秋季季风转换期间台湾海峡遥测叶绿素a的年际变动

The time series of multiple sources of satellite data are used to examine the interannual variability of chlorophyll a concentration （Chl a） and its relation to the physical environment during the autumn monsoon transitional period in the Taiwan Strait （TWS）. The satellite data included the Chl a concentration and sea surface temperature （SST） derived from the Moderate Resolution Imaging Spectroradiometer （MODIS）/ Aqua as well as the multi-sensors merged wind products from 2002 to 2012. The results show that the average Chl a concentration of the whole TWS is mainly contributed by the northern TWS. The average Chl a in the northern TWS is 3.6 times that in the southern TWS. The maximum variability of Chl a is located in the frontal regions between the cold Zhe-Min Coastal Water and the strait warm water. The temporal change of Chl a concentration is different in the northern and southern TWS. The changes in the relative strength of the cold and warm water masses is suggested to be the dominant processes in controlling the phytoplankton growth in the northern TWS, while there is wind-induced mixing in the southern TWS. Additionally, La Nina events exhibited complex effects on the interannual variability of Chl a concentration in autumn. The longterm time series of physical and biological observations are especially needed to better understand how the TWS complex ecosystem responds to climate variations.     

气候模式和再分析数据中北冰洋中层水再现能力的评估

The simulations of the Arctic Intermediate Water in four datasets of climate models and reanalyses, CCSM3, CCSM4, SODA and GLORYS, are analyzed and evaluated. The climatological core temperatures and depths in both CCSM models exhibit deviations over 0.5°C and 200 m from the PHC. SODA reanalysis reproduces relatively reasonable spatial patterns of core temperature and depth, while GLORYS, another reanalysis, shows a remarkable cooling and deepening drift compared with the result at the beginning of the dataset especially in the Eurasian Basin(about 2°C). The heat contents at the depth of intermediate water in the CCSM models are overestimated with large positive errors nearly twice of that in the PHC. To the contrary, the GLORYS in 2009 show a negative error with a similar magnitude, which means the characteristic of the water mass is totally lost. The circulations in the two reanalyses at the depth of intermediate water are more energetic and realistic than those in the CCSMs, which is attributed to the horizontal eddy-permitting resolution. The velocity fields and the transports in the Fram Strait are also investigated. The necessity of finer horizontal resolution is concluded again. The northward volume transports are much larger in the two reanalyses, although they are still weak comparing with mooring observations. Finally, an investigation of the impact of assimilation is done with an evidence of the heat input from assimilation. It is thought to be a reason for the good performance in the SODA, while the GLORYS drifts dramatically without assimilation data in the Arctic Ocean.     

Spatial and temporal variability in the net primary production of alpine grassland on the Tibetan Plateau since 1982简

