The Tibetan Plateau (TP) has experienced accelerated warming in recent decades, especially in winter. However, a comprehensive quantitative study of its long-term warming processes during daytime and nighttime is lacking. This study quantifies the different processes driving the acceleration of winter daytime and nighttime warming over the TP during 1961-2022 using surface energy budget analysis. The results show that the surface warming over the TP is mainly controlled by two processes: (a) a decrease in snow cover leading to a decrease in albedo and an increase in net downward shortwave radiation (snow-albedo feedback), and (b) a warming in tropospheric temperature (850 - 200 hPa) leading to an increase in downward longwave radiation (air warming-longwave radiation effect). The latter has a greater impact on the spatial distribution of warming than the former, and both factors jointly influence the elevation dependent warming pattern. Snow-albedo feedback is the primary factor in daytime warming over the monsoon region, contributing to about 59% of the simulated warming trend. In contrast, nighttime warming over the monsoon region and daytime/nighttime warming in the westerly region are primarily caused by the air warming-longwave radiation effect, contributing up to 67% of the simulated warming trend. The trend in the near-surface temperature mirrors that of the surface temperature, and the same process can explain changes in both. However, there are some differences: an increase in sensible heat flux is driven by a rise in the ground-atmosphere temperature difference. The increase in latent heat flux is associated with enhanced evaporation due to increased soil temperature and is also controlled by soil moisture. Both of these processes regulate the temperature difference between ground and near-surface atmosphere.

Alpine meadows are vital ecosystems on the Qinghai-Tibet Plateau, significantly contributing to water conservation and climate regulation. This study examines the energy flux patterns and their driving factors in the alpine meadows of the Qilian Mountains, focusing on how the meteorological variables of net radiation (Rn), air temperature, vapor pressure deficit (VPD), wind speed (U), and soil water content (SWC) influence sensible heat flux (H) and latent heat flux (LE). Using the Bowen ratio energy balance method, we monitored energy changes during the growing and non-growing seasons from 2022 to 2023. The annual average daily Rn was 85.29 W m-2, with H, LE, and G accounting for 0.56, 0.71, and -0.32 of Rn, respectively. Results show that Rn is the main driver of both H and LE, highlighting its crucial role in turbulent flux variations. Additionally, a negative correlation was found between air temperature and H, suggesting that high temperatures may suppress H. A significant positive correlation was observed between soil moisture and LE, further indicating that moist soil conditions enhance LE. In conclusion, this study demonstrates the impact of climate change on energy distribution in alpine meadows and calls for further research on the ecosystem's dynamic responses to changing climate conditions.

