CLDAS陆面同化资料和ERA5-Land再分析资料气温产品在江西省的适用性评估

以江西省376个气象自动观测站的逐小时气温数据为基准,采用偏差、相关性和平均绝对误差等评价指标,对比分析2017—2022年CLDAS陆面同化和ERA5 Land再分析气温资料在江西省的适用性。结果表明： 1） ERA5 Land、CLDAS资料均能很好反映大部分站点的气温变化,CLDAS资料与观测资料的相关系数为0.99,相关系数区间分布较为集中;ERA5 Land资料与观测资料的相关系数为0.97,分布较为分散。2） 相较于观测站点多年平均气温,CLDAS资料较为接近,ERA5 Land资料则偏离较大。3） CLDAS资料的平均绝对误差明显低于ERA5 Land资料,二者均存在平原、盆地部分站点平均绝对误差较小而局部高海拔山区站点异常偏大的空间特征,以及秋季最大而冬季最小的季节特征。4） ERA5 Land资料偏差的日变化范围为-0.65—0.39 ℃,整体呈现单谷形分布;CLDAS资料偏差日变化范围为-0.05—0.05 ℃,波动幅度较小,没有明显的变化特征。5） 两种格点资料均能较好反映大部分站点的低温日数变化,但对于高温日数变化,ERA5 Land资料偏差较大,CLDAS资料偏差较小。     

CLDAS气温数据在中国区域的适用性评估

以中国48 708个地面气象自动站逐小时气温数据为基础,采用平均偏差(Bias)、相关系数、均方根误差(RMSE)、平均绝对误差(MAE)等评估指标,对比分析2017年10月、2018年1月、4月、7月CLDAS-V2.0气温(分辨率为0.062 5°),探讨中国8个分区春、夏、秋、冬4个季节CLDAS与站点气温的相关性及偏差分布特征。结果表明:1) CLDAS气温较好地反映了中国气温的年际变化,非独立性检验、独立性检验与站点气温的平均相关系数分别为0.995、0.991,东北地区相关性最高,西南地区相关性最低。2) CLDAS与站点气温的Bias为-0.011℃,非独立性检验的RMSE、MAE分别为1.275、1.645℃,独立性检验的RMSE、MAE分别为0.867、1.089℃,总体上CLDAS气温误差小,可信度较高。3)春、秋季的偏差小于夏、冬季;东北、华北、江淮、华南地区的偏差小于西北、西南地区; 84.6%站的冷偏差或暖偏差在1℃内,冷暖偏差空间分布均匀。4) CLDAS的最高气温存在冷偏差,最低气温存在暖偏差,夏季最高气温的最大误差为-0.59℃。5) CLDAS平均偏差的日变化为-0.23～0.07℃,白天呈冷偏差,夜间呈暖偏差,夏季平均偏差的日变化较显著,偏差的日较差为0.26℃;全国8个分区夏季平均偏差日变化最大为1.06℃,秋、冬、春季变幅相似,西南地区平均偏差日变化最大而江淮地区最小。     

基于ANUSPLIN的京津冀区域逐日气温格点数据集建立方法研究

为建立一个高精度、高空间分辨率的逐日气温格点数据集,满足公共气象服务对于精确信息及实时信息的需要,利用2018年6—8月京津冀区域以及临近省区共3 974个国家级及区域气象观测站质控后的逐日气温资料,采用ANUSPLIN软件对逐日气温数据进行空间内插,得到了京津冀区域逐日气温格点数据集（0.01°×0.01°）,并分别利用反距离权重插值法、普通克里金插值法、样条函数法对逐日气温数据进行空间插值,采用相关系数（Corr）、平均绝对误差（MAE）、平均相对误差（MRE）等作为评估指标来检验插值精度。结果表明：1）ANUSPLIN软件满足了空间插值对精度及曲面平滑度的要求,能直观体现京津冀区域气温由北向南递增的空间分布特征;2）4种插值方法中,基于ANUSPLIN软件的插值结果最优,相关系数平均达0.97,其样本误差在1 ℃之内占比为90.59%,MAE为0.46 ℃,MRE为1.81%;3）插值误差较大的区域位于冀北高原、燕山丘陵及太行山脉一带,高海拔、低站点密度等是造成插值误差的主要原因。基于ANUSPLIN插值方法建立的逐日气温格点数据集具有分辨率高、空间插值误差小的优势,ANUSPLIN对气温的空间分布具有较好的预测能力。     

