Significant wave period is an important parameter in coastal and offshore engineering design.Traditional spectral wave models do not directly calculate this parameter,which means that it needs to be estimated from the...Significant wave period is an important parameter in coastal and offshore engineering design.Traditional spectral wave models do not directly calculate this parameter,which means that it needs to be estimated from the spectral periods using empirical formulas.The wave energy period is one of the wave periods directly output by many wave models and is often used in studies of wave energy.This study investigated the relationship between significant wave period and wave energy period using wave data measured at three stations in the coastal waters of China.The observations recorded at these stations in the South China Sea,the East China Sea,and the Bohai Sea covered a wide range of surface wave conditions.Analysis indicated that the ratio of significant wave period to wave energy period is closely related to the Goda peakedness parameter of the wave spectra.Therefore,we proposed an empirical formula in which significant wave period is a function of wave energy period and the Goda peakedness parameter.Evaluation results showed that the performance of this formula is substantially better than that of fitting formulas that use constant coefficients.展开更多
BACKGROUND Clinically significant portal hypertension(CSPH)is a crucial prognostic deter-minant for liver-related events(LREs)in patients with compensated viral cir-rhosis.Liver stiffness measurement(LSM)-related mark...BACKGROUND Clinically significant portal hypertension(CSPH)is a crucial prognostic deter-minant for liver-related events(LREs)in patients with compensated viral cir-rhosis.Liver stiffness measurement(LSM)-related markers may help to predict the risk of LREs.AIM To evaluate the value of LSM and its composite biomarkers[LSM-platelet ratio(LPR),LSM-albumin ratio(LAR)]in predicting LREs.METHODS This study retrospectively enrolled compensated viral cirrhosis patients with CSPH.The Cox regression model was employed to examine the prediction of LSM,LPR,and LAR for LREs.The model performance was assessed through receiver operating characteristic,decision curve,and time-dependent area under the curve analysis.The Kaplan-Meier curve was used to evaluate the cumulative incidence of LREs,and further stratified analysis of different LREs was per-formed.RESULTS A total of 598 patients were included,and 319 patients(53.3%)developed LREs during follow-up.Multivariate proportional hazards modeling demonstrated that LSM,LPR,and LAR were independent predictors of LREs.LPR had better performance in predicting LREs than LAR and LSM(area under the curve=0.780,0.727,0.683,respectively,all P<0.05).The cumulative incidence of LREs in the high-risk group were significantly higher than that in the low-risk group(P<0.001).Among the different LREs,LPR was superior to LSM and LAR in predicting liver decompensation,while the difference in predicting hepatocellular carcinoma and liver-related death was relatively small.CONCLUSION LPR is superior to LSM and LAR in predicting LREs in compensated viral cirrhosis patients with CSPH,especially in predicting liver decompensation.展开更多
Accurate significant wave height(SWH)prediction is essential for the development and utilization of wave energy.Deep learning methods such as recurrent and convolutional neural networks have achieved good results in S...Accurate significant wave height(SWH)prediction is essential for the development and utilization of wave energy.Deep learning methods such as recurrent and convolutional neural networks have achieved good results in SWH forecasting.However,these methods do not adapt well to dynamic seasonal variations in wave data.In this study,we propose a novel method—the spatiotemporal dynamic graph(STDG)neural network.This method predicts the SWH of multiple nodes based on dynamic graph modeling and multi-characteristic fusion.First,considering the dynamic seasonal variations in the wave direction over time,the network models wave dynamic spatial dependencies from long-and short-term pattern perspectives.Second,to correlate multiple characteristics with SWH,the network introduces a cross-characteristic transformer to effectively fuse multiple characteristics.Finally,we conducted experiments on two datasets from the South China Sea and East China Sea to validate the proposed method and compared it with five prediction methods in the three categories.The experimental results show that the proposed method achieves the best performance at all predictive scales and has greater advantages for extreme value prediction.Furthermore,an analysis of the dynamic graph shows that the proposed method captures the seasonal variation mechanism of the waves.展开更多
To analyze if clinically insignificant prostate cancer （CIPC） is more frequently detected with repeat prostate biopsies, we retrospectively analyzed the records of 2146 men diagnosed with prostate cancer after one o...To analyze if clinically insignificant prostate cancer （CIPC） is more frequently detected with repeat prostate biopsies, we retrospectively analyzed the records of 2146 men diagnosed with prostate cancer after one or more prostate biopsies. The patients were divided into five groups according to the number of prostate biopsies obtained, e.g, group I had one biopsy, group 2 had two biopsies and group 3 had three biopsies. Of the 2146 patients diagnosed with prostate cancer, 1956 （91,1%）, 142 （6.6%）, 38 （1.8%）, 9 （0.4%） and 1 （0.1%） men were in groups 1, 2, 3, 4 and 5, respectively. Groups 4 and 5 were excluded because of the small sample sizes. The remaining three groups （groups 1, 2 and 3） were statistically analyzed. There were no differences in age or prostate-specific antigen level among the three groups. CIPC was detected in 201 （10.3%）, 28 （19.7%） and 9 （23.7%） patients in groups 1, 2 and 3, respectively （P〈O.O01）. A multivariate analysis showed that the number of biopsies was an independent predictor to detect ClPC （0R=2.688 for group 2; 0R=4.723 for group 3）. In conclusion, patients undergoing multiple prostate biopsies are more likely to be diagnosed with CIPC than those who only undergo one biopsy. However, the risk still exists that the patient could have clinically significant prostate cancer. Therefore, when counseling patients with regard to serial repeat biopsies, the possibility of prostate cancer overdiagnosis and overtreatment must be balanced with the continued risk of clinically significant disease.展开更多
In this study, the statistical characterization of sea conditions in the East China Sea(ECS) is investigated by analyzing a significant wave height and wind speed data at a 6-hour interval for 30 years(1980–2009), wh...In this study, the statistical characterization of sea conditions in the East China Sea(ECS) is investigated by analyzing a significant wave height and wind speed data at a 6-hour interval for 30 years(1980–2009), which was simulated and computed using the WAVEWATCH Ⅲ(WW3) model. The monthly variations of these parameters showed that the significant wave height and wind speed have minimum values of 0.73 m and 5.15 ms^(-1) and 1.73 m and 8.24 ms^(-1) in the month of May and December, respectively. The annual, seasonal, and monthly mean sea state characterizations showed that the slight sea generally prevailed in the ECS and had nearly the highest occurrence in all seasons and months. Additionally, the moderate sea prevailed in the winter months of December and January, while the smooth(wavelets) sea prevailed in May. Furthermore, the spatial variation of sea states showed that the calm and smooth sea had the largest occurrences in the northern ECS. The slight sea occurred mostly(above 30%) in parts of the ECS and the surrounding locations, while higher occurrences of the rough and very rough seas were distributed in waters between the southwest ECS and the northeast South China Sea(SCS). The occurrences of the phenomenal sea conditions are insignificant and are distributed in the northwest Pacific and its upper region, which includes the Southern Kyushu-Palau Ridge and Ryukyu Trench.展开更多
