To reduce the uncertainty of cloud feedback, models should prioritize the evaluation of cloud response to surface warming. Using International Satellite Cloud Climatology Project‐H data sets, we ...quantified the cloud fraction response of different cloud types to surface warming in the Tibetan Plateau (TP) and examined the performance of Coupled Model Intercomparison Project Phase 6 models in reproducing cloud response. Results showed multimodel ensemble mean (MEM) exhibited a similar pattern of total cloud fraction response with the observation but severely underestimated it over the western TP. MEM also obviously underestimated cloud fraction of optically thin cirrus (bias >15%) and had a wrong trend of −0.02% 10a−1 against observed +2.44% 10a−1. Moreover, models failed to reproduce extensive negative response of optically thick clouds and exhibited significant underestimation for the negative response of optically thick but lower‐top clouds. Especially, models even simulated an opposite response with International Satellite Cloud Climatology Project for optically thin but lower‐top cloud (bias hit −0.4% K−1).
Plain Language Summary
To reduce the uncertainty in cloud feedback, knowledge about the response of cloud fraction (as the first‐order variable impacting downwelling shortwave radiation flux) to the surface warming is an important yet poorly understood process, especially over the Tibetan Plateau (TP). This study utilized 31 years of cloud top pressure (PC)‐cloud optical thickness (PC‐τ) histograms from the International Satellite Cloud Climatology Project‐H data set to characterize cloud fraction response for different cloud types and comprehensively evaluate the performance of Coupled Model Intercomparison Project Phase 6 models in reproducing cloud response over the TP. Although multimodel ensemble mean (MEM) showed similar distribution of total cloud fraction response with observation, cloud response over the western TP was significantly underestimated. For the most frequent but less simulated optically thin high cirrus, the MEM produced consistent cloud response with the observation mainly due to the offsetting effect of regional cloud response bias. In addition, we found that optically thick but lower‐top clouds (or thin high cirrus) significantly declined (or increased) with surface warming, especially under an unstable state. Nonetheless, MEM significantly underestimated an extensive negative cloud response of optically thick clouds, especially at low‐level atmosphere. These new insights will help models reduce the uncertainty in future climate projections caused by cloud feedback.
Key Points
Even if biases are partly offset, Coupled Model Intercomparison Project Phase 6 models still obviously underestimate total cloud fraction response in the western Tibetan Plateau
For more frequent but less simulated thin cirrus, models show consistent response with the observation mainly due to offsetting of the regional bias
Models severely underestimate the negative response of low‐level thick clouds and invert the positive response of low‐level thin clouds
Intermodel compensation between cloud feedback and rapid cloud adjustment has important implications for the range of model-inferred climate sensitivity. Although this negative intermodel correlation ...exists in both realistic (e.g., coupled ocean–atmosphere models) and idealized (e.g., aqua-planet) model configurations, the compensation appears to be stronger in the latter. The cause of the compensation between feedback and adjustment, and its dependence on model configuration remain poorly understood. In this study, we examine the characteristics of the cloud feedback and adjustment in model simulations with differing complexity, and analyze the causes responsible for their compensation. We show that in all model configurations, the intermodel compensation between cloud feedback and cloud adjustment largely results from offsetting changes in marine boundary-layer clouds. The greater prevalence of these cloud types in aqua-planet models is a likely contributor to the larger correlation between feedback and adjustment in those configurations. It is also shown that differing circulation changes in the aqua-planet configuration of some models act to amplify the intermodel range and sensitivity of the cloud radiative response by about a factor of 2.
Abstract
The construction industry is the fourth pillar industry in the development of the national economy. In recent years, with the growth of the macro economy, it has also developed rapidly. ...Because the urbanization develops rapidly, the scale of project construction is getting bigger and bigger, and the quality requirements are getting higher and higher, many problems in the field of construction engineering have gradually exposed. Due to limitations in all aspects, many regulations and systems cannot be systematically and effectively implemented. At the same time, the current domestic and foreign project supervision mostly stay in the “result monitoring”, it cannot achieve the “process monitoring”. At present, the most important topic is to control the progress of the project. The main investors of the project should take early measures to prevent it effectively, in this way, we can ensure the quality of the project and the safety of funds.
Cloud computing is constantly evolving with innovations. So, the cloud service providers are investing big in finding solutions for the challenges confronted by the business organizations in the ...ever-changing technological world. However, still, there is a little reluctance among the organizations to ultimately adopt the public cloud because the mission-critical applications and the mission-critical data require high-level security and availability which are questionable in the equally growing hacking technology. The hacker's comfort zone is Internet, and the Internet is the primary medium for communication between enterprises and cloud service providers. So, the cloud service providers come up with a solution called Direct-Cloud which bypasses the internet and establishes a private connection between the enterprise and cloud service provider. The primary objective of this paper is to familiarize the terminology direct-cloud as it makes a massive move in Cloud Computing. So, this paper presents a study that describes direct-cloud, its architecture, benefits, the comparison between different direct-cloud solutions and the guidelines to choose a suitable direct-cloud solution. Also, the terminologies Multi-Cloud and ConnectedCloud are gaining attention among the enterprises to meet the growing needs of the business. Hence the paper further explores the direct-cloud deployment in the multi-cloud and connected-cloud environment
Cloud phase identification is a critical aspect of cloud microphysical characteristics research, pivotal for climate studies, weather forecasting, and validation of climate models. Traditional ...methods, employing polarization lidar and millimeter cloud radar (MMCR), often rely on simplistic threshold algorithms, leading to low classification accuracy and reliability. This letter introduces a refined cloud phase recognition technique based on an optimized random forest (RF) model, addressing the nuanced identification challenges of cloud phases. The approach involves optimizing the decision trees and the number of randomly selected features within the RF model using the African vulture optimization algorithm (AVOA) to achieve near-optimal classification performance and improve accuracy to 88.10%. The proposed method has been validated and assessed using actual measurement data and compared with results from multiple data sources, including polarization lidar, MMCR, and atmospheric temperature, demonstrating high consistency.