基于多源数据的北疆春季 霜冻指标检验及其应用

为检验春季霜冻灾害和棉花播种及出苗期间的各温度指标，本文选用北疆1120个气象站和空间分辨率5km×5km的CLDAS多源融合实况数据，对2021年4月北疆春季霜冻灾害性天气中的平均气温、最低气温、最大降温幅度、温度≤0℃和温度≤12℃所有时刻的平均气温和累计小时数在北疆棉花主产区进行检验。利用气象站点数据、结合实地调查验证CLDAS数据在霜冻灾害性天气中的可用性，结果表明：CLDAS数据在均方根误差、气温预报准确率、平均气温和最低气温分布上对比地面气象站数据可信度较高，但在降温幅度、≤0℃分布区域和≤12℃持续时间上局部略有差别，总体来看在没有地面观测站点区域，CLDAS温度数据可代表当地温度，为分区域、分作物、分灾种精细服务到田间地头提供基础保障。     

CLDAS 10 m风产品在陕西的质量检验分析

以陕西省99个地面自动气象站和1台测风塔作为检验站点,评估了2018年1月1日至2020年12月31日中国气象局陆面数据同化业务系统(CLDAS)的10 m风产品在陕西省的质量.结果表明:CLDAS 10 m风速产品能够较好地反映陕西省风速的时间和空间分布特征,陕西大部分地区风速的准确率为55％～75％、平均绝对误差小...     

基于CLDAS的格点温度预报偏差订正方法

利用国家气象信息中心CLDAS格点温度实况、中央气象台SCMOC格点温度预报以及山西省站点观测温度,采用非独立性检验综合评估CLDAS在山西区域的适用性。在此基础上,采用滑动训练期订正方案,基于格点实况开展SCMOC温度预报场的客观订正。结果表明:(1)复杂地形对山西CLDAS格点温度实况的精度有一定影响,但最高气温的分析精度优于最低气温,表明地形对最低气温的偏差影响更显著,高海拔地区CLDAS最低气温一般对应为负偏差,低海拔地区一般对应为正偏差。(2)CLDAS格点温度实况的偏差空间分布具有时间延续性,进行简单的系统偏差订正后,最高、最低气温格点实况的精度分别提升1.1%、9.7%,与站点观测更为吻合。(3)基于改进后的CLDAS格点温度实况,采用滑动偏差订正方案,显著改善了山西省SCMOC温度预报的准确率。2019年,滑动偏差订正后的24 h时效最高、最低气温预报准确率较SCMOC温度预报分别提升2.7%、4.7%,订正后的短期温度预报质量有较大提高,优于预报员主观预报。     

高山区多时间尺度Anusplin气温插值精度对比分析

以中国地形起伏较大的横断山区为研究区,利用研究区内51个国家气象站点1960-2014年气温数据,以高程为协变量,采用Anusplin对不同时间分辨率(年代、年均、季节、月、日)的气温数据分布进行空间插值。通过气象站点交叉验证,结合绝对误差(平均绝对误差和均方根误差)和相对误差(平均相对误差)等量化指标,对比分析各个时间尺度气温数据的插值精度。结果表明:(1)夏季插值的绝对精度和相对精度最优,年代、年均和秋季气温插值的绝对精度水平相近,春季次之,冬季气温插值的绝对精度和相对精度最差。(2)在区域气候变化趋势方面,各个时间尺度气温插值数据的变化趋势和变化率与观测值结果一致。(3)年内各月均温和各月内日均温插值结果的相对精度和绝对精度在夏季月份精度最佳,在冬季月份精度最差,且各月内日均温插值结果在绝对精度和相对精度方面均低于各月均温插值结果的精度水平。分析显示,利用Anusplin的山区气温插值,气温海拔梯度性的优劣是造成不同时间尺度气温插值精度水平不一致的主要原因。     