The HY-2 satellite was successfully launched on 16 August 2011. The HY-2 significant wave height （SWH） is validated by the data from the South China Sea （SCS） field experiment, National Data Buoy Center （NDBC/ bu...The HY-2 satellite was successfully launched on 16 August 2011. The HY-2 significant wave height （SWH） is validated by the data from the South China Sea （SCS） field experiment, National Data Buoy Center （NDBC/ buoys and Jason-1/2 altimeters, and is corrected using a linear regression with in-situ measurements. Com- pared with NDBC SWH, the HY-2 SWH show a RMS of 0.36 m, which is similar to Jason- 1 and Jason-2 SWH with the RMS of 0.35 m and 0.37 m respectively; the RMS of corrected HY-2 SWH is 0.27 m, similar to 0.27 m and 0.23 m of corrected Jason-1 and Jason-2 SWH. Therefore the accuracy of HY-2 SWH products is close to that of Jason-1/2 SWH, and the linear regression function derived can improve the accuracy of HY-2 SWH products.展开更多
HY-2 has been launched by China on August 16, 2011 which assembles multi-microwave remote sensing payloads in a body and has the ability of monitoring ocean dynamic environments. The HY-2 satellite data need to be cal...HY-2 has been launched by China on August 16, 2011 which assembles multi-microwave remote sensing payloads in a body and has the ability of monitoring ocean dynamic environments. The HY-2 satellite data need to be calibrated and validated before being put into use. Based on the in-situ buoys from the Nation- al Data Buoy Center （NDBC）, Ku-band significant wave heights （SWH, hs） of HY-2 altimeter are validated. Eleven months of HY-2 altimeter Level 2 products data are chose from October 1, 2011 to August 29, 2012. Using NDBC 60 buoys yield 902 collocations for HY-2 by adopting collocation criteria of 30 min for tempo- ral window and 50 km for a spatial window. An overall RMS difference of the SWH between HY-2 and buoy data is 0.297 m. A correlation coefficient between these is 0.964. An ordinary least squares （OLS） regression is performed with the buoy data as an independent variable and the altimeter data as a dependent vari- able. The regression equation of hs is hs （HY-2）=0.891 × hs （NDBC）＋0.022. In addition, 2016 collocations are matched with temporal window of 30 rain at the crossing points of HY-2 and Jason-2 orbits. RMS difference of Ku-band SWH between the two data sets is 0.452 m.展开更多
1.Introduction Compared with the United States,whose annual number of tornadoes can exceed 1000,the average number of tornadoes per year in China over the past half a century is estimated to be fewer than 100（Fan and...1.Introduction Compared with the United States,whose annual number of tornadoes can exceed 1000,the average number of tornadoes per year in China over the past half a century is estimated to be fewer than 100（Fan and Yu,2015）,even though both countries are located in a similar latitudinal zone of the Northern Hemisphere.展开更多
Chinese Haiyang-2（HY-2） satellite is the first Chinese marine dynamic environment satellite. The dual-frequency （Ku and C band） radar altimeter onboard HY-2 has been working effective to provide operational signif...Chinese Haiyang-2（HY-2） satellite is the first Chinese marine dynamic environment satellite. The dual-frequency （Ku and C band） radar altimeter onboard HY-2 has been working effective to provide operational significant wave height （SWH） for more than three years （October 1, 2011 to present）.We validated along-track Ku-band SWH data of HY-2 satellite against National Data Buoy Center （NDBC） in-situ measurements over a time period of three years from October 1, 2011 to September 30, 2014, the root mean square error （RMSE） and mean bias of HY-2 SWH is 0.38 m and （-0.13±0.35） m, respectively. We also did cross validation against Jason-2 altimeter SWH data, the RMSE and the mean bias is 0.36m and （-0.22±0.28） m, respectively. In order to compare the statistical results between HY-2 and Jason-2 satellite SWH data, we validated the Jason-2 satellite radar altimeter along-track Ku-band SWH data against NDBC measurements using the same method. The results demonstrate the validation method in this study is scientific and the RMSE and mean bias of Jason-2 SWH data is 0.26 m and （0.00±0.26） m, respectively. We also validated both HY-2 and Jason-2 SWH data every month, the mean bias of Jason-2 SWH data almost equaled to zero all the time, while the mean bias of HY-2 SWH data was no less than -0.31m before April 2013 and dropped to zero after that time. These results indicate that the statistical results for HY-2 altimeter SWH are reliable and HY-2 altimeter along-track SWH data were steady and of high quality in the last three years. The results also indicate that HY-2 SWH data have greatly been improved and have the same accuracy with Jason-2 SWH data after April, 2013. SWH data provided by HY-2 satellite radar altimeter are useful and acceptable for ocean operational applications.展开更多
OSMAR071 is the latest product of the OSMAR （ocean state monitor and analysis radar） series of high frequency surface wave radar （HFSWR）, which was developed by the Radiowave Propagation Laboratory of Wuhan Univer...OSMAR071 is the latest product of the OSMAR （ocean state monitor and analysis radar） series of high frequency surface wave radar （HFSWR）, which was developed by the Radiowave Propagation Laboratory of Wuhan University. It adopts a modified Barrick waveheight inversion model. The modifications are introduced to improve the model＇s performances under the effect of noises and interferences and in the case of broad beam radar detection. The two unknown coefficients in the modified model are figured out by fitting the HFSWR significant waveheight results to those output from a wave buoy located in the radiating coverage of the radar site. The model is applied to inverse the waveheights from radar data for the duration from Dec. 1st, 2008 to Feb. 25th, 2009, and then the radar waveheights are compared with the buoy measurements. Results show that the rms difference between radar-derived significant waveheights and those from the buoy is 0.38 m and the correlation coefficient between the two series is 0.66. This study describes OSMAR071 observation of significant waveheight with relatively satisfactory accuracy during about three months.展开更多
