On the modification of operational oceanography forecasting system for South China Sea in National Marine Environmental Forecasting Center of China

2020 ◽  
Author(s):  
Ziqing Zu ◽  
Xueming Zhu ◽  
Hui Wang
Keyword(s):  
South China Sea ◽  
South China ◽  
Optimal Interpolation ◽  
Physical Parameters ◽  
Background Error ◽  
Pass Filter ◽  
China Sea ◽  
Operational Oceanography ◽  
Forecasting System ◽  
Marine Environmental

<p>Based on ROMS and Ensemble Optimal Interpolation (EnOI) method, the South China Sea operational Oceanography Forecasting System (SCSOFS) is implemented in National Marine Environmental Forecasting Center (NMEFC), to provide the forecast of the currents, temperature and salinity in South China Sea for the future 5 days. Recently, a systematic modification has been carried out to SCSOFS to improve its forecast skill.</p><p>For the data assimilation system, new methods have been implemented, such as using Increment Analysis Update (IAU) and First Guess at Appropriate Time (FGAT), using a high-pass filter to evaluate the background error, assimilating multi-source observations, using non-uniform localization radius. In addition, the respective contribution of each method will also be discussed.</p><p>An optimization system is implemented for evaluating the values of physical parameters in ROMS, to remove the long-term bias of simulation. Argo temperature profiles is assimilated in the first half of 2017, to obtain the optimal coefficients of horizontal/vertical viscosity/diffusion and linear bottom drag. An independent validation from July of 2017 to December of 2018 shows that the simulation is improved using the optimal values.</p>

scholarly journals The improvements to the regional South China Sea Operational Oceanography Forecasting System

2020 ◽  
Author(s):  
Xueming Zhu ◽  
Ziqing Zu ◽  
Shihe Ren ◽  
Yunfei Zhang ◽  
Miaoyin Zhang ◽  
...  
Keyword(s):  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
Sea Surface ◽  
Global Ocean ◽  
China Sea ◽  
Data Assimilation Scheme ◽  
Operational Oceanography ◽  
Forecasting System ◽  
Assimilation Scheme

Abstract. South China Sea Operational Oceanography Forecasting System (SCSOFS) had been built up and operated in National Marine Environmental Forecasting Center of China to provide daily updated hydrodynamic forecasting in SCS for the future 5 days since 2013. This paper presents comprehensive updates had been conducted to the configurations of the physical model and data assimilation scheme in order to improve SCSOFS forecasting skills in recent years. It highlights three of the most sensitive updates, sea surface atmospheric forcing method, tracers advection discrete scheme, and modification of data assimilation scheme. Scientific inter-comparison and accuracy assessment among five versions during the whole upgrading processes are performed by employing Global Ocean Data Assimilation Experiment OceanView Inter-comparison and Validation Task Team Class4 metrics. The results indicate that remarkable improvements have been achieved in SCSOFSv2 with respect to the original version SCSOFSv1. Domain averaged monthly mean root mean square errors decrease from 1.21 °C to 0.52 °C for sea surface temperature, from 21.6 cm to 8.5 cm for sea level anomaly, respectively.

scholarly journals The improvements to the regional South China Sea Operational Oceanography Forecasting System (SCSOFSv1)

2021 ◽  
Author(s):  
Xueming Zhu ◽  
Ziqing Zu ◽  
Shihe Ren ◽  
Miaoyin Zhang ◽  
Yunfei Zhang ◽  
...  
Keyword(s):  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
Sea Surface ◽  
China Sea ◽  
Data Assimilation Scheme ◽  
Operational Oceanography ◽  
Forecasting System ◽  
Mean Square Errors ◽  
Assimilation Scheme

