The characteristics of the Madden–Julian oscillation (MJO) have changed and are projected to continue changing with the expansion of the Indo–Pacific warm pool, which is the Earth's largest region of ...warm sea surface temperatures (SSTs). However, the likelihood of a change in MJO predictability following warm pool expansion remains unaddressed. Therefore, this study investigated the effect of warm pool expansion on MJO variability and predictability using the highly idealized aquaplanet configuration of Community Earth System Model 2 (CESM2). By expanding the warm pool in the Indo–Pacific, MJO‐like waves become more regionally confined, short‐lived convective events with weaker magnitude and less robust eastward propagating signals, possibly due to stronger zonal SST gradients and wider meridional widths of the warm pool. Perfect‐model ensemble forecast experiments revealed that the MJO predictability decreased by approximately 5 days, the forecast error proliferated, and the signal rapidly reduced following warm pool expansion.
Plain Language Summary
The Madden–Julian oscillation (MJO) is a prominent mode of tropical intra‐seasonal variability in which its convective anomalies drive anomalous circulation within the tropics and remotely in the extratropics, thus providing a “forecast of opportunity” for global weather and climate events. Over the decades, MJO characteristics have changed and are projected to continue changing with the expansion of the Indo–Pacific warm pool—the largest pool with the warmest ocean temperature on Earth. If warm pool expansion changes the MJO characteristics, it is likely that its predictability has changed and will continue to do so in the future. In this study, the change in MJO predictability by expanding the Indo–Pacific warm pool was explored using CESM2 aquaplanet model experiments. The results show that, with warm pool expansion, MJO predictability decreased by approximately 5 days. This decrease is primarily attributed to the change of the MJO‐like waves into more regionally confined, short‐lived convective events with weaker magnitude and less robust eastward propagating signals, owing to the change in SST and circulations.
Key Points
A sensitivity experiment was performed using Community Earth System Model 2 aquaplanet with different prescribed sea surface temperatures
Expanding the Indo–Pacific warm pool makes the Madden–Julian oscillation‐like waves less organized
The warm pool expansion quickens the forecast error increase and predictability decrease
There has been an accelerating interest in forecasting the weather and climate within the subseasonal time range. The Madden–Julian oscillation (MJO), an organized envelope of tropical convection, is ...recognized as one of the leading sources of subseasonal predictability. This review synthesizes the latest progress regarding the MJO predictability and prediction. During the past decade, the MJO prediction skill in dynamical prediction systems has exceeded the skill of empirical predictions. Such improvement has been mainly attributed to more observations and computer resources, advances in theoretical understanding, and improved numerical models aided in part by multinational efforts through field campaigns and multimodel experiments. The state-of-the-art dynamical forecasts have shown MJO prediction skill up to 5 weeks. Prediction skill can be extended by improving the ensemble generation approach tailored for MJO prediction and by averaging multiensembles or multimodels. MJO prediction skill can be influenced by the tropical mean state and low-frequency climate mode variations, as well as by the extratropical circulation. MJO prediction skill is proven to be sensitive to model physics, ocean–atmosphere coupling, and quality of initial conditions, while the impact of the model resolution seems to be marginal. Remaining challenges and recommendations on new research avenues to fully realize the predictability of the MJO are discussed.
This study aims to assess handgrip strength as a predictor of cognitive decline within men and women in Korea. A random-intercept logistic regression is fit to estimate the status changes in ...cognitive function throughout all rounds of the KLoSA, a nationally-representative survey of adults aged 45 years and older. Males in the highest quartile were 71.9% less likely to experience cognitive impairment than those in the lowest quartile. The odds of cognitive impairment for men in the third and second quartiles reduced by 62.6% and 60.4% respectively. Similarly, the odds of cognitive impairment for women declined as 72.7%, 63.0%, and 41.8% for fourth, third, and second quartile, respectively, compared with the lowest quartile. These results imply that assessing and monitoring handgrip strength may enable us to identify subgroups of the elderly with higher likelihood of cognitive impairment in Korea.
