Monitoring hydrological controls on dust emissions: preliminary observations from Etosha Pan, Namibia

Atmospheric dust loadings have a significant influence on global climate by affecting air temperatures through the absorption and scattering of solar radiation. Many dryland basins are significant sources of aeolian dust, but our knowledge of how dust emissions from these systems are affected by ephemeral wetting events is either limited or poor. This research uses synergistic data sets (Total Ozone Mapping Spectrometer (TOMS) and Advanced Very High Resolution Radiometer (AVHRR)) in order to identify possible hydrological controls on aeolian dust emissions from the Etosha Basin, Namibia. Data suggest that individual inundation events (detected by AVHRR) within this basin have a marked effect on immediate and subsequent dust emissions (detected by TOMS). This study also outlines the contribution of dust emissions from both the pan surface and from the ephemeral oshanas region to the north of the Etosha Basin to the persistent dust plume, and highlights the complexity of the interactions between hydrology, land use and dust emissions within ephemeral basins.     

多源信息复合NOAA影像在大尺度景观制图中的应用——以中国东北区为例

以中国东北区为例,基于GIS和RS技术,探讨应用NOAA/AVHRR数据编制景观类型图过程中如何提高制图精度。采用多源信息复合NOAA/AVHRR影像分类方法,复合影像分为:1)数字地学综合影像,由年均降水、≥10℃活动积温和数字高程模型(DEM)叠加而成,主要考虑了植被受气候以及地形的影响;2)NOAA/AVHRR四季累加影像的第一主成分影像,在一定程度上去除了多波段NOAA数据冗余;3)NOAA/AVHRR四季NDVI累加值影像,突出了植被信息。将研究区景观(土地)类型进行二级划分,其中一级划分为6大类,二级划分为16类,结果与研究区实际情况基本相符,分类精度达70%。     

利用NOAA/AVHRR资料监测南方林区森林火灾的研究

本文论述了南方林区森林火灾时间分布集中、发生率高、面积小,并以地表火为主的特征;总结了气象卫星资料的林火信息特征和非林火干扰信息规律;研究了建造林火监测专家系统的理论方法,进而提出了林火宏观实时监测系统的总体设计,并建立了以计算机图像处理为基础的、以林火背景数据库支持的、以专家系统为核心的林火监测系统。并利用南方林火模拟实验和历史林火资料对该监测系统进行了改进。最后讨论了林火监测系统改进方向和研究体会。     

Recruitment of coastal fishes and oceanographic variability in central California

Recruitment of pelagic larval fishes to the nearshore environment is dependent on a suite of biological and physical processes operating at many spatial and temporal scales. Nearshore circulation processes associated with coastal upwelling are widely upheld as major determinants of year class strength for many rockfishes (Sebastes spp.), but the mechanism by which these processes drive recruitment is largely unknown. We used Standard Monitoring Units for the Recruitment of Fishes (SMURFs) to monitor recruitment of two rockfish complexes (Sebastes spp.) and cabezon (Scorpaenichthys marmoratus) from March to September of 2004 and 2005 at 3 sites along the central California coast. We examined the relationship between recruitment of these fishes and measurements of oceanographic variability associated with upwelling dynamics, including in situ water temperature, AVHRR sea surface temperature, the Bakun upwelling index, and an index of alongshore surface water transport. We found that rockfish comprising the KCGB complex (Sebastes atrovirens, Sebastes caurinus, Sebastes carnatus, Sebastes chrysomelas) recruit during early summer, while fishes of the BYO complex (Sebastes melanops, Sebastes flavidus, Sebastes serranoides), as well as cabezon recruit during late summer. Our results provide limited support for an association between the arrival of juvenile pelagic rockfish and cabezon to the nearshore environment and physical processes related to upwelling and relaxation. Beyond the limitations of our bimonthly sampling scheme, the lack of a clear pattern may be related to the near absence of upwelling–relaxation cycles along this stretch of coast during these two study periods. Moreover, the settlement and recruitment of nearshore fishes may be closely tied to processes occurring earlier in the larval stage.     