Based on the GIMMS AVHRR NDVI data （8 km spatial resolution） for 1982-2000, the SPOT VEGETATION NDVI data （1 km spatial resolution） for 1998-2009, and observa- tional plant biomass data, the CASA model was used to model changes in alpine grassland net primary production （NPP） on the Tibetan Plateau （TP）. This study will help to evaluate the health conditions of the alpine grassland ecosystem, and is of great importance to the pro- motion of sustainable development of plateau pasture and to the understanding of the func- tion of the national ecological security shelter on the TP. The spatio-temporal characteristics of NPP change were investigated using spatial statistical analysis, separately on the basis of physico-geographical factors （natural zone, altitude, latitude and longitude）, river basin, and county-level administrative area. Data processing was carried out using an ENVI 4.8 platform, while an ArcGIS 9.3 and ANUSPLIN platform was used to conduct the spatial analysis and mapping. The primary results are as follows： （1） The NPP of alpine grassland on the TP gradually decreases from the southeast to the northwest, which corresponds to gradients in precipitation and temperature. From 1982 to 2009, the average annual total NPP in the TP alpine grassland was 177.2x1012 gC yrl（yr represents year）, while the average annual NPP was 120.8 gC m^-2 yr^-1. （2） The annual NPP in alpine grassland on the TP fluctuates from year to year but shows an overall positive trend ranging from 114.7 gC m^-2 yr^-1 in 1982 to 129.9 gC m^-2 yr^-1 in 2009, with an overall increase of 13.3%; 32.56% of the total alpine grassland on the TP showed a significant increase in NPP, while only 5.55% showed a significant decrease over this 28-year period. （3） Spatio-temporal characteristics are an important control on an- nual NPP in alpine grassland： a） NPP increased in most of the natural zones on the TP, only showing a slight decrease in the Ngari montane desert-steppe and desert zone. The positive trend in NPP in the high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone is more significant than that of the high-cold desert zone; b） with in- creasing altitude, the percentage area with a positive trend in annual NPP follows a trend of ＂increasing-stable-decreasing＂, while the percentage area with a negative trend in annual NPP follows a trend of ＂decreasing-stable-increasing＂, with increasing altitude; c） the varia- tion in annual NPP with latitude and longitude co-varies with the vegetation distribution; d） the variation in annual NPP within the major river basins has a generally positive trend, of which the growth in NPP in the Yellow River Basin is most significant. Results show that, based on changes in NPP trends, vegetation coverage and phonological phenomenon with time, NPP has been declining in certain places successively, while the overall health of the alpine grassland on the TP is improving.     

内蒙古自治区地理国情普查方法浅谈

本文介绍了地理国情普查的意义、普查依据与技术规定、普查对象。并对开展地理国情普查方法进行了详细的说明。     

不同空间分辨率DEM提取地形因子的不确定性研究——以福建省泉州市环湾规划区为例

文章以福建省泉州市环湾规划区1∶1万比例尺DEM数据为信息源,研究不同DEM分辨率对坡度、坡向信息的不确定性影响。通过对不同空间分辨率DEM坡度、坡向数据进行比较分析,获得不同空间分辨率DEM对地形因子的影响情况。结果表明,DEM的数值越大,分辨率越低,对地形的概括作用越明显,地形越趋近于平坦化。     

Effects of a Remotely Sensed Land Cover Dataset with High Spatial Resolution on the Simulation of Secondary Air Pollutants over China Using the Nested-grid GEOS-Chem Chemical Transport Model简

A number of remotely sensed land cover datasets with spatial resolutions ~〈 1 km have recently become available or are in the process of being mapped. The application of these higher resolution and more up-to-date land cover datasets in chemical transport models （CTMs） is expected to improve the simulation of dry deposition and biogenic emissions of non-methane volatile organic compounds （NMVOCs）, which affect ozone and other secondary air pollutants. In the present study, we updated the land cover dataset in the nested-grid GEOS-Chem CTM with the 1 km resolution GLC2000 land cover map and examined the resulting changes in the simulation of surface ozone and sulfate over China in July 2007. Through affecting the dry deposition velocities of ozone and its precursors, using GLC2000 in the dry deposition module can decrease the simulated surface ozone by 3% （up to 6 ppb） over China. Simulated surface sulfate shows an increase of 3% in northwestern China and a decrease of 1% in northern China. Applying GLC2000 in the biogenic emissions of the NMVOC module can lead to a 0.5--4.5 ppb increase in simulated surface ozone over East China, mainly driven by the larger cove~：age of broadleaf trees in East China in the GLC2000 dataset. Our study quantifies the large sensitivity to land cover dataset~ with different spatial resolutions and time periods of simulated secondary air pollutants over China, supporting ongoing research efforts to produce high resolution and dynamically updated land cover datasets over China, as well as for the globe.     

