6 kaBP中国陆地生态系统净初级生产力的模拟

利用植被与大气相互作用模式（AVIM）模拟了全新世中期（6 kaBP）及现代中国陆地植被净初级生产力（NPP）的大小与分布特征,计算了以上两个时期我国陆地植被NPP的碳总量。结果表明：全新世中期以来气候的变化是影响我国陆地植被NPP变化的主要原因,6 kaBP时期NPP平均值为409 g/（m2·a）, NPP碳总量为3.89 Pg/a,分别比现在高15%和19%。全新世中期至今,我国陆地植被NPP的变化特征与对应时期中国土壤碳储量的变化趋势具有很好的一致性,这表明了利用生态模式模拟长时间尺度下我国陆地植被NPP的变化特征是可行的。     

吴起县2000—2013年植被NPP变化特征

利用美国蒙大拿大学运用生物地球化学模式(Biome-BGC)估算出的净初级生产力产品(MOD17A3),研究吴起县2000—2013年植被净初级生产力(net primary productivety,NPP)的变化特征。结果表明:吴起县2000—2013年年均NPP变化范围在156.92~275.37gC·m-2·a-1,平均值为218.27gC·m-2·a-1,14a植被NPP在波动中呈显著增加趋势(P0.01);全县85.93%面积的NPP变化百分率在10%~50%,年均NPP变化百分率-10%的区域主要分布在吴起县县城周边,年均NPP变化百分率为-10%~0%的区域主要分布在吴起县西北部地区铁边城镇及王坬子乡等地,年均NPP变化百分率为0%~10%的区域主要分布在吴起县城以北及以西地区,植被NPP变化百分率50%的区域分布在吴起县南部白豹乡、楼坊坪乡及长官庙乡部分地区。     

1981-2008年中国陆地植被NPP对气候变化响应的敏感性试验

在验证CENTURY模型对中国陆地植被净初级生产力(Net Primary Productivity,NPP)模拟能力的基础上,利用该模型探讨了1981-2008年中国陆地植被NPP的年际变异和变化趋势对CO₂浓度、温度和降水变化的响应。结果表明,中国陆地植被NPP对不同气候因子的响应程度存在明显不同。其中,CO₂浓度变化对植被NPP年际变异的影响不显著,但能够引起中国大部分地区植被NPP趋势系数增大;温度对中国中高纬度地区植被NPP的年际变化影响显著,但就全国范围而言,植被NPP年际变异对温度变化的响应程度总体低于对降水变化的响应程度;降水变化是对中国植被NPP变化趋势起主导作用的气候因子。此外,综合考虑温度和降水变化的影响发现,植被NPP变化趋势的响应特征类似于降水单独变化时植被NPP变化趋势的响应特征。     

全球植被与大气之间碳通量的模式估计(英文)

用大气植被相互作用模式（AVIM）模拟了全球陆地植被的净初级生产力（NPP）。AVIM由相互耦合的两部分组成：物理过程，包括陆地表面水分和能量在土壤、植被与大气之间的传输；以及生理生态过程，如：光合、呼吸、干物质分配、凋落和物候等。全球的植被分为13类，土壤按质地分为6类。用EMDI提供的全球1637个包括不同植被类型的NPP观测点数据对模型进行了检验。NPP模拟的结果表明：全球陆地植被的平均NPP为405.13gCm-2yr-1，不同植被类型的平均 NPP变化范围在99.58 g Cm-2yr-1（苔原）到996.2 g Cm-2yr-1（热带雨林）之间。全球年总NPP为60.72GtCyr-1，其中最大的部分为热带雨林，15.84GtCyr-1，占全球的26.09％。最大的碳汇是在北半球的温带。模式模拟的NPP在全球的空间和季节分布是合理的。     

东亚季风区夏季陆地生态系统碳循环对东亚夏季风的响应

东亚地区陆地生态系统的时空变率表现出明显的对季风气候的响应特征。使用EOF（经验正交分解）方法分析了AVIM2动态植被陆面模式离线模拟试验模拟的1953～2004年东亚季风区夏季陆地生态系统总初级生产力（GPP）、生态系统净初级生产力（NPP）、净生态系统初级生产力（NEP）、植被呼吸以及土壤呼吸的时空分布特点,探讨了东亚夏季风对陆地生态系统碳循环影响机制。研究发现,在强季风年,江淮地区高温少雨的特点限制了光合作用,造成GPP偏低;而华南地区在强季风年气候温暖湿润,利于植被生长,GPP偏高。季风对于植被呼吸和土壤呼吸影响不明显,使得GPP和植被呼吸之差NPP的变化及NPP和土壤呼吸之差NEP的变化与GPP的变化保持一致。在强季风年江淮流域地区干热的气候条件使得NPP和NEP降低;但是在华南地区温度升高的同时降水增多使得在NPP偏高的基础上NEP也偏高。     

