter and precipitous points at each bin.Next,several characteristic parameters,which are used to quantify the possibility affected by the ground clutter,such as reflectivity vertical variation (GDBZ),reflectivity horizontal texture (TDBZ),velocity regional average (MDVE),and spectrum regional average (MDSW),will be derived from the reflectivity,radaial velocity,spectrum width and spatial variance information of the ground clutter and precipitous echo.The statistical results of the above characteristic parameters show the following:a large portion of these parameters vary in terms of ground clutter and precipitous echo,which indicates that the seven parameters (GDBZ,TDBZ,SPIN,SIGN,MDVE,MDSW and SDVE) contribute to the identifiable recognition of the ground clutter and precipitous echo.Based on the above conclusions,seven parameters,which are regarded as the trigger (the training factor of SVM) to establish the SVM's training model,can be randomly extracted from the database.Finally,the training model is used to automatically recognize the ground clutter and precipitation using the random data from the database.The recognition effect of the SVM method will be examined by comparing the model output with the empirical identifications,and the examination of the ANNs algorithm is the same as that of the SVM method.The comparison of the recognition effect between the SVM and ANNs methods reveals the following:(1) The statistically identifiable recognition parameter for the sSVM and ANNs methods appears to be steady,despite the fact that the Doppler radar data vary in shape and position between Anqing and Changzhou;(2) An identifying threshold must be determined for the ANNs method before the ground clutter and precipitous echo are identified,which will lead to a differently identifiable accuracy with the unlike threshold;and (3) Overall,the SVM method works better than the ANNs method in terms of radar echo identification.Moreover,the identifiable recognition accuracy of the latter increases significantly with the increasing total number of training samples,while the identifiable recognition accuracy of the former performs at a highly accurate level,which remains relatively stable with the changes in the training samples.In terms of the identification accuracy of the total samples (ground clutter and precipitous echo) and identification accuracy of the ground clutter echo,the SVM method presents better results than the ANNs method.As for the precipitous echo erroneous recognition,the ANNs method performs slightly better than the SVM,but both methods control the erroneous recognition rate at a low level.
    2023,46(3): 332-344, DOI: 10.13878/j.cnki.dqkxxb.20230303001
    [Abstract] (140) [HTML] (51) [PDF 25.22 M] (14573)
    The summer of 2022 exhibits significant characteristics of high temperature,low humidity,and rainfall in South China.Previous studies have focused on extreme events of high temperature and low rainfall in summer,whereas attention to near-ground relative humidity,which is closely related to human comfort and crop growth,has been relatively insufficient.In this study,we define events of positive temperature anomaly,negative precipitation anomaly,and negative relative humidity anomaly exceeding one time of the interannual standard deviation between 1959 and 2022 are as compound events of summer high temperature,low humidity,and rainfall.Monthly ERA5 atmospheric reanalysis data of 1959—2022 are used in this study.We study the effect of spring soil moisture on the compound events in summer by composite analysis and a dynamic adjustment approach based on constructed circulation analogs,and the physical mechanism is analyzed.The results show that:1) The hot spots of the coupling between spring soil moisture and summer climate in south China are basically consistent with the high variability of summer temperature,precipitation,and relative humidity in 2022.2) When the soil in the Yangtze River Basin and Huang-Huai area is dry in spring and the southeast area is wet,the compound events of drying and heat will occur in summer.3) The effect of spring soil moisture on summer climate variability is mainly realized by adjusting the distribution of local evapotranspiration and net radiation energy.The study of the compound extreme events of high temperature,low humidity,and rainfall is of great significance in effectively preventing all kinds of disasters and safety accidents caused by them,protecting people's lives and property,and maintaining social production order.