Mapping near-surface air temperature,pressure, relative humidity and wind speed over Mainland China with high spatiotemporal resolution

As part of a joint effort to construct an atmospheric forcing dataset for mainland China with high spatiotemporal reso- lution, a new approach is proposed to construct gridded near-surface temperature, relative humidity, wind speed and surface pressure with a resolution of 1 km× 1 km. The approach comprises two steps： （1） fit a partial thin-plate smoothing spline with orography and reanalysis data as explanatory variables to ground-based observations for estimating a trend surface; （2） apply a simple kriging procedure to the residual for trend surface correction. The proposed approach is applied to observations collected at approximately 700 stations over mainland China. The generated forcing fields are compared with the corresponding components of the National Centers for Environmental Predic- tion （NCEP） Climate Forecast System Reanalysis dataset and the Princeton meteorological forcing dataset. The comparison shows that, both within the station network and within the resolutions of the two gridded datasets, the interpolation errors of the proposed approach are markedly smaller than the two gridded datasets.     

Examining Forest Net Primary Productivity Dynamics and Driving Forces in Northeastern China During 1982–2010

Forest net primary productivity （NPP） is a key parameter for forest monitoring and management. In this study, monthly and annual forest NPP in the northeastern China from 1982 to 2010 were simulated by using Carnegie-Ames-Stanford Approach （CASA） model with normalized difference vegetation index （NDVI） sequences derived from Advanced Very High Resolution Radiometer （AVHRR） Global Invento y Modeling and Mapping Studies （GIMMS） and Terra Moderate Resolution Imaging Spectroradiometer （MODIS） products. To address the problem of data inconsistency between AVHRR and MODIS data, a per-pixel unary linear regres- sion model based on least ~;quares method was developed to derive the monthly NDVI sequences. Results suggest that estimated forest NPP has mean relative error of 18.97% compared to observed NPP from forest inventory. Forest NPP in the northeastern China in- creased significantly during the twenty-nine years. The results of seasonal dynamic show that more clear increasing trend of forest NPP occurred in spring and awmnn. This study also examined the relationship between forest NPP and its driving forces including the climatic and anthropogenic factors. In spring and winter, temperature played the most pivotal role in forest NPR In autumn, precipitation acted as the most importanl factor affecting forest NPP, while solar radiation played the most important role in the summer. Evaportran- spiration had a close correlation with NPP for coniferous forest, mixed coniferous broadleaved forest, and broadleaved deciduous forest. Spatially, forest NPP in the Da Hinggan Mountains was more sensitive to climatic changes than in the other ecological functional re- gions. In addition to climalie change, the degradation and improvement of forests had important effects on forest NPP. Results in this study are helpful for understanding the regional carbon sequestration and can enrich the cases for the monitoring of vegetation during long time series.     

DEM分辨率与平均坡度的关系分析

由DEM提取坡度时,DEM分辨率的变化会造成局部栅格提取的坡度数值的变化,其变化规律对于深刻理解平均坡度,随DEM分辨率的变化而变化的规律具有现实意义。在黄土高原的研究中,选择了8个典型地貌类型的样区,获得了以1:10 000比例尺地形图为数据源的DEM(分辨率为5 m)。从DEM分辨率对栅格坡度影响规律的分析中,得到如下结论:(1)随着DEM分辨率粗略化,所提取的坡度平均值有可能升高;(2)在所有样区,随DEM分辨率粗略化,负误差的栅格均是正误差的栅格数量的1.13倍以上,保持负误差的栅格是保持正误差的栅格数量的1.81-4.04倍,同时坡度的负误差均值是正误差均值变化幅度的3.1倍以上;(3)结合结论(2)和本文提出的指标,可准确地解释8个样区中坡度平均值随DEM分辨率变化而变化的规律;(4)DEM的分辨率对正负误差的栅格数量没有明显影响,正误差(或负误差)栅格均集中于个别坡度的分级区间,而DEM分辨率对此集中的区间没有明显影响;(5)坡度总体误差可根据本研究所提出的经验公式由DEM分辨率和分辨率为5 m的DEM所提取坡度的平均值计算出来。