Western North Pacific Region Research Articles

Large-Scale State and Evolution of the Atmosphere and Ocean during PISTON 2018

AbstractThe Propagation of Intraseasonal Tropical Oscillations (PISTON) experiment conducted a field campaign in August–October 2018. The R/V Thomas G. Thompson made two cruises in the western North Pacific region north of Palau and east of the Philippines. Using select field observations and global observational and reanalysis datasets, this study describes the large-scale state and evolution of the atmosphere and ocean during these cruises. Intraseasonal variability was weak during the field program, except for a period of suppressed convection in October. Tropical cyclone activity, on the other hand, was strong. Variability at the ship location was characterized by periods of low-level easterly atmospheric flow with embedded westward propagating synoptic-scale atmospheric disturbances, punctuated by periods of strong low-level westerly winds that were both connected to the Asian monsoon westerlies and associated with tropical cyclones. In the most dramatic case, westerlies persisted for days during and after tropical cyclone Jebi had passed to the north of the ship. In these periods, the sea surface temperature was reduced by a couple of degrees by both wind mixing and net surface heat fluxes that were strongly (~200 W m−2) out of the ocean, due to both large latent heat flux and cloud shading associated with widespread deep convection. Underway conductivity–temperature transects showed dramatic cooling and deepening of the ocean mixed layer and erosion of the barrier layer after the passage of Typhoon Mangkhut due to entrainment of cooler water from below. Strong zonal currents observed over at least the upper 400 m were likely related to the generation and propagation of near-inertial currents.

Climatological Increased Precipitation from July to August in the Western North Pacific Region Simulated by CMIP6 Models

In this study, the climatological precipitation increase from July to August over the western North Pacific (WNP) region was investigated through observations and simulations in the Coupled Model Intercomparison Project Phase 6 (CMIP6), atmospheric model simulations and historical experiments. Firstly, observational analysis showed that the precipitation increase is associated with a decrease in the local sea surface temperature (SST), indicating that the precipitation increase is not driven by the change in SST. In addition, the pattern of precipitation increase is similar to the vertical motion change at 500-hPa, suggesting that the precipitation increase is related to the circulation change. Moisture budget analysis further confirmed this relation. In addition to the observational analysis, the outputs from 26 CMIP6 models were further evaluated. Compared with atmospheric model simulations, air–sea coupled models largely improve the simulation of the climatological precipitation increase from July to August. Furthermore, model simulations confirmed that the bias in the precipitation increase is intimately associated with the circulation change bias. Thus, two factors are responsible for the bias of the precipitation increase from July to August in climate models: air–sea coupling processes and the performance in vertical motion change.

Seasonal and Diurnal Variations in Cloud-Top Phase over the Western North Pacific during 2017–2019

The cloud-top-phase climatology over the western North Pacific (WNP) has received little attention. Using 3 years (2017–2019) of cloud-top-phase products from the Advanced Himawari Imager onboard the Japanese Himawari-8 satellite, this study examines the seasonal and diurnal variations in the cloud-top phase over the WNP. Results show that over the low- and mid-latitude maritime regions, ice (water) clouds occur more (less) frequently during boreal winter than summer. Water clouds are more likely to be related to moisture conditions in the lower troposphere than to the underlying sea surface temperature. Owing to the combined effects of moist air mass transport and ocean currents (topography), the WNP region east of Hokkaido (the Sichuan Basin) has a high frequency of water clouds in summer (winter). Furthermore, supercooled water cloud populations have a clear seasonal cycle. The fraction of water clouds that are supercooled appears to be modulated by the near-surface air temperature. A diurnal cycle is seen in ice-cloud populations, which are highest in the late afternoon over both ocean and land except for the Sichuan Basin where summer nocturnal precipitation is typical. The occurrences of continental water clouds peak at noon in summer but early morning (around sunrise) in winter. An increase in the frequency of continental summer water clouds around noon is found to be associated with variations in both the cloud-top elevation of already-existing water clouds and new formations of boundary-layer clouds.

