Seasonal Variation of Surface Circulation Along Peninsular Malaysia' East Coast

2014 ◽  
Vol 71 (4) ◽  
Author(s):  
Muhammad Faiz Pa'suya ◽  
Kamaludin Mohd Omar ◽  
Benny N. Peter ◽  
Ami Hassan Md Din ◽  
Mohd Fadzil Mohd Akhir
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Peninsular Malaysia ◽  
Environmental Data ◽  
Sea Surface ◽  
Northeast Monsoon ◽  
Radar Altimeter ◽  
Sea Level Anomaly ◽  
Surface Circulation ◽  
Altimetric Data

The sea surface circulation pattern over the coast of Peninsula Malaysia's East Coast during Northeast Monsoon (NE) and Southwest Monsoon (SW) are derived using the seasonally averaged sea level anomaly (SLA) data from altimetric data and 1992-2002 Mean Dynamic Ocean Topography. This altimetric data has been derived from multi-mission satellite altimeter TOPEX, ERS-1, ERS-2, JASON-1, and ENVISAT for the period of nineteen years (1993 to 2011) using the Radar Altimeter Database System (RADS). The estimated sea level anomaly (SLA) have shown similarity in the pattern of sea level variations observed by four tide gauges. Overall, the sea surface circulations during the NE and SW monsoons shows opposite patterns, northward and southward respectively. During the SW monsoon, an anti-cyclonic circulation has been detected around the Terengganu coastal area centred at (about 5.5° N 103.5° E) and nearly consistent with previous study using numerical modelling. The estimated geostrophic current field from the altimeter is consistent with the trajectories of Argos-tracked Drifting Buoys provided by the Marine Environmental Data Services (MEDS) in Canada.

scholarly journals Arctic sea surface height maps from multi-altimeter combination

2021 ◽  
Author(s):  
Pierre Prandi ◽  
Jean-Christophe Poisson ◽  
Yannice Faugère ◽  
Amandine Guillot ◽  
Gérald Dibarboure
Keyword(s):  
Sea Level ◽  
Sea Surface Height ◽  
Open Ocean ◽  
Sea Surface ◽  
Optimal Interpolation ◽  
Independent Data ◽  
Interpolation Scheme ◽  
Sea Level Anomaly ◽  
Arctic Sea ◽  
The Cross

Abstract. We present a new Arctic sea level anomaly dataset, based on the combination of three altimeter missions using an optimal interpolation scheme. Measurements from SARAL/AltiKa, CryoSat-2 and Sentinel-3A are blended together providing an unprecedented resolution for this type of products. The final gridded fields cover all latitudes north of 50° N, on a 25 km EASE2 grid, with one grid every three days over three years from July 2016 to April 2019. We use the Adaptive retracker to process both open ocean and lead echoes on SARAL/AltiKa thus removing the need to estimate a bias between open ocean an ice covered areas. SARAL/AltiKa also provides the baseline for the cross-calibation of CryoSat-2 and Sentinel-3A data. When compared to independent data, the combined product exhibits a much better performance than previously available datasets based on the analysis of a single mission.

The new Black Sea Reanalysis System within CMEMS

2021 ◽  
Author(s):  
Leonardo Lima ◽  
Stefania Angela Ciliberti ◽  
Ali Aydogdu ◽  
Romain Escudier ◽  
Simona Masina ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Sea Level ◽  
Black Sea ◽  
General Circulation ◽  
Circulation Model ◽  
Sea Surface Height ◽  
Sea Surface ◽  
The Black Sea ◽  
Freshwater Flux ◽  
Sea Level Anomaly