    2014,37(2): 129-137, DOI:
    [Abstract] (2534) [HTML] (0) [PDF 13.30 M] (13471)
    Wind shear in the atmosphere is a serious threat to the safety of aircraft,especially the low-level wind shear which is an important factor affecting the aircraft taking off and landing.By using the Doppler radar velocity data to calculate the one-dimension tangential,one-dimensional radial and two-dimension composite shear,accurately judging the dangerous area of wind shear could provide timely warning for flight,taking off and landing.In this study,as the wind shear automatic identification product on the principal user processor(PUP) for Doppler radar applications has the shortcomings such as weak edge recognition and larger location errors,according to Doppler radar velocity distributions and taking advantage of least square fitting method,"fitting window" suitable for airborne radar parameters are chosen,and the several cases have been identified and analyzed.For the performance in wind shear's identification,location and edge discerning,the least square method could provide better reference of wind shear and warnings than PUP's identification products.
    2013,36(1): 37-46, DOI:
    [Abstract] (4027) [HTML] (0) [PDF 4.97 M] (12888)
    Based on the hourly precipitation observed by automatic weather stations(AWS) in China and retrieved from CMORPH(CPC MORPHing technique) satellite data,the merged precipitation product at hourly/0.1°lat/0.1°lon temporal-spatial resolution in China is developed through the two-step merging algorithm of PDF(probability density function) and OI(optimal interpolation).In this paper,the quality of merged precipitation product is assessed from the points of temporal-spatial characteristics of error,accuracy at different precipitation rates and cumulative times,merging effect at three station network densities and monitoring capability of the heavy rainfall.Results indicate that:1)The merged precipitation product effectively uses the advantages of AWS observations and satellite product of CMORPH,so it is more reasonable both at the precipitation amount and spatial distribution;2)The regional mean bias and root-mean-square error of the merged precipitation product are decreased remarkably,and they have a little change with time;3)The relative bias of merged precipitation product is -1.675%,less than 15% and about 30% for the medium(1.0—2.5 mm/h),medium to large(1.0—8.0 mm/h) and heavy rainfall(≥8.0 mm/h),respectively,and the product quality is improved further with the cumulative time increases.The merged precipitation product can capture the precipitation process very well and have a definite advantage in the quantitatively rainfall monitoring.
    2021,44(1): 39-49, DOI: 10.13878/j.cnki.dqkxxb.20201113007
    [Abstract] (471) [HTML] (417) [PDF 37.05 M] (10079)
    The Arctic climate,an important component of the global climate system,has moved into a new state over the past 20 years.Scientific questions and possible consequences related to these changes are now front in the midst of many important issues that the world needs to deal with in the future.These changes,including prominent atmospheric and oceanic warming and sea ice melting have been largely attributed to a combined effect of anthropogenic forcing and internal variability of the climate system.This review highlights some findings from a number of studies conducted by my research group in the past few years.The studies collectively suggest that the high latitude atmospheric circulation that is sensitive to tropical SST forcing related to the interdecadal Pacific oscillation (IPO) plays a vital role in driving the interannual and interdecadal variability of Arctic sea ice by affecting the atmospheric temperature,moisture,clouds and radiative fluxes over sea ice.In particular,the teleconnection excited by a SST cooling over the tropical Pacific is suggested to cause an enhanced melting from 2007 to 2012.In addition,it suggests that a similar internal process may also play a role to cause strong sea ice melting in summer 2020.Furthermore,the model evaluation focusing on CMIP5 models finds that most climate models have a limitation to replicate this IPO-related teleconnection,raising awareness on an urgent need to investigate the cause of this bias in models.Thus,this review is meant to offer priorities for future Arctic research so that more efforts are targeted on critical scientific questions raised in this study.
    2015,38(1): 27-36, DOI: 10.13878/j.cnki.dqkxxb.20130626001
    [Abstract] (2228) [HTML] (0) [PDF 20.93 M] (9457)
    The high-resolution numerical simulations of Hurricane Bonnie(1998) are used to analyze its intensity and structure changes in relation to its associated inertial stability under the influence of intense vertical wind shear during three different stages of its life cycle.Results show that Bonnie has high asymmetry and experiences an eyewall displacement cycle during its rapid intensifying stage.During its rapid structure change stage,the development of high inertial stability is consistent with the change in hurricane inner core size.The inertially stable region,which is usually present inside the eyewall,provides resistance to radial motions,and plays an important role in reducing the influence of vertical wind shear.The inertially stable region reduces the Rossby radius of deformation,and concentrates the latent heating,which is beneficial to the enhancing of the hurricane.This is an important factor in the development of inner core region of the hurricane.