Assessment of waterlogging risk in Lixiahe region of Jiangsu Province based on AVHRR and MODIS image

Four images of 1991 AVHRR, 2003 and 2007 MODIS were used to extract waterlogging inundated water of three years, and three inundated water maps were overlaid to estimate waterlogging affected frequency. Based on waterlogging affected frequency, waterlogging hazard of pixel scale was assessed. According to the weighed score of area percentage of different waterlogging affected frequency in 13 counties/cities of Lixiahe region, waterlogging hazard rank of every county/city was assessed. Waterlogging affected frequency map and 1 km× 1 km grid landuse map were used to assess waterlogging risk of pixel scale; and then waterlogging risk rank of every county/city was assessed by the similar method by which waterlogging hazard rank of every county/city was assessed. High risk region is located mainly in core zone of Lixiahe hinterland, medium risk region is adjacent to high risk region, and low risk region is located in the most outlying area of risk zone and mainly in south to middle part of Lixiahe region. Xinghua and Gaoyou belong to high risk city, Jiangyan belongs to medium risk city, and the other counties/cities have low or lower waterlogging risk. The method of assessing waterlogging risk in this paper is simple and applicable. This paper can provide guidance for the waterlogging risk analysis in broader area of Huaihe River Basin.     

基于MODIS冬小麦长势监测研究

本文在对比分析MODIS NDVI与AVHRR NDVI的系统误差基础上,以MODIS/AVHRR卫星资料、地面农情观测资料为主要数据源,开发出淮北平原冬小麦长势监测旬、月MODIS NDVI比较模型和MODIS NDVI半定量监测指标模型,该模型在2005年检验应用中得到与实际较一致结果。     

利用NOAA/AVHRR监测青海省草地生产力变化的研究

青海省地处青藏高原，生态环境脆弱。近20年来，由于气候变化和人类活动的共同影响，生态环境，特别是草地资源发生了较大的变化。利用美国地球资源观测系统数据中心探路者数据库(Pathfinder Data Sets)1981-1999年间的NOAA／AVHRR NDVI资料序列，分析了青海省近20年来草地生产力变化的时间特征及地区差异性。     

中红外和热红外在测算水稻种植面积上的应用

在利用ＡＶＨＲＲ数据测算水稻种值面积中,对ＡＶＨＲＲ各通道数据进行统计特征分析和影象线性拉伸处理,发现其中红外（ＣＨ３）和热红外（ＣＨ４）通道信息量丰富,且在中红外和热红外拉伸影象上存在稻田的这温较旱地低－“稻区低温”现象。因此,在测算水稻种植面积时,半加了第３、４两通道－中红外和热红外通道。实际应用证明：增加两红外通道非常有助于水稻鉴别。     

树木年轮研究的扫描图像分析方法及其在环境演变中的应用

本文主要探讨用普通扫描仪作为获取树轮信息手段的有效途径,以及研究将图像分析和数字处理技术应用于树木年轮学的方法。通过对树轮图像的分布特征和噪声变化规律的统计分析,本文设计出一套图像分割、信息提取算法和相应的处理程序。从实际的应用效果以及与其它树轮研究方法所作的对比分析结果表明,这种扫描图像处理方法不仅可行,而且高效、准确,拓宽了树木年轮学方法在环境演变研究中的应用途径。     

A-HIGHERS—The System to Produce the High Spatial Resolution Sea Surface Temperature Maps of the Western North Pacific Using the AVHRR/NOAA

To study on the oceanic variations in the western North Pacific, we developed a system to produce a high spatial resolution sea surface temperature (SST) map from the data obtained by the Advanced Very High Resolution Radiometer (AVHRR) aboard the National Oceanic and Atmospheric Administration (NOAA) satellites. As the system has been improved on the HIGHERS (Sakaida and Kawamura, 1996), it is called the Advanced-HIGHERS (A-HIGHERS). The A-HIGHERS has been developed on the super computer in the Tohoku University, which is favorable for handling of a large volume of data. Mainly because of improvements in the cloud detection algorithm, the A-HIGHERS can deal with the data obtained at dawn and dusk around the year, and at daytime in summer more effectively. The A-HIGHERS are used to produce SST maps spanning from (60°N, 120°E) to (20°N, 160°E) with a grid size of 0.01 degree.