近55a新疆植被净初级生产力的时空变化

利用大气植被相互作用模型AVIM2分析了时间长度为55 a、空间分辨率为0.05°×0.05°的新疆植被净初级生产力(NPP),分析了气候变化下NPP的时空演变特征,并研究了其与气温和降水量的关系。结果表明,(1)近55 a新疆NPP平均值为92.4 gC·m~(-2),其中1993年最高为107.1 gC·m~(-2);2014年最小为79.0 gC·m~(-2)。近55 a新疆NPP总量的时间动态变化呈缓慢增加趋势,每10 a的递增速率约为1.8 gC·m~(-2)。(2)夏季是NPP最大的季节,其次是秋季,春季列第三位。山区NPP值较平原高。(3)新疆NPP对降水量变化呈显著正相关,气温的变化对NPP的影响不显著,说明降水的增加相对气温的升高,对新疆植被净初级生产力的变化有着更加积极的影响。     

呼伦贝尔市NPP时空变化及其对气候的响应

利用2000—2015年MOD17A3数据和气象站点资料,分析呼伦贝尔市NPP的时空变化特征及其对气候变化的响应情况。研究表明,呼伦贝尔市平均植被NPP为261.02 gC/(m~2·a),总体呈自西向东依次递增的分布格局。NPP的年际变化呈波动增长趋势,平均变化率为5.51gC/(m~2·a),线性增长达到显著的区域主要位于呼伦贝尔草原、大兴安岭南部林地和大兴安岭与松嫩平原过渡的耕地。16个气象站周边的NPP与各站年降水量均呈正相关,且除莫力达瓦达斡尔族自治旗(简称莫旗)外均通过了0.01水平的显著性检验,NPP与年平均气温均呈负相关,但除海拉尔区外均未通过显著性检验,NPP与日照时数正、负相关的台站同时存在。由此可知,降水是影响呼伦贝尔市NPP变化的主要因素。     

基于遥感沿海湿地植被生产力估算研究

植被净第一性生产力是评价地表植被状况的重要指标之一,对分析和评价全球以及区域生态环境、碳循环等变化具有重要作用.植被净第一生产力的研究方法很多,本文主要运用TM影像近红外和红光通道组成的标准化差植被指数（NDVI）,借助CASA模型机理以及气象学方法,建立盐城区域净第一性生产力（NPP）遥感估算模型,并以核心区-丹顶鹤自然保护区湿地为应用案例,分析了核心区2005年间8月份净第一性生产力的变化.分析结果表明,研究区8月份的湿地各种植被NPP分别为：人工芦苇和盐蒿为1184.863266 g/m2,芦苇为1083.435262g/m2,米草为822.766878g/m2.若以NPP为衡量标准,人工芦苇和盐蒿的净第一性生产力最高.     

辽宁省净初级生产力时空演变及其对地形因子的响应

植被净初级生产力（NPP）是评估生态环境质量的重要指标之一,为了探明辽宁省生态环境变化,利用MODIS-NDVI数据及CASA模型,对辽宁省2000—2018年NPP进行估算,并在此基础上分析了近19 a辽宁省NPP时空变化特征及其对地形因子的响应。结果表明：2000—2018年辽宁省植被NPP呈波动上升趋势,空间分布特征为东部高西部低;NPP变化趋势率为2.89 gC·m^-2·a^-1,其中,87.4%的地区呈增加趋势,且辽西北地区波动变化最为显著;高程和坡度对NPP变化的影响明显高于坡向;随着高程增加,NPP表现为先增加后平稳的趋势,高程500 m左右出现NPP最大值;随着坡度增加,NPP表现为先增加后略有减小的趋势,坡度35°左右出现NPP最大值;在高程为500 m以上、坡度为15°—35°范围内,NPP值最大。     

