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The climate of the Tibetan Plateau (TP) has experienced substantial changes in recent decades as a result of the location's susceptibility to global climate change. The changes observed across the TP are closely associated with regional land–atmosphere interactions. Current models and satellites struggle to accurately depict the interactions; therefore, critical field observations on land–atmosphere interactions outlined here provide necessary independent validation data and fine-scale process insights for constraining reanalysis products, remote sensing retrievals, and land surface model parameterizations. Scientific data sharing is crucial for the TP since in situ observations are rarely available under these harsh conditions. However, field observations are currently dispersed among individuals or groups and have not yet been integrated for comprehensive analysis. This has prevented a better understanding of the interactions, the unprecedented changes they generate, and the substantial ecological and environmental consequences they bring about. In this study, we collaborated with different agencies and organizations to present a comprehensive dataset for hourly measurements of surface energy balance components, soil hydrothermal properties, and near-surface micrometeorological conditions spanning up to 17 years (2005–2021). This dataset, derived from 12 field stations covering a variety of typical TP landscapes, provides the most extensive in situ observation data available for studying land–atmosphere interactions on the TP to date in terms of both spatial coverage and duration. Three categories of observations are provided in this dataset: meteorological gradient data (met), soil hydrothermal data (soil), and turbulent flux data (flux). To assure data quality, a set of rigorous data-processing and quality control procedures are implemented for all observation elements (e.g., wind speed and direction at different height) in this dataset. The operational workflow and procedures are individually tailored to the varied types of elements at each station, including automated error screening, manual inspection, diagnostic checking, adjustments, and quality flagging. The hourly raw data series; the quality-assured data; and supplementary information, including data integrity and the percentage of correct data on a monthly scale, are provided via the National Tibetan Plateau Data Center (10.11888/Atmos.tpdc.300977, Ma et al., 2023a). With the greatest number of stations covered, the fullest collection of meteorological elements, and the longest duration of observations and recordings to date, this dataset is the most extensive hourly land–atmosphere interaction observation dataset for the TP. It will serve as the benchmark for evaluating and refining land surface models, reanalysis products, and remote sensing retrievals, as well as for characterizing fine-scale land–atmosphere interaction processes of the TP and underlying influence mechanisms. [ABSTRACT FROM AUTHOR]

The central and western Tibetan Plateau (CWTP) is characterized by harsh environment and strong interactions among the spheres of earth as well as significant changes in climate and water cycles over the past four decades. The lack of precipitation observations is a bottleneck for the study of land surface processes in this region. Over the past six years, we have designed and established two observation transects across the south-north and the west-east in this region to obtain hourly rainfall data during the warm season (May–September). The south-north transect extends from Yadong Valley on the southern slope of the Himalayas to Shuanghu County in the hinterland of the plateau, with a total of 31 stations; the west-east transect extends from Shiquanhe in the west to Naqu in the central TP, with a total of 22 stations. The observation dataset has been applied to clarify the spatiotemporal characteristics of precipitation in the CWTP, to evaluate the quality of typical gridded precipitation products, to support the development of regional climate models, and to reveal the processes of summertime lake-air interactions. The observation dataset has been released in the National Tibetan Plateau Data Center. [ABSTRACT FROM AUTHOR]

Pakistan experiences extreme flood events almost every year during the monsoon season. Recently, flood events have become more disastrous as their frequency and magnitude have increased due to climate change. This situation is further worsened due to the limited capacity of existing water reservoirs and their ability to absorb and mitigate peak floods. Thus, the simulation of stream flows using projected data from climate models is essential to assess flood events and proper water resource management in the country. This study investigates the future floods (in near future and far future periods) using the integrated flood analysis system (IFAS) model under the RCP2.6, RCP4.5, and RCP8.5 climate change scenarios. Downscaled and bias corrected climatic data of six general circulation models and their ensemble were used in this study. The IFAS model simulated the stream flow efficiently (R2 = 0.86–0.93 and Nash–Sutcliffe efficiency = 0.72–0.92) in the Jhelum River basin (JRB), Kabul River basin (KRB), and upper Indus River basin (UIRB) during the calibration and validation periods. The simulation results of the model showed significant impact of projected climate change on stream flows that will cause the mean monthly stream flow in the JRB to be lower, while that of the KRB and UIRB to be higher than that of the historical period. The highest flow months are expected to shift from May–June (Jhelum basin) and June–July (Kabul basin) to April–May with no changes in the UIRB. Higher frequencies of low to medium floods are projected in the KRB and UIRB, while the JRB expects fewer flood events. Based on the results from the IFAS model, it is concluded that stream flow in the study area will increase with several flood events. [ABSTRACT FROM AUTHOR]

