Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and ...Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.展开更多
Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics,and enhancing predictive models for weather an...Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics,and enhancing predictive models for weather and climate forecasts.This study utilizes eight years of CALIPSO data(from March 2007 to February 2015)to investigate convective and non-convective cirrus clouds.Explicit new insights include the observation that convective cirrus cloud samples are three times more numerous than non-convective cirrus clouds.Convective cirrus clouds are associated with humid conditions and demonstrate higher ice water content(IWC)values ranging from 10^(−3)to 10^(−1)g m^(−3),whereas non-convective cirrus clouds tend to be drier,exhibiting IWC values ranging from 10^(−4)to 10^(−3)g m^(−3).Both cirrus cloud types exhibit a maximum cloud fraction at 10°N.Convective cirrus reach their peak cloud fraction at an altitude of 14 km,while non-convective cirrus typically occur at altitudes between 15 and 16 km.The seasonal variability of the convective cirrus cloud fraction primarily reflects bottom-up positive specific humidity anomalies originating from convective activity,whereas the non-convective cirrus cloud fraction is influenced by top-down negative temperature anomalies.展开更多
目的采用Cirrus HD OCT测量近视人群的青光眼诊断参数差异性及近视人群的特征。方法选取2016年1月至2017年8月,就诊于我院的18~35岁不同近视程度的患者共95例(190只眼)。记录患者性别、年龄,采集其眼轴、医学验光屈光度(等效球镜)、视...目的采用Cirrus HD OCT测量近视人群的青光眼诊断参数差异性及近视人群的特征。方法选取2016年1月至2017年8月,就诊于我院的18~35岁不同近视程度的患者共95例(190只眼)。记录患者性别、年龄,采集其眼轴、医学验光屈光度(等效球镜)、视盘周围视网膜神经纤维层厚度(cpRNFL)包括平均、上下方,颞鼻侧5个参数、黄斑部神经节细胞和内丛状层(GCIPL)厚度包括平均、最小、上下方、鼻颞侧6个参数。根据屈光度分为A组(-0.25~3.0D);B组(-3.25^-6.0D);C组(>-6.0D),采用单因素方差分析进行所有参数的组间比较。采用Pear-son相关性分析不同屈光度与眼轴、GCIPL厚度、cpRNFL厚度的相关性及GCIPL厚度与cpRNFL厚度之间相关性。结果各组的性别及年龄无统计学差异。但各组间平均屈光度差异有统计学意义(F=521.963,P=0.000),眼轴和屈光度之间呈显著负相关(相关系数-0.706,P=0.000)。根据屈光度分组,所有参数各组之间均有显著差异(F=3.396~16.305,P<0.05)。cpRNFL厚度除颞侧外均与屈光度呈负相关(相关系数-0.316^-0.212,P<0.05),GCLIP厚度各参数均与屈光度呈负相关(相关系数-0.205^-0.384,P<0.05)。两种参数之间除颞侧外,其余参数均具呈正相关性(相关系数0.222~0.559),GCIPL与cpRNFL厚度在近视人群中均随屈光度发生一定的改变。结论近视眼cpRNFL厚度上下方及鼻侧象限均随屈光度增大逐渐变薄,颞侧变厚。GCIPL厚度各参数均随屈光度增大逐渐变薄,二者具有很好的一致性。近视人群采用此两种方法评估青光眼损害时,均需要考虑近视程度对参数的影响。展开更多
Two years of mid-latitude cirrus cloud macrophysical and optical properties over North China are described from Earth-orbiting Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP) satellite measurements. Global cl...Two years of mid-latitude cirrus cloud macrophysical and optical properties over North China are described from Earth-orbiting Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP) satellite measurements. Global cloud climatological studies based on active remote sensing data sets benefit from more accurate resolution of vertical structure and more reliable detection of optically thin layers.The mean values for cirrus cases over North China are 0.19±0.18 for infrared emittance,0.41±0.68 for visible optical depth, 0.26±0.12 for integrated depolarization ratio,and 0.72±0.22 for integrated color ratio.When studied using reasonable assumptions for the relationship between extinction and ice crystal backscatter coefficients,our results show that most of the cirrus clouds profiled using the 0.532μm channel data stream correspond with an optical depth of less than 1.0.The dependence of cirrus cloud properties on cirrus cloud mid-cloud temperature and geometry thickness are generally similar to the results derived from the ground-based lidar, which are mainly impacted by the adiabatic process on the ice cloud content.However,the differences in macrophysical parameter variability indicate the limits of spaceborne-lidar and dissimilarities in regional climate variability and the nature and source of cloud nuclei in different geographical regions.展开更多