Long-term variations in a sea surface wind speed （WS） and a significant wave height （SWH） are associated with the global climate change, the prevention and mitigation of natural disasters, and an ocean resource ex...Long-term variations in a sea surface wind speed （WS） and a significant wave height （SWH） are associated with the global climate change, the prevention and mitigation of natural disasters, and an ocean resource exploitation, and other activities. The seasonal characteristics of the long-term trends in China＇s seas WS and SWH are determined based on 24 a （1988-2011） cross-calibrated, multi-platform （CCMP） wind data and 24 a hindcast wave data obtained with the WAVEWATCH-III （WW3） wave model forced by CCMP wind data. The results show the following. （1） For the past 24 a, the China＇s WS and SWH exhibit a significant increasing trend as a whole, of 3.38 cm/（s.a） in the WS, 1.3 cm/a in the SWH. （2） As a whole, the increasing trend of the China＇s seas WS and SWH is strongest in March-April-May （MAM） and December-January-February （DJF）, followed by June-July-August （JJA）, and smallest in September-October-November （SON）. （3） The areal extent of significant increases in the WS was largest in MAM, while the area decreased in JJA and DJF; the smallest area was apparent in SON. In contrast to the WS, almost all of China＇s seas exhibited a significant increase in SWH in MAM and DJF; the range was slightly smaller in JJA and SON. The WS and SWH in the Bohai Sea, the Yellow Sea, East China Sea, the Tsushima Strait, the Taiwan Strait, the northern South China Sea, the Beibu Gull and the Gulf of Thailand exhibited a significant increase in all seasons. （4） The variations in China＇s seas SWH and WS depended on the season. The areas with a strong increase usually appeared in DJF.展开更多
A new method for estimating significant wave height（SWH） from advanced synthetic aperture radar（ASAR） wave mode data based on a support vector machine（SVM） regression model is presented. The model is established...A new method for estimating significant wave height（SWH） from advanced synthetic aperture radar（ASAR） wave mode data based on a support vector machine（SVM） regression model is presented. The model is established based on a nonlinear relationship between σ0, the variance of the normalized SAR image, SAR image spectrum spectral decomposition parameters and ocean wave SWH. The feature parameters of the SAR images are the input parameters of the SVM regression model, and the SWH provided by the European Centre for Medium-range Weather Forecasts（ECMWF） is the output parameter. On the basis of ASAR matching data set, a particle swarm optimization（PSO） algorithm is used to optimize the input kernel parameters of the SVM regression model and to establish the SVM model. The SWH estimation results yielded by this model are compared with the ECMWF reanalysis data and the buoy data. The RMSE values of the SWH are 0.34 and 0.48 m, and the correlation coefficient is 0.94 and 0.81, respectively. The results show that the SVM regression model is an effective method for estimating the SWH from the SAR data. The advantage of this model is that SAR data may serve as an independent data source for retrieving the SWH, which can avoid the complicated solution process associated with wave spectra.展开更多
Chinese Gaofen-3（GF-3） is the first civilian satellite to carry C-band（5.3 GHz） synthetic aperture radar（SAR）.During the period of August 2016 to December 2017, 1 523 GF-3 SAR images acquired in quad-polarizatio...Chinese Gaofen-3（GF-3） is the first civilian satellite to carry C-band（5.3 GHz） synthetic aperture radar（SAR）.During the period of August 2016 to December 2017, 1 523 GF-3 SAR images acquired in quad-polarization（vertical-vertical（VV）, horizontal-horizontal（HH）, vertical-horizontal（VH）, and horizontal-vertical（HV）） mode were recorded, mostly around China＇s seas. In our previous study, the root mean square error（RMSE） of significant wave height（SWH） was found to be around 0.58 m when compared with retrieval results from a few GF-3 SAR images in co-polarization（VV and HH） with moored measurements by using an empirical algorithm CSARWAVE. We collected a number of sub-scenes from these 1 523 images in the co-polarization channel,which were collocated with wind and SWH data from the European Centre for Medium-Range Weather Forecasts（ECMWF） reanalysis field at a 0.125° grid. Through the collected dataset, an improved empirical wave retrieval algorithm for GF-3 SAR in co-polarization was tuned, herein denoted as CSARWAVE2. An additional 92 GF-3 SAR images were implemented in order to validate CSARWAVE2 against SWH from altimeter Jason-2, showing an about 0.52 m RMSE of SWH for co-polarization GF-3 SAR. Therefore, we conclude that the proposed empirical algorithm has a good performance for wave retrieval from GF-3 SAR images in co-polarization.展开更多
·AIM:To determine the risk factors of clinically significant macular edema (CSME) in patients with non-proliferative diabetic retinopathy (NPDR) in a multi-ethnics Malaysian population. ·METHODS:We performed...·AIM:To determine the risk factors of clinically significant macular edema (CSME) in patients with non-proliferative diabetic retinopathy (NPDR) in a multi-ethnics Malaysian population. ·METHODS:We performed a case control study in which 150 patients with bilateral NPDR and CSME in either eye were compared to 150 patients with bilateral NPDR and no CSME in both eyes. CSME and NPDR were graded according to Early Treatment of Diabetic Retinopathy Study criteria. Student’s t-test, odds ratio and multiple logistic regression analysis were performed to analyze the duration of diabetes, body mass index (BMI), blood pressure(BP), total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TG), fasting blood glucose (FBG), HbA1c, full blood count, serum creatinine and proteinuria between the two groups. ·RESULTS:Both groups were matched in terms of age, gender and ethnicity. Duration of diabetes, total serum cholesterol, serum LDL, FBG, HbA1c and serum creatinine were significantly higher in the CSME group (P <0.05). The hemoglobin, packed cell volume were significantly lower in the CSME group (P <0.05). There was no significant difference for serum HDL, TG, BMI, systolic and diastolic BP. Multiple logistic regression analysis showed that total serum cholesterol and HbA1c had significantly high odds of developing CSME. ·CONCLUSION:HbA1c and total cholesterol are the two most important risk factors associated with CSME in patients with NPDR.展开更多
The significant wave height(SWH)is one of the main parameters that describe wave characteristics and is widely used in wave research fields.Wave parameters measured by radar are influenced by the offshore distance and...The significant wave height(SWH)is one of the main parameters that describe wave characteristics and is widely used in wave research fields.Wave parameters measured by radar are influenced by the offshore distance and sea state.Validation and calibration are of great significance for radar data applications.The nadir beam of surface wave investigation and monitoring(SWIM)detects the global-ocean-surface SWH.To determine the product quality of SWIM SWH,this paper carried out time-space matching between SWIM and buoy data.The data qualities were evaluated under different offshore distances and sea states.An improved calibration method was proposed based on sea state segmentation,which considered the distribution of the point collocation numbers in various sea states.The results indicate that(1)the SWIM SWH accuracy at offshore distances greater than 50 km is higher than that at distances less than 50 km,with an root mean squared error(RMSE)of 0.2444 m,scatter index(SI)of 0.1156 and relative error(RE)of 9.97%at distances greater than 50 km and those of 0.4460 m,0.2230 and18.66%at distances less than 50 km.(2)SWIM SWH qualities are better in moderate and rough sea states with RMSEs of 0.2848 m and 0.3169 m but are worse in slight and very rough sea states.(3)The effect of the improved calibration method is superior to the traditional method in each sea state and overall data,and the RMSE of SWIM SWH is reduced from the raw 0.3135 m to 0.2859 m by the traditional method and 0.1982 m by the improved method.The influence of spatiotemporal window selection on data quality evaluation was analyzed in this paper.This paper provides references for SWIM SWH product applications.展开更多