Atmospheric aerosols are essential constituents of the atmosphere and also interact with radiation and clouds. Substantial progress has been made since the industrial era majorly for observing, understanding, and modeling processes and these research efforts have helped to identify how aerosol optical properties have contributed to radiative forcing that influence regional and global climate. Research findings have also helped to quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols as well as various other ways aerosol has contributed to global warming both at the regional and global scale. Several aerosol inventories have been developed to quantify different aerosol species including the emission, life span, sizes, and transportation from one region to another and as well as the influence of the surrounding environment on aerosol characteristics. In recent times new metrics have been developed for adequate measurements to quantifying aerosol radiation and cloud interaction including Aerosol Instantaneous Radiative Forcing (IRF) which is the changes that occur in the Earth's energy balance due to the direct interaction of aerosols with incoming solar or outgoing infrared radiation and can lead to warming or cooling of the atmosphere, depending on the aerosol type (e.g., sulfate aerosols cause cooling). Rapid adjustment also referred to as a swift in atmospheric response to changes in radiative forcing, including adjustments in temperature, humidity, and cloud cover. It occurs almost immediately, influencing local and regional climate conditions alongside aerosol or greenhouse gas emissions. On the other hand, after taking into consideration quick corrections and feedbacks, the Effective Radiative Forcing (ERF) represents the net change in Earth's energy balance. By recording both short- and long-term feedbacks, it offers a more thorough knowledge of the total impact of aerosols or other agents on climate. These metrics are employed to precisely estimate net radiation perturbation, even though the actual measurement values of these three recently developed metrics continue to fluctuate inexplicably throughout the regions. This review provides information on various aspects of aerosol properties especially those that are related to radiation, cloud interaction, and extreme events. The new paradigm shifts to a modeling approach, theoretical considerations, and finetuned observational methodology are essential tools to be considered. Scattering and absorption of aerosol show different mechanisms involved when aerosols interact with short and long-wave radiation but aerosol absorption ability might not only be limited to certain aerosol species as entailed in research consensus and these might be one of the major constraints of surface radiative fluxes from aerosol-radiation interactions. The influence of anthropogenic aerosols on cloud liquid water content and cloud fraction was also considered and it has been discovered that these complex processes are less clear, and the influence on mixed-phase and ice clouds remains to be well understood. Observed changes in surface temperature increase due to radiation perturbation and the radiative fluxes both at the Top of the Atmosphere and at the surface are the major driving force for global warming and also impacts weather and climate extreme events. It is also very important to measure with high sense of accuracy the changes in the surface temperature. The degree of aerosol-induced warming on global circulation as the major carrier of moisture for precipitation processes is yet to be fully explored. The extreme events associated with flood events and as well as drought associated with extreme temperature and heat waves are key areas for current and future research. In summary, if we must consider importance and the usage of the three invented metrics for accurate and scientific quantification over the traditional Direct and Indirect aerosol radiative forcing then there is a need for proper understanding and a better research approach to allay the fear of uncertainty in this regard. The application of new technological tools and as well as new parametrization schemes development that express micro aerosol-climate interaction and processes that are smaller and cannot be resolved or captured explicitly on regional and global scales are important factors to be considered.

Solar radiation balances significantly affect Earth's surface energy balance and climate change. Studying top-of-the-atmosphere (TOA) albedo changes is of great significance for understanding Earth's energy budget and atmospheric circulation. The Loess Plateau (LP), located in the middle reaches of the Yellow River in China, is one of the most severely eroded areas in the world. In this paper, long-term remote sensing data were used to analyze the changes in the TOA albedo in the LP from 1982 to 2016. The results showed that the TOA albedo, its atmospheric contribution (AC), and surface contribution (SC) exhibited decreasing trends: -0.0012, -0.0010, and -0.0003 a-1. The spatial pattern of the TOA albedo was similar to AC, which indicates that AC dominates the change in the TOA albedo. We detected driving factors for AC and SC and found that the cloud fraction (CF) was the main driving factor of the AC, whereas the soil moisture (SM) dominated the SC. The driving factors of two typical regions with a significantly decreasing trend in the TOA albedo were also detected. The Mu Us Desert, where vegetation improved significantly, showed a decreasing trend in the TOA albedo, and we found that NDVI was the main driving factor for the change in the SC of the TOA albedo. However, the Eastern Qilian Mountains, where snow cover decreased in recent years, also showed a significant decreasing trend in the TOA albedo; the SC here was mainly driven by the changes in snow cover days (SCD). These results indicate that changes in the surface environment alter the radiation balance. SIGNIFICANCE STATEMENT: The Loess Plateau in China is one of the most severe cases of soil erosion in the world, and ecological restoration projects have been carried out to recover the fragile ecological environment. Our study was designed to explore changes in the top-of-the-atmosphere (TOA) albedo of the Loess Plateau between 1982 and 2016 using a long time series of multisource satellite products, and driving factors in the atmosphere and at the surface were analyzed. We concluded that the TOA albedo of the Loess Plateau decreased over 35 years, and its atmospheric contribution dominated the change in the TOA albedo. However, the significant ecological improvement in the Loess Plateau, especially in the central vegetation recovery region, such as the Mu Us Desert, was also strongly related to the regional changes in the surface contribution of the TOA albedo. The climate changes had a considerable impact on the eastern branch of the Qilian Mountains in the Qinghai region, where the decline in snow cover days affected the local Alpine meadow ecosystems; therefore, snow cover days also played a decisive role in the local variation of the surface contribution of the TOA albedo.

