Theoretical Study and Numerical Experiment on the Influence of Trend Changes on Correlation Coefficient

When one of two time series undergoes an obvious change in trend, the correlation coefficient between the two will be distorted. In the context of global warming, most meteorological time series have obvious linear trends, so how do variations in these trends affect the correlation coefficient? In this paper, the correlation between time series with trend changes is studied theoretically and numerically. Adopting the trend coefficient, which reflects the nature and size of the trend change, we derive a formula r = f(k, l) for the correlation coefficient of time series X and Y with respective trend coefficients k and l. Analysis of the function graph shows that the changes in correlation coefficient with respect to the trend coefficients produce a twisted saddle surface, and the saddle point coordinates are given by the trend coefficients of time series X and Y with the opposite signs. The curve f(k, l) = f(0, 0) divides the coordinate planes into regions where f(k, l) > f(0, 0) and f(k, l) < f(0, 0). When the trend coefficients k and l are very small and the correlation coefficient is also very small, then k > 0 and l > 0 (or k < 0 and l < 0) amplifies a positive correlation, whereas k > 0 and l < 0 (or k < 0 and l > 0) amplifies a negative correlation, as found in previous research. Finally, experiments using meteorological data verify the reliability and effectiveness of the theory.

A Multilevel Study of Socio-economic Inequalities in Self-reported Oral and General Health in South-east Norway

This study assesses the association between socioeconomic determinants and self-reported health using data from a regional Norwegian health survey. A total of 9,068 participants 25+ were included. Survey data were linked to registry data on education and personal income. Self-reported oral health and general health were separately assessed and categorized into ‘good’ and ‘poor’. The exposures were educational level, personal income, and economic security. Prevalence ratios (PRs) were computed to assess the associations between socioeconomic determinants and self-reported health using multilevel Poisson regression. Participants with low education or income had poorer oral and general health than those with more education or higher income. Comparing the highest education level versus the lowest, adjusted PRs for poor oral and general health were 1.44 (95%CI 1.26-1.65) and 1.53 (95%CI 1.35-1.74). Correspondingly, with the highest income quintile versus the lowest, estimates were 1.64 (95%CI 1.39-1.94) and 2.34 (95%CI 1.97-2.79) for oral and general health. Lack of economic security was also significantly associated with poor self-reported oral and general health. Positive linear trends between levels of education and income were documented for both outcomes (P-linear trends <0.001), including a pattern of socioeconomic gradients, both for oral and general health.

Latitudinal- and height-dependent long-term climatology of propagating quasi-16-day waves in the troposphere and stratosphere

The global amplitude of the westward propagating quasi-16-day waves (16DW) with wavenumber 1 (Q16W1), the strongest component of 16DW, are derived from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis temperature and zonal wind data sets from February 1979 to January 2018. In terms of temperature and zonal wind, strong climatologically average amplitudes of Q16W1 appear in the upper stratosphere at mid–high latitudes in both hemispheres, and the wave amplitude is stronger in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH). Multivariate linear regression is separately applied to calculate the responses of the Q16W1 temperature and zonal wind amplitudes to the QBO (quasi-biennial oscillation), ENSO (El Niño-Southern Oscillation), solar activity and linear trends of the Q16W1 amplitude. The QBO signatures of the Q16W1 temperature and zonal wind amplitudes are mainly located in the stratosphere. The Q16W1 has significant QBO responses at low latitudes. In addition, only the temperature amplitude presents a larger QBO signature in its strongest climatological amplitude region. No significant responses to ENSO and solar activity are observed in temperature and zonal wind amplitudes. The linear trends of the monthly mean Q16W1 temperature and zonal wind amplitude are generally positive, especially in the mid-upper stratosphere. The trend is asymmetric about the equator and significantly stronger in the NH than in the SH. The seasonal variation in the trend of the temperature amplitude is studied and illustrated to be stronger in winter and weaker in spring and autumn. Further investigation suggests that the background and local instability trends contribute most of the increasing trend of the Q16W1 amplitude. In winter in both hemispheres, a weakening trend of eastward zonal wind provides more favourable background wind for Q16W1 upward propagation, in autumn and winter in the NH and in spring, autumn and winter in the SH, and the increasing trend of local instability may enhance wave excitation. Graphical Abstract