Background: Significant portal hypertension(SPH) is a relative contraindication for patients with resectable hepatocellular carcinoma(HCC). However, increasing evidence indicates that liver resection is feasible for H...Background: Significant portal hypertension(SPH) is a relative contraindication for patients with resectable hepatocellular carcinoma(HCC). However, increasing evidence indicates that liver resection is feasible for HCC patients with SPH. Methods: HCC patients with cirrhosis who underwent laparoscopic liver resection(LLR) in two centers from January 2013 to April 2018 were included. Surgical and survival outcomes were analyzed to explore potential prognostic factors. Propensity score matching(PSM) analysis was performed to minimize bias. Results: A total of 165 patients were divided into two groups based on the presence(SPH, n = 76) or absence(non-SPH, n = 89) of SPH. Patients in the SPH group had longer operative time, more blood loss, and more advanced TNM stage than patients in the non-SPH group( P < 0.05). However, there were no significant differences in the postoperative 90-day mortality rate( n = 0), overall postoperative complications(47.4% vs. 41.6%, P = 0.455), Clavien-Dindo classification( P = 0.347), conversion to open surgery(9.2% vs. 6.7%, P = 0.557), or length of hospitalization(16 vs. 15 days, P = 0.203) between the SPH and non-SPH groups before PSM. Similar results were obtained after PSM. The 1-, 3-, and 5-year overall survival(OS) and recurrence-free survival rates in the SPH group were not significantly different from those in the non-SPH group both before and after PSM(log-rank P > 0.05). After PSM, alpha-fetoprotein(AFP) ≥ 400 μg/L [hazard ratio(HR) = 4.71, 95% confidence interval(CI): 2.69-8.25], ascites(HR = 2.18, 95% CI: 1.30-3.66), American Society of Anesthesiologists(ASA) classification(Ⅲ vs. Ⅱ)(HR = 2.13, 95% CI: 1.11-4.07) and tumor diameter > 5 cm(HR = 3.91, 95% CI: 2.02-7.56) independently predicted worse OS. Conclusions: LLR for patients with HCC complicated with SPH appears feasible at the price of increasing operative time and blood loss. AFP, ascites, ASA classification and tumor diameter may predict the prognosis of HCC complicated with SPH after LLR.展开更多
The main objective of this paper is to propose a newly developed ocean Significant Wave Height (SWH) retrieval method from Envisat Advanced Synthetic Aperture Radar (ASAR) imagery. A series of wave mode imagery from J...The main objective of this paper is to propose a newly developed ocean Significant Wave Height (SWH) retrieval method from Envisat Advanced Synthetic Aperture Radar (ASAR) imagery. A series of wave mode imagery from January, April and May of 2011 are collocated with ERA-Interim reanalysis SWH data. Based on the matched datasets, a simplified empirical relationship between 22 types of SAR imagery parameters and SWH products is developed with the Genetic Algorithms Partial Least-Squares (GA-PLS) model. Two major features of the backscattering coefficient σ0 and the frequency parameter S10 are chosen as the optimal training feature subset of SWH retrieval by using cross validation. In addition, we also present a comparison of the retrieval results of the simplified empirical relationship with the collocated ERA-Interim data. The results show that the assessment index of the correlation coefficient, the bias, the root-mean-square error of cross validation (RMSECV) and the scattering index (SI) are 0.78, 0.07 m, 0.76 m and 0.5, respectively. In addition, the comparison of the retrieved SWH data between our simplifying model and the Jason-2 radar altimeter data is proposed in our study. Moreover, we also make a comparison of the retrieval of SWH data between our developed model and the well- known CWAVE_ENV model. The results show that satisfying retrieval results are acquired in the low-moderate sea state, but major bias appears in the high sea state, especially for SWH>5 m.展开更多
In-situ observation is restricted by the strong wind and waves in the Southern Ocean.A Westerlies EnvironmentalMonitoring Buoy(WEMB)was firstly deployed in the Southern Ocean during China’s 35th Antarctic Expedition,...In-situ observation is restricted by the strong wind and waves in the Southern Ocean.A Westerlies EnvironmentalMonitoring Buoy(WEMB)was firstly deployed in the Southern Ocean during China’s 35th Antarctic Expedition,facilitating further understanding of the oceanic environmental characteristics of this region.With the develop-ment of technology and the improvement of data processing methods,the accuracy of satellite altimeter productsis constantly improved,thus making it possible to inspect and evaluate the in-situ observation data.Based on theL3 products of multiple satellite altimeters,this paper analyzes and corrects the significant wave height(SWH)data of WEMB by means of data matching,error statistics,and linear least-squares fitting.Through this study,the authors obtained the following results.The effect of gravitational acceleration changes with latitude on SWHaccuracy is fairly small.Due to the low response of WEMB to high-frequency waves,there is a systematic devia-tion.A feasible correction method is therefore proposed to improve the SWH accuracy of WEMB.The temporalvariation of the corrected SWH is highly consistent with that of the 10 m wind during the observation period,and its average value reaches 3.8 m.展开更多
A new model is proposed to estimate the significant wave heights with ERS-1/2 scatterometer data. The results show that the relationship between wave parameters and radar backscattering cross section is similar to tha...A new model is proposed to estimate the significant wave heights with ERS-1/2 scatterometer data. The results show that the relationship between wave parameters and radar backscattering cross section is similar to that between wind and the radar backscattering cross section. Therefore, the relationship between significant wave height and the radar backscattering cross section is established with a neural network algorithm, which is, if the average wave period is ≤7s, the root mean square of significant wave height retrieved from ERS-1/2 data is 0.51 m, or 0.72 m if it is >7s otherwise.展开更多
Since 2015, the China Geological Survey has implemented a major program of ＂Geology Survey of Land Energy Mineral Resources＂. Till now, a total of billions of RMB have been invested and seven engineering projects ha...Since 2015, the China Geological Survey has implemented a major program of ＂Geology Survey of Land Energy Mineral Resources＂. Till now, a total of billions of RMB have been invested and seven engineering projects have been established, all of which has greatly enhanced the geological survey and exploration of China＇s continental shale gas in an attempt to overcome the oil and gas shortage.展开更多
基金The National Natural Science Foundation of China under contract No.41821004the Basic Scientific Fund for National Public Research Institutes of China under contract No.2020Q08the Fund of Laoshan Laboratory under contract No.LSKJ202201600.