Biomass burning (BB) greatly impacts the Maritime Continent through various mechanisms including agricultural burning, land clearing and natural response to drought. The dynamic characteristics of BB in terms of its spatiotemporal distribution, seasonality, transport mechanism, and aerosol properties have prompted numerous research efforts including field campaigns, in -situ measurements, remote sensing, and modelling. Although the differing perspectives of these studies have offered insights on understanding the regional BB issues, it is challenging to compare and resolve the wider picture because of the diversity of approaches. Human -induced global warming has certainly caused multiple observed changes in the regional meteorological characteristics. In this study, we review BB events in the Maritime Continent from 2012 to 2021, focusing on the meteorological influence and knowledge evolution in cloud -aerosol -radiation (CAR). Unlike other reviews, our review examines the occurrence of BB events using synergistic application of ground -based measurement, global reanalysis model and satellite product, which allows us to examine the anomalies for comparison with other studies and identify the unique features of the event. We identified four dominant modes of variability responsible for the occurrence of large-scale BB in the Maritime Continent: (1) El Nin similar to o Southern Oscillations (ENSO), (2) extreme positiveIndian Ocean Dipole (pIOD), (3) tropical cyclone (TC) activity, and (4) Madden -Julian Oscillations (MJO). We reconcile the past CAR studies and summarize their findings based on the four key CAR mechanisms: (1) instantanous radiative forcing from aerosol -radiation interactions, IRFari (2) and its subsequent adjustments, SAari, (3) instantanous radiative forcing from aerosol -cloud interactions, IRFaci, and (4) and its subsequent adjustments, SAaci. We urge future CAR studies in the Maritime Continent should focus on accurate characterization of the composition of biomass burning plume which is a mixture of peatland, agricultural burning and anthropogenic sources.

Scientific innovation is overturning conventional paradigms of forest, water, and energy cycle interactions. This has implications for our understanding of the principal causal pathways by which tree, forest, and vegetation cover (TFVC) influence local and global warming/cooling. Many identify surface albedo and carbon sequestration as the principal causal pathways by which TFVC affects global warming/cooling. Moving toward the outer latitudes, in particular, where snow cover is more important, surface albedo effects are perceived to overpower carbon sequestration. By raising surface albedo, deforestation is thus predicted to lead to surface cooling, while increasing forest cover is assumed to result in warming. Observational data, however, generally support the opposite conclusion, suggesting surface albedo is poorly understood. Most accept that surface temperatures are influenced by the interplay of surface albedo, incoming shortwave (SW) radiation, and the partitioning of the remaining, post-albedo, SW radiation into latent and sensible heat. However, the extent to which the avoidance of sensible heat formation is first and foremost mediated by the presence (absence) of water and TFVC is not well understood. TFVC both mediates the availability of water on the land surface and drives the potential for latent heat production (evapotranspiration, ET). While latent heat is more directly linked to local than global cooling/warming, it is driven by photosynthesis and carbon sequestration and powers additional cloud formation and top-of-cloud reflectivity, both of which drive global cooling. TFVC loss reduces water storage, precipitation recycling, and downwind rainfall potential, thus driving the reduction of both ET (latent heat) and cloud formation. By reducing latent heat, cloud formation, and precipitation, deforestation thus powers warming (sensible heat formation), which further diminishes TFVC growth (carbon sequestration). Large-scale tree and forest restoration could, therefore, contribute significantly to both global and surface temperature cooling through the principal causal pathways of carbon sequestration and cloud formation. We assess the cooling power of forest cover at both the local and global scales. Our differentiated approach based on the use of multiple diagnostic metrics suggests that surface albedo effects are typically overemphasized at the expense of top-of-cloud reflectivity. Our analysis suggests that carbon sequestration and top-of-cloud reflectivity are the principal drivers of the global cooling power of forests, while evapotranspiration moves energy from the surface into the atmosphere, thereby keeping sensible heat from forming on the land surface. While deforestation brings surface warming, wetland restoration and reforestation bring significant cooling, both at the local and the global scale.image