COVID-19 Pandemic—Financial Consequences for Polish Airports—Selected Aspects

The COVID-19 pandemic has reduced the mobility of urban residents on an international level. Tourist air traffic was suspended as one of many activities. As a result, the aviation industry has suffered losses at various levels. In addition to carriers, airports are also suffering due to the effects of the pandemic. Their income comes mainly from charges for take-offs and landings of airplanes, passenger charges, and commercial and restaurant activity. In this paper, the authors attempt to estimate the level of losses incurred by six Polish airports in relation to passenger charges. Based on the data for the years 2015–2019, the forecasts of passenger flows for the year 2020 were estimated using the seasonality indicator method, the method of one-name period trends, and models of linear trends with seasonality. Research has shown that the total losses of the examined airports for the year 2020 amounted to approximately 290 million EUR, and these are losses resulting only from the lack of fees charged for servicing passengers at the airports.

The Variabilities of Convective Precipitation and Large-scale Precipitation in Southern China under Global Warming

In this paper, the spatial and temporal characteristics of convective precipitation (CP) and large-scale precipitation (LSP) in southern China during 1980-2020 are analyzed using monthly mean precipitation data from MERRA-2. In addition, the possible effects of relative humidity on CP and LSP are explored. The results indicate the following. (1) The LSP dominates the proportion of total precipitation (TP). Both LSP and CP are more prevalent in the south and less prevalent in the north, but there is a difference in the regions of their maximum centers. (2) Significant interannual and seasonal variations are observed in precipitation. TP and LSP tended to be higher than average after the 1990s, while for the CP, a negative trend has dominated the past years with considerable fluctuation. There are obvious increasing trends for TP and LSP, with area-averaged linear trends of 7.0 mm/year and 8.9 mm/year, respectively, while that of CP is -1.9 mm/year. The increasing trends of LSP are mainly contributed by the precipitation of summer and autumn. (3) The variations of LSP are affected by relative humidity in the troposphere, while CP is only influenced by the changes in relative humidity due to air temperature or specific humidity. The trend of relative humidity is -0.32%/decade, mainly due to rising temperature in the troposphere. (4) Changes in specific humidity caused by temperature or specific humidity alone act on large-scale precipitation through both interannual and interdecadal processes, causing large-scale precipitation to increase. And the convective precipitation is mainly affected by the interdecadal processes.

Trends in the prevalence of metabolic syndrome and its components in Mexican adults, 2006-2018

Objective. To examine trends in the prevalence of metabolic syndrome (MS) and its components. Materials and methods. Data from 27 800 Mexican adults who participated in Ensanut 2006, 2012, 2016 and 2018 were analyzed. Linear regression was used across each Ensanut period to assess temporal linear trends in the prevalence of MS. Logistic regression models were obtained to calculate the percentage change, p-value for the trend and the association between the presence of MS and the risk of developing type 2 diabetes mellitus (T2DM) over 10 years using the Finnish Diabetes Risk Score (FINDRISC) and cardiovascular disease (CVD) using Globorisk. Results. The prevalence of MS in Mexican adults according to the harmonized definition was: 40.2, 57.3, 59.99 and 56.31%, in 2006, 2012, 2016 and 2018 respectively (p for trend <0.0001). In 2018, 7.62% of metabolic syndrome cases had a significant risk for incident DM2 and 11.6% for CVD. Conclusion. It is estimated that there are 36.5 million Mexican adults living with metabolic syndrome, of which 2 million and 2.5 million have a high risk of developing T2DM or cardiovascular disease respectively, over the next 10 years.

