The Distribution and Variability of Simulated Chlorophyll Concentration over the Tropical Indian Ocean from Five CMIP5 Models

Performances of 5 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) in simulating the chloro-phyll concentration over the tropical Indian Ocean are evaluated. Results show that these models are able to capture the dominant spatial distribution of observed chlorophyll concentration and reproduce the maximum chlorophyll concentration over the western part of the Arabian Sea, around the tip of the Indian subcontinent, and in the southeast tropical Indian Ocean. The seasonal evolution of chlorophyll concentration over these regions is also reproduced with significant amplitude diversity among models. All of 5 mod-els is able to simulate the interannual variability of chlorophyll concentration. The maximum interannual variation occurs at the same regions where the maximum climatological chlorophyll concentration is located. Further analysis also reveals that the Indian Ocean Dipole events have great impact on chlorophyll concentration in the tropical Indian Ocean. In the general successful simulation of chlorophyll concentration, most of the CMIP5 models present higher than normal chlorophyll concentration in the eastern equatorial Indian Ocean.

Comparison of inversion of Chlorophyll concentration in the Bohai Bay based on GOCI Data

Bohai bay has poor water circulation capacity and low self-purification capacity,and a large number of land-sourced pollutants are accepted every year.The estimation of chlorophyll concentration based on remote sensing plays an important role in the study of marine red tide and the monitoring of water quality in the Bohai Bay.So it is necessary to select the best algorithm by comparing the performance of each algorithm.Choosing the best algorithm is helpful to improve the precision of chlorophyll concentration.Based on the in-situ measurement data of the Bohai Bay and the GOCI remote sensing reflectance data,the retrieval models of chlorophyll concentration were established in this paper by using the methods of fluorescence line height(FLH),OC3,blue-green band ratio and NIR-red band ratio.The above algorithms were evaluated by comparing the simulation results and the verification results.The results showed that there are obvious differences in the accuracy of different retrieval methods.The fitting and retrieval effect of FLH is the best and NIR-red band ratio is the worst,and the OC3is similar to the blue-green band ratio method.

Relationship of Abundance of Oceanic Sea Skaters, Halobates in the Tropical Pacific Ocean to Surface Biomass and Chlorophyll/Oxygen Concentrations

Relationship of population density of oceanic sea skaters collected from tropical and subtropical zones in the Pacific Ocean was examined to chlorophyll concentration/Dissolved Oxygen concentration and biomass in surface sea water. The four parameters shown above were measured at the site of 12oN 135oN during the cruise, MR13-03 cruise, and at the site of 25oN 160oE during another cruise KH-14-02. Significant and positive correlation between all biomass (especially invertebrates) and population density of oceanic sea skaters collected with a Neuston-Net trailing during 15 min was shown in overall analysis on the data of the both samplings (p oN 160oE than that at 12oN 135oN with similar value of chlorophyll value (p oN 160oE than that at 12oN 135oN for keeping high density population of oceanic sea skaters.

Prediction of chlorophyll a concentration using HJ-1 satellite imagery for Xiangxi Bay in Three Gorges Reservoir

Since the impoundment of the Three Gorges Reservoir in 2003, algal blooms have frequently been observed in it. The chlorophyll a concentration is an important parameter for evaluating algal blooms. In this study, the chlorophyll a concentration in Xiangxi Bay, in the Three Gorges Reservoir, was predicted using HJ-1 satellite imagery. Several models were established based on a correlation analysis between in situ measurements of the chlorophyll a concentration and the values obtained from satellite images of the study area from January 2010 to December 2011. Chlorophyll a concentrations in Xiangxi Bay were predicted based on the established models. The results show that the maximum correlation is between the reflectance of the band combination of B4/（B2＋B3） and in situ measurements of chlorophyll a concentration. The root mean square errors of the predicted values using the linear and quadratic models are 18.49 mg/m3 and 18.52 mg/m3, respectively, and the average relative errors are 37.79% and 36.79%, respectively. The results provide a reference for water bloom prediction in typical tributaries of the Three Gorges Reservoir and contribute to large-scale remote sensing monitoring and water quality management.

