With rapid urbanization and industrialization, urban heat island effect in Shanghai is increasing. Based on the observed
data, image data, and statistic data, temporal variation and spatial distribution of urban heat island and its relationship
with urbanization factors in Shanghai was analyzed in this study. The results indicated the UHI index between urban and
rural area increased with a rate of 0.2°C per 10 years from 1959 to 2005, while that between urban and suburban
decreased from 1995, that is to say, the heat island in Shanghai expanded. The increasing UHI index between urban and
rural area and the decreasing UHI index between urban and suburb area are related to the increase trend of mean annual
temperature among districts. The UHI in Shanghai is stronger in urban area, Minhang, Northeast and middle Songjiang,
and South Jinshan. The distribution of UHI is well corresponding with the land use types, both urban area and 9 towns in
Shanghai are all heat islands. A good logarithmic relationship was obtained between UHI index and the number of
operating buses, area of building completed, area of paved road and gross domestic product, and a good linear
relationship was occurred between UHI index and the final consumption of energy by industry, power consumption of
industry, total registered population and area of cultivated land.
Based on the meteorological data, land use date from TM images and social statistical data, the evidences of regional
temperature change with the elements of mean annual temperature, mean annual maximum and minimum temperature,
and extreme high and low temperature from 1959 to 2005, were detected, and the impact of human activities on
temperature was analyzed in the Yangtze Delta region. The results indicated an increase in mean annual temperature,
mean annual maximum and minimum temperature. Mean annual temperature in all cities in the region increased, and
the increase rate in winter was greater than that in spring and autumn. The increase of mean annual maximum and
minimum temperature was similar to that of mean annual temperature spatially. In 3 stations of Shanghai, Nanjing and
Hangzhou, most hot days, least cold days and the highest mean temperature all appeared in the first 5 years in this
century. Land use changed greatly, and a large amount of cropland was replaced with residential and constructional
areas (R/C areas) from 1980 to 2000 in the Yangtze Delta region. The change of mean annual temperature was partly
corresponding to the change of land use. Total registered population increased rapidly in 16 cities of the Yangtze Delta
region, and a good linear correlation between the tendency ratio of total registered population and the mean annual
temperature in 16 cities from 1978 to 2005. Total amount of energy consumption and GDP increased in 3 provinces of
Shanghai, Jiangsu and Zhejiang where the Yangtze Delta located, both the final consumption of energy by industry and
GDP had a relatively good linear relationship with the mean annual temperature in Shanghai from 1952 to 2005. This
paper will help the understanding and attribution of climate change and simulation of the future response of
weather-related disasters under various global change scenarios.
NPP is not only the original driver of carbon cycle, but also has significance in global change research. In this study, NPP data from GLO-PEM model and Chinese plantation data were used to explore the spatial and temporal changes of NPP in Chinese plantation area from 1981 to 2000. As the results, mean annual NPP in Chinese plantation area was about 663.37gCm-2yr-1 in the past 20 years, with higher NPP in several provinces in South China, and lower NPP in some arid and semi-arid regions in Northeast China, North China and Northwest China. NPP increased more in the eastern part of North China and in Central China and South China, but decreased in most regions of West China, North Liaoning, East Jilin and North Heilongjiang. Monthly variation of plantation NPP was mainly in phase from June to September, especially in July and August during the 4th times from 1996 to 2000, monthly NPP increased most. Mixed plantation had the highest mean annual NPP and coniferous plantation had the least. Plantation in East China had higher mean annual NPP, annual NPP increase rate and monthly NPP variation than that in West China. The increment of total annual NPP in Chinese plantation from 1980's to 1990's was 84.51×104tCyr-1. Plantation in Hainan province had the highest mean annual NPP and NPP increase, and plantation in Guangdong province had the largest total annual NPP increase in the past 20 years, but in Xinjiang province, mean annual NPP in plantation area was lowest and decreasing.
