Determination of Intraseasonal Variation of Precipitation Microphysics in the Southern Indian Ocean from Joss–Waldvogel Disdrometer Observation during the CINDY Field Campaign     

MARZUKI  Hiroyuki HASHIGUCHI  Mutya VONNISA  HARMADI  Masaki KATSUMATA 《大气科学进展》2018,35(11):1415-1427

To date, the intraseasonal variation of raindrop size distribution(DSD) in response to the Madden–Julian Oscillation(MJO) has been examined only over the Indonesian Maritime Continent, particularly in Sumatra. This paper presents the intraseasonal variation of DSD over the Indian Ocean during the Cooperative Indian Ocean experiment on Intraseasonal Variability in the Year 2011(CINDY 2011) field campaign. The DSDs determined using a Joss–Waldvogel disdrometer,which was installed on the roof of the anti-rolling system of the R/V Mirai during stationary observation(25 September to 30 November 2011) at(8°S, 80.5°E), were analyzed. The vertical structure of precipitation was revealed by Tropical Rainfall Measuring Mission Precipitation Radar(version 7) data. While the general features of vertical structures of precipitation observed during the CINDY and Sumatra observation are similar, the intraseasonal variation of the DSD in response to the MJO at each location is slightly different. The DSDs during the active phase of the MJO are slightly broader than those during the inactive phase, which is indicated by a larger mass-weighted mean diameter value. Furthermore, the radar reflectivity during the active MJO phase is greater than that during the inactive phase at the same rainfall rate. The microphysical processes that generate large-sized drops over the ocean appear to be more dominant during the active MJO phase, in contrast to the observations made on land(Sumatra). This finding is consistent with the characteristics of radar reflectivity below the freezing level, storm height, bright band height, cloud effective radius, and aerosol optical depth.  相似文献   

Response of the Tropical Indian Ocean to Greenhouse Gases and Aerosol Forcing in the GFDL CM3 Coupled Climate Model     

Zhi Li 《大气与海洋》2018,56(1):40-54

The response of the tropical Indian Ocean (TIO) to greenhouse gases (GHGs) and aerosols are investigated based on historical single-forcing and all-forcing simulations using the Geophysical Fluid Dynamics Laboratory Climate Model, version 3 (GFDL CM3). Results reveal a positive Indian Ocean Dipole (pIOD)-like pattern in GHG forcing but a negative Indian Ocean Dipole (nIOD)-like pattern in aerosol forcing. The GHG-induced pIOD-like pattern features less (more) sea surface temperature (SST) warming over the southeastern (western) TIO, accompanied by equatorial easterly anomalies, as well as a shallower thermocline off Sumatra. The aerosol-induced nIOD-like pattern displays the reverse features, characterized by less (more) SST cooling over the southeastern (western) TIO, anomalous equatorial westerlies, and a deeper thermocline off Sumatra. Although the aerosol-induced pattern appears to resemble a reversal of the GHG-induced pattern, there is a strong asymmetry in the SST changes over the southeastern TIO, where the cooling responding to aerosol forcing exceeds the warming in response to GHG forcing, and a negative SST residual is thus produced. A mixed-layer heat budget analysis suggests that the negative SST residual results mainly from asymmetric responses of shortwave radiation, zonal advection, and diffusion to GHGs and aerosols. For comparison, the formation processes for the negative SST skewness over the southeastern TIO between the internal pIOD and nIOD are also discussed.  相似文献   

VARIABILITY IN THE WESTERN PACIFIC SUBTROPICAL HIGH AND ITS RELATIONSHIP WITH SEA TEMPERATURE VARIATION CONSIDERING THE BACKGROUND OF CLIMATE WARMING OVER THE PAST 60 YEARS     

孙圣杰  李栋梁 《热带气象学报(英文版)》2018,24(4):468-480

By adopting characteristic index data for the Western Pacific Subtropical High (WPSH) from the National Climate Center of China, U.S. National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP/NCAR) reanalysis data, and the National Oceanic and Atmospheric Administration (NOAA) sea surface temperature (SST) data, we studied the WPSH variability considering the background of climate warming by using a Gaussian filter, moving averages, correlation analysis, and synthetic analysis. Our results show that with climate warming over the past 60 years, significant changes in the WPSH include its enlarged area, strengthened intensity, westward extended ridge point and southward expanded southern boundary, as well as enhanced interannual fluctuations in all these indices. The western ridge point of the WPSH consistently varies with temperature changes in the Northern Hemisphere, but the location of the ridgeline varies independently. The intensity and area of the WPSH were both significantly increased in the late 1980s. Specifically, the western ridge point started to significantly extend westward in the early 1990s, and the associated interannual variability had a significant increase in the late 1990s; in addition, the ridgeline was swaying along the north-south-north direction, and the corresponding variability was also greatly enhanced in the late 1990s. With climate warming, the SST increase becomes more weakly correlated with the WPSH intensity enhancement but more strongly correlated with the westward extension of the ridge point in the equatorial central and eastern Pacific Ocean in winter, corresponding to an expanding WPSH in space. In the northern Pacific in winter, the SST decrease has a weaker correlation with the southerly location of the ridgeline but also a stronger correlation with the westward extension of the ridge point. In the tropical western Pacific in winter, the correlations of the SST decrease with the WPSH intensity enhancement, and the westward extension of the ridge point is strengthened. These observations can be explained by strengthened Hadley circulations, the dominant effects of the southward shift, and additional effects of the weakened ascending branch of the Walker circulation during warm climatological periods, which consequently lead to strengthened intensities, increased areas, and southward expansions of the WPSH in summer.  相似文献   

THE EVALUATION, DATA FUSION AND APPLICATION OF FY2E SST IN TROPICAL CYCLONES OVER NORTHWEST PACIFIC OCEAN     

靳双龙  胡亮  邓涤菲  刘晓琳  宋宗朋 《热带气象学报(英文版)》2018,24(3):280-287

The daily FY2 E Sea Surface Temperature(SST) data from China National Satellite Meteorological Center(NSMC) was evaluated and compared with the Optimum Interpolation Sea Surface Temperature(OISST) data from US National Oceanic and Atmospheric Administration(NOAA) over Northwest Pacific Ocean(NPO) in this study. The results show that the distribution of FY2 E SST is close to OISST in tropical region over NPO, especially in typhoon active season, but the value of FY2 E SST is a little lower than that of OISST in tropical ocean, with the absolute deviation 1℃ lower and the relative deviation about 6% lower. The correlation coefficient between monthly FY2 E SST and monthly OISST is as high as 0.7, which passes the t-test at a significance level of 0.01. Based on the evaluation result, the merged SST_(FY)over NPO is calculated using a weighting function. Besides, Tropical Cyclone Heat Potential(TCHP_(FY)) is calculated and combined with the simulated sea temperature profile. From three years operational tests in NSMC, the merged SST_(FY)and TCHP_(FY)are shown to be good indexes in monitoring and predicting the intensity of tropical cyclones(TCs) over NPO.  相似文献   

宁夏夏季极端降水日数的变化规律及其成因   总被引：1，自引：0，他引：1       下载免费PDF全文

张冰  刘宣飞  郑广芬  王璠  王素艳 《大气科学学报》2018,41(2):176-185

利用1961—2015年宁夏逐日降水资料、NCEP/NCAR再分析资料及NOAA海温资料,分析了宁夏夏季极端降水的变化规律及其成因。结果表明:1)55年来宁夏夏季极端降水日数呈微弱减少趋势,但变率在1994年发生了由大到小的气候突变。各月极端降水的变化存在差异:6月极端降水日数在1982年发生突变,突变后日数显著增多;7月极端降水日数呈微弱减少趋势;8月极端降水日数在1995年发生突变,突变后日数显著减少。2)500 h Pa高度场上6月中国华北—东北与西太平洋上的偶极型异常分布、8月西西伯利亚—蒙古—副热带地区的遥相关波列和EAP异常分布型以及700h Pa上宁夏6月偏东风增强和8月偏北风增强,是导致极端降水事件变化的直接原因。3)6月菲律宾附近海温偏高,有利于500 h Pa高度距平场形成华北—东北与西太平洋的"+-"偶极型异常分布;8月拉尼娜事件的发生,有利于我国呈现西低东高分布型,激发EAP遥相关波列,冷空气与水汽条件相配合,从而导致宁夏极端降水事件频发。  相似文献   

印度洋通道及其对中国地缘环境影响   总被引：3，自引：3，他引：0  

吴良  秦奇  张丹  成升魁 《地理科学进展》2018,37(11):1510-1520

印度洋通道是中国获取能源和其他资源、出口工业产品并同南亚、西亚、非洲和欧洲国家交流合作的生命线。随着中美关系和中国周边地缘态势的深刻变化,中国需要积极谋划逐渐降低对传统的南海—马六甲海峡通道的依赖,建设新的印度洋通道,从而降低自身的地缘环境风险,并由此优化国内经济发展布局,推动西南沿边地区进一步开发与开放,并提升中国同印度洋沿岸国家和地区的交流与合作水平。本研究从通道的定义和特征出发,梳理了现有及潜在的印度洋通道,比较分析了各条通道的战略意义、前景及地缘环境影响,从而为中国的印度洋战略构建和“一带一路”倡议推进提供新的视角和见解。  相似文献   

青藏高原降水季节分配的空间变化特征   总被引：2，自引：2，他引：0  

朱艳欣  桑燕芳 《地理科学进展》2018,37(11):1533-1544

青藏高原是全球气候变化影响的敏感区域。在全球气候变暖的背景下,其水文气候过程发生了显著的变化,直接影响到区域水资源演化。然而,目前对该区域水文气候过程的时空演变规律仍认识不足。本文以青藏高原气象站点降水观测数据为基准,结合水汽通量资料,对13种不同源降水数据集质量进行对比分析;并选用质量较好的IGSNRR数据集识别了青藏高原降水季节分配特征的空间分布格局。结果表明,青藏高原东南、西南以及西北边缘地区降水集中度和集中期较小,夏季降水占全年降水比例不足50%;随着逐渐向高原腹地推进,降水集中度和集中期逐渐增大,雨季逐渐缩短且推迟,雨季降水占全年降水比例逐渐增大。降水季节分配的空间分布格局与水汽运移方向保持一致,即主要是由西风和印度洋季风的影响所致。基于此,识别出西风的影响区域主要位于高原35°N以北,印度洋季风的影响区域主要位于高原约30°N以南,而高原中部(30°N~35°N)降水受到西风和印度洋季风的共同影响。该结果有助于进一步理解和认识青藏高原水文气候过程空间差异性。  相似文献   

陕西省2021年极端秋雨成因分析     

李静睿  赵强  刘佩佩  陈小婷 《沙漠与绿洲气象(新疆气象)》2023,17(6)

利用NCEP/NCAR2.5°×2.5°的逐月再分析资料和NOAA提供的逐月海温资料等从海温异常、大尺度环流异常、水汽输送异常等角度分析了2021年秋季陕西降水异常偏多的原因,结果表明：（1）小波交叉谱分析显示Ni?o3.4区海温距平与陕西秋季降水存在2～4年的共振周期,前期冬季海温与次年秋季降水关系呈正相关的周期共振。（2）受双峰型La Ni?a事件影响,2021年9-11月副热带高压（下文简称“副高”）控制的范围明显偏大,副高脊线位置较气候态偏北1度,西伸脊点较气候态偏西23度,造成主雨带偏西偏北。（3）中低层西北太平洋到我国华北北部的异常反气旋,与孟加拉湾北侧异常的气旋中心,造成气流在我国西北地区东部异常辐合。（4）从水汽收支来看,陕西2021年秋季水汽净流入较气候态偏多66.7%,尤其是东边界的异常水汽输送,还增强了低层冷垫,利于暖湿气流在冷垫上爬升导致陕西降水较常年异常偏多。  相似文献   

青藏高原夏季热力状态和南半球大气环流的可能联系     

李文毅  张洋 《气象科学》2023,43(4):427-437

本文通过对观测和再分析数据采用最大协方差分析以及回归、合成等分析方法,研究了青藏高原夏季地表气温与南半球大气环流之间的遥相关关系。结果表明,前期(4月)南半球极地—中高纬度大气环流呈现负位势高度异常、较低纬度印度洋—西太平洋区域呈现正位势高度异常时,高原中部和东部大部分区域夏季出现暖异常。在上述遥相关中,印度洋—西太平洋海温异常可能起到了重要的中间桥梁作用。在高原夏季温度偏高的年份,前期跨赤道的印度洋—西太平洋海温也持续偏暖,带来的海陆热力对比减小、经向跨赤道气流减弱有利于削弱夏季的季风环流,使得高原夏季降水偏少,有利于形成高原夏季的暖异常。在这一高原气温—南半球大气环流的遥相关关系中,4月南半球的大气位势高度场异常和与印度洋—西太平洋海温异常相关的异常高度场分布也十分相似。这一前期的跨赤道区域海温异常与南半球中高纬度位势高度场异常的因果关系仍有待进一步揭示。  相似文献   

气候模式CAS-ESM-C对1月热带太平洋流场模态的模拟评估     

张东凌  卢姁  张铭  吕庆平 《大气科学》2023,(3):725-738

利用气候模式CAS-ESM-C从1922年起84年的模拟资料,对1月份热带太平洋上层流场作复EOF分解及小波分析,并与实况以及理论解析解作对比讨论,以考察模式对赤道大洋上层流场的模拟能力,得到主要结论：（1）复EOF分解前3个模态的方差贡献为53.5%、12.9%、9.5%,累积方差贡献为75.9%,累积方差贡献比实况更高。（2）第一、二模态空间场与实况相比总体相像,流场都为赤道所俘获,在俘获区内的流场均以偏纬向流为主;差异在于模拟资料分析的赤道俘获区范围较实况要大,流场的经向流分量及越赤道流也较实况明显。（3）第一、二模态实时间系数序列无线性变化趋势,而实况则有。复EOF模态年际及年代际变化与实况相同或相近;第一、二模态中3～7年的年际变化是厄尔尼诺与南方涛动（ENSO）的反映;第一模态22～23年的年代际变化受北太平洋主要气候模态北太平洋年代际振荡（PDO）对热带太平洋的影响,而第二模态13年的年代际变化是受北太平洋次要气候模态北太平洋环流振荡（NPGO）对热带太平洋的影响;第一、二模态还都有峰值16年的年代际变化,这可能与印尼穿越流有关。（4）模拟资料分析的结果具有理论解析解中流...  相似文献