How Accurately Can the Air Temperature Lapse Rate Over the Tibetan Plateau Be Estimated From MODIS LSTs?

2018 ◽  
Vol 123 (8) ◽  
pp. 3943-3960 ◽  
Author(s):  
Hongbo Zhang ◽  
Fan Zhang ◽  
Guoqing Zhang ◽  
Tao Che ◽  
Wei Yan
Keyword(s):  
Tibetan Plateau ◽  
Air Temperature ◽  
Lapse Rate ◽  
The Tibetan Plateau ◽  
Temperature Lapse Rate

scholarly journals Daily air temperature estimation on glacier surfaces in the Tibetan Plateau using MODIS LST data

2018 ◽  
Vol 64 (243) ◽  
pp. 132-147 ◽  
Author(s):  
HONGBO ZHANG ◽  
FAN ZHANG ◽  
GUOQING ZHANG ◽  
YAOMING MA ◽  
KUN YANG ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Air Temperature ◽  
Lapse Rate ◽  
The Tibetan Plateau ◽  
Mean Square ◽  
Night Time ◽  
Glacier Surface ◽  
Temperature Estimation ◽  
Air Temperatures ◽  
Air Temperature Estimation

ABSTRACTThe MODerate resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data have been widely used for air temperature estimation in mountainous regions where station observations are sparse. However, the performance of MODIS LST in high-elevation glacierized areas remains unclear. This study investigates air temperature estimation in glacierized areas based on ground observations at four glaciers across the Tibetan Plateau. Before being used to estimate the air temperature, MODIS LST data are evaluated at two of the glaciers, which indicates that MODIS night-time LST is more reliable than MODIS daytime LST data. Then, linear models based on each of the individual MODIS LST products from two platforms (Terra and Aqua) and two overpasses (night-time and daytime) are built to estimate daily mean, minimum and maximum air temperatures in glacierized areas. Regional glacier surface (RGS) models (mean /-mean-square differences: 3.3, 3.0 and 4.8°C for daily mean, minimum and maximum air temperatures, respectively) show higher accuracy than local non-glacier surface models (mean root-mean-square differences: 4.2, 4.7 and 5.7°C). In addition, the RGS models based on MODIS night-time LST perform better to estimate daily mean, minimum and maximum air temperatures than using temperature lapse rate derived from local stations.

Fluvial sediment fluxes response to modern climate change and human activities in the Tibetan Plateau and its margins

2021 ◽  
Author(s):  
Dongfeng Li ◽  
Xixi Lu ◽  
Ting Zhang
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Human Activities ◽  
Sediment Flux ◽  
The Tibetan Plateau ◽  
Fluvial Sediment ◽  
Sediment Fluxes ◽  
Cold Environments