The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied t...The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time. Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05 ± 2.73 km, 2.46 ± 2.08 kin, and 3.51 ± 3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ～36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89 ± 1.65 km, 9.80 ± 1.70 kin, 10.73 ± 1.86 km and 1.83± 0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ～ 25 ± 17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34 ± 0.33. Sub-visual, thin, and dense cirrus were observed in ～12%, 43%, and 45% of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.展开更多
Cirrus clouds related to transported dust layers were identified on 22 occasions with ground-based polarization lidar from December 2012 to February 2018 over Wuhan(30.5°N,114.4°E),China.All the events occur...Cirrus clouds related to transported dust layers were identified on 22 occasions with ground-based polarization lidar from December 2012 to February 2018 over Wuhan(30.5°N,114.4°E),China.All the events occurred in spring and winter.Cirrus clouds were mostly located above 7.6 km on top of the aloft dust layers.In-cloud relative humidity with respect to ice(RH_(i))derived from water vapor Raman lidar as well as from ERA5 reanalysis data were used as criteria to determine the possible ice nucleation regimes.Corresponding to the two typical cases shown,the observed events can be classified into two categories:(1)category A(3 cases),in-cloud peak RH_(i)≥150%,indicating competition between heterogeneous nucleation and homogeneous nucleation;and(2)category B(19 cases),in-cloud peak RH_(i)<150%,revealing that only heterogeneous nucleation was involved.Heterogeneous nucleation generally took place during instances of cirrus cloud formation in the upper troposphere when advected dust particles were present.Although accompanying cloud-top temperatures ranged from–51.9℃to–30.4℃,dust-related heterogeneous nucleation contributed to primary ice nucleation in cirrus clouds by providing ice nucleating particle concentrations on the order of 10^(−3)L^(−1)to 10^(2)L^(−1).Heterogeneous nucleation and subsequent crystal growth reduced the ambient RH_(i)to be less than 150%by consuming water vapor and thus completely inhibited homogeneous nucleation.展开更多
AIMTo investigate the difference of macular thickness measurements between stratus optical coherence tomography (OCT) and Cirrus OCT (Carl Zeiss Meditec, Dublin, CA, USA) in the same myopic patient and to develop a co...AIMTo investigate the difference of macular thickness measurements between stratus optical coherence tomography (OCT) and Cirrus OCT (Carl Zeiss Meditec, Dublin, CA, USA) in the same myopic patient and to develop a conversion equation to interchange macular thickness obtained with these two OCT devices.METHODSEighty-nine healthy Chinese adults with spherical equivalent (SE) ranging from -1.13 D to -9.63 D were recruited. The macular thickness was measured by Cirrus OCT and Stratus OCT. The correlation between macular thickness and axial length and the agreement between two OCT measurements were evaluated. A formula was generated to interchange macular thickness obtained with two OCT devices.RESULTSAverage macular thickness measured with Stratus OCT (r=-0.280, P=0.008) and Cirrus OCT (r=-0.224, P=0.034) were found to be negatively correlated with axial length. No statistically significant correlation was found between axial length and central subfield macular thickness (CMT) measured with Stratus OCT (r=0.191, P=0.073) and Cirrus OCT (r=0.169, P=0.113). The mean CMT measured with Cirrus OCT was 53.63±7.94 µm thicker than with Stratus OCT. The formula CMT<sub>Cirrus OCT</sub>=78.328+0.874×CMT<sub>Stratus OCT</sub> was generated to interchange macular thickness obtained with two OCT devices.CONCLUSIONMacular thickness measured with Cirrus OCT were thicker than with Stratus OCT in myopic eyes. A formula can be used to interchange macular thickness measured with two OCT devices in myopic eyes. Studies with different OCT devices and larger samples are warranted to enable the comparison of macular values measured with different OCT devices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42027804,41775026,and 41075012)。
文摘Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.
