Vertical characteristics of ozone variation over the Arctic Chukchi Sea region in 1999

1　ＩｎｔｒｏｄｕｃｔｉｏｎＡｒｃｔｉｃｃｌｉｍａｔｅａｎｄｅｎｖｉｒｏｎｍｅｎｔａｒｅｖｅｒｙｉｍｐｏｒｔａｎｔｉｎｔｈｅｇｌｏｂａｌｃｈａｎｇｅｓｙｓｔｅｍｓ(ＷＭＯ/ＵＮＥＰ 1 990 ;ＷＭＯ 1 991 ) .Ｏｂｓｅｒｖａｔｉｏｎｓａｎｄｍｏｄｅｌｉｎｇｒｅｓｕｌｔｓｉｎｄｉｃａｔｅｔｈａｔｔｈｅｇｌｏｂａｌｗａｒｍｉｎｇｗｉｌｌｂｅｅｎｈａｎｃｅｄｉｎｔｈｅｐｏｌａｒｒｅｇｉｏｎｓ ,ｅｓｐｅｃｉａｌｌｙｉｎｔｈｅＮｏｒｔｈＨｅｍｉ ｓｐｈｅｒｅ ,ｗｉｔｈａｐｒｅｄｉｃｔｅｄｗａｒｍｉｎｇｏｆａｂｏｕｔ…     

A temperature inversion in "Chinese Arctic Research Expedition 1999

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＡｒｃｔｉｃａｒｅａ ,ａｓｔｈｅｂａｃｋｇｒｏｕｎｄｏｆｇｌｏｂａｌｃｌｉｍａｔｅａｎｄｅｎｖｉｒｏｎｍｅｎｔ,ｄｒａｗｓｐｅｏ ｐｌｅ’ｓａｔｔｅｎｔｉｏｎｗｉｔｈｉｔｓｉｍｐａｃｔｏｎｇｌｏｂａｌｃｈａｎｇｅ (ＩＰＣＣ 1 990 ) .Ｇｒｅａｔａｍｏｕｎｔｏｆｅｎｅｒｇｙａｎｄｍａｓｓａｒｅｅｘｃｈａｎｇｅｄｂｅｔｗｅｅｎｔｈｅｓｅａａｎｄａｉｒｗｉｔｈｓｐｅｃｉａｌｉｎｔｅｒｆａｃｅ,ａｉｒ ｉｃｅ ｓｅａｓｕｒｆａｃｅ ,ｉｎｔｈｉｓａｒｅａ .Ｔｈｅｒｅｆｏｒｅｉｔｉ…     

地理信息系统的社会公共功能

地理信息系统已经成为商品走进人们的生活 ,它所具有的社会公共功能正引起人们越来越多的关注。     

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????Chapman?????????г????????????????????????????????й?????GPS CORS???????????й????????????????????????????????????????????????????в???????0.311 m???????????????????????????????????仯???о???????????÷????????????????н????????????????????????????????????仯????????     

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????GPS?????????“???????”?????????????????????????????????????????????????????????????????????NW???????????????????????????????????????????????5~6????????????????????2???????????????????????NW????NEE????Щ????????????????????GPS?????????????????????￡????????????????????????????????????????????????????????????????α???????????仯?????     

Combining spectral with texture features into object-oriented classification in mountainous terrain using advanced land observing satellite image

Most existing classification studies use spectral information and those were adequate for cities or plains.This paper explores classification method suitable for the ALOS(Advanced Land Observing Satellite) in mountainous terrain.Mountainous terrain mapping using ALOS image faces numerous challenges.These include spectral confusion with other land cover features,topographic effects on spectral signatures(such as shadow).At first,topographic radiometric correction was carried out to remove the illumination effects of topography.In addition to spectral features,texture features were used to assist classification in this paper.And texture features extracted based on GLCM(Gray Level Cooccurrence Matrix) were not only used for segmentation,but also used for building rules.The performance of the method was evaluated and compared with Maximum Likelihood Classification(MLC).Results showed that the object-oriented method integrating spectral and texture features has achieved overall accuracy of 85.73% with a kappa coefficient of 0.824,which is 13.48% and 0.145 respectively higher than that got by MLC method.It indicated that texture features can significantly improve overall accuracy,kappa coefficient,and the classification precision of existing spectrum confusion features.Object-oriented method Integrating spectral and texture features is suitable for land use extraction of ALOS image in mountainous terrain.     