文摘Significant wave period is an important parameter in coastal and offshore engineering design.Traditional spectral wave models do not directly calculate this parameter,which means that it needs to be estimated from the spectral periods using empirical formulas.The wave energy period is one of the wave periods directly output by many wave models and is often used in studies of wave energy.This study investigated the relationship between significant wave period and wave energy period using wave data measured at three stations in the coastal waters of China.The observations recorded at these stations in the South China Sea,the East China Sea,and the Bohai Sea covered a wide range of surface wave conditions.Analysis indicated that the ratio of significant wave period to wave energy period is closely related to the Goda peakedness parameter of the wave spectra.Therefore,we proposed an empirical formula in which significant wave period is a function of wave energy period and the Goda peakedness parameter.Evaluation results showed that the performance of this formula is substantially better than that of fitting formulas that use constant coefficients.
基金Supported by the High-Level Chinese Medicine Key Discipline Construction Project,No.zyyzdxk-2023005Capital’s Funds for Health Improvement and Research,No.2024-1-2173+2 种基金National Natural Science Foundation of China,No.82474419 and No.82474426Beijing Municipal Natural Science Foundation,No.7232272Beijing Traditional Chinese Medicine Technology Development Fund Project,No.BJZYZD-2023-12.
文摘BACKGROUND Clinically significant portal hypertension(CSPH)is a crucial prognostic deter-minant for liver-related events(LREs)in patients with compensated viral cir-rhosis.Liver stiffness measurement(LSM)-related markers may help to predict the risk of LREs.AIM To evaluate the value of LSM and its composite biomarkers[LSM-platelet ratio(LPR),LSM-albumin ratio(LAR)]in predicting LREs.METHODS This study retrospectively enrolled compensated viral cirrhosis patients with CSPH.The Cox regression model was employed to examine the prediction of LSM,LPR,and LAR for LREs.The model performance was assessed through receiver operating characteristic,decision curve,and time-dependent area under the curve analysis.The Kaplan-Meier curve was used to evaluate the cumulative incidence of LREs,and further stratified analysis of different LREs was per-formed.RESULTS A total of 598 patients were included,and 319 patients(53.3%)developed LREs during follow-up.Multivariate proportional hazards modeling demonstrated that LSM,LPR,and LAR were independent predictors of LREs.LPR had better performance in predicting LREs than LAR and LSM(area under the curve=0.780,0.727,0.683,respectively,all P<0.05).The cumulative incidence of LREs in the high-risk group were significantly higher than that in the low-risk group(P<0.001).Among the different LREs,LPR was superior to LSM and LAR in predicting liver decompensation,while the difference in predicting hepatocellular carcinoma and liver-related death was relatively small.CONCLUSION LPR is superior to LSM and LAR in predicting LREs in compensated viral cirrhosis patients with CSPH,especially in predicting liver decompensation.
基金The National Key R&D Program of China under contract No.2021YFC3101604。
文摘Accurate significant wave height(SWH)prediction is essential for the development and utilization of wave energy.Deep learning methods such as recurrent and convolutional neural networks have achieved good results in SWH forecasting.However,these methods do not adapt well to dynamic seasonal variations in wave data.In this study,we propose a novel method—the spatiotemporal dynamic graph(STDG)neural network.This method predicts the SWH of multiple nodes based on dynamic graph modeling and multi-characteristic fusion.First,considering the dynamic seasonal variations in the wave direction over time,the network models wave dynamic spatial dependencies from long-and short-term pattern perspectives.Second,to correlate multiple characteristics with SWH,the network introduces a cross-characteristic transformer to effectively fuse multiple characteristics.Finally,we conducted experiments on two datasets from the South China Sea and East China Sea to validate the proposed method and compared it with five prediction methods in the three categories.The experimental results show that the proposed method achieves the best performance at all predictive scales and has greater advantages for extreme value prediction.Furthermore,an analysis of the dynamic graph shows that the proposed method captures the seasonal variation mechanism of the waves.
文摘To analyze if clinically insignificant prostate cancer （CIPC） is more frequently detected with repeat prostate biopsies, we retrospectively analyzed the records of 2146 men diagnosed with prostate cancer after one or more prostate biopsies. The patients were divided into five groups according to the number of prostate biopsies obtained, e.g, group I had one biopsy, group 2 had two biopsies and group 3 had three biopsies. Of the 2146 patients diagnosed with prostate cancer, 1956 （91,1%）, 142 （6.6%）, 38 （1.8%）, 9 （0.4%） and 1 （0.1%） men were in groups 1, 2, 3, 4 and 5, respectively. Groups 4 and 5 were excluded because of the small sample sizes. The remaining three groups （groups 1, 2 and 3） were statistically analyzed. There were no differences in age or prostate-specific antigen level among the three groups. CIPC was detected in 201 （10.3%）, 28 （19.7%） and 9 （23.7%） patients in groups 1, 2 and 3, respectively （P〈O.O01）. A multivariate analysis showed that the number of biopsies was an independent predictor to detect ClPC （0R=2.688 for group 2; 0R=4.723 for group 3）. In conclusion, patients undergoing multiple prostate biopsies are more likely to be diagnosed with CIPC than those who only undergo one biopsy. However, the risk still exists that the patient could have clinically significant prostate cancer. Therefore, when counseling patients with regard to serial repeat biopsies, the possibility of prostate cancer overdiagnosis and overtreatment must be balanced with the continued risk of clinically significant disease.
基金supported by the National Key Research and Development Program of China(No.2016YFC1401405)the National Natural Science Foundation of China(No.41376010)
文摘In this study, the statistical characterization of sea conditions in the East China Sea(ECS) is investigated by analyzing a significant wave height and wind speed data at a 6-hour interval for 30 years(1980–2009), which was simulated and computed using the WAVEWATCH Ⅲ(WW3) model. The monthly variations of these parameters showed that the significant wave height and wind speed have minimum values of 0.73 m and 5.15 ms^(-1) and 1.73 m and 8.24 ms^(-1) in the month of May and December, respectively. The annual, seasonal, and monthly mean sea state characterizations showed that the slight sea generally prevailed in the ECS and had nearly the highest occurrence in all seasons and months. Additionally, the moderate sea prevailed in the winter months of December and January, while the smooth(wavelets) sea prevailed in May. Furthermore, the spatial variation of sea states showed that the calm and smooth sea had the largest occurrences in the northern ECS. The slight sea occurred mostly(above 30%) in parts of the ECS and the surrounding locations, while higher occurrences of the rough and very rough seas were distributed in waters between the southwest ECS and the northeast South China Sea(SCS). The occurrences of the phenomenal sea conditions are insignificant and are distributed in the northwest Pacific and its upper region, which includes the Southern Kyushu-Palau Ridge and Ryukyu Trench.