基金supported financially by the National Natural Science Foundation of China[grant numbers 42027804,41775026,and 41075012]。
文摘Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics,and enhancing predictive models for weather and climate forecasts.This study utilizes eight years of CALIPSO data(from March 2007 to February 2015)to investigate convective and non-convective cirrus clouds.Explicit new insights include the observation that convective cirrus cloud samples are three times more numerous than non-convective cirrus clouds.Convective cirrus clouds are associated with humid conditions and demonstrate higher ice water content(IWC)values ranging from 10^(−3)to 10^(−1)g m^(−3),whereas non-convective cirrus clouds tend to be drier,exhibiting IWC values ranging from 10^(−4)to 10^(−3)g m^(−3).Both cirrus cloud types exhibit a maximum cloud fraction at 10°N.Convective cirrus reach their peak cloud fraction at an altitude of 14 km,while non-convective cirrus typically occur at altitudes between 15 and 16 km.The seasonal variability of the convective cirrus cloud fraction primarily reflects bottom-up positive specific humidity anomalies originating from convective activity,whereas the non-convective cirrus cloud fraction is influenced by top-down negative temperature anomalies.
文摘目的采用Cirrus HD OCT测量近视人群的青光眼诊断参数差异性及近视人群的特征。方法选取2016年1月至2017年8月,就诊于我院的18~35岁不同近视程度的患者共95例(190只眼)。记录患者性别、年龄,采集其眼轴、医学验光屈光度(等效球镜)、视盘周围视网膜神经纤维层厚度(cpRNFL)包括平均、上下方,颞鼻侧5个参数、黄斑部神经节细胞和内丛状层(GCIPL)厚度包括平均、最小、上下方、鼻颞侧6个参数。根据屈光度分为A组(-0.25~3.0D);B组(-3.25^-6.0D);C组(>-6.0D),采用单因素方差分析进行所有参数的组间比较。采用Pear-son相关性分析不同屈光度与眼轴、GCIPL厚度、cpRNFL厚度的相关性及GCIPL厚度与cpRNFL厚度之间相关性。结果各组的性别及年龄无统计学差异。但各组间平均屈光度差异有统计学意义(F=521.963,P=0.000),眼轴和屈光度之间呈显著负相关(相关系数-0.706,P=0.000)。根据屈光度分组,所有参数各组之间均有显著差异(F=3.396~16.305,P<0.05)。cpRNFL厚度除颞侧外均与屈光度呈负相关(相关系数-0.316^-0.212,P<0.05),GCLIP厚度各参数均与屈光度呈负相关(相关系数-0.205^-0.384,P<0.05)。两种参数之间除颞侧外,其余参数均具呈正相关性(相关系数0.222~0.559),GCIPL与cpRNFL厚度在近视人群中均随屈光度发生一定的改变。结论近视眼cpRNFL厚度上下方及鼻侧象限均随屈光度增大逐渐变薄,颞侧变厚。GCIPL厚度各参数均随屈光度增大逐渐变薄,二者具有很好的一致性。近视人群采用此两种方法评估青光眼损害时,均需要考虑近视程度对参数的影响。
基金supported by the National Natural Science Foundation of China(Grant No.40875084)National Natural Science Foundation for Youth Science Foundation of China(Grant No.40705012).
文摘Two years of mid-latitude cirrus cloud macrophysical and optical properties over North China are described from Earth-orbiting Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP) satellite measurements. Global cloud climatological studies based on active remote sensing data sets benefit from more accurate resolution of vertical structure and more reliable detection of optically thin layers.The mean values for cirrus cases over North China are 0.19±0.18 for infrared emittance,0.41±0.68 for visible optical depth, 0.26±0.12 for integrated depolarization ratio,and 0.72±0.22 for integrated color ratio.When studied using reasonable assumptions for the relationship between extinction and ice crystal backscatter coefficients,our results show that most of the cirrus clouds profiled using the 0.532μm channel data stream correspond with an optical depth of less than 1.0.The dependence of cirrus cloud properties on cirrus cloud mid-cloud temperature and geometry thickness are generally similar to the results derived from the ground-based lidar, which are mainly impacted by the adiabatic process on the ice cloud content.However,the differences in macrophysical parameter variability indicate the limits of spaceborne-lidar and dissimilarities in regional climate variability and the nature and source of cloud nuclei in different geographical regions.
