Area In Winter Research Articles

Distribution and community characteristics of planktonic copepods in the northwest coastal waters off Hainan Island

We analyzed the structure, distribution, and seasonal changes of planktonic copepod communities, as well as their relationships with environmental factors using data collected from 21 stations in the northwest coastal waters off Hainan Island between November 2008 and July 2009. A total of 44 species of planktonic copepods was identified, with 25, 23, 22, and 23 species found in autumn (November), winter (January), spring (April) and summer (July), respectively. The dominant species were mainly warm water species, such as Canthocalanus pauper, Subeucalanus subcrassus, Temora turbinate, Acartia spinicauda, Calanopia elliptica and Euchaeta concinna, etc. There were significant changes in copepod abundance among seasons; total copepod abundance was highest in winter with 409 ind./m, followed by autumn with 144 ind./m, spring with 55 ind./m and summer with 17 ind./m, respectively. Distributional data showed that an area of high copepod density appeared in the southern portion of the study area in winter, while there was an area of high copepod density in the center of the survey area in autumn. Copepod abundance was higher in deeper waters, and lower in the coastal areas in spring and summer. Species diversity index was highest in summer and followed by spring, autumn and winter in turn. The evenness index of spring and summer copepod communities was higher than those of autumn and winter. The structure of these planktonic copepod communities reflects tropical and subtropical floristic characteristics. Species composition varied significantly with season, and copepod abundance was noticeably affected by water temperature and diatom cell abundance. We 第 3 期 孙柔鑫等: 海南岛西北沿岸海域浮游桡足类的分布及群落特征 321 detected no obvious correlationship between copepod abundance and salinity.

Developing a Thermal Comfort Index for Vegetated Open Spaces in Cities of Arid Zones

The degree of thermal comfort that people experience in open spaces is one of the determinants for use, especially in areas with extreme climates. It has a wide range of indices in the international literature. However, the study of five indices (THI, PE, TS, PMV and COMFA) regarding subjective responses presented low percentages of predictive successes in the city of study, characterized by an arid climate and intense urban vegetation. Therefore, the aim of this work is to develop a new thermal comfort index to predict more accurately the thermal sensation of the local residents. For this, there were campaigns monitoring of microclimatic parameters and field surveys about the real sensation of the people on a pedestrian street of Mendoza Metropolitan Area (MMA) in both winter and summer. The proposed new model is established through the correlation of environmental variables and individual subjective responses. The multivariate correlation is performed by linear regression. The theory of Akaike's information is used as criterion to model selection. The new model IZA is a lineal relation of air temperature, relative humidity, wind speed and solar radiation, generally all available weather variables. We found a high correlation between subjective responses and the new model. Besides the Pearson coefficient which gives the new index is higher than other traditional indices evaluated. The percentage of success of the new index exceeds 85%, demonstrating the effectiveness of the proposed model. In conclusion, the use of IZA as a predictor of thermal comfort will allow a fair assessment of the effect of design and composition of space on your comfort conditions, without the need to carry out thermal perception surveys. This will facilitate the evaluation and decision-making regarding the thermal rehabilitation of open spaces.

Impact of mesoscale eddies on surface flow between the Pacific Ocean and the Bering Sea across the Near Strait

The Lagrangian technique is applied to model the eddy dynamics and the flow across the Near Strait (NS) based on satellite derived SSH anomalies. Daily Lagrangian latitudinal maps, computed with the AVISO surface velocity field, and calculation of the flow across the strait, connecting the Pacific Ocean with the Bering Sea, show that the water flux is highly variable and controlled by mesoscale and submesoscale eddies. On the seasonal scale, the flux through the western part of the NR is negatively correlated with the flux through its eastern part (r=-0.93). On the interannual time scale, a significant positive correlation (r=0.72) is diagnosed between the NS flow and the wind stress in winter. Increased southward component of the wind stress decreases the northward water flow through the strait. Positive wind stress curl over the strait area in winter–spring generates a cyclonic circulation and thereby enhances the southward flow in the western part (r=-0.68) and northward flow in the eastern part (r=0.61). In fall, the water flow in different parts of the NS is determined by the strength of the anticyclonic mesoscale eddy located in the Alaskan Stream area.