基金The Marine Public Welfare Project of China under contract No.201105032the National High-Tech Project of China undercontract No.2008AA09A403the fund of State Administration for Science,Technology and Industry for National Defense
文摘The HY-2 satellite was successfully launched on 16 August 2011. The HY-2 significant wave height （SWH） is validated by the data from the South China Sea （SCS） field experiment, National Data Buoy Center （NDBC/ buoys and Jason-1/2 altimeters, and is corrected using a linear regression with in-situ measurements. Com- pared with NDBC SWH, the HY-2 SWH show a RMS of 0.36 m, which is similar to Jason- 1 and Jason-2 SWH with the RMS of 0.35 m and 0.37 m respectively; the RMS of corrected HY-2 SWH is 0.27 m, similar to 0.27 m and 0.23 m of corrected Jason-1 and Jason-2 SWH. Therefore the accuracy of HY-2 SWH products is close to that of Jason-1/2 SWH, and the linear regression function derived can improve the accuracy of HY-2 SWH products.
基金The Special Funds of State Oceanic Administration for Marine Commonweal Research under contract Nos 201105032-1and 201305032the Special Project of State Oceanic Administration of Poles Environmental Investigation and Assessment under contract No.CHINARE2012-02-04the European Space Agency (ESA)-Minister of Science and Technology of the Peoples Republic of China (MOST) Dragon 3 Cooperation Programme under contract No.10466
文摘HY-2 has been launched by China on August 16, 2011 which assembles multi-microwave remote sensing payloads in a body and has the ability of monitoring ocean dynamic environments. The HY-2 satellite data need to be calibrated and validated before being put into use. Based on the in-situ buoys from the Nation- al Data Buoy Center （NDBC）, Ku-band significant wave heights （SWH, hs） of HY-2 altimeter are validated. Eleven months of HY-2 altimeter Level 2 products data are chose from October 1, 2011 to August 29, 2012. Using NDBC 60 buoys yield 902 collocations for HY-2 by adopting collocation criteria of 30 min for tempo- ral window and 50 km for a spatial window. An overall RMS difference of the SWH between HY-2 and buoy data is 0.297 m. A correlation coefficient between these is 0.964. An ordinary least squares （OLS） regression is performed with the buoy data as an independent variable and the altimeter data as a dependent vari- able. The regression equation of hs is hs （HY-2）=0.891 × hs （NDBC）＋0.022. In addition, 2016 collocations are matched with temporal window of 30 rain at the crossing points of HY-2 and Jason-2 orbits. RMS difference of Ku-band SWH between the two data sets is 0.452 m.
基金supported by the Ministry of Science and Technology of China National "973" Fundamental Research Program (Grant No.2013CB430103)
文摘1.Introduction Compared with the United States,whose annual number of tornadoes can exceed 1000,the average number of tornadoes per year in China over the past half a century is estimated to be fewer than 100（Fan and Yu,2015）,even though both countries are located in a similar latitudinal zone of the Northern Hemisphere.
基金The Public Science and Technology Research Funds Projects of Ocean under contract Nos 201105032,201305032 and 201005030the National High Technology Research and Development Program(863 Program)of China under contract No.2013AA09A505+2 种基金Global Change and Air-Sea Interaction Project of China under contract No.GASI-03-03-01-01the International Science&Technology Cooperation Program of China under contract No.2011DFA22260the Open funds of State Key Laboratory of Satellite Ocean Environment Dynamics under contract No.SOED1411
文摘Chinese Haiyang-2（HY-2） satellite is the first Chinese marine dynamic environment satellite. The dual-frequency （Ku and C band） radar altimeter onboard HY-2 has been working effective to provide operational significant wave height （SWH） for more than three years （October 1, 2011 to present）.We validated along-track Ku-band SWH data of HY-2 satellite against National Data Buoy Center （NDBC） in-situ measurements over a time period of three years from October 1, 2011 to September 30, 2014, the root mean square error （RMSE） and mean bias of HY-2 SWH is 0.38 m and （-0.13±0.35） m, respectively. We also did cross validation against Jason-2 altimeter SWH data, the RMSE and the mean bias is 0.36m and （-0.22±0.28） m, respectively. In order to compare the statistical results between HY-2 and Jason-2 satellite SWH data, we validated the Jason-2 satellite radar altimeter along-track Ku-band SWH data against NDBC measurements using the same method. The results demonstrate the validation method in this study is scientific and the RMSE and mean bias of Jason-2 SWH data is 0.26 m and （0.00±0.26） m, respectively. We also validated both HY-2 and Jason-2 SWH data every month, the mean bias of Jason-2 SWH data almost equaled to zero all the time, while the mean bias of HY-2 SWH data was no less than -0.31m before April 2013 and dropped to zero after that time. These results indicate that the statistical results for HY-2 altimeter SWH are reliable and HY-2 altimeter along-track SWH data were steady and of high quality in the last three years. The results also indicate that HY-2 SWH data have greatly been improved and have the same accuracy with Jason-2 SWH data after April, 2013. SWH data provided by HY-2 satellite radar altimeter are useful and acceptable for ocean operational applications.
基金Supported by the National High Technology Research and Development Program of China (863 Program) (2001AA631050)the National Natural Science Foundation of China (60571065)Open fund of State Key Laboratory of Offshore Marine Environment (Xiamen University)
文摘OSMAR071 is the latest product of the OSMAR （ocean state monitor and analysis radar） series of high frequency surface wave radar （HFSWR）, which was developed by the Radiowave Propagation Laboratory of Wuhan University. It adopts a modified Barrick waveheight inversion model. The modifications are introduced to improve the model＇s performances under the effect of noises and interferences and in the case of broad beam radar detection. The two unknown coefficients in the modified model are figured out by fitting the HFSWR significant waveheight results to those output from a wave buoy located in the radiating coverage of the radar site. The model is applied to inverse the waveheights from radar data for the duration from Dec. 1st, 2008 to Feb. 25th, 2009, and then the radar waveheights are compared with the buoy measurements. Results show that the rms difference between radar-derived significant waveheights and those from the buoy is 0.38 m and the correlation coefficient between the two series is 0.66. This study describes OSMAR071 observation of significant waveheight with relatively satisfactory accuracy during about three months.