The Yellow River floodplain represents a fertile landmass that contributes significantly to human welfare and thus has been colloquially known as the birthplace of Chinese civilization. The sediment-laden nature of the Yellow River gave rise to a super-elevated channel belt, which is prone to failure particularly in the summer months when excessive precipitation occurs, resulting in cataclysmic floods traditionally regarded as "China's Sorrow." Therefore, a deeper understanding of levee breach frequency in this area is especially important for the assessment of socio-economic risk of levee breaches associated with future climate changes. To better understand the nature, evolution, and driving mechanisms of levee breaches on the lower Yellow River, it is necessary to place the instrumental data within a longer time framework. Here, we retrieve past information about levee breaches on the lower Yellow River since AD 11 from various documentary sources such as official histories of China. We evaluated each line of descriptions and narratives about the location, timing, and nature of each event in these documents, ending up with a detailed timeline of levee breaches on the lower Yellow River during the last 2000 years on an annual time scale. Our results reveal remarkable variations in the frequency of levee breaches superimposed on a long-term increasing trend. In addition to climate changes, the iterative embankment-siltation-breaching process caused a feedback: more breaches result in much more channel siltation, which in turn leads to even more breaches. The enhanced farming in the Loess Plateau played a pivotal role in the formation and operation of this positive feedback. Our findings may not only help improve the assessment of socio-economic risk of levee breaches associated with future climate changes, but also provide consulting information for hydraulic engineering and infrastructural designs in the lower Yellow river area. [ABSTRACT FROM AUTHOR]

As a region that is highly sensitive to global climate change, the Tibetan Plateau (TP) experiences an intra‐seasonal soil water deficient due to the reduced precipitation during the South Asia monsoon (SAM) breaks. Few studies have investigated the impact of SAM breaks on TP ecological processes, although a number of studies have explored the effects of inter‐annual and decadal climate variability. In this study, the response of vegetation activity to SAM breaks was investigated. The data used are: (1) soil moisture from in situ, satellite remote sensing and data assimilation; and (2) the normalized difference vegetation index (NDVI) and solar‐induced chlorophyll fluorescence (SIF). We found that in the SAM break‐impacted region, which is distributed in the central‐eastern part of TP, photosynthesis become more active during SAM breaks. And temporal variability in the photosynthesis of this region is controlled mainly by solar radiation variability and has little sensitivity to soil moisture. We adopted a diagnostic process‐based modeling approach to examine the causes of enhanced plant activity during SAM breaks on the central‐eastern TP. Our analysis indicates that more carbon assimilated by photosynthesis in the reduced precipitation is stimulated by increases in solar radiation absorbed and temperature. This study highlights the importance of sub‐seasonal climate variability for characterizing the relationship between vegetation and climate. Key Points: South Asia monsoon (SAM) breaks occur almost every year impacting a wide area on the central‐eastern Tibetan Plateau (roughly east of 92°E)The carbon assimilation becomes more active during SAM breaksThe increase in solar radiation absorbed boosts grass productivity during SAM break on the central‐eastern Tibetan Plateau [ABSTRACT FROM AUTHOR]

Most regions of the world have experienced significant climate warming in recent decades, generally characterized by a faster rise in minimum temperature than in maximum temperature. This study shows that the temperature changes on the north side of the central and eastern Himalayas were similar to the global change values from 1972 to 2014, while on the south side of the Himalayas (SHM) the change in minimum temperature has been negligible over the past 40 years except for a significant warming trend during the monsoon season. SHM temperature changes are closely related to changes in cloud fraction and downward longwave radiation. Over the SHM, cloud fraction has decreased due to weaker uplift, leading to reduced downward longwave radiation at night. Therefore, the increase rate in minimum temperature diminished significantly. During the 40‐year period, changes in albedo on both sides of Himalayas were small, and thus played a negligible role. Overall, our results may contribute to a better understanding of temperature changes and their effects on environmental changes in the Himalayas, in the context of global warming. [ABSTRACT FROM AUTHOR]