<p>Ocean reanalyses are becoming increasingly important to reconstruct and provide an overview of the ocean state from the past to the present-day. These products require advanced scientific methods and techniques to produce a more accurate ocean representation. In the scope of the Copernicus Marine Environment Monitoring Service (CMEMS), a new Black Sea (BS) reanalysis, BS-REA (BSE3R1 system), has been produced by using an advanced variational data assimilation method to combine the best available observations with a state-of-the-art ocean general circulation model. The hydrodynamical model is based on Nucleus for European Modeling of the Ocean (NEMO, v3.6), implemented for the BS domain with horizontal resolution of 1/27° x 1/36°, and 31 unevenly distributed vertical levels. NEMO is forced by atmospheric surface fluxes computed via bulk formulation and forced by ECMWF ERA5 atmospheric reanalysis product. At the surface, the model temperature is relaxed to daily objective analysis fields of sea surface temperature from CMEMS SST TAC. The exchange with Mediterranean Sea is simulated through relaxation of the temperature and salinity near Bosporus toward a monthly climatology computed from a high-resolution multi-year simulation, and the barotropic Bosporus Strait transport is corrected to balance the variations of the freshwater flux and the sea surface height measured by multi-satellite altimetry observations. A 3D-Var ocean data assimilation scheme (OceanVar) is used to assimilate sea level anomaly along-track observations from CMEMS SL TAC and available in situ vertical profiles of temperature and salinity from both SeaDataNet and CMEMS INS TAC products. Comparisons against the previous Black Sea reanalysis (BSE2R2 system) show important improvements for temperature and salinity, such that errors have significantly decreased (about 50%). Temperature fields present a continuous warming in the layer between 25-150 m, within which there is the presence of the Black Sea Cold Intermediate Layer (CIL). SST exhibits a positive bias and relatively higher root mean square error (RMSE) values are present in the summer season. Spatial maps of sea level anomaly reveal the largest RMSE close to the shelf areas, which are related to the mesoscale activity along the Rim current. The BS-REA catalogue includes daily and monthly means for 3D temperature, salinity, and currents and 2D sea surface height, bottom temperature, mixed layer fields, from Jan 1993 to Dec 2019.  The BSE3R1 system has produced very accurate estimates which makes it very suitable for assessing more realistic climate trends and indicators for important ocean properties.</p>

Long-term assessment of surface dynamics in the Tyrrhenian Sea

2020 ◽  
Author(s):  
Enrico Zambianchi ◽  
Naomi Krauzig ◽  
Pierpaolo Falco
Keyword(s):  
Sea Level ◽  
Spatial Scales ◽  
Sea Surface ◽  
Extreme Weather Events ◽  
Tyrrhenian Sea ◽  
Surface Dynamics ◽  
Surface Circulation ◽  
Spatial Coverage ◽  
Temporal And Spatial

<p>The variability of surface dynamics has been investigated extensively in the Mediterranean Sea for different temporal and spatial coverage, whereas a specific evaluation for the area of the Tyrrhenian Sea does not exist. Thus, this study is focused on the Tyrrhenian basin, a subbasin of the western Mediterranean, which is considered sensitive to climatic variations due to its small size and isolated nature. The main scope is to provide a comprehensive and up-to-date assessment of the sea surface warming, the sea level changes and the general surface circulation in the Tyrrhenian Sea, as well as to improve the understanding of the relation to large-scale teleconnection patterns and to regional air-sea interaction. The long-term spatio-temporal variability and trends were investigated using satellite-derived, in-situ and reanalysis-based datasets up to the end of 2018. Further, the possible linkage with the occurrence of extreme weather events was assessed using observations from the European Severe Weather Database. The different datasets cover multiple temporal and spatial scales and enable the investigation of the potential physical processes related to the non-homogeneous, time-depended spatial variability. The results indicate a significant increase in sea level and sea surface temperature which appears to be linked with the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO), respectively. Moreover, analysis of the basin’s surface circulation together with local air-sea exchanges of heat, freshwater and momentum indicated a significant influence of the wind-driven Ekman pumping variability.</p>

The marine environment and its influence on seafaring and maritime routes in the prehistoric Aegean

2008 ◽  
Vol 11 (2-3) ◽  
pp. 199-222 ◽  
Author(s):  
Despoina Papageorgiou
Keyword(s):  
Early Growth ◽  
Environmental Data ◽  
Sea Surface ◽  
Dense Network ◽  
Aegean Area ◽  
The Third ◽  
Aegean Islands ◽  
Surface Circulation ◽  
Sea Currents ◽  
Prehistoric Aegean

This article seeks to illustrate the decisive contribution of the sea environment and particularly the sea-surface circulation (which is determined by the circulation of sea currents and the winds) to the early growth of seafaring and maritime communications in the prehistoric Aegean. Given the means and techniques of navigation in that era, an attempt is made to reveal a dense network of sea routes which vessels could follow through the Aegean, in order to facilitate their trip. These sea routes are primarily based on environmental data and are confirmed concurrently by archaeological evidence and data of ancient sources. Therefore, it is evident that these sea routes played an important role not only in the early inhabitation of the Aegean islands and the foundation of coastal settlements throughout the Aegean area from the sixth millennium BC to the end of the third millennium BC, but in the development of the Aegean civilization during earlier prehistoric times as well.