The sea level variability and its projections over the Indo‐Pacific Ocean in CMIP5 models

The present study examines the representation of interannual and decadal variability of sea level over the Indo-Pacific region in the Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations and future projections. The thermocline ridge region of the Indian Ocean (TRIO) shows strong sea level variability on both the interannual and decadal timescales in the CMIP5 historical simulations. Meanwhile, prominent interannual variability is seen in the tropical western Pacific and central to eastern equatorial Pacific, whereas, the decadal sea level variability is dominant in the North Pacific and western Pacific regions. CMIP5 models project similar spatial patterns of sea level variability over the Indo-Pacific region for the twenty-first century under the mid-range and high future emission scenarios, although with some differences in the amplitude and inter-model disagreement. In the interannual timescale, there is a regional contrast in the projected future variability between the Pacific (with increase in variability with increasing greenhouse gas emissions) and TRIO (with decrease of ~ 6 % variability), which is evident in both RCP4.5 and RCP8.5 future emission scenarios with inter-model consensus. On the other hand, increase in decadal sea level variability (~ 6 % and ~ 8 % in RCP4.5 and RCP8.5 scenarios respectively) is projected over the North Pacific region (north of 30°N). In the Indian Ocean, increase in decadal sea level variability is projected over the northwestern region including Arabian Sea, though it is not a region of large decadal variability (in the reanalysis and historical simulations). Analysis revealed that the local wind forcing (wind stress curl) plays a dominant role in the sea level variability over the Indo-Pacific region on both interannual and decadal timescales.

The inter-annual variations of the significant wave height in the Western North Pacific and South China Sea region

The spatio-temporal variations of the significant wave height (SWH) in the Western North Pacific and South China Sea (WNP-SCS) region, as well as their driving mechanisms, are investigated based on the long-term (1981–2014) simulation by a coupled ocean–atmosphere model and a WAVEWATCH III model. The Empirical Orthogonal Function modes of SWH anomalies show different patterns in the cold and warm seasons. In winter, the first mode (explaining 40.63% of the variance) shows a monopole pattern with large loadings lying in SCS and the WNP to the east of the Philippine Islands, which is primarily associated with the El Nino-Southern Oscillation (ENSO) on inter-annual time scales. The second mode (explaining 19.62% of the variance) shows a dipole pattern with negative loadings in the northeastern SCS and positive loadings to the east of Japan, which is prominently connected with the intensity variation and longitudinal shift of Aleutian Low on decadal time scales. In summer, the first leading mode (explaining 73.47% of the variance) presents large loadings located mainly in the WNP region between 10° N and 30° N and secondarily in the central SCS, which is associated with the ENSO-affected tropical cyclone activities and South China Sea summer monsoon, respectively.

Evaluation and comparison of CMIP6 and CMIP5 model performance in simulating the seasonal extreme precipitation in the Western North Pacific and East Asia

This study evaluates the performance of the Coupled Model Intercomparison Project Phases 6 models (CMIP6) in simulating the seasonal evolution and extreme precipitation indices in the western North Pacific and East Asia region (WNP-EA), and compare the results with those from CMIP Phases 5 (CMIP5). In the ensemble of CMIP6 models, the seasonal evolution simulation demonstrates improvements in seasonal northward migration of the rain band from spring to summer and more intense precipitation, resulting in a higher skill score in the CMIP6 ensemble than the CMIP5 one. In general, the skill scores for the spatial pattern of simple daily intensity (SDII), total rainfall occurrence (Totfq), and consecutive dry days (CDD) are higher than those of extreme precipitation intensity (R99p). The CMIP6 ensemble mostly gains higher skill scores for extreme precipitation indices in the wet season. However, the improvement is limited in extreme indices during spring and fall. The probability distributions for maximum 1-day precipitation (RX1day), maximum 5-day precipitation (RX5day), and R99p in the CMIP6 models demonstrate a more realistic shape and stronger intensity, indicating the improvement over the CMIP5 models. However, the biased distributions of the overestimated (underestimated) occurrence for lighter (heavier) SDII and shorter (longer) duration CDD cases remain as a problem in CMIP6 model simulations. The higher skill scores for the spatial pattern of SDII, Totfq, and CDD are likely due to the compensation between the biased distributions mentioned above, implying further improvements are needed for correcting the deficiency in simulating the precipitation occurrence.