The accurate analysis of breast imaging is important because it has been reported that an increase in breast density of only 1% results in a 2% increase in the relative risk of breast cancer. The ...proteins, water, and lipids that determine breast density are important biomarkers in the diagnosis of breast cancer. In mammography, photon-counting detectors (PCDs) with energy-discrimination capabilities can cause errors in the measurement of chemical composition when the attenuation coefficient is small. This is typically the case with proteins, water, and lipids because of the low photon efficiency in each bin. In this study, a dual-energy technique for PCDs was developed based on a non-local means denoising technique for accurate material decomposition and the quantification of protein, water, and lipid content. To evaluate the proposed material decomposition algorithm, spectral images were acquired with a modeled PCD using the Geant4 Application for Tomographic Emission (GATE) version 6.0. Linear, quadratic, and rational models were used for three-material decomposition based on the spectral images acquired using the PCD. The proposed algorithm yielded the best results for the estimation of breast density, composed of three materials. It was determined that the developed approach improved the accuracy of three-material decomposition using a PCD with energy-discrimination capabilities. The presented material decomposition algorithm has the potential to improve the diagnostic accuracy of breast cancer detection based on the quantitative measurement of breast density using PCDs.
Song-level feature summarization is fundamental for the browsing, retrieval, and indexing of digital music archives. This study proposes a deep neural network model, CQTXNet, for extracting ...song-level feature summary for cover song identification. CQTXNet incorporates depth-wise separable convolution, residual network connections, and attention models to extend previous approaches. An experimental evaluation of the proposed CQTXNet was performed on two publicly available cover song datasets by varying the number of network layers and the type of attention modules.
We investigate how the Madden‐Julian Oscillation (MJO), the dominant mode of tropical subseasonal variability, modulates the lifecycle of cool‐season North Pacific atmospheric rivers (ARs). When the ...enhanced (suppressed) convection center is located over the Indian Ocean (western Pacific), more AR events originate over eastern Asia and with fewer over the subtropical northern Pacific. When the enhanced (suppressed) convection is over the western Pacific (Indian Ocean), the opposite changes occur, with more AR events originate over the subtropical northern Pacific and fewer over eastern Asia. Dynamical processes involving anomalous MJO wind and seasonal mean moisture are found to be the dominant factors impacting these variations in AR origins. The MJO‐related anomalous geopotential height patterns are also shown to modulate the propagation of the AR events. These MJO–AR lifecycle relationships are further supported by model simulations.
Plain Language Summary
Atmospheric rivers (ARs) are strong moisture transport events that convey water vapor from the tropics to high latitudes. Precipitation generated from landfalling ARs is important freshwater sources to coastal regions like the west coast of North America. Here, we investigate the connections between the lifecycle of North Pacific ARs and the Madden‐Julian Oscillation (MJO), which is the most dominant form of tropical subseasonal variability. Results indicate that the MJO can affect the whole lifecycle of ARs including the origin, propagation, and termination. ARs are more active during certain MJO phases, which can be explained by the changes in wind and geopotential height associated with the evolution and propagation of the MJO. These findings may help to better predict AR activity and understand how ARs will change in the future.
Key Points
The Madden‐Julian Oscillation significantly influences the number, lifetime, and propagation of North Pacific atmospheric rivers (ARs)
More ARs with longer lifetime occur over the subtropical North Pacific when enhanced convection is over the western Pacific
Dynamical processes are the dominant factors in the modulation of ARs by the Madden‐Julian Oscillation
Abstract
Future changes in boreal winter MJO teleconnections over the Pacific–North America (PNA) region are examined in 15 Coupled Model Intercomparison Project phase 6 models (CMIP6s) under SSP585 ...(i.e., Shared Socioeconomic Pathway 5 following approximately the representative concentration pathway RCP8.5) scenarios. The most robust and significant change is an eastward extension (∼4° eastward for the multimodel mean) of MJO teleconnections in the North Pacific. Other projected changes in MJO teleconnections include a northward extension, more consistent patterns between different MJO events, stronger amplitude, and shorter persistence; however, these changes are more uncertain and less significant with a large intra- and intermodel spread. Mechanisms of the eastward teleconnection extension are investigated by comparing impacts of the future MJO and basic state changes on the anomalous Rossby wave source (RWS) and teleconnection pathways with a linear baroclinic model (LBM). The eastward extended jet in the future plays a more important role than the eastward-extended MJO in influencing the east–west position of MJO teleconnections. It leads to more eastward teleconnection propagation along the jet due to the eastward extension of turning latitudes before they propagate into North America. MJO teleconnections thus are positioned 2.9° more eastward in the North Pacific in the LBM. The eastward extended MJO, on the other hand, helps to generate a more eastward-extended RWS. However, negligible change is found in the east–west position of MJO teleconnections (only 0.3° more eastward in the LBM) excited from this RWS without the jet impacts. The above results suggest the dominant role of the jet change in influencing future MJO teleconnection position by altering their propagation pathways.