<p>Sediment flux in cold environments is a crucial proxy to link glacial, periglacial, and fluvial systems and highly relevant to hydropower operation, water quality, and the riverine carbon cycle. However, the long-term impacts of climate change and multiple human activities on sediment flux changes in cold environments remain insufficiently investigated due to the lack of monitoring and the complexity of the sediment cascade. Here we examine the multi-decadal changes in the in-situ observed fluvial sediment fluxes from two types of basins, namely, pristine basins and disturbed basins, in the Tibetan Plateau and its margins. The results show that the fluvial sediment fluxes in the pristine Tuotuohe headwater have substantially increased over the past three decades (i.e., a net increase of 135% from 1985–1997 to 1998–2017) due to the warming and wetting climate. We also quantify the relative impacts of air temperature and precipitation on the increases in the sediment fluxes with a novel attribution approach and finds that climate warming and intensified glacier-snow-permafrost melting is the primary cause of the increased sediment fluxes in the pristine cold environment (Tuotuohe headwater), with precipitation increase and its associated pluvial processes being the secondary driver. By contrast, the sediment fluxes in the downstream disturbed Jinsha River (southeastern margin of the Tibetan Plateau) exhibit a net increase of 42% from 1966-1984 to 1985-2010 mainly due to human activities such as deforestation and mineral extraction (contribution of 82%) and secondly because of climate change (contribution of 18%). Then the sediment fluxes dropped by 76% during the period of 2011-2015 because of the operations of six cascade reservoirs since 2010. In an expected warming and wetting climate for the region, we predict that the sediment fluxes in the pristine headwaters of the Tibetan Plateau will continue to increase throughout the 21st century, but the rising sediment fluxes from the Tibetan Plateau would be mostly trapped in its marginal reservoirs.</p><p>Overall, this work has provided the sedimentary evidence of modern climate change through robust observational sediment flux data over multiple decades. It demonstrates that sediment fluxes in pristine cold environments are more sensitive to air temperature and thermal-driven geomorphic processes than to precipitation and pluvial-driven processes. It also provides a guide to assess the relative impacts of human activities and climate change on fluvial sediment flux changes and has significant implications for water resources stakeholders to better design and manage the hydropower dams in a changing climate. Such findings may also have implications for other cold environments such as the Arctic, Antarctic, and other high mountainous basins.</p><p>Furthermore, this research is under the project of "Water and Sediment Fluxes Response to Climate Change in the Headwater Rivers of Asian Highlands" (supported by the IPCC and the Cuomo Foundation) and the project of "Sediment Load Responses to Climate Change in High Mountain Asia" (supported by the Ministry of Education of Singapore). Part of the results are also published in Li et al., 2018 Geomorphology, Li et al., 2020 Geophysical Research Letters, and Li et al., 2021 Water Resources Research.</p>

scholarly journals Downscaling of ERA-Interim Temperature in the Contiguous United States and Its Implications for Rain–Snow Partitioning

2018 ◽  
Vol 19 (7) ◽  
pp. 1215-1233 ◽  
Author(s):  
Guoqiang Tang ◽  
Ali Behrangi ◽  
Ziqiang Ma ◽  
Di Long ◽  
Yang Hong
Keyword(s):  
United States ◽  
Air Temperature ◽  
Nearest Neighbor ◽  
Reanalysis Data ◽  
Lapse Rate ◽  
Critical Threshold ◽  
Eastern United States ◽  
Temperature Lapse Rate ◽  
Mountainous Regions ◽  
Precipitation Phase

Abstract Precipitation phase has an important influence on hydrological processes. The Integrated Multisatellite Retrievals for Global Precipitation Measurement (IMERG) uses temperature data from reanalysis products to implement rain–snow classification. However, the coarse resolution of reanalysis data may not reveal the spatiotemporal variabilities of temperature, necessitating appropriate downscaling methods. This study compares the performance of eight air temperature Ta downscaling methods in the contiguous United States and six mountain ranges using temperature from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) as the benchmark. ERA-Interim Ta is downscaled from the original 0.75° to 0.1°. The results suggest that the two purely statistical downscaling methods [nearest neighbor (NN) and bilinear interpolation (BI)] show similar performance with each other. The five downscaling methods based on the free-air temperature lapse rate (TLR), which is calculated using temperature and geopotential heights at different pressure levels, notably improves the accuracy of Ta. The improvement is particularly obvious in mountainous regions. We further calculated wet-bulb temperature Tw, for rain–snow classification, using Ta and dewpoint temperature from ERA-Interim and PRISM. TLR-based downscaling methods result in more accurate Tw compared to NN and BI in the western United States, whereas the improvement is limited in the eastern United States. Rain–snow partitioning is conducted using a critical threshold of Tw with Snow Data Assimilation System (SNODAS) snowfall data serving as the benchmark. ERA-Interim-based Tw using TLR downscaling methods is better than that using NN/BI and IMERG precipitation phase. In conclusion, TLR-based downscaling methods show promising prospects in acquiring high-quality Ta and Tw with high resolution and improving rain–snow partitioning, particularly in mountainous regions.

scholarly journals Air pollution slows down surface warming over the Tibetan Plateau