基金The National Basic Research Program of China under contract Nos 2015CB453200,2013CB956200,2012CB957803 and2010CB950400the National Natural Science Foundation of China under contract Nos 41275086 and 41475070
文摘Long-term variations in a sea surface wind speed （WS） and a significant wave height （SWH） are associated with the global climate change, the prevention and mitigation of natural disasters, and an ocean resource exploitation, and other activities. The seasonal characteristics of the long-term trends in China＇s seas WS and SWH are determined based on 24 a （1988-2011） cross-calibrated, multi-platform （CCMP） wind data and 24 a hindcast wave data obtained with the WAVEWATCH-III （WW3） wave model forced by CCMP wind data. The results show the following. （1） For the past 24 a, the China＇s WS and SWH exhibit a significant increasing trend as a whole, of 3.38 cm/（s.a） in the WS, 1.3 cm/a in the SWH. （2） As a whole, the increasing trend of the China＇s seas WS and SWH is strongest in March-April-May （MAM） and December-January-February （DJF）, followed by June-July-August （JJA）, and smallest in September-October-November （SON）. （3） The areal extent of significant increases in the WS was largest in MAM, while the area decreased in JJA and DJF; the smallest area was apparent in SON. In contrast to the WS, almost all of China＇s seas exhibited a significant increase in SWH in MAM and DJF; the range was slightly smaller in JJA and SON. The WS and SWH in the Bohai Sea, the Yellow Sea, East China Sea, the Tsushima Strait, the Taiwan Strait, the northern South China Sea, the Beibu Gull and the Gulf of Thailand exhibited a significant increase in all seasons. （4） The variations in China＇s seas SWH and WS depended on the season. The areas with a strong increase usually appeared in DJF.
基金The National Key Research and Development Program of China under contract Nos 2016YFA0600102 and2016YFC1401007the National Natural Science Youth Foundation of China under contract No.61501130the Natural Science Foundation of China under contract No.41406207
文摘A new method for estimating significant wave height（SWH） from advanced synthetic aperture radar（ASAR） wave mode data based on a support vector machine（SVM） regression model is presented. The model is established based on a nonlinear relationship between σ0, the variance of the normalized SAR image, SAR image spectrum spectral decomposition parameters and ocean wave SWH. The feature parameters of the SAR images are the input parameters of the SVM regression model, and the SWH provided by the European Centre for Medium-range Weather Forecasts（ECMWF） is the output parameter. On the basis of ASAR matching data set, a particle swarm optimization（PSO） algorithm is used to optimize the input kernel parameters of the SVM regression model and to establish the SVM model. The SWH estimation results yielded by this model are compared with the ECMWF reanalysis data and the buoy data. The RMSE values of the SWH are 0.34 and 0.48 m, and the correlation coefficient is 0.94 and 0.81, respectively. The results show that the SVM regression model is an effective method for estimating the SWH from the SAR data. The advantage of this model is that SAR data may serve as an independent data source for retrieving the SWH, which can avoid the complicated solution process associated with wave spectra.
基金The National Key Research and Development Program of China under contract Nos 2016YFC1401905 and2017YFA0604901the National Natural Science Foundation of China under contract Nos 41776183,41676014,41606024 and 41506033the National Social Science Foundation of China under contract No.15ZDB170
文摘Chinese Gaofen-3（GF-3） is the first civilian satellite to carry C-band（5.3 GHz） synthetic aperture radar（SAR）.During the period of August 2016 to December 2017, 1 523 GF-3 SAR images acquired in quad-polarization（vertical-vertical（VV）, horizontal-horizontal（HH）, vertical-horizontal（VH）, and horizontal-vertical（HV）） mode were recorded, mostly around China＇s seas. In our previous study, the root mean square error（RMSE） of significant wave height（SWH） was found to be around 0.58 m when compared with retrieval results from a few GF-3 SAR images in co-polarization（VV and HH） with moored measurements by using an empirical algorithm CSARWAVE. We collected a number of sub-scenes from these 1 523 images in the co-polarization channel,which were collocated with wind and SWH data from the European Centre for Medium-Range Weather Forecasts（ECMWF） reanalysis field at a 0.125° grid. Through the collected dataset, an improved empirical wave retrieval algorithm for GF-3 SAR in co-polarization was tuned, herein denoted as CSARWAVE2. An additional 92 GF-3 SAR images were implemented in order to validate CSARWAVE2 against SWH from altimeter Jason-2, showing an about 0.52 m RMSE of SWH for co-polarization GF-3 SAR. Therefore, we conclude that the proposed empirical algorithm has a good performance for wave retrieval from GF-3 SAR images in co-polarization.
文摘·AIM:To determine the risk factors of clinically significant macular edema (CSME) in patients with non-proliferative diabetic retinopathy (NPDR) in a multi-ethnics Malaysian population. ·METHODS:We performed a case control study in which 150 patients with bilateral NPDR and CSME in either eye were compared to 150 patients with bilateral NPDR and no CSME in both eyes. CSME and NPDR were graded according to Early Treatment of Diabetic Retinopathy Study criteria. Student’s t-test, odds ratio and multiple logistic regression analysis were performed to analyze the duration of diabetes, body mass index (BMI), blood pressure(BP), total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TG), fasting blood glucose (FBG), HbA1c, full blood count, serum creatinine and proteinuria between the two groups. ·RESULTS:Both groups were matched in terms of age, gender and ethnicity. Duration of diabetes, total serum cholesterol, serum LDL, FBG, HbA1c and serum creatinine were significantly higher in the CSME group (P <0.05). The hemoglobin, packed cell volume were significantly lower in the CSME group (P <0.05). There was no significant difference for serum HDL, TG, BMI, systolic and diastolic BP. Multiple logistic regression analysis showed that total serum cholesterol and HbA1c had significantly high odds of developing CSME. ·CONCLUSION:HbA1c and total cholesterol are the two most important risk factors associated with CSME in patients with NPDR.
基金The National Key R&D Program of China under contract No.2017YFC1405600the National Natural Science Foundation of China under contract Nos 61931025,41974144 and 41976173+1 种基金the Graduate Innovation Project of China University of Petroleum(East China)under contract No.YCX2021124the Shandong Provincial Natural Science Foundation of China under contract No.ZR2019MD016。
文摘The significant wave height(SWH)is one of the main parameters that describe wave characteristics and is widely used in wave research fields.Wave parameters measured by radar are influenced by the offshore distance and sea state.Validation and calibration are of great significance for radar data applications.The nadir beam of surface wave investigation and monitoring(SWIM)detects the global-ocean-surface SWH.To determine the product quality of SWIM SWH,this paper carried out time-space matching between SWIM and buoy data.The data qualities were evaluated under different offshore distances and sea states.An improved calibration method was proposed based on sea state segmentation,which considered the distribution of the point collocation numbers in various sea states.The results indicate that(1)the SWIM SWH accuracy at offshore distances greater than 50 km is higher than that at distances less than 50 km,with an root mean squared error(RMSE)of 0.2444 m,scatter index(SI)of 0.1156 and relative error(RE)of 9.97%at distances greater than 50 km and those of 0.4460 m,0.2230 and18.66%at distances less than 50 km.(2)SWIM SWH qualities are better in moderate and rough sea states with RMSEs of 0.2848 m and 0.3169 m but are worse in slight and very rough sea states.(3)The effect of the improved calibration method is superior to the traditional method in each sea state and overall data,and the RMSE of SWIM SWH is reduced from the raw 0.3135 m to 0.2859 m by the traditional method and 0.1982 m by the improved method.The influence of spatiotemporal window selection on data quality evaluation was analyzed in this paper.This paper provides references for SWIM SWH product applications.