In an assessment of 29 global climate models (GCMs), Part I of this study identified biases in boreal winter MJO teleconnections in anomalous 500-hPa geopotential height over the Pacific–North ...America (PNA) region that are common to many models: an eastward shift, a longer persistence, and a larger amplitude. In Part II, we explore the relationships of the teleconnection metrics developed in Part I with several existing and newly developed MJO and basic state (the mean subtropical westerly jet) metrics. The MJO and basic state diagnostics indicate that the MJO is generally weaker and less coherent and propagates faster in models compared to observations. The mean subtropical jet also exhibits notable biases such as too strong amplitude, excessive eastward extension, or southward shift. The following relationships are found to be robust among the models: 1) models with a faster MJO propagation tend to produce weaker teleconnections; 2) models with a less coherent eastward MJO propagation tend to simulate more persistent MJO teleconnections; 3) models with a stronger westerly jet produce stronger and eastward shifted MJO teleconnections; 4) models with an eastward extended jet produce an eastward shift in MJO teleconnections; and 5) models with a southward shifted jet produce stronger MJO teleconnections. The results are supported by linear baroclinic model experiments. Our results suggest that the larger amplitude and eastward shift biases in GCM MJO teleconnections can be attributed to the biases in the westerly jet, and that the longer persistence bias is likely due to the lack of coherent eastward MJO propagation.
With an increase in the number of Green Standard for Energy and Environmental Design (G-SEED)-certified apartments in South Korea, people are receiving incentives from the government to purchase ...them. Since 2013, many benefits for G-SEED-certified buildings have been offered, such as tax reductions and deregulation of building codes/guidelines. As beneficial incentives are granted to G-SEED-certified buildings, follow-up management of the buildings is also necessary. However, to date, there are no appropriate follow-up management systems or legal regulations for G-SEED-certified buildings. Buildings that are certified by G-SEED in Korean housing buildings account for 6.25% of Korea’s total area. In addition, G-SEED certification has been obtained for more than 20% of the total completed housing area (2014–2017). Therefore, the energy efficiency-management of G-SEED certified buildings is also very important economically for reducing greenhouse gas emissions. In this study, domestic and foreign energy efficiency follow-up management systems were analyzed, and the amount of energy that is used by apartment houses with incentives was investigated. We have identified problems with the G-SEED system by analyzing evaluation methods, evaluation items, and points of G-SEED certification in related research studies. We also compared the energy consumption of an apartment building with G-SEED certification with that of adjacent complexes, thereby applying original research methods. The results show that energy use in G-SEED-certified buildings was not efficient. Accordingly, the study confirms that continuous management after G-SEED certification by establishing a follow-up management system is needed. In this study, domestic and foreign follow-up management systems were compared, problems with the apartment housing information management system run by the government were examined, and improvement measures were suggested.
Many climate models struggle with a poor simulation of the Madden‐Julian Oscillation (MJO), especially its propagation across the Maritime Continent (MC). This study quantitatively evaluates the ...robustness of MJO propagation over the MC in climate models that participated in Coupled Model Intercomparison Project Phase 5 (CMIP5) and Phase 6 (CMIP6) with a newly developed MC propagation metric. The results show that the CMIP6 models simulate MJO propagation over the MC more realistically than the CMIP5 models. Lower free‐tropospheric moisture budget analysis highlights that the greater horizontal moisture advection is responsible for the enhanced MJO propagation over the MC. The increase in horizontal moisture advection in the CMIP6 models is mainly attributed to the steeper horizontal mean state moisture gradient around the MC, which is associated with the reduction of the equatorial dry bias.
Plain Language Summary
The Madden‐Julian Oscillation (MJO), planetary‐scale eastward propagating tropical convective cloud clusters coupled with large‐scale circulation, is the dominant mode of intraseasonal variability in the tropics and thereby influences a wide range of weather and climate phenomena. Unfortunately, however, many contemporary climate models struggle to simulate a realistic MJO propagation across the Maritime Continent, and this common bias had persisted over the previous generations of the Coupled Model Intercomparison Project (CMIP). We show that, in the newly released CMIP Phase 6 (CMIP6) models, the simulation of the MJO propagation is significantly improved when compared to their predecessors—CMIP Phase 5 (CMIP5) models. The improvement in the MJO simulation is mainly due to the reduction of the dry bias that many CMIP5 models exhibit over the Indo‐Pacific Warm Pool region.
Key Points
A metric indicating the robustness of MJO propagation across the MC is developed and applied to 30 CMIP5 and 34 CMIP6 models
CMIP6 models represent MJO propagation over the MC more realistically than the CMIP5 models
The improvement in MJO propagation is due to the steepening of the mean state moisture gradient around the MC
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