With the significant attention on global climate change, regional integrated energy systems (RIES) in low-carbon city planning has become one of the most important ways for global cities to achieve the goal of energy conservation and emission reduction. However, the planning strategy used in the primary stage of RIES establishment will greatly affect the system economy and environment. In view of the lack of planning guidance mechanisms for the large-scale RIES in China, a method for RIES preliminary overall planning, focused on energy types and use, is proposed in this paper. A graph theory-based mathematical optimal model was established with the lifetime costs of the whole system as the economic goal, and an improved Prim algorithm was put forward to solve the costs of the transmission and distribution network with the dynamic weight set of pipeline flow. The model was solved by an algorithm based on the idea of a dynamic minimum spanning tree and optimal path planning. The model and method were applied in a China–U.S. low-carbon demonstration city to verify feasibility and validity. The results could help us to comprehensively integrate regional energy and accurately plan future cities. [ABSTRACT FROM AUTHOR]

Identifying the changes in precipitation and temperature at a regional scale is of great importance for the quantification of climate change. This research investigates the changes in precipitation and surface air temperature indices in the seven irrigation zones of Punjab Province during the last 50 years; this province is a very important region in Pakistan in terms of agriculture and irrigated farming. The reliability of the data was examined using double mass curve and autocorrelation analysis. The magnitude and significance of the precipitation and temperature were visualized by various statistical methods. The stations' trends were spatially distributed to better understand climatic variability across the elevation gradient of the study region. The results showed a significant warming trend in annual Tmin (minimum temperature) and Tmean (mean temperature) in different irrigation zones. However, Tmax (maximum temperature) had insignificant variations except in the high elevation Thal zone. Moreover, the rate of Tmin increased faster than that of Tmax, resulting in a reduction in the diurnal temperature range (DTR). On a seasonal scale, warming was more pronounced during spring, followed by that in winter and autumn. However, the summer season exhibited insignificant negative trends in most of the zones and gauges, except in the higher-altitude Thal zone. Overall, Bahawalpur and Faisalabad are the zones most vulnerable to warming annually and in the spring, respectively. Furthermore, the elevation-dependent trend (EDT) indicated larger increments in Tmax for higher-elevation (above 500 m a.s.l.) stations, compared to the lower-elevation ones, on both annual and seasonal scales. In contrast, the Tmin showed opposite trends at higher- and lower-elevation stations, while a moderate increase was witnessed in Tmean trends from lower to higher altitude over the study region. An increasing trend in DTR was observed at higher elevation, while a decreasing trend was noticed at the lower-elevation stations. The analysis of precipitation data indicated wide variability over the entire region during the study period. Most previous studies reported no change or a decreasing trend in precipitation in this region. Conversely, our findings indicated the cumulative increase in annual and autumn precipitation amounts at zonal and regional level. However, EDT analysis identified the decrease in precipitation amounts at higher elevation (above 1000 m a.s.l.) and increase at the lower-elevation stations. Overall, our findings revealed unprecedented evidence of regional climate change from the perspectives of seasonal warming and variations in precipitation and temperature extremes (Tmax and Tmin) particularly at higher-elevation sites, resulting in a variability of the DTR, which could have a significant influence on water resources and on the phenology of vegetation and crops at zonal and station level in Punjab. [ABSTRACT FROM AUTHOR]

The source region of the Indus River (SRIR), which is located in the Hindukush, Karakoram and Himalayan (HKH) mountainous range and on the Third Pole (TP), is very sensitive to climate change, especially precipitation changes, because of its multifarious orography and fragile ecosystem. Climate changes in the SRIR also have important impacts on social and economic development, as well as on the ecosystems of the downstream irrigation areas in Pakistan. This paper investigates the changes in precipitation characteristics by dividing the daily precipitation rate into different classes, such as light (0–10 mm), moderate (10.1–25 mm) and heavy precipitation (>25 mm). Daily precipitation data from gauging and non-gauging stations from 1961–2015 are used. The results of the analysis of the annual precipitation and rainy day trends show significant (p < 0.05) increases and decreases, respectively, while light and heavy precipitation show significant decreasing and increasing trends, respectively. The analysis of the precipitation characteristics shows that light precipitation has the highest number of rainy days compared to moderate or heavy precipitation. The analysis of the seasonal precipitation trends shows that only 18 stations have significant increasing trends in winter precipitation, while 27 stations have significant increasing trends in summer precipitation. Both short and long droughts exhibit increasing trends, which indicates that the Indus Basin will suffer from water shortages for agriculture. The results of this study could help policymakers cope with floods and droughts and sustain eco-environmental resources in the study area. [ABSTRACT FROM AUTHOR]