CMIP5模式对未来升温情景下全球陆地生态系统净初级生产力变化的预估

针对《巴黎协定》提出的温控目标,利用耦合模式比较计划第五阶段（CMIP5）模式在RCP2.6、RCP4.5和RCP8.5情景下的模拟结果,初步分析了全球升温情景下陆地生态系统净初级生产力（NPP）相对于参考时段（1986—2005年）的变化,重点分析了1.5℃和2℃升温时NPP相对于参考时段的变化量,并探讨了大气CO₂浓度、气温、降水和辐射的变化及其对NPP变化的影响。CMIP5基于各典型浓度路径模拟的全球陆地生态系统NPP均呈增加趋势,且NPP增加量与升温幅度成正比。在相同的升温幅度下,基于各典型浓度路径模拟的各环境因子和NPP的变化量较为一致。陆地生态系统NPP总量增加主要由大气CO₂浓度上升驱动,其他环境因子的影响相对较弱。中国东南部、非洲中部、美国东南部和亚马孙雨林西部地区NPP增加最明显。NPP变化量的空间格局主要由大气CO₂浓度增加和升温控制,降水和辐射的影响相对较小。具体而言,大气CO₂浓度上升对中低纬度的NPP变化贡献最大,对北方高纬度地区NPP变化贡献较小。温度上升有利于促进北方高纬度地区和青藏高原地区NPP,但对中低纬度地区的NPP有较强的抑制作用。鉴于既有典型浓度路径和地球系统模型的限制,本文对未来升温情景下陆地生态系统NPP的预估仍存在较大的不确定性,需要在未来的研究中进一步改进。     

加强业务管理提高测报质量

我局从1999～2003年,测报工作连续4年未出现错情,在此期间共有1个250个班,9个百班无错通过上级业务部门验收.在仪器保管、使用、维护上符合要求,对外报送的各种表、簿都能做好出门合格.     

Quantifying the uncertainty of the annular mode time scale and the role of the stratosphere

The impact of high resolution modern vegetation cover on the West African climate is examined using the International Centre for Theoretical Physics Regional Climate Model implementing the NCAR Community Land Model. Two high resolution 25 km long-term simulations driven by the output from a coarser 50-km resolution simulation are performed for the period 1998–2010. One high resolution simulation uses an earlier and coarser-resolution version of plant functional type distribution and leaf area index, while the other uses a more recent, higher-quality, and finer-resolution version of the data. The results indicate that the new land cover distribution substantially alters the distribution of temperature with warming in Central Nigeria, northern Gulf of Guinea and part of the Sahel due to the replacement of C4 grass with corn; and cooling along the coastlines of the Gulf of Guinea and in Central Africa due to the replacement of C4 grass with tropical broadleaf evergreen trees. Changes in latent heat flux appear to be largely responsible for these temperature changes with a net decrease (increase) in regions of warming (cooling). The improved land cover distribution also results in a wetter monsoon season. The presence of corn tends to favor larger precipitation amounts via more intense events, while the presence of tropical broadleaf evergreen trees tends to favor the occurrence of both more intense and more frequent events. The wetter conditions appear to be sustained via (1) an enhanced soil moisture feedback; and (2) elevated moisture transport due to increased low-level convergence in regions south of 10N where the most substantial land cover differences are present. Overall the changes induced by the improved vegetation cover improve, to some extent, the performance of the high resolution regional climate model in simulating the main West African summer monsoon features.     

由中国历史气候记录对季风导致唐朝灭亡说的质疑

2007年1月4日杂志发表了Yancheva等10人的题为"Influence of the intertropical convergence zone on the East-Asian monsoon"(热带辐合带对东亚季风的影响)的论文[1],这是德国波兹坦地学研究中心气候动力与沉积学科的主管豪格(G.H.Haug)率领的科研小组的一项成果,认为是季风的变化引起的长期干旱导致了唐朝的灭亡.     