Seasonal observations and machine-learning-based spatial model predictions for the common raven (Corvus corax) in the urban, sub-arctic environment of Fairbanks, Alaska

The common raven (Corvus corax) is an abundant generalist of the northern hemisphere, known to congregate and roost near human-related food sources. Due to a growing human-footprint and associated anthropogenic food subsidies, raven populations have increased dramatically over the past several years throughout the USA. The sub-arctic region has also witnessed increased urbanization and industrialization, and ravens have taken advantage of these changes. During 2004 and 2006, we surveyed parking lots on a bi-weekly basis in the city of Fairbanks in interior Alaska, showing an influx of ravens in winter. Between 2010 and 2012, we documented the presence and absence of ravens at a permanent set of 30 suspected raven locations and 21 randomized locations within the city limits of Fairbanks. We used machine learning (RandomForests) and 12 spatial GIS datasets from the Fairbanks North Star Borough to accurately model-predict the relative occurrence of ravens during winter and summer in Fairbanks. Our research showed a positive correlation between raven occurrence and commercial and residential zones in both winter and summer, as well as an inverse geographic relationship between ravens and the waste transfer station in the study area in winter, and a direct correlation near restaurants in summer. These results emphasize the link that ravens have with commercial, anthropogenic food sources, and how Fairbanks and its subsidized, urban habitat may be shaping part of the wider sub-arctic biodiversity landscape.

A Study on the Change of Fog Frequency and Duration Hours in South Korea

This study aimed to investigate the change of fog frequency and duration hours hours in South Korea. Using daily mean fog days(about 50 years) and fog duration hours(about 46 years) during the period of 1961~2010 for long-term observational data of 14 weather stations in South Korea, the change of temperature rise was analyzed. The change of fog days had a decreasing trend for the period of 1961~2010. There was a distinctly decreasing trend in Seoul and South-Eastern Coast area. The seasonal decreasing trend of fog days and fog duration hours was similar in spring and summer. On the other hand the change of Chupungnyeong in autumn and the West Coast in summer had a increasing trend. The change of fog duration hours was rarely changed. It was affected by the change of fog days. In addition, the change of fog days and fog duration hours of South-Eastern Coast area in autumn and winter had to decreasing trend. Otherwise the change of Jeonju in spring and Mokpo in summer had a increasing trend. There was a negative correlation between temperature element and fog days, and fog duration hours. But the change of fog days and fog duration hours was not decreasing trend in all areas. The decreasing trend of fog days was affected by temperature rise. However, there was not shown significant result of fog duration hours.

The summer foraging ranges of adult spectacled petrels Procellaria conspicillata

AbstractSatellite transmitters were attached to eight adult spectacled petrels Procellaria conspicillata Gould captured during the early incubation period at their breeding grounds on Inaccessible Island, one of the Tristan da Cunha Islands in the central South Atlantic Ocean. Data on their at-sea distribution was obtained for up to six months. All birds remained within the South Atlantic from 24–44°S, with most between 25 and 40°S. Breeding birds mainly foraged in oceanic waters, but failed breeders or non-breeders concentrated their foraging activity over the Rio Grande Rise and the Walvis Ridge and along the shelf break off the east coast of South America. Little foraging occurred along the Benguela shelf break off southern Africa. Non-breeders favoured relatively warm water with low chlorophyll concentrations, reducing the risk of bycatch in fisheries. Tracked birds spent 16% of their time in areas with high levels of tuna longline fishing activity, with overlap greater for non-breeding birds (22%) than breeding birds (3%). Birds in this study foraged in shallower waters along the continental shelf edge off South America than spectacled petrels tracked in this area in winter, potentially increasing their risk of exposure to demersal longline fisheries in this area in summer.

Soundscape of the West Lake Scenic Area with profound cultural background—a case study of Evening Bell Ringing in Jingci Temple, China

From the case study of Evening Bell Ringing at Nanping Hill, one of the West Lake Cultural Landscapes in Hangzhou, China, we investigated the soundscape of a scenic area with a profound cultural background. First, we conducted the soundscape physical index of the area in both winter and spring seasons to analyze its objective graphical expression. Second, we focused on people’s reactions to the soundscape in order to obtain a subjective evaluation of each component in the soundscape and integrated environment. Then, the relationship between the objective data and the subjective evaluation was analyzed. Finally, the impacts of the natural environment, history, and cultural factors on the evaluation of the Jingci Temple soundscape were studied. It was found that natural sounds, cultural sounds, and historic sounds were widely acclaimed in people’s subjective feelings, which indicated the close relationships among historical and cultural background, soundscape, and natural environment. Thus, the conclusion was made that soundscape should be consistent with the local natural environment and the historical and cultural background.

