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1.
应用MODIS地表反照率产品MCD43C3,结合青藏高原自然带数据、积雪覆盖率和植被指数数据,采用一元线性回归方法分析了2000~2016年青藏高原地表反照率的分布及变化特征,结果表明:1）高原地表反照率空间分布差异大,整体上东南部低、西北部高,受地形和地表覆盖影响较大。2）高原地表反照率四季的空间分布变化明显,高海拔山脉和高寒灌丛草甸是高原地表反照率年内和年际变化的敏感地区。3）高原地表反照率年变化介于0.19~0.26,一定程度上表现为“双峰单谷”型,与地表覆盖类型的季节变化密切相关。4）高原地表反照率年际变化整体呈缓慢波动减小的趋势,平均变率约为－0.4×10-3 a-1,减小的区域约占高原总面积的66%,川西 —藏东针叶林带的西南部地区减小得最快,减小速率超过1.0×10-2 a-1。5）高原地表反照率减小与冰川消融和积雪减少密切相关,高原植被覆盖改善也是一个重要因素。 相似文献
2.
基于遥感数据监测若尔盖高原植被覆盖度变化 总被引：1，自引：0，他引：1
《高原气象》2016,(3)
基于1982-2006年的AVHRR NDVI和2000-2013年的MODIS NDVI数据,通过数据一致性拟合建立了若尔盖高原的1982-2 013年NDVI长时间序列数据集,在此基础上运用像元二分模型计算得到若尔盖高原32年的逐月植被覆盖度。验证结果表明,平均绝对误差为10.51%,均方根误差为13.49%,R~2为0.62,具有较好的精度,说明遥感估算值合理可信。根据遥感计算得到的植被覆盖度,分析了若尔盖高原1982-2013年植被覆盖度的时空变化规律。若尔盖高原32年平均植被覆盖度为43.77%,在空间上表现出东部高、西部低的分布特征。1982-2013年期间若尔盖高原植被覆盖度整体上呈现上升趋势,平均变化速率为0.08%·a~(-1),其中1982-2001年植被覆盖度呈较大幅度波动,但是没有明显的上升或者下降趋势,2001-2013年则呈现较明显的上升趋势。32年期间植被覆盖度年变化率的空间差异性显著,中心区域整体上呈现较低的上升趋势,而在大部分地区植被覆盖度显著上升和显著下降的区域交错分布。 相似文献
3.
植被覆盖变化对区域气候影响的研究进展 总被引：31，自引：4，他引：31
陆面植被覆盖变化作为全球及区域气候变化的重要影响因素之一，在近几十年来逐渐受到科学家们的关注，特别是通过大量的数值模拟研究了不同陆面覆盖状况对大气和气候变化的影响，取得了重要进展。研究结果普遍认为，植被覆盖变化通过改变地表反照率、粗糙度和土壤湿度等地表属性，从而影响辐射平衡、水分平衡等过程，最终可以导致区域降水、环流形势及大气温度、湿度等气候变化。总结了近十年国内外的相关研究及初步成果，尤其是植被变化对中国区域气候的影响，大部分研究认为，大范围植被退化使我国地表温度升高，东亚夏季风环流减弱，降水减少，使华北干旱加剧。同时指出了研究中存在问题及今后的工作重点。 相似文献
4.
利用2000～2016年MODIS地表反照率和ECMWF/ERA-Interim再分析资料,选取有代表性的高原季风指数DPMI,统计分析了青藏高原地表反照率与高原季风之间的联系,结果表明:1)11月高原地表反照率大小与次年高原夏季风爆发存在密切关系:11月高原地表反照率偏低(高),次年4月高原夏季风爆发偏早(晚),强度偏强(弱)。2)可能的影响机制为:当前期11月高原地表反照率偏低时,后期高原主体对大气的感热加热信号更强,从而引起4月高原上空近地面层上升运动明显加强,这有利于热量向高空传输,导致对流层加热作用加强,高原上空对流层温度偏高,使得高原季风环流系统加强,最终导致高原季风季节变化相应提前;反之亦然。 相似文献
5.
利用MODIS卫星资料反演中国地区晴空地表短波反照率及其特征分析 总被引：16，自引：0，他引：16
利用MODIS地表双向反照率产品(MOD43B1),结合地表海拔高度和地表覆盖类型资料,计算并分析了中国地区晴空反照率的时空分布,以及地表反照率与地形和地表覆盖的关系.首先,利用改则自动气象站的地基观测对MODIS地表反照率进行了对比验证.验证结果表明卫星观测可以较好地反映反照率随时间的变化,MODIS地表反照率与地表实测反照率符合较好.年平均地表反照率与海拔高度有很好的相关,反照率的高值出现在高海拔山区.冬春季节,我国高海拔山区因积雪覆盖成为反照率的高值区;夏秋季节,地表反照率主要受地表土壤湿度和植被盖度的影响,沙地和沙漠地带反照率最高.最后,计算了中国典型地表类型的反照率随时间的变化,结果表明大部分地表类型的反照率具有较大的时间变化,地表反照率在春秋季节较大,夏季反照率较小. 相似文献
6.
青藏高原地表特征时空分布 总被引：12，自引：3，他引：9
通过利用地理信息数据库、卫星反演参数、气象观测数据,分析了我国青藏高原地区地表植被覆盖、地表反照率分布、地表蒸发分布、地表积雪分布.结果显示,随着青藏高原地表年平均气温的显著升高,青藏高原部分区域地表覆盖特征也发生了改变.在青藏高原南缘湿润大区降水充分地区,地表反照率相对较低,潜热蒸发量最大,1982～2000年期间地表植被覆盖呈明显增加趋势.青藏高原地区积雪覆盖在各个气候区域也呈现同步变化特征,自1970～1989期间,降雪量呈持续增加趋势,但之后至2000年期间,全区降雪量呈下降趋势,其中积雪覆盖变化最强烈的时段发生在10月～4月之间,变化幅度最大的区域位于青藏高原的东南部区域. 相似文献
7.
本文在利用NOAA/AVHRR数据反演得到1982～2000年青藏高原地区地表反照率时空分布的基础上,分析了地表反照率的时空变化及其与温度和降水之间的关系,得到地表反照率与温度和降水之间的统计方程,并用此方程计算了青藏高原地区地表反照率的时空分布。研究结果表明：青藏高原地区年均地表反照率的分布与高原自然地理带的分布特征大致吻合;地表反照率与温度和降水均有较好的相关性,相关性因下垫面植被类型的不同而有较大的差异,滞后1个月的温度和滞后2个月的降水的综合作用与地表反照率的相关性最好;月均地表反照率与温度和降水之间的二元曲线回归方程可以比较好的统计回归计算出青藏高原地区地表反照率的空间分布,该模型的系统偏差比较小,回归计算的效果比较好。 相似文献
8.
青藏高原GLASS地表反照率产品精度分析 总被引：2，自引：0，他引：2
应用2003年青藏高原3个站点的地表反照率观测结果,对比分析了GLASS(Global LAnd Surface Satellites)地表反照率1 km×1 km分辨率产品的精度,结果表明,GLASS黑空反照率、白空反照率与地表反照率地面观测结果的总体变化趋势基本一致,能够有效地反映实际地表状态的变化;局地积雪和云覆盖对GLASS地表反照率产品的精度影响较大,云覆盖导致GLASS地表反照率可能比实际地表反照率高;消除云覆盖和局地积雪的影响后,GLASS黑空反照率、白空反照率与地表反照率地面观测结果的均方根误差显著降低,分别为0.0155和0.0190。 相似文献
9.
MODIS反照率产品在模拟黄河源区陆面过程和降水中的应用 总被引：4，自引：0，他引：4
地表反照率是陆面过程中一个重要的物理量, 其变化直接影响地表能量的收支状况, 进而可以影响气温和降水等其它气象要素。本文利用WRF (Weather Research and Forecasting) 模式, 通过两组数值模拟试验分别探讨了地表反照率改变在黄河源区不同下垫面情况下潜热、 感热的分配关系, 详细分析了地表反照率改变对降水变化的影响机制, 最后应用EOS/MODIS地表反照率产品替代原模式低时空分辨率的地表反照率。研究结果表明: (1)当地表反照率减少(增加)时, 模拟的区域平均地表温度、感热、潜热数值相应增大(减少)。当地表反照率减少0.1时, 地表温度上升约1.0 K, 感热和潜热量增量比约为3∶1。 (2) 地表反照率改变对降水量变化影响最大的区域是黄河源区下游的草场区域, 其次是黄河源头区域, 最小的是黄河源区北部的稀疏植被区域。地表反照率通过对大气动力、 热力以及水汽条件的影响, 使得降水发生的环境改变, 主要体现在: 当地表反照率减少时, 地表气压的减少使得大气低层的辐合气流增强, 有利于上升运动的发生; 2.0 m气温的升高增强了大气近地层的热力不稳定度; 2.0 m比湿的增加表明近地层空气水汽含量增加。 (3) 与实况对比分析发现, 使用卫星遥感产品后在月尺度上能够更准确地模拟降水量的变化过程。 相似文献
10.
为了揭示青藏高原三江源区草地退化对生态系统地表反照率的影响,利用2006年12月至2007年11月一整年的观测数据,分析了地表反照率的季和日变化特征及其影响因子。退化草地生态系统的年均地表反照率为0.22,生长季(5～9月)的平均地表反照率为0.18,非生长季为0.25。在植物生长初期的5月,地表反照率主要受土壤水分影响,5月末至6月初出现全年最低值;植物生长旺季的7～8月,受植被的影响地表反照率相对较稳定,并略高于生长季中其它各月。地表反照率的日变化呈"U"型,阴天的地表反照率高于晴天。全年地表反照率出现的最大频率集中在0.20附近,非生长季在0.22附近,生长季在0.18附近。退化草地生态系统生长季地表反照率的变化受土壤水分和植被的的影响,而非生长季受积雪的影响较大。 相似文献
11.
A numerical study of the influence of urban expansion on monthly climate in dry autumn over the Pearl River Delta, China 总被引：6，自引：0，他引：6
W. S. Lin C.-H. Sui L. M. Yang X. M. Wang R. R. Deng S. J. Fan C. S. Wu A. Y. Wang S. K. Fong H. Lin 《Theoretical and Applied Climatology》2007,89(1-2):63-72
Summary In this study, we employed a regional model to simulate the impact of urban expansion on monthly climate in Pearl River Delta
(PRD) region. Two experiments were performed by prescribing two different land covers in the PRD region. One land cover represents
vegetation in the 1970s which is derived from the United States Geological Survey (USGS) data with 24-category (hereafter
referred to as NU). The other land cover represents the current urban condition which is derived from remote sensing data
acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) in 2004 (hereafter referred to as HU). Using the two
land cover datasets, monthly climate of October 2004 was simulated, which was a very dry season in the PRD region. The results
obtained from the numerical simulation show a distinct difference in simulated shelter-level temperature, humidity, surface
fluxes and the height of planetary boundary layer (PBL) with two different land cover data sets being specified. The maximum
difference in simulated monthly mean temperature over urban areas was 0.9 °C. A large temperature difference was found in
urbanized area in Guangzhou, Dongguan, Zhongshan and Shenzhen. The monthly mean relative humidity in urban areas decreased
by 1.4% as a result of urban expansion (from 59.2% in NU to 57.8% in HU). The maximum decrease in mixing ratio was 0.4 g/kg
in Guangzhou and Dongguan, whereas the maximum decrease in relative humidity was 2.4%. There was an increase of sensible heat
flux in developed lands and the maximum increase was 90 W m−2. In contrast, latent hear flux in urban area decreased and the maximum decrease was 300 W m−2. In addition, the increase in mean height of PBL ranged from 20 to 80 m (HU compared with NU), and the maximum change of
the height was 180 m over urban area in city of Guangzhou. 相似文献
12.
In this paper, the effects of land cover changes on the climate of the La Plata Basin in southern South America are investigated using the Weather and Research Forecasting (WRF) Model configured on a 30/10km two-way interactive nested grid. To assess the regional climate changes resulting from land surface changes, the standard land cover types are replaced by time-varying Ecosystem Functional Types (EFTs), which is a newly devised land-cover classification that characterizes the spatial and interannual variability of surface vegetation dynamics. These variations indicate that natural and anthropogenic activities have caused changes in the surface physical parameters of the basin, such as albedo and roughness length, that contributed to regional climate changes. EFTs are obtained from functional attributes of vegetation computed from properties of the Normalized Difference Vegetation Index (NDVI) to represent patches of the land surface with homogeneous energy and gas exchanges with the atmosphere. Four simulations are conducted, each experimental period ranging from September to November in two contrasting years, 1988 and 1998. The influence of an identical EFT change on the surface heat fluxes, 2-m temperature and humidity, 10-m winds, convective instabilities and large-scale moisture fluxes and precipitation are explored for 1988 (a dry year) and 1998 (a wet year). Results show that the surface and atmospheric climate has a larger response to the same EFT changes in a dry year for 2-m temperature and 10-m wind; the response is larger in a wet year for 2-m water vapor mixing ratio, convective available potential energy, vertically integrated moisture fluxes and surface precipitation. For EFTs with high productivity and a weak seasonal cycle, the nearsurface temperature during the spring of 1988 and 1998 increased by as much as 1℃ in the central and western portions of La Plata Basin. Additionally, for higher productivity EFTs, precipitation differences were generally positive in both dry and wet years, although the patterns are not uniform and exhibit certain patchiness with drier conditions. 相似文献
13.
Noah S. Diffenbaugh 《Climate Dynamics》2005,24(2-3):237-251
In order to test the sensitivity of regional climate to regional-scale atmosphere-land cover feedbacks, we have employed a regional climate model asynchronously coupled to an equilibrium vegetation model, focusing on the western United States as a case study. CO2-induced atmosphere-land cover feedbacks resulted in statistically significant seasonal temperature changes of up to 3.5°C, with land cover change accounting for up to 60% of the total seasonal response to elevated atmospheric CO2 levels. In many areas, such as the Great Basin, albedo acted as the primary control on changes in surface temperature. Along the central coast of California, soil moisture effects magnified the temperature response in JJA and SON, with negative surface soil moisture anomalies accompanied by negative evaporation anomalies, decreasing latent heat flux and further increasing surface temperature. Additionally, negative temperature anomalies were calculated at high elevation in California and Oregon in DJF, MAM and SON, indicating that future warming of these sensitive areas could be mitigated by changes in vegetation distribution and an associated muting of winter snow-temperature feedbacks. Precipitation anomalies were almost universally not statistically significant, and very little change in mean seasonal atmospheric circulation occurred in response to atmosphere-land cover feedbacks. Further, the mean regional temperature sensitivity to regional-scale land cover feedbacks did not exceed the large-scale sensitivity calculated elsewhere, indicating that spatial heterogeneity does not introduce non-linearities in the response of regional climate to CO2-induced atmosphere-land cover feedbacks. 相似文献
14.
中国区域陆面覆盖变化的气候效应模拟研究 总被引：3，自引：0，他引：3
基于MODIS和CLCV陆面覆盖资料,利用区域气候模式RegCM4分别进行两组24年（1978-2001年）的数值模拟试验,研究中国区域陆面覆盖变化对区域气候的影响。结果表明,以荒漠化和植被退化为主要特征的陆面覆盖变化通过改变陆面能量、水分平衡与大尺度环流进而对气候要素产生重要影响。夏季,中国南方地区普遍降温,季风边缘区及藏北高原气温升高,降水减少;季风边缘区与西北地区气温年际波动加剧;内蒙古中东部地区西南风增强,进而水汽输送增强,一定程度上增加了该地区降水。冬季,中国东部地区偏北气流增强,更多干燥冷空气南下,使得黄河以南地区降水减少、气温降低。 相似文献
15.
