基于MODIS的华东地区气溶胶光学厚度时空变化特征分析

选用2001年1月-2015年12月MODIS数据,运用线性趋势等方法研究华东地区气溶胶光学厚度(AOD)的变化特征及影响因素。结果表明,2001-2015年华东地区AOD平均值变化范围在0.4~0.7之间,且呈现递减趋势。山东省西部、安徽省北部及江苏省AOD相对较高;福建省、浙江省南部及江西省南部地区AOD较低。华东地区气溶胶最低值出现在12月,最高值出现在6月;虽然冬季AOD变化趋势增长较高,但最高值仍出现在夏季。AOD主要受地形、NDVI、风速及人类活动等因素的影响,地形、NDVI、风速均与AOD呈负相关。     

Application of a new leaf area index algorithm to China's landmass using MODIS data for carbon cycle research

An operational system was developed for mapping the leaf area index (LAI) for carbon cycle models from the moderate resolution imaging spectroradiometer (MODIS) data. The LAI retrieval algorithm is based on Deng et al. [2006. Algorithm for global leaf area index retrieval using satellite imagery. IEEE Transactions on Geoscience and Remote Sensing, 44, 2219-2229], which uses the 4-scale radiative transfer model [Chen, J.M., Leblancs, 1997. A 4-scale bidirectional reflection model based on canopy architecture. IEEE Transactions on Geoscience and Remote Sensing, 35, 1316-1337] to simulate the relationship of LAI with vegetated surface reflectance measured from space for various spectral bands and solar and view angles. This algorithm has been integrated to the MODISoft platform, a software system designed for processing MODIS data, to generate 250 m, 500 m and 1 km resolution LAI products covering all of China from MODIS MOD02 or MOD09 products. The multi-temporal interpolation method was implemented to remove the residual cloud and other noise in the final LAI product so that it can be directly used in carbon models without further processing. The retrieval uncertainties from land cover data were evaluated using five different data sets available in China. The results showed that mean LAI discrepancies can reach 27%. The current product was also compared with the NASA MODIS MOD15 LAI product to determine the agreement and disagreement of two different product series. LAI values in the MODIS product were found to be 21% larger than those in the new product. These LAI products were compared against ground TRAC measurements in forests in Qilian Mountain and Changbaishan. On average, the new LAI product agrees with the field measurement in Changbaishan within 2%, but the MODIS product is positively biased by about 20%. In Qilian Mountain, where forests are sparse, the new product is lower than field measurements by about 38%, while the MODIS product is larger by about 65%.     

基于决策树的黑龙江省旱耕地分类

基于决策树和EOS/MODIS数据,参考黑龙江省的农事活动和农作物发育期数据,对该省旱耕地进行了分类。结果表明,利用MODIS较高时间分辨率的特点,提取该省植被物候信息,可以在较短时间内实现对旱耕地分布及面积的定量描述;由于黑龙江省的干湿冷暖差异较大,按气候特征分区进行旱耕地判识的效果较好,总体精度可达到85.27%,Kappa系数0.8415。该项研究可为黑龙江省旱耕地面积数据的及时获取提供参考。     

台湾海峡及周边海区气溶胶时空分布特征的遥感分析

首次利用连续3年(2002～2004)的MODIS气溶胶卫星遥感资料分析了台湾海峡及周边海区的气溶胶时空分布特征.研究表明,台湾海峡及周边海区气溶胶多年平均光学厚度沿岸呈带状分布且表现出随离岸距离呈指数降低的空间分布特征.各典型海区中,台湾海峡多年平均气溶胶光学厚度最高;其次为东海南部和南海北部,西北太平洋海区的气溶胶光学厚度最低.4个季节的气溶胶光学厚度时空分布特征明显不同,呈现出春季高、冬季略高于秋季、夏季低的特点.春季受我国北方沙尘天气影响,整个海区气溶胶光学厚度高于其它季节,达到0.32;沙尘气溶胶在冬季季风的作用下能够向南跨越东海,最远传输到西北太平洋海区上空,使得该海区的气溶胶光学厚度值达到0.22,明显高于其它季节,夏季则由于东南季风和多降雨天气的影响,陆源污染物向海扩散条件差,气溶胶光学厚度低,仅为0.12,气溶胶类型分布分析表明,近岸海区的气溶胶类型主要以来自陆源的污染和烟尘气溶胶为主,春、秋以及冬季在大气动力的作用下可以输送到较远的海区上空;远岸海区的气溶胶类型则可能主要以海盐气溶胶或沙尘气溶胶(春季)为主;近远海之间海区的气溶胶类型分布则主要以污染气溶胶和海盐气溶胶(或沙尘气溶胶)混合为主.     