基金supported by the Ministry of Science and Technology of China (Grant Nos. Change: 2013CB955802 to 2012AA120901)State Laboratory of Earth Surface Process and Resource Ecology, National Science Foundation of China (41175019)the US Department of Energy (Grant Nos. DEFG0208ER64571and DE-SC0007171)
文摘The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time. Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05 ± 2.73 km, 2.46 ± 2.08 kin, and 3.51 ± 3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ～36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89 ± 1.65 km, 9.80 ± 1.70 kin, 10.73 ± 1.86 km and 1.83± 0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ～ 25 ± 17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34 ± 0.33. Sub-visual, thin, and dense cirrus were observed in ～12%, 43%, and 45% of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.
基金funded by the National Natural Science Foundation of China (Grant Nos. 42005101 and 41927804)Hubei Provincial Natural Science Foundation of China (Grant No. 2020CFB229)+1 种基金the Fundamental Research Funds for the Central Universities Grant (Grant Nos. 2042020kf0018 and 2042021kf1066)The Meridian Space Weather Monitoring Project (China) also provides financial support for lidar maintenance
文摘Cirrus clouds related to transported dust layers were identified on 22 occasions with ground-based polarization lidar from December 2012 to February 2018 over Wuhan(30.5°N,114.4°E),China.All the events occurred in spring and winter.Cirrus clouds were mostly located above 7.6 km on top of the aloft dust layers.In-cloud relative humidity with respect to ice(RH_(i))derived from water vapor Raman lidar as well as from ERA5 reanalysis data were used as criteria to determine the possible ice nucleation regimes.Corresponding to the two typical cases shown,the observed events can be classified into two categories:(1)category A(3 cases),in-cloud peak RH_(i)≥150%,indicating competition between heterogeneous nucleation and homogeneous nucleation;and(2)category B(19 cases),in-cloud peak RH_(i)<150%,revealing that only heterogeneous nucleation was involved.Heterogeneous nucleation generally took place during instances of cirrus cloud formation in the upper troposphere when advected dust particles were present.Although accompanying cloud-top temperatures ranged from–51.9℃to–30.4℃,dust-related heterogeneous nucleation contributed to primary ice nucleation in cirrus clouds by providing ice nucleating particle concentrations on the order of 10^(−3)L^(−1)to 10^(2)L^(−1).Heterogeneous nucleation and subsequent crystal growth reduced the ambient RH_(i)to be less than 150%by consuming water vapor and thus completely inhibited homogeneous nucleation.
基金Supported by Shantou University Medical College Clinical Research Improve Projects in 2014 (No.201417)
文摘AIMTo investigate the difference of macular thickness measurements between stratus optical coherence tomography (OCT) and Cirrus OCT (Carl Zeiss Meditec, Dublin, CA, USA) in the same myopic patient and to develop a conversion equation to interchange macular thickness obtained with these two OCT devices.METHODSEighty-nine healthy Chinese adults with spherical equivalent (SE) ranging from -1.13 D to -9.63 D were recruited. The macular thickness was measured by Cirrus OCT and Stratus OCT. The correlation between macular thickness and axial length and the agreement between two OCT measurements were evaluated. A formula was generated to interchange macular thickness obtained with two OCT devices.RESULTSAverage macular thickness measured with Stratus OCT (r=-0.280, P=0.008) and Cirrus OCT (r=-0.224, P=0.034) were found to be negatively correlated with axial length. No statistically significant correlation was found between axial length and central subfield macular thickness (CMT) measured with Stratus OCT (r=0.191, P=0.073) and Cirrus OCT (r=0.169, P=0.113). The mean CMT measured with Cirrus OCT was 53.63±7.94 µm thicker than with Stratus OCT. The formula CMT<sub>Cirrus OCT</sub>=78.328+0.874×CMT<sub>Stratus OCT</sub> was generated to interchange macular thickness obtained with two OCT devices.CONCLUSIONMacular thickness measured with Cirrus OCT were thicker than with Stratus OCT in myopic eyes. A formula can be used to interchange macular thickness measured with two OCT devices in myopic eyes. Studies with different OCT devices and larger samples are warranted to enable the comparison of macular values measured with different OCT devices.