The recent increase in central eastern China summer rainfall and its possible mechanism

This study investigated interdecadal variations in summer rainfall in central eastern China before and after the mid-1990s. The mean difference in rainfall between the two epochs (average rainfall in the 1981–1995 period: 5.0 mm day−1; average rainfall in the 1996–2010 period: 6.0 mm day−1) was significant at the 95% confidence level. This study explored the cause of the recent increase in summer rainfall in central eastern China by analyzing the difference in average rainfall between 1996–2010 (hereafter, Epoch II) and 1981–1995 (hereafter, Epoch I). Analysis of rainfall revealed that positive anomalies were observed in a southwest–northeast direction across the south-central region of eastern China, Korea, and Japan, while negative anomalies were observed at latitudes of 40–50°N and in most areas in the western North Pacific region. These findings suggest that summer rainfall in central eastern China is part of East Asian summer monsoons and have an out-of-phase relationship with western North Pacific monsoons. To identify the cause of the recent increase in summer rainfall in central eastern China, the difference in 850 hPa stream functions between Epoch II and Epoch I was analyzed. This study found that anomalous huge anticyclonic circulations were strengthened in the western North Pacific region and anomalous cyclonic circulations were strengthened in the south-central region of eastern China. As a result, anomalous northeasterlies originating from anomalous cyclones centered on Lake Baikal and anomalous southerlies originating from anomalous cyclones in the south-central area of eastern China joined in central eastern China. The typical anomalous atmospheric circulations in the negative Pacific Decadal Oscillation (PDO) phase and the average PDO index and summer rainfall in central eastern China from June to August exhibited a high negative correlation, which was presumed to have been present since the previous winter.

Evaluation of Tropical Cyclone Intensity Forecasts from Five Global EnsemblePrediction Systems During 2015-2019

This study presented an evaluation of tropical cyclone (TC) intensity forecasts from five global ensemble prediction systems (EPSs) during 2015-2019 in the western North Pacific region. Notable error features include the underestimation of the TC intensity by ensemble mean forecast and the under-dispersion of the probability forecasts.The root mean square errors (brier scores) of the ensemble mean(probability forecasts) generally decrease consecutively at long lead times during the five years, but fluctuate between certain values at short lead times.Positive forecast skill appeared in the most recent two years (2018-2019) at 120 h or later as compared with the climatology forecasts. However, there is no obvious improvement for the intensity change forecasts during the 5-year period, with abrupt intensity change remaining a big challenge. The probability forecasts show no skill for strong TCs at all the lead times. Among the five EPSs, ECMWF-EPS ranks the best for the intensity forecast, while NCEPGEFS ranks the best for the intensity change forecast, according to the evaluation of ensemble mean and dispersion.As for the other probability forecast evaluation, ECMWF-EPS ranks the best at lead times shorter than 72 h, while NCEP-GEFS ranks the best later on.

Advanced mosasaurs from the Upper Cretaceous Nakaminato Group in Japan

AbstractPlotosaurus is a highly aquatically adapted mosasaur, which is supposed to inhabit the deep ocean basin. The geographic occurrence of this genus has been limited only to the west coast of North America. In this study, two Plotosaurus‐type mosasaur caudal vertebrae derived from the Upper Cretaceous Nakaminato Group in Ibaraki Prefecture, Japan, are described with discussion on the paleobiogeographic significance of the Late Cretaceous mosasaur fauna in the Northwestern Pacific region. The two specimens are an intermediate caudal vertebra found in a beach cobble, which presumably originated from the Hiraiso Formation (upper Campanian), and a terminal caudal vertebra found in situ in the lower Isoai Formation (lower Maastrichtian). Because their relative centrum lengths (ratio of centrum length/centrum height, ~0.7) are very close to that of Plotosaurus, the specimens are referred to cf. Plotosaurus sp. The two specimens provide the first evidence that highly specialized Plotosaurus‐type mosasaurs inhabited the Northwestern Pacific Ocean, suggesting that such forms had a wider distribution than previously recognized and might have existed since the late Campanian in the Northwestern Pacific Ocean.