Impacts of Future Urban Expansion on Regional Climate in the Northeast Megalopolis, USA

In this paper, evidences for influences of future urban expansion on regional climate in the Northeast megalopolis, USA, are presented. The model-based analysis shows that future urban expansion will significantly result in regional climate change. An average annual temperature increase ranging from 2°C to 5°C in new urban area and an average annual temperature decrease ranging from 0.40°C to 1.20°C in the south of the megalopolis will be caused by future urban expansion. The average annual precipitation of the simulation area will decrease due to future urban expansion by 5.75 mm, 7.10 mm, and 8.35 mm in the periods of 2010–2020, 2040–2050, and 2090–2100, respectively. The warming effect of future urban expansion in original and new urban area and drought effects in nonurban area will be more serious in summer than in winter. A cooling effect will turn up in original urban area in winter. This research further shows that a study at the scale of megalopolis helps to understand the integrated effect of combination and interaction of multiple cities and their surrounding areas which may crucially determine regional climate pattern and should be highly valued in the future.

Climate variability and trends in downscaled high-resolution simulations and projections over Metropolitan France

In order to fulfill the society demand for climate information at the spatial scale allowing impact studies, long-term high-resolution climate simulations are produced, over an area covering metropolitan France. One of the major goals of this article is to investigate whether such simulations appropriately simulate the spatial and temporal variability of the current climate, using two simulation chains. These start from the global IPSL-CM4 climate model, using two regional models (LMDz and MM5) at moderate resolution (15–20 km), followed with a statistical downscaling method in order to reach a target resolution of 8 km. The statistical downscaling technique includes a non-parametric method that corrects the distribution by using high-resolution analyses over France. First the uncorrected simulations are evaluated against a set of high-resolution analyses, with a focus on temperature and precipitation. Uncorrected downscaled temperatures suffer from a cold bias that is present in the global model as well. Precipitations biases have a season- and model-dependent behavior. Dynamical models overestimate rainfall but with different patterns and amplitude, but both have underestimations in the South-Eastern area (Cevennes mountains) in winter. A variance decomposition shows that uncorrected simulations fairly well capture observed variances from inter-annual to high-frequency intra-seasonal time scales. After correction, distributions match with analyses by construction, but it is shown that spatial coherence, persistence properties of warm, cold and dry episodes also match to a certain extent. Another aim of the article is to describe the changes for future climate obtained using these simulations under Scenario A1B. Results are presented on the changes between current and mid-term future (2021–2050) averages and variability over France. Interestingly, even though the same global climate model is used at the boundaries, regional climate change responses from the two models significantly differ.

Multi-scalar analysis of bird communities in Monferrato Astigiano woodlands

In this study we focused on deciduous managed forests in north-western Italy and investigated relationships between bird diversity and forest descriptors both at the habitat and landscape level through a seasonal, guild-based approach. Birds were censused by point counts in randomly selected plots of 50 m radius. Each census plot was described in habitat structure terms by using the Bitterlich variable plot-radius method. Landscape metrics were measured within 250, 500 and 1000 m radius circles of each plot using an existing GIS database. We first identified specialist and generalist species according to the presence/absence of each species in relation to habitat structure measurements, then we tested for the effects of habitat and landscape variables on community and guild parameters (bird species richness, abundance and Shannon diversity) using generalized linear models (GLMs). Our analyses showed that in general, guild parameters relative to specialists were especially influenced by oak biomass and oak core area irrespective of the season, while parameters of generalists were influenced by oak core area in winter and by landscape fragmentation parameters in spring. Results clearly showed that the retention of native oaks both at the habitat and landscape level is the key-factor for the conservation of diversity of specialist bird species in deciduous, originally oak-dominated woods.

