全文获取类型
| 收费全文 | 55篇 |
| 免费 | 35篇 |
| 国内免费 | 82篇 |
专业分类
| 测绘学 | 13篇 |
| 大气科学 | 124篇 |
| 地球物理 | 5篇 |
| 地质学 | 4篇 |
| 海洋学 | 8篇 |
| 综合类 | 13篇 |
| 自然地理 | 5篇 |
出版年
| 2024年 | 4篇 |
| 2023年 | 2篇 |
| 2022年 | 6篇 |
| 2021年 | 9篇 |
| 2020年 | 8篇 |
| 2019年 | 12篇 |
| 2018年 | 13篇 |
| 2017年 | 10篇 |
| 2016年 | 8篇 |
| 2015年 | 12篇 |
| 2014年 | 16篇 |
| 2013年 | 12篇 |
| 2012年 | 14篇 |
| 2011年 | 9篇 |
| 2010年 | 6篇 |
| 2009年 | 8篇 |
| 2008年 | 4篇 |
| 2007年 | 5篇 |
| 2006年 | 1篇 |
| 2005年 | 2篇 |
| 2000年 | 4篇 |
| 1999年 | 1篇 |
| 1995年 | 1篇 |
| 1994年 | 1篇 |
| 1989年 | 3篇 |
| 1982年 | 1篇 |
排序方式： 共有172条查询结果，搜索用时 109 毫秒
41.
往返平飘式探空通过一次探空气球施放实现“上升段-平飘段-下降段”三段观测,其下降段能实现在06时(世界时,下同)和18时自动垂直加密观测大气,具备提升区域高分辨率快速同化循环预报系统在06时和18时的预报技巧潜力。为了实现往返平飘式探空在区域高分辨率模式中的同化,分析其对预报的影响,初步提出了“选取模式层最接近观测”的垂直稀疏化方法来预处理资料,深入分析了稀疏化对同化效果的影响,论证了资料垂直稀疏化对于同化应用的必要性;在此基础上,开展了为期1个月的批量同化影响试验,着重分析了往返平飘式探空在长江中下游区域的组网观测对CMA-MESO模式预报技巧的影响。稀疏化敏感性试验结果表明,同化不稀疏化的往返平飘式探空相比同化传统业务探空,分析和预报误差显著增加,降水预报评分也显著降低,相反,“选取最接近模式层”数据的垂直稀疏化方案能提高模式的分析和预报技巧,表明往返平飘式探空同化前必须进行垂直稀疏化。批量同化试验结果表明,在冷启动时刻(00时和12时,为常规探空释放时刻),同化往返平飘式探空(上升段)相对同化传统业务探空,分析误差和预报误差变化较小。但在暖启动时刻(03、06、09、15、18、... 相似文献
42.
基于云南探空仪换型平行观测期间各标准等压面上的温度和位势高度观测数据以及对应的ECMWF模式预报场数据,利用偏差、标准差、均方根误差和相关系数等对新、旧探空仪观测数据进行对比分析和评估。结果表明:新、旧探空仪观测数据一致性较好,在100 hPa以下两者温度绝对偏差小于1.0℃,位势高度绝对偏差小于30 gpm,100 hPa以上温度和位势高度最大绝对偏差分别为3.9℃和151.0 gpm。除高层个别等压面外,新、旧探空仪观测数据离散性基本一致或新探空仪离散性相对较小。新探空仪观测数据与模式数据更为一致,在中高层表现更为明显;相对于模式数据,新、旧探空仪温度偏差分别集中在±0.7℃、±0.9℃左右,最大均方根误差分别为3.0℃、4.5℃,平均相关系数分别约为0.78、0.73;新、旧探空仪位势高度最大偏差分别为28.5 gpm、130.9 gpm,最大均方根误差分别为87.6 gpm、136.9 gpm,平均相关系数分别约为0.86、0.78。 相似文献
43.
44.