北疆地区MODIS 3km气溶胶光学厚度与PM10质量浓度的相关性分析

利用2016年MODIS 3 km分辨率的气溶胶光学厚度(AOD)日产品、PM_(10)质量浓度以及相关气象数据,开展了北疆地区AOD与PM_(10)质量浓度的相关性分析.结果表明,AOD与PM_(10)质量浓度的直接相关程度较低,相关系数仅为0.294.对比分析了利用能见度数据对AOD进行垂直订正,然后再用相对湿度数据对其进行二次订正(AOD垂直-湿度订正)和利用能见度数据对AOD进行垂直订正和相对湿度数据对PM_(10)质量浓度进行订正(AOD垂直订正-PM_(10)湿度订正)两种订正方法,结果指出"AOD垂直订正-PM_(10)湿度订正"可显著提高二者之间的相关性.订正之后,北疆地区AOD与PM_(10)质量浓度的相关系数达到0.755,呈显著正相关;阿勒泰的订正效果最好,相关系数为0.837.最后,基于垂直订正后的AOD和湿度订正后PM_(10)建立两者之间的最优拟合模型,并利用新建的模型反演了北疆地区PM_(10)质量浓度.反演得到的PM_(10)质量浓度与经过湿度订正后PM_(10)呈显著正相关,相关系数为0.688;昌吉和伊宁的反演效果最好,相关系数分别为0.910和0.829.本研究结果表明MODIS 3 km AOD产品经过垂直和湿度订正后,可作为北疆地区监测PM_(10)质量浓度的一个有效手段.     

基于遥感估产的2006—2015年青海果洛与玉树地区草畜平衡分析

三江源区草地资源丰富,开展草畜平衡研究,可为草原环境保护和区域经济可持续发展提供决策支持。论文以青海省果洛藏族自治州和玉树藏族自治州作为研究区,基于产草量反演和载畜量计算,结合草畜平衡指数和草地载畜压力指数两大指标开展草畜平衡分析。结果表明：2006—2013年两自治州的平均草畜平衡指数自47.1%变化至-13.8%,草畜平衡状况整体在不断改善,2014—2015年超载情况有所加重;相比于果洛藏族自治州的年均草畜平衡指数为38.15%,玉树藏族自治州的年均草畜平衡指数为33.51%,草畜平衡状况较好。建议两地区有关部门加强规划和政策调控,按照“以草定畜”的原则加强草畜平衡精细化管理,并以大数据驱动草畜平衡决策支持信息化建设。     

Vegetation Mapping for Change Detection on an Arid-Zone River

A vegetation mapping system for change detection was tested at the Havasu National Wildlife Refuge (HNWR) on the Lower Colorado River. A low-cost, aerial photomosaic of the 4200 ha, study area was constructed utilizing an automated digital camera system, supplemented with oblique photographs to aid in determining species composition and plant heights. Ground-truth plots showed high accuracy in distinguishing native cottonwood (Populus fremontii) and willow (Salix gooddingii) trees from other vegetation on aerial photos. Marsh vegetation (mainly cattails, Typha domengensis) was also easily identified. However, shrubby terrestrial vegetation, consisting of saltcedar (Tamarix ramosissima), arrowweed (Pluchea sericea), and mesquite trees (Prosopis spp.), could not be accurately distinguished from each other and were combined into a single shrub layer on the final vegetation map. The final map took the form of a base, shrub and marsh layer, which was displayed as a Normalized Difference Vegetation Index map from a Landsat Enhanced Thematic Mapper (ETM+) image to show vegetation intensity. Native willow and cottonwood trees were digitized manually on the photomosaic and overlain on the shrub layer in a GIS. By contrast to present, qualitative mapping systems used on the Lower Colorado River, this mapping system provides quantitative information that can be used for accurate change detection. However, better methods to distinguish between saltcedar, mesquite, and arrowweed are needed to map the shrub layer.     