Aggregation of nano-sized alum–humic primary particles

In order to understand the mechanism of floc formation and growth in coagulation process, effect of zeta potential and surface characteristic of nano sized primary particles on coagulation efficiency were investigated by coagulation of humic acid with alum in this study. It was demonstrated that only 1min rapid mixing was enough for adsorption of humic acid onto the precipitates of alum, and 15min flocculation (slow mixing) only induced the formation and growth of flocs. The primary particle size of alum–humic flocs was near 50nm and spherical. Mathematical model deduced from Derjaguin–Landau–Verwey–Overbeek (DLVO) theory showed that the formation of micro-flocs (or lag time) was determined by the square value of zeta potential of nano-sized primary particles and intensity of Brownian motion, which is closely related to water temperature. There was an absolute critical zeta potential, i.e. 13.5mV in this study, determining whether two nano-sized particles could overcome the energy barrier consisted of Van der Waals force and electrical double layer repulsion force to allow floc formation to occur at a certain temperature. The Brownian motion determined whether the nano-sized primary particles (aluminum hydroxide precipitates with humic acid) had the opportunity to overcome the repulsive force and cement with each other. Low coagulation efficiency at high latitude area in winter is caused by low collision frequency, which is mainly attributed to the low intensity of Brownian motion at a low temperature. Furthermore, it was demonstrated that aggregation of micro-flocs or their clusters significantly depended on activated sites on the primary particles rather than the zeta potential of primary particles when sweep flocculation dominated the coagulation mechanism if the size of flocs was larger than some value.

The proportions and variations of the light absorption coefficients of major ocean color components in the East China Sea

The East China Sea (ECS), one of the largest continental seas, has dynamic hydrology and complex optical characteristics that make ocean color remote-sensing retrieval difficult. The distributions and proportions of the light absorption coefficients of major ocean color components based on two large-scale investigations in the ECS are presented, showing these features in typical summer and winter seasons. The absorption coefficient aCDOM, aNAP and aphy of colored dissolved organic matter, non-algal particle, and pigment of phytoplankton show a decreasing trend from the coast to the outer shelf. According to the aCDOM distribution at 440 nm, the Changjiang River plume shows an abnormal southeastward transport. An extremely high aNAP value patch at 440 nm is present in the middle coast. The chlorophyll-a-specific phytoplankton pigment absorption (aphy*) is much higher in winter than in summer, which may cause serious underestimated results when applying the averaged aphy* into remote-sensing algorithms for chlorophyll concentration retrieval. The importance of phytoplankton size was evident in outer shelf waters. The absorption of aCDOM(440) is a dominant component accounting for over half of the total seawater absorption in summer. The aNAP(440) accounts for 64% of the absorption of the ECS coastal area in winter.

Seasonal thermocline in the China Seas and northwestern Pacific Ocean

Climatological seasonal variations of the thermocline in the China Seas and northwestern Pacific Ocean were studied using historical data from 1930 through 2001 (707,624 profiles). The quantitative roles of surface thermal buoyancy (Bq), haline buoyancy flux (Bp), and total buoyancy flux (B) against the wind‐induced mixing (τ) in different seasons and regions were also explored using the buoyancy ratio (R = ∣Bq/Bp∣) and the Monin‐Obukhov depth ratio (δ), respectively. The thermocline has obvious seasonal variations in the study area north of 20°N. There is no thermocline along the west coast of the Bohai Sea (BS), Yellow Sea (YS), and northern East China Sea from December to March resulting from surface cooling and wind mixing. The significantly different variation of the thermocline strength on and off the Chinese shelf is mainly caused by the fact that the thermal stratification is enhanced by bottom tidal mixing on the shelf. The δ indicates that the thermocline depth on the Chinese shelf is mainly dominated by B in summer, while it is dominated by τ in winter. It reveals an opposite feature in the Kuroshio region; the dominating factor is B in winter, associated with the large heat buoyancy loss there. South of 20°N, the dominating factor is similar to that on the shelf, with the more obvious B dominant characteristic during the monsoon transition periods. The R demonstrates that B is mainly controlled by Bq all year round, with some sporadically Bp‐dominated regions in the tropical area in winter and in the BS and eastern YS in September.

Statistical and dynamical downscaling assessments of precipitation extremes in the Mediterranean area