scholarly journals Global Assessments of the HY-2B Measurements and Cross-Calibrations with Jason-3

2020 ◽  
Vol 12 (15) ◽  
pp. 2470 ◽  
Author(s):  
Yongjun Jia ◽  
Jungang Yang ◽  
Mingsen Lin ◽  
Youguang Zhang ◽  
Chaofei Ma ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Sea Level ◽  
Surface Wind ◽  
Sea Surface ◽  
Radar Altimeter ◽  
Significant Wave ◽  
Comparison Results ◽  
Wave Heights ◽  
Significant Wave Heights

The HY-2B satellite was successfully launched on 25 October 2018. One of the main payloads of the HY-2B was a radar altimeter. In the present study, the quality of the HY-2B along-track sea surface heights (SSH), significant wave heights (SWH), and sea surface wind speeds (SSWS) were assessed, including their precision and accuracy. In order to achieve this goal, the mono-mission metrics of the HY-2B were analyzed and compared with those of the Jason-2 and Jason-3 over the same periods of time. The results of both direct comparison and cross comparison methods were presented in this study. The comparison results indicated that the quality of the HY-2B satellite’s geophysical data records (GDRs) data was excellent, with 95% of the sea surfaces effectively observed between 82 degrees north and south latitudes. In addition, the standard deviation of the sea level anomalies (SLA) at the single mission crossovers was 4.6 cm to 5.8 cm, and at the dual-crossovers with Jason-3, the standard deviation was determined to be 5.1 cm to 5.8 cm. The accuracy levels of the significant wave heights and products of the HY-2B satellite radar altimeter were observed to be greater than 0.3 m and 1.4 m/s (STD), respectively. Therefore, it was concluded in this study that the data quality and system performance of the HY-2B satellite were excellent and stable, and could be widely utilized in such fields as global sea-level change monitoring, wave numerical assimilation predictions etc.

scholarly journals Statistical Modeling of RPCA-FCM in Spatiotemporal Rainfall Patterns Recognition

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 145
Author(s):  
Siti Mariana Che Mat Nor ◽  
Shazlyn Milleana Shaharudin ◽  
Shuhaida Ismail ◽  
Sumayyah Aimi Mohd Najib ◽  
Mou Leong Tan ◽  
...  
Keyword(s):  
Statistical Modeling ◽  
East Coast ◽  
Monsoon Season ◽  
Clustering Algorithms ◽  
Breakdown Point ◽  
Peninsular Malaysia ◽  
Northeast Monsoon ◽  
Number Of Components ◽  
Torrential Rainfall ◽  
Rainfall Patterns

This study was conducted to identify the spatiotemporal torrential rainfall patterns of the East Coast of Peninsular Malaysia, as it is the region most affected by the torrential rainfall of the Northeast Monsoon season. Dimension reduction, such as the classical Principal Components Analysis (PCA) coupled with the clustering approach, is often applied to reduce the dimension of the data while simultaneously performing cluster partitions. However, the classical PCA is highly insensitive to outliers, as it assigns equal weights to each set of observations. Hence, applying the classical PCA could affect the cluster partitions of the rainfall patterns. Furthermore, traditional clustering algorithms only allow each element to exclusively belong to one cluster, thus observations within overlapping clusters of the torrential rainfall datasets might not be captured effectively. In this study, a statistical model of torrential rainfall pattern recognition was proposed to alleviate these issues. Here, a Robust PCA (RPCA) based on Tukey’s biweight correlation was introduced and the optimum breakdown point to extract the number of components was identified. A breakdown point of 0.4 at 85% cumulative variance percentage efficiently extracted the number of components to avoid low-frequency variations or insignificant clusters on a spatial scale. Based on the extracted components, the rainfall patterns were further characterized based on cluster solutions attained using Fuzzy C-means clustering (FCM) to allow data elements to belong to more than one cluster, as the rainfall data structure permits this. Lastly, data generated using a Monte Carlo simulation were used to evaluate the performance of the proposed statistical modeling. It was found that the proposed RPCA-FCM performed better using RPCA-FCM compared to the classical PCA coupled with FCM in identifying the torrential rainfall patterns of Peninsular Malaysia’s East Coast.

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