Abstract. South China Sea Operational Oceanography Forecasting System (SCSOFS) had been constructed and operated in National Marine Environmental Forecasting Center of China to provide daily updated hydrodynamic forecasting in SCS for the future 5 days since 2013. This paper presents recent comprehensive updates of the configurations of the physical model and data assimilation scheme in order to improve SCSOFS forecasting skills. It highlights three of the most sensitive updates, including sea surface atmospheric forcing method, tracers advection discrete scheme, and modification of data assimilation scheme. Inter-comparison and accuracy assessment among five versions during the whole upgrading processes are performed by employing OceanPredict Inter-comparison and Validation Task Team Class4 metrics. The results indicate that remarkable improvements have been achieved in SCSOFSv2 with respect to the original version known as SCSOFSv1. Domain averaged monthly mean root mean square errors decrease from 1.21 °C to 0.52 °C for sea surface temperature, from 21.6 cm to 8.5 cm for sea level anomaly, respectively.

scholarly journals Asian Winter Monsoon Imprint on the Water Column Structure at the Northern South China Sea Coast

2021 ◽  
Vol 9 ◽  
Author(s):  
Yancheng Zhang ◽  
Kai Zhu ◽  
Chao Huang ◽  
Deming Kong ◽  
Yuxin He ◽  
...  
Keyword(s):  
South China Sea ◽  
Water Column ◽  
South China ◽  
Northern South China Sea ◽  
Critical Factor ◽  
Ice Age ◽  
Physical Parameters ◽  
Monsoon Circulation ◽  
China Sea ◽  
Effective Manner

Coastal regions of the northern South China Sea (SCS) strongly interact with the Asian monsoon circulation (AMC). Thus, variations of sea surface temperature (SST) here are newly suggested to document AMC changes in an effective manner, but additional physical parameters of oceanic conditions, probably also in relation to the AMC system, remain poorly understood. In this study, we analyzed glycerol dialkyl glycerol tetraethers (GDGTs) from a well-dated sediment core YJ, retrieved at the northern SCS coast, to further scrutinize the intrinsic response of water column to winter AMC strength. It shows that within the time frame of past ∼1,000 years, the tetraether index of lipids with 86 carbon atoms (TEX86) and published alkenone (U37K′) temperature records together confirm a reduced thermal gradient during the Little Ice Age (LIA), in comparison to that during the Medieval Climate Anomaly (MCA). Considering concurrent variations of the branched and isoprenoid tetraether (BIT) and the ratio of archaeol to caldarchaeol (ACE), for example, with decreased values (<∼0.3) for the former and relatively high values for the latter at the LIA, indicative of stratification and salinity changes, respectively, these multiple lines of evidence thereby call for well mixing of onsite water at site YJ correspondingly. Our results suggest that winter AMC strength is a critical factor for mixing subsurface waters and modifying thermal/saline conditions at the northern SCS coasts through the last millennium and also, perhaps, on longer timescales.

scholarly journals Inversion and Validation of Improved Marine Gravity Field Recovery in South China Sea by Incorporating HY-2A Altimeter Waveform Data

2020 ◽  
Vol 12 (5) ◽  
pp. 802 ◽  
Author(s):  
Shengjun Zhang ◽  
Ole Baltazar Andersen ◽  
Xiangxue Kong ◽  
Hang Li
Keyword(s):  
South China Sea ◽  
Gravity Field ◽  
South China ◽  
Pass Filter ◽  
Gravity Field Model ◽  
Waveform Data ◽  
Low Pass Filter ◽  
China Sea ◽  
Gravity Field Recovery ◽  
Marine Gravity

HaiYang-2A (HY-2A, where ‘Haiyang’ means ‘Ocean’ in Chinese) has provided reliable sea surface height observations for gravity with uniform ocean data coverage on a global scale for more than 8 years, particularly with denser across track sampling during the geodetic mission since March 2016. This paper aims at modeling and evaluating the regional marine gravity field at 1′×1′ resolution by incorporating HY-2A altimeter waveform data from 7 complete 168-day cycles in the geodetic mission phase. Initial evaluation indicates that, firstly, the measurements in the geodetic mission stay at a consistent accuracy level with observations at the start-of-life stage according to statistics of discrepancies at crossover points cycle by cycle. Secondly, range precision improvement can be achieved using a two-pass weighted least-squares retracker. Thirdly, a downsampling procedure combined with a low-pass filter is designed for HY-2A 20 Hz data to obtain 5 Hz measurements with enhanced precision. We calculate the 1′×1′ marine gravity field model over the South China Sea area by using the EGM2008 model as a reference field with the remove/restore method. The verifications with published models and shipborne gravimetric data show that HY-2A GM data is capable of improving marine gravity field modeling. Results show slightly higher accuracy than other models with similar input datasets but not including HY-2A. The accuracy is also compared with the latest DTU17 and SIO V27.1 model.