Ex treme precipitation events in theMediterranean area have been defined by different percentile-based indices of extreme precipitation for autumn and winter: the number of events exceeding the 95 th percentile of daily pr ecipitation, percentage, total amount, and mean daily intensity of precipitation from these events. Results from statistical downscaling applying canonical correlation analysis as well as from dynamical downscaling using the regional climate model REMO are mapped for the 1961–1990 baseline period as well as for the magnitude of change for the future time slice 2021–2050 in relation to the former period. Direct output of the coupled global circulation model ECHAM5 is used as an additional source of information. A qualitative comparison of the two different downscaling techniques indicates that under the present climate both the dynamical and the statistical techniques have skill to reproduce extreme precipitation in the Mediterranean area. A good representation of the frequency of extreme precipitation events arises from the statistical downscaling approach, whereas the intensity of such events is adequately modelled by the dynamical downscaling. Concerning the change of extreme precipitation in the Mediterranean area until the mid-21 st century, it is projected that the frequency of extreme precipi tation events will decrease in most parts of the Mediterranean area in autumn and winter. The change of the mean intensity of such events shows a rather heterogeneous pattern with intensity increases in winter most likely at topographical elevations exposed to the West, where the uplift of humid air profits by the increase of atmospheric moisture under climate change conditions. For the precipitation total from events exceeding the 95 th percentile of daily precipitation, wi despread decreases are indicated in autumn, whereas in winter increases occur over the western part of the Iberian Peninsula and southern France, and reductions over southern Turkey, the eastern Mediterranean area, parts of Italy and some North African regions.

Modelling spatial dynamics of cropping systems to assess agricultural practices at the catchment scale

Assessing the environmental impacts of agricultural practices at the catchment scale increasingly involves the use of spatially distributed models that include cropping systems as input. Use of these models for diagnosis and evaluation requires large datasets at large spatial and temporal scales. The description of spatial dynamics of cropping systems at a fine resolution (i.e. field level) is particularly needed. As these data are scarce or not available, our objective was to propose a model that first reconstructs spatial dynamics of past cropping systems from available data, and second constructs alternative spatial cropping systems, corresponding to agricultural practice scenarios. Classification systems for farms and fertilisation practices were defined to classify farm-level organisation for crop-succession and crop management strategies, in particular nitrogen fertilisation. Winter cover crops and multiple strategies per crop at the farm level can be represented with this model. Cropping systems are modelled in three steps: we modelled crop cover succession in summer with Markov chains based on empirical data and in winter with rules based on expert agronomic knowledge; lastly a Knapsack-based algorithm was used to allocate a crop management system to fields with constraints on several crop management strategies per crop type. Results of a case study performed on the Frémeur catchment (western France) show that this model respects the main constraints for cropping system modelling to assess agricultural practices at the catchment scale. From a scenario discussed with stakeholders and regional authorities characterised by stable areas of summer crops, the decrease in bare soil area in winter and overall reduction in total nitrogen fertilisation for different types of crops and farms we demonstrate the model’s ability to simulate coherent cropping systems. Thus, if faced with a lack of data or knowledge about the local factors that drive changes in cropping systems, the model can construct the spatial dynamics of cropping systems, which can be used as input to distributed nitrate transfer models to assess agricultural practices at the catchment scale.

Identifying indirect habitat loss and avoidance of human infrastructure by northern mountain woodland caribou

Understanding the impact of indirect habitat loss resulting from avoidance of human infrastructure is an important conservation priority. We evaluated resource selection for 10 global positioning system collared northern mountain woodland caribou ( Rangifer tarandus caribou) in British Columbia, Canada, with seasonal resource selection functions (RSF) developed at the second-order (landscape) and third-order (within home range) scales. To estimate how much habitat was lost due to avoidance, we estimated the zone of influence (ZOI) around multiple developments and modeled realized and potential habitat. Potential habitat was approximated by removing the ZOI from RSF models. By calculating the spatial difference between potential and realized habitat we estimated the amount of indirect habitat loss. Caribou displayed hierarchical avoidance of development, with the greatest avoidance occurring at the second-order. During both seasons caribou avoided high-use roads by 2 km and low-use roads by 1 km. In winter, caribou avoided town by 9 km compared to 3 km in summer. However, in summer caribou avoided mines by 2 km and cabins and camps by 1.5 km, while in winter when human activity was low, avoidance of these features was minor. As a result of avoidance of the cumulative ZOI, approximately 8% and 2% of high quality habitat was lost in the study area in winter and summer, respectively. Our study provides an approach to identify the extent and quality of habitat influenced by indirect avoidance. Conservation efforts should prioritize protecting areas of high quality habitat degraded by avoidance in the vicinity of human development.

Forecasting Model of Humidity in Chinese Solar Greenhouse in the North Drought Cold Area and Experiment in Winter

Based on the research results of light environment and thermal environment model and the principle of mass balance, the dynamic forecasting model of Humidity in Chinese solar greenhouse in the north drought cold area was established. The influenced factors correlative with water vapor change such as crop transpiration, soil evaporation, covered material condensation and natural or winded of closed situation ventilation were included in the model. To validate the correctness of the model, an experiment was carried out in the Chinese solar greenhouse in the Inner Mongolia agriculture science and technology park. The results showed that the inner relative humidity forecasted agreed well with the measured data in the north drought cold area in winter, and the relative error is less than 10%.

