Highlighted publications https://goodd889.com/en/academic-departments-and-centers/department-of-space-and-applications-sa/research-sa/publications-sa/highlighted-publications/ Tue, 06 Aug 2024 05:58:34 +0000 en-US hourly 1 Performance ranking of multiple CORDEX-SEA sensitivity experiments: towards an optimum choice of physical schemes for RegCM over Southeast Asia https://goodd889.com/en/performance-ranking-of-multiple-cordex-sea-sensitivity-experiments-towards-an-optimum-choice-of-physical-schemes-for-regcm-over-southeast-asia-9516/ https://goodd889.com/en/performance-ranking-of-multiple-cordex-sea-sensitivity-experiments-towards-an-optimum-choice-of-physical-schemes-for-regcm-over-southeast-asia-9516/#respond Tue, 06 Aug 2024 05:04:05 +0000 https://goodd889.com/en/?p=9516 This study conducted and evaluated 44 experiments using the non-hydrostatic version of the regional climate model RegCM4 (RegCM4-NH) and an additional three experiments with RegCM version 5 (RegCM5) over Southeast Asia for the period 2010–2015. The initiative was part of the coordinated regional climate downscaling experiment—Southeast Asia (CORDEX-SEA) project, in preparation for downscaling the latest […]

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This study conducted and evaluated 44 experiments using the non-hydrostatic version of the regional climate model RegCM4 (RegCM4-NH) and an additional three experiments with RegCM version 5 (RegCM5) over Southeast Asia for the period 2010–2015. The initiative was part of the coordinated regional climate downscaling experiment—Southeast Asia (CORDEX-SEA) project, in preparation for downscaling the latest coupled model intercomparison project Phase 6 (CMIP6) global climate models (GCMs). The RegCM4-NH experiments, forced by the ERA5 reanalysis, were configured using combinations of four cumulus, three planetary boundary layer (PBL), and three explicit moisture schemes. The spatiotemporal variability of simulated 2m-temperature and rainfall for 2010–2015 was evaluated against observational datasets. The best experiments demonstrated reasonable reproduction of observed annual cycles and spatial distribution, while many exhibited unrealistic biases. A score ranking system was implemented to objectively compare the performance of experiments, enabling the identification of top-ranked experiments for Southeast Asia. The ensemble mean of the 44 RegCM4-NH experiments exhibited commendable performance, ranking 11th overall. Furthermore, the three additional RegCM5 experiments did not yield improved results compared to RegCM4-NH under the same physical configuration, suggesting that opting for RegCM4-NH would be a prudent choice for the CORDEX-SEA community in the forthcoming CMIP6 downscaling cycle for Southeast Asia.

The article can be found here:

Ngo-Duc, T.*, T. Nguyen-Duy, Q. Desmet, L. Trinh-Tuan, L. Ramu, F. Cruz, J.M. Dado, J.X. Chung, T. Phan-Van, H. Pham-Thanh, K. Truong-Ba, F.T. Tangang, L. Juneng, J. Santisirisomboon, R. Srisawadwong, D. Permana, U.A. Linarka, D. Gunawan, 2024: Performance Ranking of Multiple CORDEX-SEA Sensitivity Experiments: Towards an Optimum Choice of Physical Schemes for RegCM over Southeast Asia. Climate Dynamics,

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]]> https://goodd889.com/en/performance-ranking-of-multiple-cordex-sea-sensitivity-experiments-towards-an-optimum-choice-of-physical-schemes-for-regcm-over-southeast-asia-9516/feed/ 0 Comparison of Synthetic Aperture Radar Sentinel-1 and ALOS-2 observations for lake monitoring https://goodd889.com/en/comparison-of-synthetic-aperture-radar-sentinel-1-and-alos-2-observations-for-lake-monitoring-9139/ https://goodd889.com/en/comparison-of-synthetic-aperture-radar-sentinel-1-and-alos-2-observations-for-lake-monitoring-9139/#respond Mon, 13 May 2024 07:48:14 +0000 https://goodd889.com/en/?p=9139 This work investigates the efficacy of L-band and C-band Synthetic Aperture Radar (SAR) sensors onboard ALOS-2 and Sentinel-1 satellites, as compared to optical sensors onboard Sentinel-2 satellite, for mapping open water of the Tri An reservoir, one of the largest artificial reservoirs in South Vietnam, during the 2016-2023 period. The Google Earth Engine (GEE) was […]