CLDAS温湿产品在贵州的适用性评估及订正

使用贵州自动观测站逐时资料对2019年中国气象局陆面数据同化系统（CLDAS）温度、相对湿度产品进行了检验评估及线性订正。结果表明,CLDAS温度同观测有较好的一致性,相对湿度产品系统性低于观测,使用本地资料订正CLDAS温湿产品提高了产品的可用性。全年CLDAS温度产品在贵州的平均误差为0.2985℃,均方根误差为1.5578℃,相关系数为0.9822。12.4%的站点温度年均方根误差超过了2℃。从00:00-23:00（北京时）温度平均误差先减小后增大,均方根误差在中午前后存在最大值。订正后,CLDAS温度产品平均误差绝对值、均方根误差缩小,相关系数增大,全年均方根误差减小至1.2369℃。订正格点产品时有效距离越小订正效果越好。全年CLDAS相对湿度产品在贵州的平均误差为-4.501%,均方根误差为9.021%,相关系数为0.863,夜间相关系数为0.711。相对湿度产品平均误差及相关系数在中午前后达到最大值,均方根误差则是在日夜交换之际存在最值。线性订正对相对湿度产品有明显的正效果。订正后全年相对湿度均方根误差减小了2.317%,夜间相关系数较订正前增加了0.104。夜间时刻相...     

基于WRF-LES的崇礼复杂地形局地风场模拟研究

采用四重嵌套的WRF-LES,针对2022年北京冬奥会张家口崇礼赛区开展局地风场模拟试验,基于地面自动气象站和激光雷达观测资料,对一次晴空高压系统控制下的具有明显局地风环流特征的天气个例模拟结果进行检验评估。文中引入了STRM1 30 m地形数据、glc2015 27 m土地利用数据和CL‐DAS的土壤湿度数据用以提高模拟结果的准确性,并设计了敏感性试验来探讨不同资料对模拟结果的影响。结果表明：(1)WRF-LES能够呈现出复杂地形下局地风场的时空变化特征,各站风向绝对误差在10°～60°,风速绝对误差在0.5～2 m·s^-1。在山谷和山沟区域,模拟风场和观测风场都表现出明显的日变化特征,海拔较高站点的误差比海拔相对较低站点的误差更小。海拔较低站点在山谷风或上下坡风发展稳定时段风向误差较小,风向转换时段误差较大。(2)更新地形、土地利用以及CLDAS土壤湿度初始场对模拟结果都有一定程度改善。其中更新CLDAS土壤湿度初始场对风向和2 m气温的改善效果最为明显,风向绝对误差减小4.26°,2 m气温绝对误差减小0.84℃。更新土地利用对风速的改善效果最明显,风速绝对...     

CLDAS地面要素产品在陕西的适用性评估

基于陕西省1 540个地面自动气象站的观测资料,采用平均误差、平均绝对误差、均方根误差、相关系数等评估指标对5 km分辨率的CLDAS小时产品——2 m气温、2 m相对湿度、能见度、10 m风速在陕西的适用性进行了评估检验。结果表明:CLDAS 2 m气温、2 m相对湿度产品在陕西质量较好,能见度次之,10 m风速质量相较差。对CLDAS 2 m气温评估结果的进一步分析表明,各评估指标具有一定的月变化、日变化特征,但整体质量趋于稳定;高海拔地区,评估指标变化明显,代表性相对差。CLDAS 2 m气温对日最高、最低气温也有很好的指示性。分辨率为1 km与5 km的CLDAS 2 m气温产品对比评估表明,1 km气温产品的误差较小,相关系数更大,尤其对于高海拔地区,质量有明显改善,代表性增强。     

LOW-FREQUENCY CIRCULATION AND EXTENDED-RANGE FORECAST IN CONNECTION WITH AUTUMN EXTREME HEAVY RAINFALL PROCESS IN HAINAN

Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.     

AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING–TIANJIN–HEBEI REGION UNDER CLIMATE CHANGE

Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.     

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.     

CHARACTERISTICS AND TRENDS OF CLIMATIC EXTREMES IN CHINA DURING 1959–2014

The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.     

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正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted     

A Brief Introduction to Marine Meteorological Science Experiment Base at Bohe Town,Maoming City,Guangdong Province

<正>With the support of specialized funds for national science institutions,the Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration set up in October 2008 an experiment base for marine meteorology and a number of observation systems for the coastal boundary layer,air-sea flux,marine environmental elements,and basic meteorological elements at Bohe town,Maoming city,Guangdong province,in the northern part of the South China Sea.     

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AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.     

Information for Authors

AIMS AND SCOPE Atmospheric and Oceanic Science Letters （AOSL） pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome.     

Information for Authors

正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences