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The increase of anthropogenic activities has triggered global sea level rise to threaten many low-lying and unprotected coastal areas. Without measures, global sea levels will continue to rise at an accelerating rate in the 21st century. This paper quantifies sea level trends around the Malaysian seas using measurements from multiple altimeter missions over 1993–2015. Sea level anomalies (SLAs) are determined using data from the Radar Altimeter Database System (RADS) covering 8 altimeter missions. We use an enhanced processing strategy to optimize sea surface heights from RADS for the derivation of SLAs, including filtering, data gridding and moving average. Tidal height measurements at eight tide gauge stations around Peninsular Malaysia and East Malaysia are used to assess SLAs from altimetry. Our assessment results in similar patterns of SLAs, high correlation coefficients (>0.9) and small (few cm) root mean square differences (RMSE) between SLAs from altimetry and tide gauges over the same period. Sea level trends are determined by the robust fit regression analysis for the SLA time series. Our result shows that sea level rise trends around Malaysia range from 3.27 ± 0.12 mm yr−1 off eastern Malaysia to 4.95 ± 0.15 mm yr−1 west of Malaysia. Over 1993–2015, the mean rising rate around Malaysia is 4.22 ± 0.12 mm yr−1, and the cumulative sea level rise is 0.05 m. This paper predicts the impact of such rising sea levels on environment, urban planning and climatology in the coastal areas of Malaysia.

The Earth’s potential information is important for exploration of the Earth’s gravity field. The techniques of measuring the Earth’s gravity using the terrestrial and ship borne technique are time consuming and have limitation on the vast area. With the space-based measuring technique, these limitations can be overcome. The satellite gravity missions such as Challenging Mini-satellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity-Field and Steady-State Ocean Circulation Explorer Mission (GOCE) has introduced a better way in providing the information on the Earth’s gravity field. From these satellite gravity missions, the Global Geopotential Models (GGMs) has been produced from the spherical harmonics coefficient data type. The information of the gravity anomaly can be used to predict the bathymetry because the gravity anomaly and bathymetry have relationships between each other. There are many GGMs that have been published and each of the models gives a different value of the Earth’s gravity field information. Therefore, this study is conducted to assess the most reliable GGM for the Malaysian Seas. This study covered the area of the marine area on the South China Sea at Sabah extent. Seven GGMs have been selected from the three satellite gravity missions. The gravity anomalies derived from the GGMs are compared with the airborne gravity anomaly, in order to figure out the correlation (R2) and the root mean square error (RMSE) of the data. From these assessments, the most suitable GGMs for the study area is GOCE model, GO_CONS_GCF_2_TIMR4 with the R2 and RMSE value of 0.7899 and 9.886 mGal, respectively. This selected model will be used in the estimating the bathymetry for Malaysian Seas in future.

Global geopotential models (GGMs) are vital in computing global geoid undulations heights. Based on the ellipsoidal height by Global Navigation Satellite System (GNSS) observations, the accurate orthometric height can be calculated by adding precise and accurate geoid undulations model information. However, GGMs also provide data from the satellite gravity missions such as GRACE, GOCE and CHAMP. Thus, this will assist to enhance the global geoid undulations data. A statistical assessment has been made between geoid undulations derived from 4 GGMs and the airborne gravity data provided by Department of Survey and Mapping Malaysia (DSMM). The goal of this study is the selection of the best possible GGM that best matches statistically with the geoid undulations of airborne gravity data under the Marine Geodetic Infrastructures in Malaysian Waters (MAGIC) Project over marine areas in Sabah. The correlation coefficients and the RMS value for the geoid undulations of GGM and airborne gravity data were computed. The correlation coefficients between EGM 2008 and airborne gravity data is 1 while RMS value is 0.1499.In this study, the RMS value of EGM 2008 is the lowest among the others. Regarding to the statistical analysis, it clearly represents that EGM 2008 is the best fit for marine geoid undulations throughout South China Sea.

The advancement of satellite altimeter technology has generated many evolutions to oceanographic and geophysical studies. A multi-mission satellite altimeter consists with TOPEX, Jason-1 and Jason-2, ERS-2, Envisat-1, CryoSat-2 and Saral are extracted in this study and has been processed using Radar Altimeter Database System (RADS) for the period of January 2005 to December 2015 to produce the sea surface height (hereinafter referred to SSH). The monthly climatology data from SSH is generated and averaged to understand the variation of SSH during monsoon season. Then, SSH data are required to determine the localised and new mean sea surface (MSS). The differences between Localised MSS and DTU13 MSS Global Model is plotted with root mean square error value is 2.217 metres. The localised MSS is important towards several applications for instance, as a reference for sea level variation, bathymetry prediction and derivation of mean dynamic topography.

Long-term water level changes have generally been estimated using tidal data. Tide gauges are common tools used to determine the continuous time series of relative water level. This paper presents an effort to interpret the water level from tidal data over Malaysian seas. There are 21 tide gauge stations involved and taken from Permanent Service for Mean Sea Level (PSMSL) with monthly averaged data from 1993 to 2011. The monthly tidal data is then converted to tidal sea level anomaly. For sea level trend analysis, robust fit regression is employed. Next, the sea levels were analysed based on the pattern of seasonal variation and extreme meteorological effects such as El-Nino and La-Nina. In summary, the relative sea level trend in Malaysian seas is rising and varying from 2 to 6.5 mm/yr. This study offers valuable sea level information to be applied in wide range of climatology, related environmental issue such as flood and global warming in Malaysia.

The development of the latest technology in agriculture such as using Unmanned Aerial Vehicle (UAV) platform, oil palm tree monitoring can be carried out efficiently by smallholders. Therefore, this study aims to determine the spectral response curve of oil palm tree growth for smallholders by using UAV Platform and payloaded with digital compact camera. The series of UAV images are then to be used to generate an orthophotos image whereby contains two types of spectrum bands which are single spectrum of near Infra-Red (NIR) and three spectrums of visible bands (RGB), respectively. Hence, a spectral response curve graph of oil palm tree condition is able to be produced based on the orthophoto as well as on-site ground validation using handheld spectroradiometer. The growth of the oil palm trees also able to be determined by analyzing the reflectance recorded from the images after generating the Normalized Difference Vegetation Index (NDVI) and Modified Soil-Adjusted Vegetation Index 2 (MSAVI2), respectively. This study is successful determined that the low cost UAV platform and digital compact camera able to be used by smallholders in monitoring the oil palm tree growth condition by utilizing remote sensing techniques. As conclusion, this study has showed a good approach for smallholders in determining their oil palm crops condition whereby the results indicate all are identified healthy palm tree after spectral analysis from combination of NIR and RGB UAV images, respectively.