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]]> This work investigates the efficacy of L-band and C-band Synthetic Aperture Radar (SAR) sensors onboard ALOS-2 and Sentinel-1 satellites, as compared to optical sensors onboard Sentinel-2 satellite, for mapping open water of the Tri An reservoir, one of the largest artificial reservoirs in South Vietnam, during the 2016-2023 period. The Google Earth Engine (GEE) was the primary computing platform to pre-process all satellite observations. The Otsu threshold algorithm was employed to generate water/non-water maps derived from the VH- and HH-polarized backscatter coefficient data acquired by Sentinel-1 and ALOS-2 satellites and from the Modified Normalized Difference Water Index (MNDWI) data acquired by Sentinel-2 satellite, respectively. The findings reveal the stability of Tri An reservoir’s surface water extent from 2017 to 2022, followed by a significant decline of nearly 70% during the dry season of 2023 to approximately 100 km2. This substantial decrease can be explained by the impact of a robust El Niño phase occurring in the region simultaneously. Overall, there is a high consistency between results derived from SAR and optical sensors, but the correlation between Sentinel-1 and Sentinel-2 (R = 0.9774) was higher than that between ALOS-2 and Sentinel-2 (R = 0.9145). During the drought period, both C-band and L-band SAR sensors overestimate the reservoir’s surface water extent due to the similarity in their backscatter coefficient between water and dry flat soil surfaces. This misclassification is more pronounced in ALOS-2 data than Sentinel-1 data, suggesting that the C-band sensor is more suitable than the L-band sensor for mapping the lake’s open water areas.

The article can be found here:

Pham Duc, B. (2024). Comparison of Synthetic Aperture Radar Sentinel-1 and ALOS-2 observations for lake monitoring. Vietnam Journal of Earth Sciences.

Spatial comparison between surface water maps of Tri An Reservoir, extracted from the three satellite platforms. Sentinel-2 observations were acquired on March 13, 2020, while Sentinel-1 and ALOS-2 observations were acquired on March 15, 2020

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]]> https://goodd889.com/en/comparison-of-synthetic-aperture-radar-sentinel-1-and-alos-2-observations-for-lake-monitoring-9139/feed/ 0 Identification and trend analysis of compound meteorological hazards along Vietnam’s coastline https://goodd889.com/en/identification-and-trend-analysis-of-compound-meteorological-hazards-along-vietnams-coastline-9107/ https://goodd889.com/en/identification-and-trend-analysis-of-compound-meteorological-hazards-along-vietnams-coastline-9107/#respond Tue, 07 May 2024 09:50:08 +0000 https://goodd889.com/en/?p=9107 The concept of compound hazards refers to the simultaneous occurrence or rapid succession of multiple hazards within a specific area. In this study, we identified compound meteorological hazards based on three types of individual hazards: high temperatures, heavy rainfall, and tropical cyclones (TCs). We computed the number of each type of individual hazards and their […]

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]]> The concept of compound hazards refers to the simultaneous occurrence or rapid succession of multiple hazards within a specific area. In this study, we identified compound meteorological hazards based on three types of individual hazards: high temperatures, heavy rainfall, and tropical cyclones (TCs). We computed the number of each type of individual hazards and their compounds at 10 selected stations along the coastline of Vietnam for the period 1980–2018. A temperature hazard (rainfall hazard) is identified if the maximum temperature (rainfall amount) on a given day exceeds the 95th percentile of all daily values recorded over the study period. A location is considered exposed to a TC hazard on a given day if the distance from that location to the TC center is less than 250 km. Subsequently, a compound hazard event is identified if the interval between the ending time of one individual hazard event and the starting time of the following one is less than 10 days. The results indicate that the annual number of compound hazards shows increasing trends at the majority of the stations, mainly due to the increase in temperature hazards. At the seasonal scale, compound hazards typically occur from March to November, primarily associated with temperature hazards in the first half of the year and with TCs and rainfall hazards in the later months. The identification and analysis of compound hazards in this study provide essential information for resilience and adaptation planning in Vietnam.

Nguyen-Duy, T., Ngo-Duc, T.*, Nguyen-Le, D., Nguyen-Xuan, T., Phan-Van, T. (2024) Identification and trend analysis of compound meteorological hazards along Vietnam’s coastline. Natural Hazards.

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]]> https://goodd889.com/en/identification-and-trend-analysis-of-compound-meteorological-hazards-along-vietnams-coastline-9107/feed/ 0 Comparison of multi-source satellite remote sensing observations for monitoring the variations of small lakes: a case study of Dai Lai Lake (Vietnam) https://goodd889.com/en/comparison-of-multi-source-satellite-remote-sensing-observations-for-monitoring-the-variations-of-small-lakes-a-case-study-of-dai-lai-lake-vietnam-9104/ https://goodd889.com/en/comparison-of-multi-source-satellite-remote-sensing-observations-for-monitoring-the-variations-of-small-lakes-a-case-study-of-dai-lai-lake-vietnam-9104/#respond Tue, 07 May 2024 09:48:07 +0000 https://goodd889.com/en/?p=9104 This study compares the capability of Sentinel-1, Sentinel-2, and PlanetScope (PS) satellites in monitoring the variations of surface water of Dai Lai Lake, located in North Vietnam, for the 2018–2023 period. The analysis involves the utilization of Google Earth Engine to partially process Sentinel-1 and Sentinel-2 observations, while PS observations are processed using local computers, […]