2020 ◽  
Vol 20 (2) ◽  
pp. 881-899 ◽  
Author(s):  
Aolin Jia ◽  
Shunlin Liang ◽  
Dongdong Wang ◽  
Bo Jiang ◽  
Xiaotong Zhang
Keyword(s):  
Climate Change ◽  
Air Pollution ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Cmip5 Models ◽  
The Tibetan Plateau ◽  
Anthropogenic Aerosols ◽  
Surface Warming

Abstract. The Tibetan Plateau (TP) plays a vital role in regional and global climate change. The TP has been undergoing significant surface warming starting from 1850, with an air temperature increase of 1.39 K and surface solar dimming resulting from decreased incident solar radiation. The causes and impacts of solar dimming on surface warming are unclear. In this study, long-term (from 1850 to 2015) surface downward radiation datasets over the TP are developed by integrating 18 Coupled Model Intercomparison Project phase 5 (CMIP5) models and satellite products. The validation results from two ground measurement networks show that the generated downward surface radiation datasets have a higher accuracy than the mean of multiple CMIP5 datasets and the fused datasets of reanalysis and satellite products. After analyzing the generated radiation data with four air temperature datasets, we found that downward shortwave radiation (DSR) remained stable before 1950 and then declined rapidly at a rate of −0.53 W m−2 per decade, and that the fastest decrease in DSR occurs in the southeastern TP. Evidence from site measurements, satellite observations, reanalysis, and model simulations suggested that the TP solar dimming was primarily driven by increased anthropogenic aerosols. The TP solar dimming is stronger in summer, at the same time that the increasing magnitude of the surface air temperature is the smallest. The cooling effect of solar dimming offsets surface warming on the TP by 0.80±0.28 K (48.6±17.3 %) in summer since 1850. It helps us understand the role of anthropogenic aerosols in climate warming and highlights the need for additional studies to be conducted to quantify the influence of air pollution on regional climate change over the TP.

scholarly journals Air pollution slows down surface warming over the Tibetan Plateau

2019 ◽  
Author(s):  
Aolin Jia ◽  
Shunlin Liang ◽  
Dongdong Wang ◽  
Bo Jiang ◽  
Xiaotong Zhang
Keyword(s):  
Climate Change ◽  
Air Pollution ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Cmip5 Models ◽  
The Tibetan Plateau ◽  
Anthropogenic Aerosols ◽  
Surface Warming

Abstract. The Tibetan Plateau (TP) plays a vital role in regional and global climate change. The TP has been undergoing significant surface warming since 1850, with an air temperature increase of 1.39 K and surface solar dimming resulting from decreased incident solar radiation. The causes and impacts of solar dimming on surface warming are unclear. In this study, long-term (from 1850–2015) surface downward radiation datasets over the TP are developed by integrating 18 Coupled Model Intercomparison Project Phase 5 (CMIP5) models and satellite products. The validation results from two ground measurement networks show that the generated downward surface radiation datasets have higher accuracy than the mean of multiple CMIP5 and the fused datasets of reanalysis and satellite products. After analyzing the generated radiation data with four air temperature datasets, we found that downward shortwave radiation (DSR) remained stable before 1950 and then declined rapidly at a rate of −0.53 W m−2 per decade and that the fastest decrease in DSR is in the southeastern TP. Evidence from site measurements, satellite observations, reanalysis, and model simulations suggested that TP solar dimming was primarily driven by increased anthropogenic aerosols. The TP solar dimming is stronger in summer, at the same time that the increasing magnitude of the surface air temperature is the smallest. The cooling effect of solar dimming offsets surface warming on the TP by 0.80 ± 0.28 K (48.6 ± 17.3 %) in summer. It helps us understand the role of anthropogenic aerosols in climate warming, and highlights the need for additional studies to be conducted to quantify the influence of air pollution on regional climate change over the TP.

Relationships between δ18O in precipitation and air temperature and moisture origin on a south–north transect of the Tibetan Plateau

2008 ◽  
Vol 87 (2) ◽  
pp. 158-169 ◽  
Author(s):  
Wusheng Yu ◽  
Tandong Yao ◽  
Lide Tian ◽  
Yaoming Ma ◽  
Kimpei Ichiyanagi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Air Temperature ◽  
The Tibetan Plateau
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