Pre-Existing Health Conditions and Severe COVID-19 Outcomes: Umbrella Review and Meta-Analysis of Global Evidence

Background: This umbrella review summarises the global evidence on the risk of severe COVID-19 outcomes in patients with pre-existing health conditions. Methods: Systematic reviews (SRs) were identified in PubMed, Embase/Medline, and seven pre-print servers until December 11, 2020. Risk estimates (odds ratio (OR), hazard ratio (HR), relative risk (RR)) for hospitalisation, intensive care unit admission, intubation, and death were extracted from primary studies. Meta-analyses were performed stratified by regions of the World Health Organisation. The evidence certainty was assessed using GRADE. Registration number CRD42020215846.Findings: 160 primary studies from 120 SRs contributed 464 estimates for 42 pre-existing conditions. Most studies were conducted in North America, European, and Western Pacific regions. Evidence from Africa, South/Latin America, and Eastern Mediterranean region was scarce. No evidence was available from South-East Asia region. Diabetes (HR 1∙2-2∙0 (1∙1-2∙8)), obesity (OR 1∙5-1∙75 (1∙1-2∙3)), heart failure (HR 1∙3-3∙3(0∙9-8∙2)), COPD (HR 1∙12-2∙2 (1∙1-3∙2)), and dementia (HR 1∙4-7.7 (1∙2-39∙6)) were associated with fatal COVID-19 in different regions, although the estimates varied. Evidence from Europe and North America showed that liver cirrhosis (OR 3∙2-5∙9 (0∙9-27∙7)) and active cancer (OR 1∙6-4∙7 (0∙5-14∙9)) were also associated with increased risk of death. Association between HIV and severe COVID-19 showed regional heterogeneity, with an increased risk of death in Africa (HR 1∙7 (1∙3-2∙2)). GRADE certainty was moderate to high for most associations.Interpretation: Risk of severe COVID-19 is consistently increased in certain patient subgroups across geographical regions, showing high variability in others. The results can be used to inform COVID-19 vaccine prioritisation or other intervention strategies.Funding Statement: Project ImVaCov – German Federal Ministry of HealthDeclaration of Interests: Authors declare no conflicts of interest.

Submesoscale Currents in the Subtropical Upper Ocean Observed by Long-Term High-Resolution Mooring Arrays

AbstractAlthough observational efforts have been made to detect submesoscale currents (submesoscales) in regions with deep mixed layers and/or strong mesoscale kinetic energy (KE), there have been no long-term submesoscale observations in subtropical gyres, which are characterized by moderate values of both mixed layer depths and mesoscale KE. To explore submesoscale dynamics in this oceanic regime, two nested mesoscale- and submesoscale-resolving mooring arrays were deployed in the northwestern Pacific subtropical countercurrent region during 2017–19. Based on the 2 years of data, submesoscales featuring order one Rossby numbers, large vertical velocities (with magnitude of 10–50 m day−1) and vertical heat flux, and strong ageostrophic KE are revealed in the upper 150 m. Although most of the submesoscales are surface intensified, they are found to penetrate far beneath the mixed layer. They are most energetic during strong mesoscale strain periods in the winter–spring season but are generally weak in the summer–autumn season. Energetics analysis suggests that the submesoscales receive KE from potential energy release but lose a portion of it through inverse cascade. Because this KE sink is smaller than the source term, a forward cascade must occur to balance the submesoscale KE budget, for which symmetric instability may be a candidate mechanism. By synthesizing observations and theories, we argue that the submesoscales are generated through a combination of baroclinic instability in the upper mixed and transitional layers and mesoscale strain-induced frontogenesis, among which the former should play a more dominant role in their final generation stage.

Changes in Intensity and Variability of Tropical Cyclones over the Western North Pacific and Their Local Impacts under Different Types of El Niños

This study investigated the effects of El Niño events on tropical cyclone (TC) characteristics over the western North Pacific (WNP) region. First, TC characteristics associated with large-scale atmospheric phenomena (i.e., genesis position, frequency, track, intensity, and duration) were investigated in the WNP in relation to various types of El Niño events—moderate central Pacific (MCP), moderate eastern Pacific (MEP), and strong basin-wide (SBW). Subsequently, the seasonal and regional variability of TC-induced rainfall across China was analyzed to compare precipitation patterns under the three El Niño types. When extreme El Niño events of varying degrees occurred, the local rainfall varied during the developmental and decaying years. The development of MEP and SBW was associated with a distinct change in TC-induced rainfall. During MEP development, TC-induced rainfall occurred in eastern and northeastern China, whereas in SBW, TC-induced heavy rainfall occurred in southwest China. During SBW development, the southwestern region was affected by TCs over a long period, with the eastern and northeastern regions being affected significantly fewer days. During El Niño decay, coastal areas were relatively more affected by TCs during MCP events, and the Pearl River basin was more affected during SBW events. This study’s results could help mitigate TC-related disasters and improve water-supply management.