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]]> This study compares the capability of Sentinel-1, Sentinel-2, and PlanetScope (PS) satellites in monitoring the variations of surface water of Dai Lai Lake, located in North Vietnam, for the 2018–2023 period. The analysis involves the utilization of Google Earth Engine to partially process Sentinel-1 and Sentinel-2 observations, while PS observations are processed using local computers, to generate VH-polarized backscatter coefficient, Normalized Difference Water Index (NDWI), and Modified of Normalized Difference Water Index (MNDWI) maps. The method for making binary water/non-water maps primarily employs the Otsu algorithm on each single map derived from the previous step. Findings reveal that the lake’s water extent remains relatively stable over the 6-year period, and is not strongly affected by the seasonal cycle. Although the spatial distribution patterns of the lake exhibit significant similarity, average water extent of the lake derived from 3-m resolution PS imagery is about 2.17 and 5.60% more than that obtained from 10-m resolution Sentinel-2 and Sentinel-1 imagery, respectively. PS observations are effective for monitoring small lakes, but it is advised to check the quality of its NIR band. Sentinel-2 observations prove great effectiveness for lake monitoring, using both NDWI and MNDWI. For Sentinel-1 observations, potential misclassifications could arise due to similarities in VH-polarized backscatter coefficients between water surfaces and other flat surfaces.

Binh Pham-Duc; Comparison of multi-source satellite remote sensing observations for monitoring the variations of small lakes: a case study of Dai Lai Lake (Vietnam). Journal of Water and Climate Change 1 January 2024; 15 (1): 157–170. doi:

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]]> https://goodd889.com/en/comparison-of-multi-source-satellite-remote-sensing-observations-for-monitoring-the-variations-of-small-lakes-a-case-study-of-dai-lai-lake-vietnam-9104/feed/ 0 Characterization of temperature and humidity effects on extreme heat stress under global warming and urban growth in the Pearl and Yangtze River Deltas of China https://goodd889.com/en/characterization-of-temperature-and-humidity-effects-on-extreme-heat-stress-under-global-warming-and-urban-growth-in-the-pearl-and-yangtze-river-deltas-of-china-9100/ https://goodd889.com/en/characterization-of-temperature-and-humidity-effects-on-extreme-heat-stress-under-global-warming-and-urban-growth-in-the-pearl-and-yangtze-river-deltas-of-china-9100/#respond Tue, 07 May 2024 09:45:04 +0000 https://goodd889.com/en/?p=9100 With global warming accelerating, the heavily populated and rapidly urbanized coastal regions of the Pearl River Delta (PRD) and the Yangtze River Delta (YRD) stand as representative areas with mounting concerns about extreme heat stress. This study analyzes differentiated effects of temperature (TAS) and relative humidity (RH) on human heat stress measured by wet-bulb globe […]

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]]> With global warming accelerating, the heavily populated and rapidly urbanized coastal regions of the Pearl River Delta (PRD) and the Yangtze River Delta (YRD) stand as representative areas with mounting concerns about extreme heat stress. This study analyzes differentiated effects of temperature (TAS) and relative humidity (RH) on human heat stress measured by wet-bulb globe temperature (WBGT) in those urban regions based on machine learning and mathematical derivation, while also examining the impacts of global warming and urbanization on prospective heat risks. To generate fine-scale climate projections targeted at the PRD and YRD, two global projections forced by Representative Concentration Pathway (RCP) 8.5 scenario are dynamically downscaled using non-hydrostatic Regional Climate Model version 4.7 (RegCM4), with the urban density and extent updated every year based on Shared Socioeconomic Pathways 5-8.5 (SSP5) scenario, thereby incorporating the transient urban growth into future projections. The bias-corrected downscaled simulations effectively capture the distinct interdependencies between TAS and RH on WBGT across different regions, similar to the observed patterns during the historical period. While the absolute contribution of TAS to WBGT is larger than RH regardless of warming levels and regions, the relative increase in RH becomes more pronounced with warming. Under RCP8.5 scenario, unprecedentedly extreme WBGT is projected to emerge in the far future (2080–2099). In contrast, the effect of urbanization appears to be more dominant in the near future (2030–2049) as urban density under SSP5 scenario is projected to peak around the 2040s and gradually decrease afterwards. The reduction of RH is found in the intensely urbanized areas locally, but it does not significantly lower WBGT because the positive contribution of increased TAS is more dominant. As a result, highly urbanized regions still exhibit higher WBGT compared to other areas. In addition, urban heat island effect is more pronounced for compact areas with high urban density (i.e., PRD) and at night. Despite the smaller temperature increase from urban heat island effect compared to global warming, it can play a critical role in exacerbating heat stress, adding to the already dangerous humid and hot conditions.

Zhou Z., T. Nguyen-Xuan, H. Liao, L. Qiu, E-S. Im, 2024: Characterization of temperature and humidity effects on extreme heat stress under global warming and urban growth in the Pearl and Yangtze River deltas of China. Weather and Climate Extremes, 

 

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