Previous studies on convective precipitation forecasting in South China have focused on the effects of multiscale dynamics and microphysics parameterizations. However, limited investigation has been ...conducted on how uncertainty in aerosol data might cause errors in quantitative precipitation forecast for South China's coastal convection. In this case study, we evaluated the impact of aerosol uncertainties on South China's severe coastal convection using convection‐permitting simulations. We estimated the variability range of aerosol concentrations with observations for the pre‐summer months. The simulation results suggest that the rainfall pattern and intensity change notably when aerosol concentrations are varied. Decreasing the concentration of water‐friendly (WF) aerosols intensifies precipitation through reduced cloud water number concentration and increased droplet size. Increasing the concentration of ice‐friendly (IF) aerosols results in up to 40% increase in vertical velocity and latent heat compared to minimal IF aerosol condition, by enhancing the heterogeneous process and dynamically intensifying convection. Consequently, the simulation with minimal WF and maximal IF aerosol concentrations shows prolonged intense precipitation over the entire life cycle of convection. However, when both WF and IF aerosols are set to minimal concentrations, the simulation produces the maximum peak rainfall rate, which is about 50% stronger than the simulation with the climatological mean concentration, due to an enhanced homogeneous process that results in a higher ice concentration and more efficient ice‐phase precipitation growth. Meanwhile, variation in aerosol concentration affects convection initiation (CI), with a lower concentration of WF aerosol inducing earlier CI onset. Decreasing hygroscopicity leads to higher precipitation.
Plain Language Summary
Convective weather frequently happens in South China during the pre‐summer season with limited forecast skills. Previous studies have investigated the impact of large‐scale circulation, water vapor conditions, and complex topography in forming convective precipitation systems. However, how chemistry interacts with weather dynamics has limited investigation in the context of convective weather in South China's coastal area. Aerosols can serve as cloud condensation nuclei (CCN) and ice nuclei (IN), and their concentration or property variation can affect various processes in cloud and precipitation formation. To estimate the impact of aerosol uncertainty on South China's pre‐summer rainfall, we conducted simulations of a severe convection case with different aerosol concentrations and properties. We found that the typical aerosol concentration and property variability changed the convective system notably, which further influenced the rainfall pattern and intensity. The aerosols invigorate convection when they cause more latent heating or shift the vertical heating distribution upward, for instance, decreasing the water‐friendly aerosol or increasing the ice‐friendly aerosol can enhance the convection. This work contributes to understanding the aerosol effects of different kinds of aerosols on convection initiation, and precipitation intensity and suggests the potential benefits of increasing aerosol observations in the future to improve the operational numerical forecast.
Key Points
Deceasing water‐friendly (WF) aerosol generates more precipitation, and increasing ice‐friendly (IF) aerosol enhances precipitation intensity
Deceasing WF aerosol triggers early convection initiation while increasing IF aerosol results in stronger initiation
Nonlinear relationship exists between the aerosol concentration and convection intensity
This paper proposes a secure inter-cloud authorization scheme using ciphertext-policy attribute-based encryption (CP-ABE). The proposed scheme enables data owners to access files which are stored in ...cloud storage servers, managed by a service provider, using web applications which may be registered with another service provider. To access the stored files using a web application, the data owner can issue one time access tokens. For issuing the access tokens, the data owner does not need collaboration with any other entities in the cloud environments. In addition, single access token can be used to access several files, which reduces the number of required access tokens. Moreover, ciphertext re-encryption is performed to prevent unauthorized access. The re-encryption is delegated to a cloud storage service provider to reduce overhead on the data owner side. The security analysis of the proposed scheme has been done under the Decisional Bilinear Diffie–Hellman assumption and it is proven to be secure against Chosen Plaintext Attack. Moreover, performance analysis of the proposed scheme shows that it incurs low overhead in terms of communication and storage and it takes minimum delay and computation costs while providing better functionality.
•An inter-cloud authorization scheme is proposed for secure file sharing.•Data owners can control scalability in file sharing based on his discretion.•The scheme employs a ciphertext re-encryption phase to prevent unauthorized access.•The proposed scheme is provably secure against Chosen Plaintext Attack.
Cloud technologies are currently experiencing a remarkable degree of pervasiveness in most of the applications and services that are consumed daily by both individual users and companies. The sheer ...volume of sensitive data and operations that are regularly outsourced to the cloud calls for the adoption of adequate measures to fulfill the existing security requirements and to increase the trust into cloud providers.
The papers included in this special issue address a variety of concerns related to the development of secure, reliable, and trusted cloud applications, including: enforcement of specific security mechanisms (e.g., to protect shared data), integrity verification of virtualized environments, and selection of the most appropriate cloud services/resources for application deployment.
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