The impact of land cover change on the atmospheric circulation 总被引：9，自引：1，他引：9
The NCAR Community Climate Model (version 3), coupled to the Biosphere Atmosphere Transfer scheme and a mixed layer ocean
model is used to investigate the impact on the climate of a conservative change from natural to present land cover. Natural
vegetation cover was obtained from an ecophysiologically constrained biome model. The current vegetation cover was obtained
by perturbing the natural cover from forest to grass over areas where land cover has been observed to change. Simulations
were performed for 17 years for each case (results from the last 15 years are presented here). We find that land cover changes,
largely constrained to the tropics, SE Asia, North America and Europe, cause statistically significant changes in regional
temperature and precipitation but cause no impact on the globally averaged temperature or precipitation. The perturbation
in land cover in the tropics and SE Asia teleconnect to higher latitudes by changing the position and strength of key elements
of the general circulation (the Hadley and Walker circulations). Many of the areas where statistically significant changes
occur are remote from the location of land cover change. Historical land cover change is not typically included in transitory
climate simulations, and it may be that the simulation of the patterns of temperature change over the twentieth century by
climate models will be further improved by taking it into account.
Received: 27 May 1999 / Accepted: July 2000 相似文献
16.
中国西部植被覆盖变化对北方夏季气候影响的数值模拟 总被引：6，自引：0，他引：6
植被覆盖的变化是气候变化的成因之一,植被改变对气候的反馈可能会加强或者减缓气候的变化.文中利用CCM3全球气候模式以及20世纪70年代和90年代中国西部的植被覆盖资料进行数值模拟试验,研究了这两个时期植被变化对北方夏季区域气候的影响.模拟结果表明:植被增加的地方,地面吸收的辐射通量增加;植被减少的地方,地面吸收的辐射通量减少.地面辐射平衡的变化造成局地大气热量异常,并引起周边大气热量的调整,从而导致东亚地区夏季大气环流异常.相对于70年代的植被状况,用90年代植被模拟的北方地区对流层上层为异常气旋性环流,而中、低层为异常反气旋环流,东北亚到中国东部盛行异常北风,同时西太平洋副热带高压强度偏弱、位置偏南.这种异常环流特征说明模拟的90年代中国东部夏季风明显减弱,异常的环流形势造成华北和东北地区夏季水汽输送减少,水汽辐合减弱,年降水量减少了40 mm,呈现减少的特征,这是和观测事实是比较吻合的.降水和环流的异常还造成华北和东北夏季平均地面气温降低了0.4-0.8℃.因此近30年来中国西部植被变化可能是东亚夏季风年代际变化以及北方夏季降水减少的一个重要因素. 相似文献
17.
土地利用变化对我国区域气候影响的数值试验 总被引：29，自引：0，他引：29
使用RegCM2区域气候模式单向嵌套澳大利亚CSIRO R21L9全球海-气耦合模式,通过将中国区域植被覆盖由理想状况改变为实际状况的数值试验对比分析,探讨了当代中国土地利用变化对中国区域气候的影响,并对结果进行了统计显著性检验。研究表明,土地利用的变化,会导致我国西北等地区年平均降水减少,导致年平均气温在内陆部分地区升高和在沿海个别地区降低,引起许多地方夏季日平均最高气温升高,而冬季日平均最低气温则在我国东部部分地区降低的同时在西北地区升高,土壤湿度的变化表现为大范围的降低。研究同时表明,相同的土地变化在不同的地理环境下引起的气候要素变化有一定的不一致性。 相似文献
18.