基金supported by grants from the National Natu-ral Science Foundation of China(81701950 and 82172135)Medi-cal Research Projects of Chongqing for staffagainst the epidemic(2020FYYX248)the Kuanren Talents Program of the Second Affiliated Hospital,Chongqing Medical University(KY2019Y002).
文摘Background: Significant portal hypertension(SPH) is a relative contraindication for patients with resectable hepatocellular carcinoma(HCC). However, increasing evidence indicates that liver resection is feasible for HCC patients with SPH. Methods: HCC patients with cirrhosis who underwent laparoscopic liver resection(LLR) in two centers from January 2013 to April 2018 were included. Surgical and survival outcomes were analyzed to explore potential prognostic factors. Propensity score matching(PSM) analysis was performed to minimize bias. Results: A total of 165 patients were divided into two groups based on the presence(SPH, n = 76) or absence(non-SPH, n = 89) of SPH. Patients in the SPH group had longer operative time, more blood loss, and more advanced TNM stage than patients in the non-SPH group( P < 0.05). However, there were no significant differences in the postoperative 90-day mortality rate( n = 0), overall postoperative complications(47.4% vs. 41.6%, P = 0.455), Clavien-Dindo classification( P = 0.347), conversion to open surgery(9.2% vs. 6.7%, P = 0.557), or length of hospitalization(16 vs. 15 days, P = 0.203) between the SPH and non-SPH groups before PSM. Similar results were obtained after PSM. The 1-, 3-, and 5-year overall survival(OS) and recurrence-free survival rates in the SPH group were not significantly different from those in the non-SPH group both before and after PSM(log-rank P > 0.05). After PSM, alpha-fetoprotein(AFP) ≥ 400 μg/L [hazard ratio(HR) = 4.71, 95% confidence interval(CI): 2.69-8.25], ascites(HR = 2.18, 95% CI: 1.30-3.66), American Society of Anesthesiologists(ASA) classification(Ⅲ vs. Ⅱ)(HR = 2.13, 95% CI: 1.11-4.07) and tumor diameter > 5 cm(HR = 3.91, 95% CI: 2.02-7.56) independently predicted worse OS. Conclusions: LLR for patients with HCC complicated with SPH appears feasible at the price of increasing operative time and blood loss. AFP, ascites, ASA classification and tumor diameter may predict the prognosis of HCC complicated with SPH after LLR.
基金The National Science Foundation for Young Scientists of China under contract No.61501130the National Key Research and Development Program of China under contract Nos 2016YFB0502504 and 2016YFB0502500the National Natural Science Foundation of China under contract Nos 41431174,61471358 and 41401427
文摘The main objective of this paper is to propose a newly developed ocean Significant Wave Height (SWH) retrieval method from Envisat Advanced Synthetic Aperture Radar (ASAR) imagery. A series of wave mode imagery from January, April and May of 2011 are collocated with ERA-Interim reanalysis SWH data. Based on the matched datasets, a simplified empirical relationship between 22 types of SAR imagery parameters and SWH products is developed with the Genetic Algorithms Partial Least-Squares (GA-PLS) model. Two major features of the backscattering coefficient σ0 and the frequency parameter S10 are chosen as the optimal training feature subset of SWH retrieval by using cross validation. In addition, we also present a comparison of the retrieval results of the simplified empirical relationship with the collocated ERA-Interim data. The results show that the assessment index of the correlation coefficient, the bias, the root-mean-square error of cross validation (RMSECV) and the scattering index (SI) are 0.78, 0.07 m, 0.76 m and 0.5, respectively. In addition, the comparison of the retrieved SWH data between our simplifying model and the Jason-2 radar altimeter data is proposed in our study. Moreover, we also make a comparison of the retrieval of SWH data between our developed model and the well- known CWAVE_ENV model. The results show that satisfying retrieval results are acquired in the low-moderate sea state, but major bias appears in the high sea state, especially for SWH>5 m.
基金supported by the National Key R&D Program of China[grant number 2017YFC1403300 and 2016YFC1401701]。
文摘In-situ observation is restricted by the strong wind and waves in the Southern Ocean.A Westerlies EnvironmentalMonitoring Buoy(WEMB)was firstly deployed in the Southern Ocean during China’s 35th Antarctic Expedition,facilitating further understanding of the oceanic environmental characteristics of this region.With the develop-ment of technology and the improvement of data processing methods,the accuracy of satellite altimeter productsis constantly improved,thus making it possible to inspect and evaluate the in-situ observation data.Based on theL3 products of multiple satellite altimeters,this paper analyzes and corrects the significant wave height(SWH)data of WEMB by means of data matching,error statistics,and linear least-squares fitting.Through this study,the authors obtained the following results.The effect of gravitational acceleration changes with latitude on SWHaccuracy is fairly small.Due to the low response of WEMB to high-frequency waves,there is a systematic devia-tion.A feasible correction method is therefore proposed to improve the SWH accuracy of WEMB.The temporalvariation of the corrected SWH is highly consistent with that of the 10 m wind during the observation period,and its average value reaches 3.8 m.
基金Supported by the National High Technology Research and Development Program of China (863 Program) (No.2008AA09Z102)the Canadian Space Agency (CSA) GRIP Program.
文摘A new model is proposed to estimate the significant wave heights with ERS-1/2 scatterometer data. The results show that the relationship between wave parameters and radar backscattering cross section is similar to that between wind and the radar backscattering cross section. Therefore, the relationship between significant wave height and the radar backscattering cross section is established with a neural network algorithm, which is, if the average wave period is ≤7s, the root mean square of significant wave height retrieved from ERS-1/2 data is 0.51 m, or 0.72 m if it is >7s otherwise.
文摘Since 2015, the China Geological Survey has implemented a major program of ＂Geology Survey of Land Energy Mineral Resources＂. Till now, a total of billions of RMB have been invested and seven engineering projects have been established, all of which has greatly enhanced the geological survey and exploration of China＇s continental shale gas in an attempt to overcome the oil and gas shortage.