中国区域再分析湿度资料与均一化探空湿度资料的对比分析 总被引：2，自引：2，他引：0
利用1980—2010年中国98个探空站均一化月平均温度和温度露点差资料(OBS)和NCEP/NCAR(NCEP)、ERAInterim(ERA)、JRA-25(JRA)3种再分析月平均比湿资料,使用相似分析、趋势分析等方法对中国区域4种资料高空比湿进行了对比分析。结果表明:(1)从空间分布特征分析,JRA比湿与OBS比湿的空间分布相似系数最大。(2)3种再分析资料比湿普遍大于OBS比湿,除个别站点个别层次外,JRA和OBS比湿更加接近;再分析比湿和OBS比湿的相对偏差随高度增加而增大,且冬春季大于夏季。(3)从长期变化趋势分析,在对流层低层,JRA和0BS比湿较接近,在对流层中高层ERA和OBS比湿较接近。 相似文献
45.
GPS/MET水汽资料因其建设维护成本低、时间分辨率高、可全天候、无人、自动观测等优点,已经成为获取大气水汽资料新的重要手段。以阳江第八届国际探空比对试验资料为基础,对比分析了GPS/MET与4种探空仪和微波辐射计获取的水汽资料。探空与GPS/MET测量的水汽值有较强的相关性,相关系数在0.57~0.74之间,但探空水汽值比GPS/MET偏高0.71~1.47mm,方差在3.48~3.96之间。其中RS92探空仪测量的水汽变幅与GPS/MET基本相当,但国内探空仪水汽测量值的变幅明显高于GPS/MET,偏高近1.6~1.8倍。微波辐射计在天气较好时,测量精度较高,基本上以3个国产探空仪数据相当;但微波辐射计在雨天受罩子上的雨水影响,误差较大,与GPS/MET的测量值不相关。 相似文献
46.
Validation of the “HY-2” altimeter wet tropospheric path delay correction based on radiosonde data 总被引：2，自引：1，他引：1
Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- mate PD values, the ＂HY-2＂ system includes a calibration microwave radiometer （CMR） operating at 18.7, 23.8 and 37 GHz. The PD data of the CMR were compared and validated by coincident radiosonde profiles from ten globally distributed radiosonde stations during October 2011 to August 2012. The temporal interval was 1 h. In order to avoid land contamination, different spatial intervals between these two data sets were tested. The empirical fit function of PD uncertainty and spatial interval was found and extrapolated to the ideal situation that the data of CMR and radiosonde were totally coincident. The stability of the brightness temperature of the CMR and its impact on the PD correction was also studied. Consequently, the uncertainty of the PD algorithm of the CMR was estimated to be 2.1 cm. 相似文献
47.
Reconciling upper-air temperature trends derived from radiosonde and satellite observations is a necessary step to confidently determine the global warming rate. This study examines the raw and homogenized radiosonde observations over China and compares them with layer-mean atmospheric temperatures derived from satellite microwave observations for the lower-troposphere(TLT), mid-troposphere(TMT), upper-troposphere(TUT), and lower-stratosphere(TLS) by three research groups. Comparisons are for averages over China, excluding the Tibetan Plateau, and at individual stations where metadata contain information on radiosonde instrument changes. It is found that major differences between the satellite and radiosonde observations are related to artificial systematic changes. The radiosonde system updates in the early 2000 s over China caused significant discontinuities and led the radiosonde temperature trends to exhibit less warming in the middle and upper troposphere and more cooling in the lower stratosphere than satellite temperatures. Homogenized radiosonde data have been further adjusted by using the shift-point adjustment approaches to match with satellite products for China averages. The obtained trends during 1979–2015 from the re-adjusted radiosonde observation are respectively 0.203 ± 0.066, 0.128 ± 0.044, 0.034 ± 0.039, and –0.329 ± 0.135 K decade–1 for TLT, TMT, TUT, and TLS equivalents. Compared to satellite trends, the re-adjusted radiosonde trends are within 0.01 K decade–1 for TMT and TUT, 0.054 K decade–1 warmer for TLT, and 0.051 K decade–1 cooler for TLS. The results suggest that the use of satellite data as a reference is helpful in identifying and removing inhomogeneities of radiosonde temperatures over China and reconciling their trends to satellite microwave observations. Future efforts are to homogenize radiosonde temperatures at individual stations over China by using similar approaches. 相似文献
48.