    2016,39(6): 722-734, DOI: 10.13878/j.cnki.dqkxxb.20161028003
    [Abstract] (1442) [HTML] (0) [PDF 5.22 M] (8253)
    The present paper has mainly analysed the process and mechanisms of genesis and development of the 2014-2016 mega El Niño event.It is shown that the entire lifecycle of the event is about 2 years(from April 2014 to May 2016),with four stages identified for its evolutive process:(1)Early and continuous westerly wind bursts(December 2013 to April 2014).The continuous three westerly wind burstsnot only changed the state of the easterly trade wind prevailing tropical central and easterly in the Pacific for long period of time,but also changed the cold water state in this region for the most recent 12 years,thus leading to SST rise and warming.Until early spring 2014,the SSTA exceeded 0.5℃,marking the possible occurrence of a new El Niño event.(2)Alternative weakening period(June 2014 to August 2015).Six westerly wind bursts continued to occur,thus maintaining and enhancing the warming of the equatorial central and eastern Pacific,while at the same time overcoming two periods of SST warming decrease or barrier,so that the initial development of El Niño was not aborted,and even changed into the stage of strong El Niño.Correspondingly,in the sub layer of the equatorial central and eastern Pacific,six warm Kelvin waves were observed to propagate eastward.The heat contents of these oceanic waves not only maintained the continuous warming in the equatorial central and eastern Pacific,but also caused El Niño to change from CP to EP type.(3)Peak period of development (September 2015 to February 2016).Two stronger westerly wind bursts were observed,which corresponded to very vigorous convective activity on the equatorial central and eastern Pacific.Rapid warming occurred in the Niño3.4 region,with 3℃observed in November 2015,classified as the mega-El Niño event.(4)Accelerating weakening stage(March to May 2016).The intensity of the El Niño rapidly weakened from 2 to 0.5℃ in the Niño3.4 region,then accelerated the transition to the cold water phase.In July to August 2016,the SSTA in the Niño3.4 region already approached -0.5℃.This rapid phase shift is a manifestation of the theory of delayed oscillation.From the above results,it is concluded that the development and shift of warm and cold phases is observationally consistent with the mechanism derived from the paradigm of the current theory of recharge oscillation and/or delayed oscillation theory.This clearly demonstrates that the results of the El Niño theory effectively underpin the development of related operational prediction.
    2022,45(4): 502-511, DOI: 10.13878/j.cnki.dqkxxb.20220529013
    [Abstract] (424) [HTML] (544) [PDF 29.68 M] (8002)
    The second working group of the IPCC Sixth Assessment Report (IPCC AR6 WGⅡ) focuses on the impact,risk,adaptation and vulnerability of climate change.The report quantitatively assesses the impact of climate change on natural and human systems with the latest data,detailed evidence and diverse methods.Compared to AR5,the following progress has been made:Firstly,The content clarifies that the impact of climate change is attributable to three categories:anthropogenic climate forcing,non-climate factor action and weather sensitivity identification,127 key risks from climate change will become widespread or irreversible,and limiting global warming to 1.5 ℃ can greatly reduce climate change loss and damage to natural and human systems,pointing to the importance of adapting to transition.Secondly,AR6 WGⅡ adopts the latest combination of SSPs and RCPS in terms of evaluation method,which is more comprehensive.Thirdly,AR6 WGⅡ has focus on risks and solutions,and on the basis of AR5 WGⅡ,it is clarified that under different future warming scenarios,the risk level of the key risks facing the five “reasons for concern (RFCs)” will be relied on lower to very high levels of global warming.Finally,AR6 WGⅡ clarifies the urgency of climate action,combining adaptation and mitigation to support sustainable development is essential for climate resilience development pathways,pointing to the importance of immediate action to address climate risks.
    2014,37(5): 653-664, DOI: 10.13878/j.cnki.dqkxxb.20111230001
    [Abstract] (2414) [HTML] (0) [PDF 33.55 M] (7500)
    Studies have shown that large-scale monsoon gyre activity is closely associated with tropical cyclogenesis over the western North Pacific.In this study,two cases of monsoon gyre activities in 2002 and 2009 were first examined.It was found that a monsoon gyre can be linked to the formation of one or more tropical cyclones,which usually occur near or to the east of the gyre center.Further analysis of the monsoon gyre activity during the period of 2000—2009 indicates that tropical cyclogenesis mainly occurs near or to the east of the gyre center,although the definition of a monsoon gyre depends on its duration and the circulation intensity.It is suggested that the tropical cyclogensis may be associated with the Rossby wave energy dispersion of monsoon gyres.
    2010,33(6): 667-679, DOI:
    [Abstract] (2727) [HTML] (0) [PDF 2.74 M] (7467)
    利用IAEA\WMO\GNIP的降水稳定同位素资料,分析了中国降水稳定同位素的时空分布特征及其影响因素。结果表明,整体来看我国降水稳定同位素有明显的大陆效应和高度效应。各地大气降水线存在地域差异,内陆地区同一站点冬、夏半年也有明显差异,显示出水汽团特性的不同。不同地区降水稳定同位素(δ和过量氘)的季节变化特征明显不同,表明主要水汽来源存在季节性差异。通过对比长序列降水稳定同位素的年际变化与季风和ENSO指数的关系,发现ENSO与降水稳定同位素有显著的正相关,但不一定通过影响降水量来引起降水稳定同位素(stable isotope in precipitation, SIP)的变化。重点分析了我国降水量效应、温度效应的特点,指出沿海和西南等季风区主要受降水量的影响,北方非季风区温度效应起主要作用,交叉地带则两种效应都有影响。
    2011,34(2): 251-256, DOI:
    [Abstract] (2596) [HTML] (0) [PDF 2.67 M] (7223)
    A new atmospheric correction algorithm based on dark object method and the look up table developed from MODTRAN model was introduced for Landsat images in the paper.The infomation of the satellite remote sensing images was used to support the atmospheric correction.The algorithm was applied to the Landsat ETM+imagery and comparisons show that the influence on Landsat imagery caused by molecules,water vapor,ozone,and aerosol particles in the atmosphere was effectively reduced after the correction.The surface reflectivity was more precisely,which is beneficial for remote sensing information extraction and thematic interpretation.
    2015,38(2): 184-194, DOI: 10.13878/j.cnki.dqkxxb.20140508002
    [Abstract] (2227) [HTML] (0) [PDF 16.29 M] (6808)
    The observed SST data and CMIP5 data are used to analyze climate state and interdecadal variation of sea surface temperature(SST) over Northwest Pacific(20—60°N,120°E—120°W).Results indicate that the selected 22 models can simulate the climate state perfectly.More importantly,the selected models can simulate the annual and interdecadal variations of SST over Northwest Pacific.Total standard deviation of SST simulted by the models is the largest in Kuroshio extension region.The majority of models have an ability to simulate the first EOF mode of SST.The SST over Northwest Pacific has a significant interdecadal oscillation phenomenon.SSTs simulated by the 13/22 models have obvious interdecadal oscillations.Meanwhile,the simulated deviation of SST climate state has a great effect on the periodic oscillation of SST,especially in Kuroshio extension region.
    2010,33(6): 738-744, DOI:
    [Abstract] (2507) [HTML] (0) [PDF 2.05 M] (6577)
    2010,33(4): 489-495, DOI:
    [Abstract] (2859) [HTML] (0) [PDF 1.91 M] (6378)


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