Inversion and verification of chlorophyll a concentration in the Bohai Bay

Chlorophyll a concentration is to characterize the amount of phytoplankton.In this paper,the chlorophyll a concentration is retrieved using the OC3M and OC2algorithms based on the MODIS remote sensing data,and using the band ratio,OC3G and YOC algorithms based on the GOCI remote sensing data.Based on the chlorophyll a measured data in the Bohai Bay in spring,2012,the spatial distribution trends of retrieval results are consistent with the measured results.By the inversion precision analysis,the accuracy of retrieval results of band ratio method based on GOCI is similar to that of OC3M method based on the MODIS.The precision retrieval results of YOC method based on GOCI are higher than the other methods.

Declined trends of chlorophyll a in the South China Sea over 2005–2019 from remote sensing reconstruction

Chlorophyll a concentration(CHL)is an important proxy of the marine ecological environment and phytoplankton production.Long-term trends in CHL of the South China Sea(SCS)reflect the changes in the ecosystem’s productivity and functionality in the regional carbon cycle.In this study,we applied a previously reconstructed 15-a(2005–2019)CHL product,which has a complete coverage at 4 km and daily resolutions,to analyze the long-term trends of CHL in the SCS.Quantile regression was used to elaborate on the long-term trends of high,median,and low CHL values,as an extended method of conventional linear regression.The results showed downward trends of the SCS CHL for the 75th,50th,and 25th quantile in the past 15 a,which were−0.0040 mg/(m^(3)·a)(−1.62%per year),−0.0023 mg/(m^(3)·a)(−1.10%per year),and−0.0019 mg/(m^(3)·a)(−1.01%per year).The negative trends in winter(November to March)were more prominent than those in summer(May to September).In terms of spatial distribution,the downward trend was more significant in regions with higher CHL.These led to a reduced standard deviation of CHL over time and space.We further explored the influence of various dynamic factors on CHL trends for the entire SCS and two typical systems(winter Luzon Strait(LZ)and summer Vietnam Upwelling System(SV))with single-variate linear regression and multivariate Random Forest analysis.The multivariate analysis suggested the CHL trend pattern can be best explained by the trends of wind speed and mixed-layer depth.The divergent importance of controlling factors for LZ and SV can explain the different CHL trends for the two systems.This study expanded our understanding of the long-term changes of CHL in the SCS and provided a reference for investigating changes in the marine ecosystem.

Response of Chlorophyll a, SPAD Values and Chlorophyll Fluorescence Parameters in Leaves of Apricot Affected Some Abiotic Factors

Experimental trail conducted in Jasenica, Bosnia and Herzegovina have showed apricot （Prunus persica L） leaf injures especially on the edges in the middle of the season. Leaf edges show chlorosis starting from the tip due to lack of Chlorophyll. Affected leaves start falling and renew leaves masse as respond to stress conditions which also delay fruits maturation. Technological development in detecting the stress of high plants trough the leaf fluorescence and Chlorophyll concentration have led to the introduction of instruments which utilize fluorescence as a basis for determining stress level. The paper was aimed to show whether the productivity values calculated from Chlorophyll fluorescence Fv/Fm were comparable to those produced by spectrophotometric method in detecting Chlorophyll a concentration and SPAD values detected by Chlorophyll meter （SPAD-502）. Measurements of nitrogen content were also provided in order to obtain accuracy of SPAD meter since Chlorophyll molecules contain nitrogen in their structure. To test the relationship between these three technique regression relationship was obtained. Regression coefficient between Fv/Fm values and Chlorophyll a concentration mg g-t was high. Also, strong regression coefficient was observed between Chlorophyll a and SPAD values indicating a good accuracy of this device which was also confirmed by good regression between nitrogen content and SPAD values. Fluorometer measurements on injured leaves samples of apricot have also reviled the Fv/Fm values below 0.83 which is in according with numerous authors who considered a line for indicating stress factors.

