A study on zooplankton distribution patterns and indicator species in Kuroshio upstream area and adjacent East China Sea

On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of zooplankton in the Kuroshio and adjacent waters of the East China Sea are preliminarily studied. The results are as follows:The horizontal distribution of zooplankton biomass and the abundance of copepods, chaetognaths and siphonophores arecurred in the continent area northwest of Taiwan and the south-centre section of the East China Sea continent, which are the mix front of different waters. Zooplankton in the water area inside of Ryukyu Islands presented low abundance and high diversity. There are clear seasonal variations in zooplankton biomass and abundance in the study area. The strength or weakness of different water masses and fronts is the basic reason for the variations of zooplankton biomass and abundance.The species composition of zooplankton in the study area is complex and varies, however, the tropic oceanic species predominates overwhelmingly. The distribution of different ecotype species evidences the distribution of different water masses and the state of mixture. The indicator species of each water mass are listed in the paper so as to provide grounds for the variation of currents in the Kuroshio area.The temperature and salinity of sea water are important factors affecting zooplankton distribution, composition and diversity , however the role of salinity is major. With the replacement of one season by another, the correlative levels of temperature and salinity to various zooplankton taxa are more or less significant.

Seasonal and inter-annual variations of Arctic cyclones and their linkage with Arctic sea ice and atmospheric teleconnections

The seasonal and inter-annual variations of Arctic cyclone are investigated. An automatic cyclone tracking algorithm developed by University of Reading was applied on the basis of European Center for Medium-range Weather Forecasts（ECMWF） ERA-interim mean sea level pressure field with 6 h interval for 34 a period. The maximum number of the Arctic cyclones is counted in winter, and the minimum is in spring not in summer.About 50% of Arctic cyclones in summer generated from south of 70°N, moving into the Arctic. The number of Arctic cyclones has large inter-annual and seasonal variabilities, but no significant linear trend is detected for the period 1979–2012. The spatial distribution and linear trends of the Arctic cyclones track density show that the cyclone activity extent is the widest in summer with significant increasing trend in CRU（central Russia）subregion, and the largest track density is in winter with decreasing trend in the same subregion. The linear regressions between the cyclone track density and large-scale indices for the same period and pre-period sea ice area indices show that Arctic cyclone activities are closely linked to large-scale atmospheric circulations, such as Arctic Oscillation（AO）, North Atlantic Oscillation（NAO） and Pacific-North American Pattern（PNA）. Moreover,the pre-period sea ice area is significantly associated with the cyclone activities in some regions.

Scour and silting evolution and its influencing factors in Inner Mongolian Reach of the Yellow River

Rivers with fluvial equilibrium are characterized by bed deformation adjustment. The erosion-deposition area in cross-section reflects this characteristic, which is a base of researching the river scour and deposition evolution by time series analysis. With an ero- sion-deposition area indicator method proposed in this paper, the time series of ero- sion-deposition area quantity at Bygl and Shhk stations were obtained with the series duration of 31 years from 1976 to 2006. After analysis of its trend and mutation, three different ten- dencies about the evolution were observed in general from the quasi-equilibrium phase through a rapid shrinkage to the final new quasi-equilibrium. It is also found that the trend of erosion-deposition area series will change once a big flood occurred in some of the tributaries and its ever greater influence is due to the decrease of deluge with the completion of up- stream reservoirs. Almost all the turning points were coincident with the time when hy- per-concentrated sediment flood occurred in some tributaries. With the time series of clear mutations since the late 1990s, the Inner Mongolian Reach has been in a new equilibrium phase. This can be concluded in two aspects. 1. The absence of big floods and sediment transportation from tributaries result in the river shrinkage, and to regain the channel flow-carrying capacity in Inner Mongolian Reach a large flood is needed both of high peak discharge and of lengthy interval to destroy the new equilibrium. 2. The proposed method of erosion-deposition area indicator is of great help to channel scour-deposition evolution analysis because it can demonstrate real time deformation of cross section in quantity.

Study on the Urban Heat Island Effects and Its Relationship with Surface Biophysical Characteristics Using MODIS Imageries

This study assesses surface urban heat island (UHI) and its associated surface physical characteristics using remote sensing approaches. TERRA/MODIS images acquired in 2005 in three different seasons were selected to generate land surface tem-perature and surface characteristics for the Changsha-Zhuzhou-Xiangtan metropolitan area in China. The intensity of urban heat is-land effects and its seasonal variations were examined. The result showed that UHI effects were significant both in the summer and the spring. Land surface temperatures in the city were 8 ℃ to 10℃ warmer than those in surrounding rural areas in the spring and the summer seasons. Although UHI effects exist in winter, they are not significant. Land surface temperature in the city was 4℃ warmer than that in surrounding rural areas in winter. This study uses normalized difference vegetation index (NDVI) and normal-ized difference built-up index (NDBI) as indicators of surface physical characteristics and investigates the relationship among land surface temperature (LST), NDVI and NDBI. The results from this study indicate that, while the relationship between LST and NDVI changes in different seasons, there is a strong positive linear relationship between NDBI and LST for all seasons. The amount of slope and intercept of the linear relationship between NDBI and LST can indicate the magnitude of UHI for different seasons. This finding suggests that NDBI provides an alternative physical indicator for analyzing LST quantitatively over different seasons, and therefore providing a useful way to study UHI effects using remote sensing.