探空温度资料质量控制技术研究 总被引：3，自引：1，他引：2
探空资料质量控制是探空资料在数值模式同化应用取得较好效果的重要保障,随着模式分辨率不断提高,探空资料飘移信息越来越需要应用到同化算子。本文通过全球谱模式T639L60(简称T639)分析场和掩星探测系统COSMIC资料对2011年7月我国119个探空站温度资料进行分析,同时结合探空气球随高度飘移信息以及温度残余误差等因素,开展探空温度质量控制技术研究。研究结果表明：探空气球飘移距离随高度而增大,在300~100 hPa之间飘移速率较大;基于探空温度资料残余误差和飘移因素建立的双权重标准质量控制方法能有效保障资料质量,是否考虑温度残余误差和飘移信息对质量控制结果有明显影响。当考虑温度残余误差时,300 hPa以上离群资料量显著减少;考虑飘移信息时,高层飘移速率较大区间离群资料量明显减少;模式地形与测站地形的高度差异对质量控制结果有明显影响,当测站地形高度低于模式地形时,易出现离群点,且两种地形差异大小与离群点呈正相关,即地形差异越大,低层离群资料越多。 相似文献
49.
Hui XU Jianping GUO Jian LI Lin LIU Tianmeng CHEN Xiaoran GUO Yanmin LYU Ding WANG Yi HAN Qi CHEN Yong ZHANG 《大气科学进展》2021,38(9):1552-1565
The satellite-based quantification of cloud radiative forcing remains poorly understood, due largely to the limitation or uncertainties in characterizing cloud-base height (CBH). Here, we use the CBH data from radiosonde measurements over China in combination with the collocated cloud-top height (CTH) and cloud properties from MODIS/Aqua to quantify the impact of CBH on shortwave cloud radiative forcing (SWCRF). The climatological mean SWCRF at the surface (SWCRFSUR), at the top of the atmosphere (SWCRFTOA), and in the atmosphere (SWCRFATM) are estimated to be ?97.14, ?84.35, and 12.79 W m?2, respectively for the summers spanning 2010 to 2018 over China. To illustrate the role of the cloud base, we assume four scenarios according to vertical profile patterns of cloud optical depth (COD). Using the CTH and cloud properties from MODIS alone results in large uncertainties for the estimation of SWCRFATM, compared with those under scenarios that consider the CBH. Furthermore, the biases of the CERES estimation of SWCRFATM tend to increase in the presence of thick clouds with low CBH. Additionally, the discrepancy of SWCRFATM relative to that calculated without consideration of CBH varies according to the vertical profile of COD. When a uniform COD vertical profile is assumed, the largest SWCRF discrepancies occur during the early morning or late afternoon. By comparison, the two-point COD vertical distribution assumption has the largest uncertainties occurring at noon when the solar irradiation peaks. These findings justify the urgent need to consider the cloud vertical structures when calculating the SWCRF which is otherwise neglected. 相似文献
50.
????GPS?????????????(PWV)??????????????????????????SA????????????????GPS???????????????????GPS????????????????????????θ???????????????ù??????????????????????????С??100 m???????????????????μ????????????Saastamoinen?????????????????????????????????IGS???BJFS??KUNM??LHAZ??TWTF??????????????????????????????????GPS PWV????????????????????RS PWV?????ж???????????????????????????θ???????????????????GPS PWV??RS PWV??????????????1~3 mm?????????????????????????????????GPS????PWV?? 相似文献