Validation and Spatiotemporal Distribution of GEOS-5-Based Planetary Boundary Layer Height and Relative Humidity in China     

Yidan SI  Shenshen LI  Liangfu CHEN  Chao YU  Zifeng WANG  Yang WANG  Hongmei WANG 《大气科学进展》2018,35(4):479-492

Few studies have specifically focused on the validation and spatiotemporal distribution of planetary boundary layer height(PBLH) and relative humidity(RH) data in China. In this analysis, continuous PBLH and surface-level RH data simulated from GEOS-5 between 2004 and 2012, were validated against ground-based observations. Overall, the simulated RH was consistent with the statistical data from meteorological stations, with a correlation coefficient of 0.78 and a slope of 0.9. However, the simulated PBLH was underestimated compared to LIDAR data by a factor of approximately two,which was primarily because of poor simulation in late summer and early autumn. We further examined the spatiotemporal distribution characteristics of two factors in four regions—North China, South China, Northwest China, and the Tibetan Plateau. The results showed that the annual PBLH trends in all regions were fairly moderate but sensitive to solar radiation and precipitation, which explains why the PBLH values were ranked in order from largest to smallest as follows: Tibetan Plateau, Northwest China, North China, and South China. Strong seasonal variation of the PBLH exhibited high values in summer and low values in winter, which was also consistent with the turbulent vertical exchange. Not surprisingly, the highest RH in South China and the lowest RH in desert areas of Northwest China(less than 30%). Seasonally, South China exhibited little variation, whereas Northwest China exhibited its highest humidity in winter and lowest humidity in spring,the maximum values in the other regions were obtained from July to September.  相似文献   

Role of Microphysical Parameterizations with Droplet Relative Dispersion in IAP AGCM 4.1     

Xiaoning XIE  He ZHANG  Xiaodong LIU  Yiran PENG  Yangang LIU 《大气科学进展》2018,35(2):248-259

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全球变暖、AMO、IPO对全球陆地降水变化的相对贡献          下载免费PDF全文

蔡琳  陶丽  赵久伟  张梦 《大气科学学报》2022,45(5):755-767

本文探究了不同海表温度（SST）模态对6—8月和12月—次年2月全球陆地降水的趋势以及年代际变化的相对贡献。首先对热带地区陆地降水和SST进行SVD分析,得到影响陆地降水的趋势和年代际变化主要的海洋模态为：海洋中的全球变暖（Global Warming,GW）、大西洋多年代际振荡（Atlantic Multidecadal Oscillation,AMO）和太平洋多年代际振荡（Interdecadal Pacific Oscillation,IPO）。其次利用多元线性回归模型进一步定量评估了全球变暖、AMO和IPO对不同地区陆地降水的相对贡献大小。结果表明,全球变暖对陆地降水变化的贡献在冬夏季都是最大的,AMO在6—8月的贡献次之。IPO在12月—次年2月的贡献次之。不同纬度带,三者的贡献不同。GW的贡献在6—8月期间对10°N以北地区较大,南半球受GW的贡献相对较小,GW在12月—次年2月对40°N以北降水贡献异常显著;AMO主要在6—8月对10°～40°S和50°～60°S纬度带上的降水变化的贡献比较大;而IPO主要在12月—次年2月对北半球中纬度降水变化的贡献比较大。GW对许多地区降水变化的方差贡献都是最大的,例如6—8月期间,对北美洲东北部和亚洲降水变化贡献最大,12月—次年2月期间,对欧洲降水变化贡献最大。AMO对6—8月降水变化的方差贡献最大的区域为非洲萨赫勒、西伯利亚和南美洲。12月—次年2月期间,IPO对美国西南部的降水变化贡献最大,此外,北美洲东北部、南美洲西北部、非洲南部、澳大利亚东部、南亚季风区和我国北部的降水在12月—次年2月期间同样受IPO影响显著。进一步利用信息流的方法,探究了GW、AMO和IPO与陆地降水变化之间的因果关系,验证了上述结论。  相似文献   

Evaluation of Surface Relative Humidity in China from the CRA-40 and Current Reanalyses     

Jingpeng ZHANG  Tianbao ZHAO  Zhi LI  Chunxiang LI  Zhen LI  Kairan YING  Chunxiang SHI  Lipeng JIANG  Wenyu ZHANG 《大气科学进展》2021,38(11):1958-1976

Recently, the China Meteorological Administration (CMA) released a new Global Atmospheric Reanalysis (CRA-40) dataset for the period 1979-2018. In this study, surface relative humidity (RH) from CRA-40 and other current reanalyses (e.g., CFSR, ERA5, ERA-Interim, JRA-55, and MERRA-2) is comprehensively evaluated against homogenized observations over China. The results suggest that most reanalyses overestimate the observations by 15％-30％ (absolute difference) over the Tibetan Plateau but underestimate the observations by 5％-10％ over most of northern China. The CRA-40 performs relatively well in describing the long-term change and variance seen in the observed surface RH over China. Most of the reanalyses reproduce the observed surface RH climatology and interannual variations well, while few reanalyses can capture the observed long-term RH trends over China. Among these reanalyses, the CFSR does poorly in describing the interannual changes in the observed RH, especially in Southwest China. An empirical orthogonal function (EOF) analysis also suggests that the CRA-40 performs better than other reanalyses to capture the first two leading EOF modes revealed by the observations. The results of this study are expected to improve understanding of the strengths and weaknesses of the current reanalysis products and thus facilitate their application.  相似文献   

Quantitative Precipitation Forecast Experiment Based on Basic NWP Variables Using Deep Learning     

Kanghui ZHOU  Jisong SUN  Yongguang ZHENG  Yutao ZHANG 《大气科学进展》2022,39(9):1472-1486

The quantitative precipitation forecast (QPF) performance by numerical weather prediction (NWP) methods depends fundamentally on the adopted physical parameterization schemes (PS). However, due to the complexity of the physical mechanisms of precipitation processes, the uncertainties of PSs result in a lower QPF performance than their prediction of the basic meteorological variables such as air temperature, wind, geopotential height, and humidity. This study proposes a deep learning model named QPFNet, which uses basic meteorological variables in the ERA5 dataset by fitting a non-linear mapping relationship between the basic variables and precipitation. Basic variables forecasted by the highest-resolution model (HRES) of the European Centre for Medium-Range Weather Forecasts (ECMWF) were fed into QPFNet to forecast precipitation. Evaluation results show that QPFNet achieved better QPF performance than ECMWF HRES itself. The threat score for 3-h accumulated precipitation with depths of 0.1, 3, 10, and 20 mm increased by 19.7%, 15.2%, 43.2%, and 87.1%, respectively, indicating the proposed performance QPFNet improved with increasing levels of precipitation. The sensitivities of these meteorological variables for QPF in different pressure layers were analyzed based on the output of the QPFNet, and its performance limitations are also discussed. Using DL to extract features from basic meteorological variables can provide an important reference for QPF, and avoid some uncertainties of PSs.  相似文献   

中国地面均一化相对湿度月值格点数据集的建立   总被引：3，自引：3，他引：0  

赵煜飞  朱亚妮 《气象》2017,43(3):333-340

基于1951—2014年2400余个中国国家级地面气象站均一化相对湿度资料,采用薄盘样条法,进行空间内插,得到了中国地面均一化相对湿度月值0.5°×0.5°格点数据集(CR数据集)。数据集的质量评估结果表明:冬季插值误差相对夏季偏高。冬、春、夏、秋季分析值与站点实测值的插值偏差空间区域特征不显著,平均偏差分别为0.002%/月、0.013%/月、0.008%/月和0.007%/月。冬、春、夏、秋季平均相对误差分别为0.431%/月、0.439%/月、0.286%/月和0.382%/月。分析值与站点实测值间的平均相关系数达0.89。整体来看,插值后的格点化相对湿度资料能够比较准确、细致地描述我国年平均相对湿度场的东南湿、西北干的主要空间特征。能够较好地展现长江以南地区、黄河以南长江以北地区、西北地区、天山南北麓、塔里木盆地等大地形的相对湿度变化特征。由于青藏高原台站稀少,格点数据集对该地区空气相对湿度特征的刻画是否合理很难给出定性、定量的判断。通过对CR数据集进行长时间序列气候变化趋势分析,表明60年来全国平均相对湿度呈减小趋势。  相似文献   

基于单差模糊度的 GPS／GLONASS 组合相对定位模型研究     

章太馨  刘炎炎  鲍立桂  叶世榕  李志 《测绘工程》2016,25(4):33-36

采用频分多址技术(FDMA),GLONASS系统双差模糊度固定存在两个问题:不同卫星波长不一致,双差后不能保持模糊度整数特性;共视卫星频率不同,不同卫星之间存在大小不同的频间偏差(IFB)。传统的双差不能很好处理GLONASS相对定位模糊度固定问题。文中考虑将双差所涉及的两颗卫星的站间单差模糊度分别求解,不受共视卫星波长不一致的影响。同时采用参数估计法消除不同厂商接收机的频间偏差影响。试验结果表明采用文中方法可以正确固定GLONASS模糊度,并且达到与GPS相当的解算精度,GPS/GLONASS组合定位精度和可靠性也比GPS单系统有所提高。  相似文献   

基于聚类分析的多波束测深数据滤波方法研究     

彭刚跃  吉渊明  岳建平  李静  宋亚宏 《测绘工程》2016,25(9):31-34

现有的多波束测深数据滤波方法,在滤波效果和有效信息的保留问题上还不够完善。文中提出对测深数据滤波时,先设定小阈值,尽可能地剔除错误数据,再对滤出数据作聚类分析回收有效信息,防止信息丢失。  相似文献   

一种简易的GNSS接收机自检方法     

张永毅  张兴福 《测绘科学》2016,41(6):162-167

针对GNSS接收机检定费用较高、检定机构数量少且检定周期长的问题,该文提出了一种简易快速的GNSS接收机检定方法。该方法根据GNSS接收机天线相位中心的几何关系,通过自设简易检定场,利用相对定位法及超短基线法分别检测接收机天线的相位中心偏差和内部噪声水平,并编写了相应的计算程序对检测数据进行快速的处理。4次独立实验结果表明:该文实验方案具有较高的精度和可靠性,适用于快速对GNSS接收机天线相位中心偏差和内部噪声水平进行自检。  相似文献   

暴雨期间GNSS遥感气象要素的时序变化   总被引：1，自引：0，他引：1  

李黎  田莹  袁志敏  王虎  沈军 《测绘科学》2016,41(10):82-87

针对暴雨短临预报准确率不高的问题,该文结合香港地区的暴雨实例,分析暴雨发生期间天气尺度特征和GNSS气象要素的时序变化特点及其各要素之间的相关性。研究结果表明:强烈的西南气流带来丰富水汽,高空强烈的辐散抽吸引起低层气压降低和对流运动的发展,配合中层低槽过境和低层冷空气南下,为暴雨发生提供条件;天顶对流层延迟变化的主要贡献来自大气水汽含量,可以用天顶对流层延迟替代大气水汽含量分析大气中的水汽累计及变化情况;暴雨发生前,气温较高,大气水汽含量和相对湿度时序增长快速,增长强度及其维持高水平状态的时长与后续雨量有较好的对应关系;大气水汽含量和相对湿度时序的上升分别反映了降水之前的充足水汽供应和水汽正在转向于饱和状态。  相似文献