Statistical Prediction of Typhoon-Induced Rainfall over China Using Historical Rainfall, Tracks, and Intensity of Typhoon in the Western North Pacific

Typhoons or mature tropical cyclones (TCs) can affect inland areas of up to hundreds of kilometers with heavy rains and strong winds, along with landslides causing numerous casualties and property damage due to concentrated precipitation over short time periods. To reduce these damages, it is necessary to accurately predict the rainfall induced by TCs in the western North Pacific Region. However, despite dramatic advances in observation and numerical modeling, the accuracy of prediction of typhoon-induced rainfall and spatial distribution remains limited. The present study offers a statistical approach to predicting the accumulated rainfall associated with typhoons based on a historical storm track and intensity data along with observed rainfall data for 55 typhoons affecting the southeastern coastal areas of China from 1961 to 2017. This approach is shown to provide an average root mean square error of 51.2 mm across 75 meteorological stations in the southeast coastal area of China (ranging from 15.8 to 87.3 mm). Moreover, the error is less than 70 mm for most stations, and significantly lower in the three verification cases, thus demonstrating the feasibility of this approach. Furthermore, the use of fuzzy C-means clustering, ensemble averaging, and corrections to typhoon intensities, can provide more accurate rainfall predictions from the method applied herein, thus allowing for improvements to disaster preparedness and emergency response.

Discrepancies between MICS-Asia III simulation and observation for surface ozone in the marine atmosphere over the northwestern Pacific Asian Rim region

Abstract. In order to identify the causes of overestimate of the surface-level O3 mixing ratio simulated by three regional chemical-transport models, NAQPMS v.3 (abbreviated as NAQM in this paper), CMAQ v.5.0.2, and CMAQ v.4.7.1, compared to the EANET observational data at a marine remote site at Oki in July 2010, analyses of hourly O3 mixing ratios and net ozone production were made in the context of MICS-Asia III. In addition to Oki, model-simulated and observational data for two other EANET marine sites, Hedo and Ogasawara, were also examined. Three factors, i.e., long-range transport from the continent, in situ photochemical formation, and dry deposition of O3 on seawater, have been identified as contributing to the overestimate by these regional models at Oki. The calculated O3 mixing ratios during long-range transport from the continent were much higher for all three models than those of the observation. In situ photochemical formation, demonstrated by a distinct diurnal variation which was not discerned in the observational data, was seen in the simulated data of all three models and ascribed to the virtual transport of NOx from the southern urban areas of the main island of Japan. The overestimate of the O3 mixing ratio in the background oceanic air mass has been discussed referring to dry deposition velocity (Vd) of O3 over oceanic water. Sensitivity analysis of the dry deposition velocity to the concentration of O3 was made for Oki in July. An increase in Vd from 0.0005 to 0.001 cm s−1 used in the standard runs for CMAQ by a factor of 10 decreases the O3 mixing ratio by more than 20 ppbv on an event basis in certain periods of time and by ca. 4.9 ppbv as a monthly mean in July. The dry deposition velocity of O3 in Bohai Bay and the Yellow Sea has been assumed to be comparable to that of the open ocean in all three models, which could have resulted in the overestimate of O3 mixing ratios in this area and also in the long-range transport of O3 from the continent to Oki. A higher value of dry deposition velocity in this marine area is expected considering the higher content of organics in the surface sea layer brought by rivers and atmospheric wet deposition. Empirical measurements of the mixing ratios and dry deposition flux of O3 in this area are highly recommended, since they would affect the simulated mixing ratios in the downwind region in the Pacific Rim region.