Desertification is a worldwide concern and the assessment of aeolian desertification has become one hotspot in global ecosystem research. In this paper, hyperspectral data acquired from modular OMIS-I imaging spectrometer, combined with ETM data and field survey data, was used to assess the aeolian desertification in Korqin Sand, Inner Mongolia, China by pixel-level. The results indicated that hyperspectral image, combined with ETM image and little field works, is capable to monitor and assess desertification through quantitative retrieval of assessing parameters directly from hyperspectral data or indirectly from the encoding map by visual interpretation of hyperspectral image and ETM image. For the retrieval of vegetation biomass and coverage, polynomial fit curve is suitable to regions where shrubs and grasses coexist, while linear fit curve is suitable to single vegetation type and was highly restricted by region. The retrieval of surface soil water content based on soil thermal inertia is suitable in flat terrain and sparse vegetation, and it can resist vegetation disturbance. The algorithms for numerical evaluation and quantitative retrieval for hyperspectral image are also practicable for aeolian desertification in Korqin Sand, China.
A classifier of great capabilities and a good-selection of different features are two key and difficult keys answering for a high accuracy classification result. On the classifier, although there are all kinds of algorithms, most of them couldn't be used widely because of multifarious theoretical limitations. In this paper, based on the TM data, several representative interpretation features, including original bands, texture measurements and spatial metrics, are compared systemically for landcover/landuse classification test with the same classifier and the same training samples. The results show that different feature source has different relationship with the original band and they play the different roles. Summarily, the original bands are the most useful and essential feature source and play the important role and the others can only be seen as equivalent or enhanced feature source. Among which, the texture mean have equivalent capability as that of the original bands, and the spatial metrics and other texture measurements can be seen as compensatory source. For the combination of different features, the classification accuracy can be improved by using the texture measurements or the combination with original bands. As a sort of newly features, the classification accuracy was very poor if only landscape metrics were used, comparatively the accuracy can be greatly improved by combing with the original bands. So, the combination of original bands and texture measurements is the preference for TM dataset.
Study on seasonal change of terrestrial net primary production (NPP) and its responses to climate are to help understand the responses of terrestrial ecosystem to climate change and mechanisms of annual NPP increases. In this study, GLO-PEM simulating NPP data and corresponding climate data were used to explore the seasonal changes of terrestrial NPP and their geographical differences in China from 1981 to 2000. As the results, seasonal total NPP in China showed a significant increase for all four seasons during the past 20 years. The spring NPP indicated the largest increase rate, while the summer NPP was with the largest increase in magnitude. The area of NPP increase was largest in summer, and that of NPP decrease was largest in autumn. Seasonal NPP changed differently in different regions. Increased temperature or precipitation or their comprehensive functions might contribute to the NPP increase, and decreased precipitation might answer for the decreased NPP in most regions. South China had the largest NPP increase in spring, autumn and winter and the highest NPP increase rate in autumn, North China had the largest NPP increase rate in spring and winter, while Central China had the largest NPP increase and increase rate in summer.
The Tibetan Plateau is among the fewest extensive regions remote far from the influences of human activities. It provides an ideal site to study the response of vegetation cover to water/thermal (WT) conditions, esp. the response of natural vegetation cover. The paper aims to discuss the spatial variation and then the relations of WT climate elements with satellite derived NDVI. The discussion is taken with the supports of ground climatic observation data and AVHRR NDVI product (8 Km) from year 1982 to 2000, in central and east Tibetan Plateau where the gauge is basically dense enough to qualify related analyses. Based on the simulation of egetation spatial distribution trend surfaces, the transect comparison of different directions and the work of vegetation grouping, the relationships between NDVI and precipitation (N-P for short), between NDVI and temperature (N-T for short) are respectively investigated and analyzed, both spatially and biologically. The results presented by this study indicate that in central/east Plateau annual mean NDVI is less influenced by WT conditions if the covered vegetation is dense and evergreen or totally sparse; the N-T and N-P values of peripheral Plateau regions are low while the values of main plateau body are higher than 0.75; in addition, altitude tends to play an obvious negative role in the spatial distribution of thermal condition, and then in the distribution of vegetation cover.