Aerosols are liquid and solid particles suspended in the atmosphere and have a broad size range; they can cool the Earth by scattering radiation back to space or warm the Earth by absorbing radiation directly. Since the industrial revolution, the loading of aerosols in the Earth's atmosphere has increased significantly, yielding modifications to the Earth's energy budget and further affecting the climate state. Aerosol direct radiative forcing (ADRF), defined as the difference in radiation with and without total or specific aerosols, is an important concept used to describe the direct impact of aerosols on radiation. Accurate quantification of ADRF is the premise for understanding and predicting the Earth's climate state. To improve the estimation and evaluation of ADRF, numerous researchers have dedicated their efforts to developing a series of observations and models in recent decades. However, due to the limited availability of wide spatial and high-precision observations of aerosol optical characteristics, as well as an insufficient model description of aerosol properties and physical and chemical processes, the ADRF uncertainty is still high. This paper first reviews the spatio-temporal distribution of aerosol optical depth (AOD), single scattering albedo (SSA) and corresponding ADRF by using observations and models. The aerosol optical properties and ADRF show distinct discrepancies among various regions due to the impact of anthropogenic emissions and meteorological and climate conditions. In regions with rapid economic development, such as India, AOD demonstrates a long-term increasing trend with higher average values. However, regions influenced by environmental protection policies, such as North America and Europe, show a long-term decreasing trend in AOD, accompanied by lower average values. Based on site observations, most of Europe, North America, Africa, and Asia exhibit a significant long-term increasing trend in SSA. However, in seasons with biomass burning or dust outbreaks, specific regions, such as southern and southwestern China in late autumn and early spring, and northern and northwestern China in spring, exhibit a reduction in SSA. In the future, with the global and regional emissions of aerosols and precursors declining, ADRF is expected to weaken, highlighting the warming effect of greenhouse gases. However, the ADRF trend is closely linked to the present development level and trajectory of each region. Second, we systematically summarize the impacts of the influential factors on the ADRF, considering the AOD, SSA, surface albedo (SA), solar zenith angle (SZA), asymmetry factor (ASY), relative altitude between aerosols and clouds, and relative altitude between different types of aerosols. Subsequently, we proceed to review the sensitivities of ADRF to different influential factors, as well as the contributions of these factors to the overall uncertainty of ADRF, which indicate that ADRF is more sensitive to AOD and SSA while SSA emerges as the most significant source of uncertainty in ADRF due to the larger errors associated with its measurement. It should be noted that the uncertainty caused by SA and ASY cannot be ignored in polluted regions. Finally, from the perspective of observations and models, a brief outlook on improving the accuracy of ADRF evaluation is provided. In the future, advanced observation technologies, such as multi-angle, hyperspectral, polarized remote sensing observations, and precise in-situ measurements, should be developed to obtain more accurate information about the aerosols and environment. Furthermore, we need to properly combine various observations and models, including Earth system models, to improve the simulation of aerosols and their precursors. With improved understanding of aerosol-radiation interactions and refining techniques in observations and model simulations, the evaluation of ADRF will be more accurate.