Combining otolith elemental signatures with multivariate analytical models to verify the migratory pattern of Japanese Spanish mackerel (Scomberomorus niphonius) in the southern Yellow Sea

Japanese Spanish mackerel, Scomberomorus niphonius, is a commercially important, highly migratory species that is widely distributed throughout the northwestern Pacific region. However, its life history and migratory patterns are only partially understood. This study used otolith chemistry to investigate the migratory pattern of S. niphonius in the southern Yellow Sea, an important fishing ground. Transverse sections of otoliths from 15 age-1 spawning or spent individuals, comprising up to one complete migration cycle, were analyzed from the core to the margin by using laser ablation inductively coupled plasma mass spectrometry. The ratios of the element to Ca were integrated with microstructural analysis to produce age-related elemental profiles. Combining multielemental analysis of otolith composition with multivariate analytical models, we quantified structural changes in otolith chemistry profiles. Results revealed there were diverse changing patterns of otolith chemistry profiles for detected elements and the elements of Na, Mg, Sr and Ba were important for the chronological signal. Five clusters were identified through chronological clustering, representing the five life stages from the early stage to the spawning stage. Variation of Ba:Ca ratio was most informative, showing a step-decreasing pattern in the first four stages and a rebound in the spawning stage. These results support the hypothesized migratory pattern of S. niphonius: hatching and spending their early life in the coastal sandy ridges system of the southern Yellow Sea, migrating northeastward and offshore for feeding during juvenile stage, aggregating in early October and migrating outward to the Jeju Island for wintering, and returning to the coastal waters for spawning. This study demonstrated the value of life-history related otolith chemistry profiles combined with multivariate analytical models was a means to verify the migration patterns of S. niphonius at regional scales with potential application in fisheries assessment and management.

A report of a new species and new record of Cadlina (Nudibranchia, Cadlinidae) from South Korea.

Of the four species in the genus Cadlina present in the northwestern Pacific region, C. japonica has been the only species recorded from South Korea. For the purpose of investigating Cadlina in Korean waters, specimens were collected from the Korean East Sea (Sea of Japan) by scuba diving. The radula and morphology of these specimens were examined by stereoscopic and scanning electron microscopy. Based on morphology, three species were identified in Korean waters, including the new species, Cadlina koreanasp. nov., C. umiushi (first record in South Korea), and C. japonica. Cadlina koreanasp. nov. somewhat resembles C. umiushi but differs in both its morphology as well as the structure of its radula. The background color of Cadlina koreanasp. nov. is translucent white, tubercles on the dorsum are opaque white and the yellow marginal band is absent. The radular formula of Cadlina koreanasp. nov. is 57 × 23.1.23 with a rectangular rachidian tooth. In addition, mitochondrial cytochrome c subunit 1 (COI), 16S ribosomal RNA (16S rRNA), and nuclear 28S ribosomal RNA (28S rRNA) gene sequences were generated and used for analysis of Automatic Barcode Gap Discovery (ABGD) and reconstruction of the phylogenetic tree. Morphological distinction and genetic analyses confirm that three Cadlina species are present in Korean waters of which Cadlina koreana is a new species.

The Footprint of Atlantic Multidecadal Oscillation on the Intensity of Tropical Cyclones Over the Western North Pacific

Sea surface temperature (SST) over the western North Pacific (WNP) exhibits strong decadal to multidecadal variability and in this region, warm waters fuel the tropical cyclones (TCs). Observational records show pronounced decadal variations in WNP TC metrics during 1950–2018. Statistical analysis of the various TC metrics suggests that the annual average intensity of WNP TCs is closely linked to the AMO (r = 0.86 at decadal timescales, p < 0.05). Observations and coupled atmosphere-ocean simulations show that the decadal WNP SST variations regarded as the primary driver of TC intensity, are remotely controlled by the AMO. Corresponding to the WNP SST warming, the local SLP gets lower and the tropospheric air becomes warmer and moister, enhancing atmospheric instability and the generation of convective available potential energy. These favorable changes in the background environment provide more “fuel” to the development of deep convection and intensify the WNP TCs. The footprints of AMO in WNP SST and atmospheric states through trans-basin interaction eventually exert a significant impact on the TC intensity over the WNP region.

Tropical cyclone movement features in the western North Pacific region based on multi‐dimensional statistical analyses