SAR image coregistration using fringe definition detection

In order to overcome the limitation of cross correlation coregistration method for Synthetic Aperture Radar(SAR) interferometric pairs with low coherence,a new image coregistration algorithm based on Fringe Definition Detection(FDD) is presented in this paper.The Fourier transformation was utilized to obtain spectrum characteristics of interferometric fringes.The ratio between spectrum mean and peak was proposed as the evaluation index for identifying homologous pixels from interferometric images.The satellites ERS-1/2 C-band SAR acquisitions covering the Yangtze River plain delta,eastern China and ALOS/PALSAR L-band images over the Longmen Shan mountainous area,southwestern China were respectively employed in the experiment to validate the proposed coregistration method.The testing results suggested that the derived Digital Elevation Model(DEM) from FDD method had good agreement with that from the cross correlation method as well as the reference DEM at high coherence area.However,The FDD method achieved a totally improved topographic mapping accuracy by 24 percent in comparison to the cross correlation method.The FDD method also showed better robustness and achieved relatively higher performance for SAR image coregistration in mountainous areas with low coherence.     

Responses of primary productivity to current and climate changes in the mud area to the southwest of Cheju Island during the past 800 years

The biogenic silica (BSi), total organic carbon (TOC), total nitrogen (TN) and grain size were analyzed with a gravity core (3250-6) collected from the mud area in the north East China Sea. The average deposition rate of the upper core was about 0.078 cm yr^?1 based on the results of ²¹⁰Pb_ex. The mean grain size increased with depth in general. The frequency distribution of grain size showed that two marked changes of deposition environment occurred at 30 cm and 50 cm depths (about 1550 AD and 1300 AD, respectively). The variations of BSi and TOC indicated two distinct major periods of primary productivity over the past 800 years: a stage of low primary productivity corresponding to weak upwelling and low nutrient input below 30 cm depth (about 1200–1550 AD), and a stage of high primary productivity with strong currents and upwelling above 30 cm depth (about 1550–1950 AD). The stage with high primary productive appeared to be due to the northward-expanded muddy area caused by strong Asian Winter Monsoon and enhanced Yellow Sea Warm Current in winter. In conclusion, the BSi and TOC in the muddy sediments, the symbols of marine primary productivity, can be then used to investigate the evolution history of currents and relative climate change in the offshore areas.     

Phase evolution of Holocene paleoenvironmental changes in the southern Yellow Sea: Benthic foraminiferal evidence from core C02

Assemblages of benthic foraminifera in a sediment core (C02) near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the Holocene marine transgression. It appears that during the early Holocene (11.2–10.1 kyr BP), the faunal was dominated by low salinity and shallow water species Cribrononion subincertum, Buccella frigida and Ammonia beccarii, reflecting a near coast depositional environment. A rapid increase of the relative abundance of Ammonia compressiuscula between 10.1–9.3 kyr BP indicates that the sea level rose rapidly during that time period. From 9.3–7.7 kyr BP, the benthic foraminiferal assemblage was dominated by high percentage of A. compressiscula, suggesting that the sea level was relatively stable. An obvious transition of benthic foraminifera, from the A. compressiuscula-dominated assemblage to an Ammonia ketienziensis-dominated assemblage, occurred between 7.7–6.2 kyr BP, possibly corresponding to a second sea level rapid rise period in the Yellow Sea during the Holocene. This transition may correspond to the gradually strengthened Yellow Sea warm current (YSWC) and finally is established the modern-type circulation in the Yellow Sea. It may also mark the formation of the Yellow Sea cold bottom water (YSCBW) during that period. Since then, the benthic foraminiferal assemblage based on core C02 was dominated by typical YSCBW species, A. ketienziensis, Astrononion italicum and Hanzawaia nipponica, at 6.2–4 kyr BP. A non-deposition period occurred since ～4 kyr BP, which possibly related to the hydrology changes caused by the East Asia monsoon. The two obvious benthic foraminiferal transitions recorded in core C02 during the early and middle Holocene provide evidence that the Yellow Sea has undergone a two-phase rapid sea level rise during the Holocene marine transgression.