Summary Soil moisture is a key variable in climate system, and its accurate simulation needs effective soil parameter values. Conventional approaches may obtain soil parameter values at point scale, but they are costly and not efficient at grid scale (10–100 km) of current climate models. This study explores the possibility to estimate soil parameter values by assimilating AMSR-E (Advanced Microwave Scanning Radiometer for Earth Observing System) brightness temperature (TB) data. In the assimilation system, the TB is simulated by the coupled system of a land surface model (LSM) and a radiative transfer model (RTM), and the simulation errors highly depend on parameters in both the LSM and the RTM. Thus, sensitive soil parameters may be inversely estimated through minimizing the TB errors. A crucial step for the parameter estimation is made to suppress the contamination of uncertainties in atmospheric forcing data. The effectiveness of the estimated parameter values is evaluated against intensive measurements of soil parameters and soil moisture in three grasslands of the Tibetan Plateau and the Mongolian Plateau. The results indicate that this satellite data-based approach can improve the data quality of soil porosity, a key parameter for soil moisture modeling, and LSM simulations with the estimated parameter values reasonably reproduce the measured soil moisture. This demonstrates it is feasible to calibrate LSMs for soil moisture simulations at grid scale by assimilating microwave satellite data, although more efforts are expected to improve the robustness of the model calibration. [ABSTRACT FROM AUTHOR]

Analyses of the spatial and temporal variation of reference evapotranspiration (ET 0 ) and aridity index (AI) can further understand climate change and its effect on hydrology. In this study, based on date from 58 standard meteorological stations, the spatio-temporal variations and trends of ET 0 and AI were calculated for the Loess Plateau Region (LPR) from 1961 to 2012 using the Mann–Kendall test, the moving t -test, and the Morlet wavelet methods. The results demonstrated: (1) the annual ET 0 displayed a statistically significant decrease of −10.3 mm/10 y ( P < 0.05) during 1961–2012. At that time, AI also had a decreasing trend of −0.013/10 y over the past 52 years. Compared with ET 0 , the inter-decadal variations of AI over the LPR seemed to show similar declined trends. (2) Spatially, about 81% stations displayed a decreasing trend for annual ET 0 during 1961–2012, and most of them were distributed in the western, northern and southeastern LPR. In addition, about 60% of stations showed statistically decreasing trends for AI, and the major decreases were mainly in the east Qinghai division and northern LPR. (3) Abrupt changes were detected in annual ET 0 series in the 1980s and in annual AI series in 1987. Wavelet analysis indicated significant 2 year and non-significant 7, 10 and 14 years in annual ET 0 series, and there existed periods of 4, 8 and 12 years for AI. (4) For ET 0 , wind speed was the most sensitive meteorological factor, followed by sunshine hours, precipitation, and relative humidity. For AI, ET 0 and precipitation were the sensitive factors. This study provides an understanding of the effect of recent climate change on hydrological cycle in the LPR. [ABSTRACT FROM AUTHOR]

Abstract: The Tibetan Plateau (TP) exerts strong thermal forcing on the atmosphere over Asian monsoon region and supplies water resources to adjacent river basins. Recently, the Plateau experienced evident climate changes, which have changed atmospheric and hydrological cycles and thus reshaped the local environment. This study reviewed recent research progress in the climate changes and explored their impacts on the Plateau energy and water cycle, based on which a conceptual model to synthesize these changes was proposed and urgent issues to be explored were summarized. The TP has experienced an overall surface air warming and moistening, solar dimming, and wind stilling since the beginning of the 1980s. The surface warming depends on elevation and its horizontal pattern is consistent with the one of the glacier change. Accompanying the warming was air moistening, and both facilitated the trigger of more deep-clouds, which resulted in solar dimming. Surface wind speed declined from the 1970s, as a result of atmospheric circulation adjustment caused by the differential surface warming between the Asian high-latitude and low-latitude. The climate changes had weakened the thermal forcing over the TP. The warming and wind stilling lowered the Bowen ratio and led to less surface sensible heating. Atmospheric radiative cooling was enhanced, mainly by outgoing longwave emission from the warming planetary system and slightly by solar radiation reflection. Both processes contributed to the thermal forcing weakening over the Plateau. The water cycle was also altered by the climate changes. The wind stilling may have weakened water vapor exchange between the Asia monsoon region and the Plateau and thus led to less precipitation in the monsoon-impacted southern and eastern Plateau, but the warming enhanced land evaporation. Their overlap resulted in runoff reduction in the southern and eastern Plateau regions. By contrast, more convective precipitation over the central TP was triggered under the warmer and moister condition and yielded more runoff; meanwhile, the solar dimming weakened lake evaporation. The two together with enhanced glacier melts contributed to the lake expansion in the central TP. [Copyright &y& Elsevier]