Seasonal variation of the shape and location of the Luzon cold eddy

Using observational data from multiple satellites,we studied seasonal variations of the shape and location of the Luzon cold eddy(LCE)northwest of Luzon Island.The shape and location of the LCE have obvious seasonal variations.The LCE occurs,develops,and disappears from December to April of the next year.During this period,the shape of the LCE changed from a flat ellipse to a circular ellipse,and the change in shape can be reflected by the increase of the ellipticity of the LCE from 0.16 to 0.82.The latitude of center location of the LCE changes from 17.4°N to 19°N,and the change in latitude can reach 1.6°.Further study showed that seasonal variation of the northeast monsoon intensity leads to the change in the shape and location of the LCE.The seasonal variation of the LCE shape can significantly alter the spatial distribution of the thermal front and chlorophyll a northwest of the Luzon Island by geostrophic advection.

On Radar Signatures of Upwelling

In studies of upwelling,usually data from infrared and optical sensors is used which provides information on the sea surface temperature(SST)and the chlorophyll-a(Chl-a)concentration.In this paper,we show that also synthetic aperture radars(SAR)images can give valuable contribution to such studies.Upwelling regions become detectable by SAR because they are associated with a reduction of the radar backscatter due to(1)the change of the stability of the air-sea interface or/and(2)the presence of biogenic slicks.Furthermore,the boundary of upwelling regions consists of a line of increased radar backscatter due to the presence of convergent surface flow.

Estimation of ocean primary productivity and its spatio-temporal variation mechanism for East China Sea based on VGPM model

According to calculation results of ocean chlorophyll concentration based on SeaWiFS data by SeaBAM model and synchronous ship-measured data, this research set up an improved model for CaseⅠand CaseⅡwater bodies respectively. The monthly chlorophyll distribution in the East China Sea in 1998 was obtained from this improved model on calculation results of SeaBAM. The euphotic depth distribution in 1998 in the East China Sea is calculated by using remote sensing data of K 490 from SeaWiFS according to the relation between the euphotic depth and the oceanic diffuse attenuation coefficient. With data of ocean chlorophyll concentration, euphotic depth, ocean surface photosynthetic available radiation (PAR), daily photoperiod and optimal rate of daily carbon fixation within a water column, the monthly and annual primary productivity spatio-temporal distributions in the East China Sea in 1998 were obtained based on VGPM model. Based on analysis of those distributions, the conclusion can be drawn that there is a clear bimodality character of primary productivity in the monthly distribution in the East China Sea. In detail, the monthly distribution of primary productivity stays the lowest level in winter and rises rapidly to the peak in spring. It gets down a little in summer, and gets up a little in autumn. The daily average of primary productivity in the whole East China Sea is 560.03 mg/m 2 /d, which is far higher than the average of subtropical ocean areas. The annual average of primary productivity is 236.95 g/m 2 /a. The research on the seasonal variety mechanism of primary productivity shows that several factors that affect the spatio-temporal distribution may include the chlorophyll concentration distribution, temperature condition, the Yangtze River diluted water variety, the euphotic depth, ocean current variety, etc. But the main influencing factors may be different in each local sea area.

Inversion of Biochemical Parameters by Selection of Proper Vegetation Index in Winter Wheat

Recent studies have demonstrated the application of vegetation indices from canopy reflectedspectrum for inversion of chlorophyll concentration. Some indices are both response tovariations of vegetation and environmental factors. Canopy chlorophyll concentration, anindicator of photosynthesis activity, is related to nitrogen concentration in green vegetationand serves as an indicator of the crop response to soil nitrogen fertilizer application. Thecombination of normalized difference vegetation index (NDVI) and photochemical reflectanceindex (PRI) can reduce the effect of leaf area index (LAI) and soil background. The canopychlorophyll inversion index (CCII) was proved to be sensitive to chlorophyll concentration andvery resistant to the other variations. This paper introduced the ratio of TCARI/OSAVI to makeaccurate predictions of winter wheat chlorophyll concentration under different cultivars. Itindicated that canopy chlorophyll concentration could be evaluated by some combined vegetationindices.