AbstractIn order to protect and mitigate the disaster caused by tropical cyclone (TC) in the western North Pacific (WNP) region, further understandings of the characteristics of historical TCs are important. In this study, multi‐dimensional statistical analyses are carried out to reveal the TC movement features in the WNP. Two representative TC datasets provided by China Meteorological Administration (CMA) and Japan Meteorological Agency (JMA) are used to investigate the historical TC properties in the WNP covering a time duration from 1951 to 2018. TC movement features generally show the great consistency with respect to these two datasets. Based on the regional (zero‐dimensional analysis) and zonally averaged (one‐dimensional analysis) results, it is found that TCs move northwest with a small velocity at low latitudes, whereas they tend to drift northeast with a large velocity at high latitudes. The recurvature occurs near 25°N where the direction of zonal drift velocity reverses. Applying the bivariate normal distribution method (quasi‐two‐dimensional analysis), the randomness of the zonal component is found to be generally greater than that of the meridional component. Accordingly, relevant attentions, rather than universal ones, should be paid to forecast the TC movement in different regions. Regarding the complete two‐dimensional analysis, it is found that compared with other areas, TCs have a smaller magnitude of drift velocity but stronger intensity with higher passage frequencies in the area enclosed by 10–25°N and 110–140°E, where significant TC‐induced disasters are prone to occur, resulting in a serious threat to the safety of human beings and local societies.

Dentists’ knowledge, attitudes, and professional behavior toward the COVID-19 pandemic: A multisite survey of dentists’ perspectives

BackgroundCOVID-19 continues to affect the dental community worldwide. The authors conducted a cross-sectional electronic study using a multisite survey to examine dentists’ knowledge, attitudes, and professional behavior toward COVID-19 and the affect on their livelihood. MethodsA questionnaire was circulated via e-mail and social media platforms to dentists in North America, Europe, Eastern Mediterranean, and Western Pacific regions. It covered demographic characteristics and questions about the COVID-19 outbreak related to dentists’ levels of comfort for preventive and safety measures, provision of treatment, affect on work, and financial implications. Responses were tabulated and analyzed by means of χ2 or Fisher exact test. Mann-Whitney and Kruskal-Wallis tests were used to compare means. P < .05 was considered significant. ResultsA total of 1,251 dentists responded. General dentists represented 63.9% of the respondents and 62.5% worked in private practice. The global score for level of comfort with the preventive measures and provisions of treatment during the COVID-19 pandemic was low (14 of 30), and differences between regions were significant (P < .01); dentists working in private practice and general dental practitioners were less comfortable (P < .01). Conclusions and Practical ImplicationsThe respondents reported a lack of preparedness to confront a highly infectious respiratory disease. A new level of protective armamentarium in the dental operatory and updated operational guidance and policies are required, necessitating educators and regulators to ensure the delivery of knowledge and skills to oral health care providers. Dentists need to address the sustainability of their practices and have a robust business plan.

Performance of CMIP5 atmospheric general circulation model simulations over the Asian summer monsoon region

Performance of twenty-eight state of art atmosphere general circulation models (AGCMs) in simulating regional characteristic features of summer monsoon rainfall and circulation over the south Asian and the western-north Pacific regions are examined. AGCMs depict good representation of climatological spatial distribution of monsoon rainfall over both the regions. Interestingly, the year-to-year variability of the south Asian (Indian) monsoon rainfall is well simulated by the models compared to the circulation features. Whereas, for the western-north Pacific region, the AGCMs depict poor representation of monsoon rainfall variability, but circulation features are simulated with better skill. Thus suggesting that, models with good performance of monsoon rainfall variability need not necessarily have better representation of monsoon circulation features. Further analysis indicate that most models with good skill in simulating monsoon variability have better representation of monsoon-SST teleconnections with the Indo-Pacific SSTs. For the south Asian region, better simulating models have good representation of monsoon-ENSO teleconnection whereas most models have poor representation of monsoon-IOD relationship, suggesting requirement for realistic representation of these teleconnections in the models. For the western-north Pacific region, most models have unrealistic relationship of monsoon rainfall with SSTs during preceding winter and concurrent monsoon season, indicating that the poor (better) skill in simulating rainfall (circulation) probably arise from the unrealistic (realistic) representation of monsoon-SST teleconnections. Thus, the importance of realistic representation of monsoon-SST teleconnections in the climate models have been brought out for better simulation of monsoon variability over the south Asian and the western-north Pacific regions. • Performance of twenty-eight state of art atmosphere general circulation models in representing the summer monsoon rainfall and circulation over the south Asia and the western-north Pacific are examined. • Study brings out the importance of realistic representation of monsoon-SST teleconnections in the climate models for better simulation of the monsoon over the south Asia and the western-north Pacific. • The models which depict higher skill in simulating the interannual variability of monsoon have a better representation of monsoon-SST teleconnection over most of the Indo-Pacific region.