This study examines the role of vegetation dynamics in regional predictions of future climate change in western Africa using
a dynamic vegetation model asynchronously coupled to a regional climate model. Two experiments, one for present day and one
for future, are conducted with the linked regional climate-vegetation model, and the third with the regional climate model
standing alone that predicts future climate based on present-day vegetation. These simulations are so designed in order to
tease out the impact of structural vegetation feedback on simulated climate and hydrological processes. According to future
predictions by the regional climate-vegetation model, increase in LAI is widespread, with significant shift in vegetation
type. Over the Guinean Coast in 2084–2093, evergreen tree coverage decreases by 49% compared to 1984–1993, while drought deciduous
tree coverage increases by 56%. Over the Sahel region in the same period, grass cover increases by 31%. Such vegetation changes
are accompanied by a decrease of JJA rainfall by 2% over the Guinean Coast and an increase by 23% over the Sahel. This rather
small decrease or large increase of precipitation is largely attributable to the role of vegetation feedback. Without the
feedback effect from vegetation, the regional climate model would have predicted a 5% decrease of JJA rainfall in both the
Guinean Coast and the Sahel as a result of the radiative and physiological effects of higher atmospheric CO2 concentration. These results demonstrate that climate- and CO2-induced changes in vegetation structure modify hydrological processes and climate at magnitudes comparable to or even higher
than the radiative and physiological effects, thus evincing the importance of including vegetation feedback in future climate
predictions. 相似文献
19.
中国农田下垫面变化对气候影响的模拟研究 总被引：1，自引：0，他引：1
使用同期的美国国家环境预报中心/能源部(NCEP/DOE)再分析资料驱动区域气候耦合模式AVIM-RIEMS2.0,从遥感卫星图像资料中获取3期中国土地利用/覆盖数据中的农田植被类型,将其分别引入到AVIM-RIEMS2.0模式进行积分,研究中国农田下垫面变化对东亚区域气候的影响。结果表明:中国农田变化对气候影响具有冬季弱、夏季强的季节性变化,夏季气温和降水的差异在一些地区通过了95%的显著性检验;20世纪80年代农田扩张,林地、草地为主的植被类型转化为农田,植被变化区域的叶面积指数降低,反照率升高,且通过了95%的显著性检验,使得中国东部地区的气温由南到北呈现增加—减少—增加—减少的相间变化趋势,而降水的变化趋势大体相反;20世纪90年代农田面积减少,除东北地区外,农田变化引起的植被变化与80年代基本相反,叶面积指数变化、反照率以及由此导致的气候各要素也呈现大体相反的变化趋势;不同时期农田变化引起的植被类型转化的差异,使850 hPa风场变化趋势基本相反,可能是导致气温和降水变化趋势差异的主要原因之一。 相似文献
20.
Heidrun Matthes Annette Rinke Paul A. Miller Peter Kuhry Klaus Dethloff Annett Wolf 《Climatic change》2012,111(2):197-214
This paper discusses the effects of vegetation cover and soil parameters on the climate change projections of a regional climate
model over the Arctic domain. Different setups of the land surface model of the regional climate model HIRHAM were realized
to analyze differences in the atmospheric circulation caused by (1) the incorporation of freezing/thawing of soil moisture,
(2) the consideration of top organic soil horizons typical for the Arctic and (3) a vegetation shift due to a changing climate.
The largest direct thermal effect in 2 m air temperature was found for the vegetation shift, which ranged between −1.5 K and
3 K. The inclusion of a freeze/thaw scheme for soil moisture shows equally large sensitivities in spring over cool areas with
high soil moisture content. Although the sensitivity signal in 2 m air temperature for the experiments differs in amplitude,
all experiments show changes in mean sea level pressure (mslp) and geopotential height (z) throughout the troposphere of similar
magnitude (mslp: −2 hPa to 1.5 hPa, z: −15 gpm to 5 gpm). This points to the importance of dynamical feedbacks within the
atmosphere-land system. Land and soil processes have a distinct remote influence on large scale atmospheric circulation patterns
in addition to their direct, regional effects. The assessment of induced uncertainties due to the changed implementations
of land surface processes discussed in this study demonstrates the need to take all those processes for future Arctic climate
projections into account, and demonstrates a clear need to include similar implementations in regional and global climate
models. 相似文献