Seasonally frozen soil (SFS) is a critical component of the Cryosphere, and its heat-moisture-deformation characteristics during freeze-thaw processes greatly affect ecosystems, climate, and infrastructure stability. The influence of solar radiation and underlying surface colors on heat exchange between the atmosphere and soil, and SFS development, remains incompletely understood. A unidirectional freezing-thawing test system that considers solar radiation was developed. Subsequently, soil unidirectional freezing-thawing tests were conducted under varying solar radiation intensities and surface colors, and variations in heat flux, temperature, water content, and deformation were monitored. Finally, the effects of solar radiation and surface color on surface thermal response and soil heat-moisture-deformation behaviors were discussed. The results show that solar radiation and highabsorptivity surfaces can increase surface heat flux and convective heat flux, and linearly raise surface temperature. The small heat flux difference at night under different conditions indicates that soil ice-water phase change effectively stores solar energy, slowing down freezing depth development and delaying rapid and stable frost heave onset, ultimately reducing frost heave. Solar radiation causes a significant temperature increase during initial freezing and melting periods, yet its effect decreases notably in other freezing periods. Soil heatwater-deformation characteristics fluctuate due to solar radiation and diurnal soil freeze-thaw cycles exhibit cumulative water migration. Daily maximum solar radiation of 168 W/m(2) and 308 W/m(2) can cause heatmoisture fluctuations in SFS at depths of 6 cm and 11 cm, respectively. The research findings offer valuable insights into the formation, development, and use of solar radiation to mitigate frost heave in SFS.

Downward solar radiation (DSR) and air temperature (Ta) have significant influences on the thermal state of frozen ground. These parameters are also important forcing terms for physically based land surface models (LSMs). However, the quantitative influences of inaccuracies in DSR and Ta products on simulated frozen ground temperatures remain unclear. In this study, three DSR products (CMFD-SR, Tang-SR, and GLDAS-SR) and two Ta products (CMFD-Ta and GLDAS-Ta) were used to force an LSM model in an alpine watershed in Northwest China, to investigate the sensitivity of simulated ground temperatures to different DSR and Ta products. Compared to a control model (CTRL) forced by in situ observed DSR, ground temperatures simulated by the experimental model forced by GLDAS-SR are obviously decreased because GLDAS-SR is much lower than in situ observations. Instead, simulation results in models forced by CMFD-SR and Tang-SR are much closer to those of CTRL. Ta products led to significant errors in simulated ground temperatures. In conclusion, both CMFD-SR and Tang-SR could be used as good alternatives to in situ observed DSR for forcing a model, with acceptable errors in simulation results. However, more care need to be paid for models forced by Ta products instead of Ta observations, and conclusions should be carefully drawn.

In this work, we report the ongoing implementation of online-coupled aerosol-cloud microphysical-radiation interactions in the Brazilian global atmospheric model (BAM) and evaluate the initial results, using remote-sensing data for JFM 2014 and JAS 2019. Rather than developing a new aerosol model, which incurs significant overheads in terms of fundamental research and workforce, a simplified aerosol module from a preexisting global aerosol-chemistry-climate model is adopted. The aerosol module is based on a modal representation and comprises a suite of aerosol microphysical processes. Mass and number mixing ratios, along with dry and wet radii, are predicted for black carbon, particulate organic matter, secondary organic aerosols, sulfate, dust, and sea salt aerosols. The module is extended further to include physically based parameterization for aerosol activation, vertical mixing, ice nucleation, and radiative optical properties computations. The simulated spatial patterns of surface mass and number concentrations are similar to those of other studies. The global means of simulated shortwave and longwave cloud radiative forcing are comparable with observations with normalized mean biases <= 11% and <= 30%, respectively. Large positive bias in BAM control simulation is enhanced with the inclusion of aerosols, resulting in strong overprediction of cloud optical properties. Simulated aerosol optical depths over biomass burning regions are moderately comparable. A case study simulating an intense biomass burning episode in the Amazon is able to reproduce the transport of smoke plumes towards the southeast, thus showing a potential for improved forecasts subject to using near-real-time remote-sensing fire products and a fire emission model. Here, we rely completely on remote-sensing data for the present evaluation and restrain from comparing our results with previous results until a complete representation of the aerosol lifecycle is implemented. A further step is to incorporate dry deposition, in-cloud and below-cloud scavenging, sedimentation, the sulfur cycle, and the treatment of fires.