Based on the GLO-PEM simulated data, net primary productivity (NPP) and its spatiotemporal patterns in Loess Plateau were studied from 1981 to 2000. Our research indicated that the distribution of annual NPP in Loess Plateau was obviously different from east to west and from south to north. The average of annual total NPP is 0.15PgC, with an annual increasing rate of 0.01%. NPP decreased in most parts of Loess Plateau, with the largest decrease in the southeast of Shanxi Province and northeast of Loess Plateau, But it increased in the area along the boundary between Shaanxi Province, Inner Mongolia Province and Lanzhou Basin in the west of Loess Plateau, The early 1990s (1991-1995) is the time with fastest NPP increase. The variation of NPP is different seasonally. It decreased mostly in winter, with an annual rate of 0.57%, and increased with an annual rate of 0.51% from April to May.
Artificial object identification and image classification are two basic issues in remote sensing (RS) information extraction. All kinds of methods, from the pixel-based to window-based, have been tried respectively in two domains for many years, but the accuracy is not well until now. Two obvious limitations explain the reasons. One is that the processing cell can’t correspond with the true target in the real world, and the other is the feature, which participates in the identification procedure, is far from enough to describe the intrinsical characteristics of the object of interest. During recent two years, an object-oriented classification method is put forward to supply these gaps of the conventional classification method. On the one hand, by using the segmentation technique, the pixel clusters are extracted based on their similarities to form so-called object having thematic meaning; on the other hand, vectorization of these objects is performed by integrating the GIS (geographical information system) idea into the RS which makes it possible to describe the various features of each object, such as shape information and its spatial relationship to neighboring object. In this study, the authors attempt to use this new method to artificial object identification by taking example for ship extraction with the help of one spectral feature and eight shape features. Results indicate the object-oriented classification is feasible in practice, and it opens a new way for artificial object extraction.
Based on the GLO-PEM simulation data, Net primary productivity (NPP) and its spatiotemporal patterns in Northeast China were studied from 1981 to 2000. Our research indicated that the distribution of annual NPP in Northeast China was obviously different from east to west. The averaged annual total NPP is 0.50PgC, with an annual increasing rate of 0.55%. NPP increased in most parts of Northeast China from 1981 to 2000, with the largest increase in the western part of Liaoning province, but it decreased in eastern Hulun Buir Plateau, Horqin Sandy Land, Changbai Mountains and northern Da Xingan Ling mountains. The early 1990s (1991-1995) is the time with fastest NPP increasing. NPP varies in different seasons. It increases mostly in summer, with an annual rate of 0.65%, but it decreasing in non-growing
Hyperspectral image possesses incomparable advantage over spaceborne multispectral image when it is employed to quantitatively retrieve these parameters such as vegetation type, coverage, biomass, bare soil moisture, etc. This paper focuses on crucial issues present in the pre-processing of hyperspectral image: band selection, edge radiant correction, tangent correction and spectral reflectivity conversion, exemplified by a case study in which modular airborne OMIS-I imaging spectrometer data are employed to evaluate desertification. The author gives comprehensive consideration to the statistic characteristics of each spectral band, diagnostic spectral reflection of different targets and the purpose of practical application, and fixed upon 41 applicable bands after trying different bands. In the course of edge radiant correction, one correction method based on histogram matching was used, and its result was satisfactory. In addition, tangent correction directing against tangent distortion was carried out, which enriched the normal geometric rectification. Lastly, during the process of surface feature spectral reflectivity conversion, the author converted symbolic model into statistic model by employing some necessary theoretical inference and parameter-setting. The result suggests the quality of OMIS-I data get better improved after these processing and basically can meet the requirements of quantitative retrieval for desertification evaluation.