scholarly journals Improving the Real-time Marine Forecasting of the Northern South China Sea by Assimilation of Glider-observed T/S Profiles

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shiqiu Peng ◽  
Yuhang Zhu ◽  
Zhijin Li ◽  
Yineng Li ◽  
Qiang Xie ◽  
...  
Keyword(s):  
South China Sea ◽  
Real Time ◽  
South China ◽  
Northern South China Sea ◽  
Argo Data ◽  
The Real ◽  
China Sea ◽  
Model Biases ◽  
Underwater Gliders ◽  
Forecasting System

AbstractPrediction of marine conditions is notoriously challenging in the northern South China Sea (NSCS) due to inadequate observations in the region. The underwater gliders that were developed during the past decade may provide observing platforms that could produce required observations. During a field experiment, temperature/salinity (T/S) profiles from a set of underwater gliders were assimilated into a real-time marine forecasting system, along with the assimilation of climatological monthly mean Argo data to constrain the basin-wide model biases. The results show that, in addition to the reduction of the basin-wide model biases by the assimilation of the climatological monthly mean Argo data, the assimilation of glider-observed T/S profiles is efficient to reduce the local biases of the NSCS marine forecasting by as much as 28–31% (19–36%) in 24 h to 120 h forecasts for temperature (salinity) from sea surface to a depth of 1000 m. Our results imply that the real-time marine forecasting for the NSCS can largely benefit from a sustainable glider observing network of the NSCS in the future.

A Real-Time Regional Forecasting System Established for the South China Sea and Its Performance in the Track Forecasts of Tropical Cyclones during 2011–13

2015 ◽  
Vol 30 (2) ◽  
pp. 471-485 ◽  
Author(s):  
Shiqiu Peng ◽  
Yineng Li ◽  
Xiangqian Gu ◽  
Shumin Chen ◽  
Dongxiao Wang ◽  
...  
Keyword(s):  
South China Sea ◽  
Real Time ◽  
Tropical Cyclones ◽  
South China ◽  
Dynamical Downscaling ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Forecasting System ◽  
Atmosphere Model

Abstract A real-time regional forecasting system for the South China Sea (SCS), called the Experimental Platform of Marine Environment Forecasting (EPMEF), is introduced in this paper. EPMEF consists of a regional atmosphere model, a regional ocean model, and a wave model, and performs a real-time run four times a day. Output from the Global Forecast System (GFS) from the National Centers for Environmental Prediction (NCEP) is used as the initial and boundary conditions of two nested domains of the atmosphere model, which can exert a constraint on the development of small- and mesoscale atmospheric perturbations through dynamical downscaling. The forecasted winds at 10-m height from the atmosphere model are used to drive the ocean and wave models. As an initial evaluation, a census on the track predictions of 44 tropical cyclones (TCs) during 2011–13 indicates that the performance of EPMEF is very encouraging and comparable to those of other official agencies worldwide. In particular, EPMEF successfully predicted several abnormal typhoon tracks including the sharp recurving of Megi (2010) and the looping of Roke (2011). Further analysis reveals that the dynamically downscaled GFS forecasts from the most updated forecast cycle and the optimal combination of different microphysics and PBL schemes primarily contribute to the good performance of EPMEF in TC track forecasting. EPMEF, established primarily for research purposes with the potential to be implemented into operations, provides valuable information not only to the operational forecasters of local marine/meteorological agencies or international TC forecast centers, but also to other stakeholders such as the fishing industry and insurance companies.

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