Healthy People Countdown 2030: reaching 5% cigarette smoking prevalence among US adults through state cigarette excise tax increases

ObjectiveThe Healthy People 2030 goal is to reduce US current adult cigarette smoking prevalence to 5% by 2030. The objective of this report is to investigate if this goal is achievable using state cigarette excise tax increases.MethodsState-specific linear trends in smoking prevalence over 2011–2019 were determined using fractional logit regression and compared with the desired linear trends for achieving 5% smoking prevalence by 2030 in individual states and the District of Columbia (DC). The gaps between price-adjusted and desired trends were used in a simulation model for identifying state-specific systematic annual increases in state cigarette excise tax rates based on state-specific price elasticity of smoking prevalence, maintaining the status quo in other non-tax tobacco control measures.ResultsThe price-adjusted trends in smoking prevalence observed over 2011–2019 exceed the desired trends for achieving 5% smoking prevalence target by 2030 in only five states (eg, Washington, Utah, Rhode Island, Massachusetts and Maryland) and the DC. It suggests that majority of states and USA overall will miss the target smoking prevalence at the current rate of reduction in smoking. 45 states would need systematic annual increases in cigarette excise tax rate in a range of $0.02–$1.37 per pack over 2022–2030 to meet the target.ConclusionsThe feasibility of reaching the Healthy People 2030 goal would critically depend on the acceleration of progress in tobacco control. Tax increases tailored to the needs of individual states combined with scaled-up non-tax tobacco control policy interventions can help achieve the desired progress.

Temporal rainfall trend analysis in different agro-ecological regions of southern Africa

Rainfall is a major driver of food production in rainfed smallholder farming systems. This study was conducted to assess linear trends in (i) different daily rainfall amounts (<5, 5–10, 11–20, 21–40 and >40 mm∙day-1), and (ii) monthly and seasonal rainfall amounts. Drought was determined using the rainfall variability index. Daily rainfall data were derived from 18 meteorological stations in southern Africa. Daily rainfall was dominated by <5 mm∙day-1 followed by 5–10 mm∙day-1. Three locations experienced increasing linear trends of <5 mm∙day-1 amounts and two others in sub-humid region had increases in the >40 mm day-1 category. Semi-arid location experienced increasing trends in <5 and 5–10 mm∙day-1 events. A significant linear trend in seasonal rainfall occurred at two locations with decreasing rainfall (1.24 and 3 mm∙season-1). A 3 mm∙season-1 decrease in seasonal rainfall was experienced under semi-arid conditions. There were no apparent linear trends in monthly and seasonal rainfall at 15 of the 18 locations studied. Drought frequencies varied with location and were 50% or higher during the November–March growing season. Rainfall trends were location and agro-ecology specific, but most of the locations studied did not experience significant changes between the 1900s and 2000s.

Measuring Coastal Absolute Sea-Level Changes Using GNSS Interferometric Reflectometry

Rising sea levels pose one of the greatest threats to coastal zones. However, sea-level changes near the coast, particularly absolute sea-level changes, have been less well monitored than those in the open ocean. In this study, we aim to investigate the potential of Global Navigation Satellite Systems Interferometric Reflectometry (GNSS-IR) to measure coastal absolute sea-level changes and tie on-land (coastal GNSS) and offshore (satellite altimetry) observations into the same framework. We choose three coastal GNSS stations, one each in regions of subsidence, uplift and stable vertical land motions, to derive both relative sea levels and sea surface heights (SSH) above the satellite altimetry reference ellipsoid from 2008 to 2020. Our results show that the accuracy of daily mean sea levels from GNSS-IR is <1.5 cm compared with co-located tide-gauge records, and amplitudes of annual cycle and linear trends estimated from GNSS-IR measurements and tide-gauge data agree within uncertainty. We also find that the de-seasoned and de-trended SSH time series from GNSS-IR and collocated satellite altimetry are highly correlated and the estimated annual amplitudes and linear trends statistically agree well, indicating that GNSS-IR has the potential to monitor coastal absolute sea-level changes and provide valuable information for coastal sea-level and climate studies.

Long-term and seasonal anomalies of the Sea of the Azov thermohaline structure for 1913 – 2018

Variability of temperature and salinity as well as quantifying global trends are fundamental for understanding changes in the Earth's climate. In current paper, a long-term variability of the hydrological regime of the Sea of Azov for 1913–2018 is studied. On the basis of oceanographic information, the seasonal variability of temperature and salinity by the areas of the Sea of Azov is analysed. Temperature anomalies have been revealed, periods of salinization and desalination of the Sea of Azov have been noted and linear trends of the anomaly have been obtained.