On the forecast of the onset and end of the convective season in the Amazon

Summary ?Some features of the climate system that can be considered predictors of the onset and end of the convective season over the Amazon were identified using one-month lag correlations and field composites. The fields analyzed were sea surface temperature (SST), outgoing long-wave radiation (OLR), vertical velocity and upper tropospheric winds. Warm (cold) anomalies in the SST in the tropical North Atlantic and the Caribbean Sea tend to be associated with delayed (early) onsets. Likewise, there is a tendency towards a delayed (early) end of the convective season with cold (warm) anomalies in these ocean regions. In addition, the SST in the cold tongue region of the equatorial Pacific is negatively, though weakly correlated with the onset date. The signal of this SST is more evident in the case of the end date, which is earlier with respect to its mean date in most of El Ni?o cases. The convective activity intensity itself conditions the onset and the end of the convective season, as it is evidenced by the behavior of the OLR and the vertical velocity fields. The more (less) intense the convective activity over South America during the preceding month, the earlier the onset and the later the end of the convective season on the Amazon region. The prediction of the onset and end dates of the convective season in the Amazon region was explored using a simple multiple regression technique based on the variables that have shown precursor signals with respect to these dates. The correlation coefficient between the predicted and the observed onset date is 0.81, and in the case of the end date, it is 0.76. The skill to predict early, delayed and normal categories was high, since in more than two thirds of the cases the category was successfully predicted, and there were no predictions of categories opposed to those observed. Received July 23, 2001; revised February 22, 2002; accepted April 26, 2002     

Comparing the theoretical versions of the Beaufort scale, the T-Scale and the Fujita scale

2005 is the bicentenary of the Beaufort Scale and its wind-speed codes: the marine version in 1805 and the land version later. In the 1920s when anemometers had come into general use, the Beaufort Scale was quantified by a formula based on experiment. In the early 1970s two tornado wind-speed scales were proposed: (1) an International T-Scale based on the Beaufort Scale; and (2) Fujita's damage scale developed for North America. The International Beaufort Scale and the T-Scale share a common root in having an integral theoretical relationship with an established scientific basis, whereas Fujita's Scale introduces criteria that make its intensities non-integral with Beaufort. Forces on the T-Scale, where T stands for Tornado force, span the range 0 to 10 which is highly useful world wide. The shorter range of Fujita's Scale (0 to 5) is acceptable for American use but less convenient elsewhere. To illustrate the simplicity of the decimal T-Scale, mean hurricane wind speed of Beaufort 12 is T2 on the T-Scale but F1.121 on the F-Scale; while a tornado wind speed of T9 (= B26) becomes F4.761. However, the three wind scales can be uni-fied by either making F-Scale numbers exactly half the magnitude of T-Scale numbers [i.e. F′half = T / 2 = (B / 4) − 4] or by doubling the numbers of this revised version to give integral equivalence with the T-Scale. The result is a decimal formula F′double = T = (B / 2) − 4 named the TF-Scale where TF stands for Tornado Force. This harmonious 10-digit scale has all the criteria needed for world-wide practical effectiveness.     

准两年振荡对大气中微量气体分布的影响

NCAR的包含化学、辐射、动力相互作用的两维模式（SOCRATES）移植回国后进行了初步的模拟试验,用以研究某些对环境问题重要的微量气体的化学、辐射、动力传输过程。在不考虑极地平流层云和气溶胶表面非均相化学等情况下,模式积分多年,计算结果稳定,模拟的风场、温度场显示出正常的季节变化,模拟的微量气体分布与卫星实测资料对照,结果也比较一致。为了探讨热带平流层风场的准两年周期振荡（QBO）对平流层微量气体分布的影响,我们做了QBO强迫的数值试验,即在模式中加入QBO强迫,并与不考虑QBO强迫的模拟结果对比。结果表明,QBO与其相关的次级环流所引起动力输送的变化,使平流层微量气体分布发生变化。     

Analysis of the Characteristics of the Low-level Jets in the Middle Reaches of the Yangtze River during the Mei-yu Season

Here, we analyze the characteristics and the formation mechanisms of low-level jets(LLJs) in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5) reanalysis dataset. Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs) concentrated at heights of 900–1200 m.The BLJs occur most frequently at 230...     

流场配置及地形对西南低涡形成的动力作用

本文采用定常二层模式讨论较小地形及高、低层流场配置对西南低涡形成的动力作用。指出了西南低涡的形成是与盆地、河谷以及其上气流分层有关的一种定常态.在上、下为西风分层时期,低层的浅薄暖湿西风有利于西南低涡的形成.在上、下为东、西风分层时期,上层浅薄东风亦有利于西南低涡的形成.小型的凸起山脉对西南低涡的形成没有作用.