6 research outputs found

    Performance of GLASS and MODIS Satellite Albedo Products in Diagnosing Albedo Variations during Different Time Scales and Special Weather Conditions in the Tibetan Plateau

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    Surface albedo is a crucial parameter in accurately and quantitatively estimating energy and water budget on the Tibetan Plateau (TP) and is also one of the largest radiative uncertainties in land surface modelling attempts. Based on an 8-year ground-based observation of the surface albedo over typical alpine meadows at Maqu and Maduo sites in the eastern TP, the performance of surface albedo products of Global LAnd Surface Satellite (GLASS) and Moderate Resolution Imaging Spectroradiometer (MODIS) in describing albedo variations at daily, 8-day, seasonal timescales, and during different special weather conditions were analyzed. Compared with the ground-based observation in Maqu, the 8-day albedo products from GLASS and MCD43B3 present maximum negative biases of −0.030 and −0.027 at Maqu, respectively. The black-sky albedo (BSA) of GLASS product coincides well with the ground-based observation in Maduo, with root mean square error (RMSE) of 0.092 and correlation coefficient (R) of 0.833, whereas that of MCD43B3 had an RMSE of 0.072 and R of 0.752. However, they are underestimated when the albedo is greater than 0.4. At the seasonal timescale, the BSA of GLASS and MCD43B3 underestimated the ground-based observation of Maqu by 0.015 in summer, while their white-sky albedo (WSA) are slightly overestimated and closer to the ground-based observation. In daily timescale, the response of surface albedo to soil moisture is different in semihumid and semiarid areas in summer. For both sites, the blue-sky-albedo of MCD43A3 has better agreement with the ground-based observation than GLASS and MCD43B3, as it improves the temporal resolution and calculates the albedo by weighting multiple observations within 16 days to be closer to the actual surface. However, even MCD43A3 could not capture the slowdown processes of albedo changes resulted by small snowfall processes or the snow aging due to cloud cover and inversion algorithms

    The Response of Vegetation to Regional Climate Change on the Tibetan Plateau Based on Remote Sensing Products and the Dynamic Global Vegetation Model

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    Changes in vegetation dynamics play a critical role in terrestrial ecosystems and environments. Remote sensing products and dynamic global vegetation models (DGVMs) are useful for studying vegetation dynamics. In this study, we revised the Community Land Surface Biogeochemical Dynamic Vegetation Model (referred to as the BGCDV_CTL experiment) and validated it for the Tibetan Plateau (TP) by comparing vegetation distribution and carbon flux simulations against observations. Then, seasonal–deciduous phenology parameterization was adopted according to the observed parameters (referred to as the BGCDV_NEW experiment). Compared to the observed parameters, monthly variations in gross primary productivity (GPP) showed that the BGCDV_NEW experiment had the best performance against the in situ observations on the TP. The climatology from the remote sensing and simulated GPPs showed similar patterns, with GPP increasing from northwest to southeast, although the BGCDV_NEW experiment overestimated GPP in the semi-arid and arid regions of the TP. The results show that temperature warming was the dominant factor resulting in the increase in GPP based on the remote sensing products, while precipitation enhancement was the reason for the GPP increase in the model simulation

    Half-Century of Scientific Advancements Since the Cooperative Study of the Kuroshio and Adjacent Regions (CSK) Programme-Need for a new Kuroshio Research

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    Through the Cooperative Study of the Kuroshio and Adjacent Regions (CSK) program during 1965 & ndash;1979, the capacities of current member states (MSs) of the Sub-Commission for the Western Pacific (WESTPAC) of the Intergovernmental Oceanographic Commission (IOC) were enhanced with regard to regional ocean science and data management. Following the termination of the CSK in 1979, each MS continued the work to advance ocean science. The results of scientific studies of the Kuroshio and its adjacent regions have been published by various experts including many from the MSs of the WESTPAC; however, to-date, there has been no systematic approach to the research of the Kuroshio and its adjacent regions. This review considered the Kuroshio from the regional perspective of experts of the MSs, that is, from the perspectives of MSs, science, and the future prospects. Experts from each MS reviewed past activities and contributions and reviewed the knowledge gaps in the fields of physical, biological, and biogeochemical science. Many scientific questions remain regarding the path of the Kuroshio from south to north, as well as associated phenomena, including mesoscale eddies and fronts, the important roles of ocean variations in adjacent regions, and the different roles and mechanisms of air & ndash;sea interactions in low-and mid-latitude areas. Despite considerable effort by many biologists, substantial gaps remain in our biological knowledge of the region. The Kuroshio and its adjacent regions comprise one of the areas of the world with high biodiversity; however, there has been insufficient research into what is the cause of this high biodiversity. From a biogeochemical aspect, high resolution spatiotemporal observations will be required to understand interactions with physical processes both in the Kuroshio region and in the marginal seas. It has been highlighted that long-term fixed-location observations will be needed to understand the key mechanisms of biogeochemical processes, particularly in relation to climate change. Finally, the report summarized the future perspectives. Based on recognition of the current circumstances and with acknowledgment of the potential short-term future capabilities of MSs, the possible uses of new technologies and frameworks were discussed. Since the implementation of the United Nations Convention on the Law of the Sea, which came into force in 1994, it has been difficult to conduct observations in the exclusive economic zone (EEZ) of other regional states. Thus, new frameworks and/or technologies will be needed to ensure the success of future studies of the Kuroshio
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