Long-Term Observation of Asian Dust in Changchun and Kagoshima

Monitoring of Asian dust at two stations in Changchun, Jilin Province in northeast China, and Kagoshima, southwest Japan, is discussed. In Changchun, interval records were made with digital and video cameras from 18 March 2003. In Kagoshima, a web camera system to monitor volcanic clouds has been working since December 2000, which also provides data for studies of dust. A heavy dust episode on 11 November 2002, affecting both stations, was detected using 11 and 12 μm channels of NOAA/AVHRR. We observed dust in Changchun on 26 March, 7, 14–16 April, 1–2, 8, 10, 19 May, 8, 23 June, and 12 July in 2003. The observed images corresponded well to NOAA/AVHRR imagery and with 8.6, 11 and 12 μm Terra/MODIS results, although conditions were too cloudy for satellite verification in some cases.     

福建近岸海域悬浮泥沙浓度遥感定量监测研究

论文在分析MODIS数据对海洋水体反射光谱特征的基础上,选用合适的探测波段构成悬浮泥沙遥感参数,并根据2003~2004年福建近岸海域海洋监控区内9个站点的海洋水色数据建立悬浮泥沙浓度遥感定量反演模式。利用已建立的模式对2001~2005年福建近岸海域悬浮泥沙浓度进行遥感反演,根据反演结果分析该海域悬浮泥沙浓度的分布及其变化特征,着重分析闽江口海域的悬浮泥沙运动特点。结果表明:福建近岸海域悬浮泥沙浓度与基于MODIS蓝光(0.438~0.448μm)和绿光(0.545~0.565μm)探测波段数据构成的遥感参数呈指数函数关系,定量反演效果比较理想,反演结果能客观地揭示福建近岸海域悬浮泥沙的浓度分布及其变化特征,为今后对该海域悬浮泥沙运动规律的深化研究奠定了基础。     

近10年中国大陆MODlS遥感气溶胶光学厚度特征

应用2001-2010年MODIS大气气溶胶光学厚度（AOD）资料,分析中国550nmAOD年和季节平均分布。还选取了10个代表性区域,分析AOD变化特征。这些分析建立起了近10年来中国气溶胶光学厚度的气候学特征：中国年平均AOD空间区域分布中心大体呈现两低两高。两低中心位于植被覆盖度高和人烟稀少的（1）黑龙江和内蒙古东北高纬度地区（－0．2）;（2）川、滇与青藏高原交界的西南高海拔地区（0．1-0．2）。一个AOD低值带（0．2－0．3）连接这两个低中心,呈东北西南走向跨过中国大陆。在此低值带两侧,各有一片AOD高值中心（－0．8）：（1）人口密集和工业化发展带来的大量人为气溶胶形成了一个覆盖了华北、长江流域（从四川盆地,两湖地区到长三角）到华南珠江三角洲相联的大片高AOD中心区域;（2）以沙尘为主的自然气气溶胶造就了西北塔克拉玛干沙漠及周边高AOD区。中国AOD这一两低两高区域分布特征基本保持四季不变,但其中心强度呈现各自区域性季节变化。中国春季AOD高值区的面积最大,其次是夏季,然后是秋季,面积最小的是冬季。南方AOD月变化规律多为双峰型,即3－5和8－9月出现2次高峰,5－7月从南向北先后出现波谷,变化规律与季风响应。北方为单峰型,6－7月为高峰,11到来年2月为低谷。用弱季风年（2002）和强季风年（2003）季风影响区域气象条件和气溶胶数据对比分析表明,大陆AOD的月空间分布和变化与季风气候,以及风速、风向、降水、温度和湿度等的变化有关。