Composite Analysis of North Atlantic Extratropical Cyclones in NCEP–NCAR Reanalysis Data

Composite analysis of North Atlantic midlatitudinal winter cyclones is performed using NCEP–NCAR reanalysis data for the 60-yr period from 1948 to 2007. The composites were developed using an advanced methodology involving the coordinate transform of cyclones into a nondimensional azimuthal coordinate system and the further collocation of fields. Composite analysis is performed for air–sea turbulent fluxes, heat content, precipitable water, and precipitation for 576 oceanic cyclones generated in the Gulf Stream area in winter (January–March) from 1948 to 2007. For the region of cyclone generation over the Gulf Stream, composites were analyzed for different cyclone intensities. Over the whole North Atlantic, composites were developed throughout the life cycle and for different cyclone types classified by the regions of their migration. These classifications allow the case-to-case variability to be minimized and the robustness of the composite to be boosted. In the region of cyclone generation over the Gulf Stream, characteristics of the composites strongly depend on the cyclone intensity quantified through the radial sea level pressure difference between the cyclone’s edge and its center. Stronger cyclone intensity implies larger turbulent fluxes in the rear of a cyclone and stronger precipitation in the forward part. Cyclones gradually dry with the water content and precipitation rate decreasing by about 40% and 50%–70%, respectively, during the lifetime. Although composites of air–sea turbulent fluxes show locally very strong positive fluxes in the rear part of the cyclone, the total air–sea turbulent fluxes provided by cyclones are not significantly different from the averaged background fluxes. This shows that the formation of extreme air–sea fluxes by cyclones is connected to the larger-scale circulation conditions, particularly to the cyclone–anticyclone transition zones.

Nitrogen dynamics in Lake Okeechobee: forms, functions, and changes

Total nitrogen (TN) in Lake Okeechobee, a large, shallow, turbid lake in south Florida, has averaged between 90 and 150 μM on an annual basis since 1983. No TN trends are evident, despite major storm events, droughts, and nutrient management changes in the watershed. To understand the relative stability of TN, this study evaluates nitrogen (N) dynamics at three temporal/spatial levels: (1) annual whole lake N budgets, (2) monthly in-lake water quality measurements in offshore and nearshore areas, and (3) isotope addition experiments lasting 3 days and using 15N-ammonium (15NH4+) and 15N-nitrate (15NO3−) at two offshore locations. Budgets indicate that the lake is a net sink for N. TN concentrations were less variable than net N loads, suggesting that in-lake processes moderate these net loads. Monthly NO3− concentrations were higher in the offshore area and higher in winter for both offshore and nearshore areas. Negative relationships between the percentage of samples classified as algal blooms (defined as chlorophyll a > 40 μg l−1) and inorganic N concentrations suggest N-limitation. Continuous-flow experiments over intact sediment cores measured net fluxes (μmol N m−2 h−1) between 0 and 25 released from sediments for NH4+, 0–60 removed by sediments for NO3−, and 63–68 transformed by denitrification. Uptake rates in the water column (μmol N m−2 h−1) determined by isotope dilution experiments and normalized for water depth were 1,090–1,970 for NH4+ and 59–119 for NO3−. These fluxes are similar to previously reported results. Our work suggests that external N inputs are balanced in Lake Okeechobee by denitrification.

The grain-size distribution of the suspended particulate matter in the Huanghe Estuary and its adjacent sea area in winter

The grain-size of suspended particulate matter (SPM) in the Huanghe Estuary and its adjacent sea area was investigated with an in situ laser particle size analyzer (LISST-100) in November 2006. The spatial distribution of the grain-size parameters was very complicated. The results show that (1) the mean particle size of SPM ranged from 3.00Φ to 6.41Φ, with an average value of 4.66Φ; (2) the frequency distribution patterns of the SPM grain-size showed three different types, which were mono-mode, dual-mode and tri-mode, respectively; (3) C-M chart suggested that the transportation-processes of the SPM not only included suspended mode, but also the bed load transportation mode. The bed load transportation mode mainly occurred at the bottom layer. The characteristics and space distribution of SPM grain-size might be mainly controlled by sediment discharge of the Huanghe River, hydrodynamics condition, surface sediment types, and biological process within the study area.