Wind Waves in the Mediterranean Sea: An ERA5 Reanalysis Wind-Based Climatology

A climatology of the wind waves in the Mediterranean Sea is presented. The climate patterns, their spatio-temporal variability and change are based on a 40-year (1980–2019) wave hindcast, obtained by combining the ERA5 reanalysis wind forcing with the state-of-the-art WAVEWATCH III spectral wave model and verified against satellite altimetry. Results are presented for the typical (50th percentile) and extreme (99th percentile) significant wave height and, for the first time at the regional Mediterranean Sea scale, for the typical and extreme expected maximum individual wave height of sea states. The climate variability of wind waves is evaluated at seasonal scale by proposing and adopting a definition of seasons for the Mediterranean Sea states that is based on the satellite altimetry wave observations of stormy (winter) and calm (summer) months. The results, initially presented for the four seasons and then for winter and summer only, show the regions of the basin where largest waves occur and those with the largest temporal variability. A possible relationship with the atmospheric parameter anomalies and with teleconnection patterns (through climate indices) that motivates such variability is investigated, with results suggesting that the Scandinavian index variability is the most correlated to the Mediterranean Sea wind-wave variability, especially for typical winter sea states. Finally, a trend analysis shows that the Mediterranean Sea typical and extreme significant and maximum individual wave heights are decreasing during summer and increasing during winter.

Atmospheric Anomaly Analysis Related to Ms > 6.0 Earthquakes in China during 2020–2021

The attention towards links of atmospheric parameter variation and earthquakes has increased exponentially by utilizing new methods and more accurate observations. Persistent research makes it possible to gain insight into the precursor mechanism of earthquakes. In this paper, we studied the universality of detecting atmospheric anomalies associated with earthquakes based on tidal force fluctuation in China for earthquakes of Ms > 6.0, and explored the influence of tidal force on tectonic stress. The data of air temperature, geopotential height, ozone mixing ratio, and relative humidity from the National Center for Environmental Prediction (NCEP) were analyzed to reveal the spatiotemporal variation of atmospheric anomalies at multiple isobaric surfaces. Furthermore, the coupling of atmospheric parameters was investigated. The results showed that continuous solicitation exerted by tidal forces could change the strength of tectonic stress that causes earthquakes. The evolution pattern of air temperature, geopotential height, and relative humidity could be supported by atmospheric thermal vertical diffusion, while the anomalies of ozone mixing ratio was not evident. This verified the feasibility of detecting multi-parameter atmospheric anomalies associated with earthquakes based on tidal force fluctuation. Our results provide more evidence for understanding the atmospheric precursor characteristics of earthquakes.

Absolute humidity of atmospheric air and COVID-19

Today COVID-19 is number one global point of focus. Therefore, study of the effects of environmental conditions, in which exist pandemic subjects — people and viruses, on pandemic dynamics and results is extremely important. The authors made a correlation analysis of dependence between incidence/mortality of population and absolute and relative humidity in 73 countries and regions on different continents of the Earth. The methodology developed defines how and in what periods of time the environmental factors effect on human incidence and mortality, how strongly particular atmospheric parameter affects the process of infection and disease flow. The undertaken calculations allowed to prove that the absolute humidity is one of the dominant natural factor which influences on pandemic COVID-19 and other infectious diseases dynamics. The growth of absolute air humidity can have both positive and negative effect on incidence and mortality of population while the effect’s character depends on absolute humidity’s own level and other atmospheric parameters. Correlation of absolute and relative humidity with incidence/mortality at the same time can be different in value or sign. Existing regulations at the federal level in Russian Federation are established without taking into account the minimum allowable and physiologically optimal value of absolute humidity, and need corrections. The question of the impact of absolute humidity is of great importance for northern territories, where most of the year the value of absolute humidity is less than the minimum allowed. The achieved results show high degree of the impact of absolute humidity on incidence and mortality of population due to COVID-19 and contribute to better understanding of pandemic peaks cyclicality and conscious forecasting of start of periods of the most dangerous epidemiological reality.

A 7-Year Climatology of Warm-Sector Heavy Rainfall over South China during the Pre-Summer Months

In view of the limited predictability of heavy rainfall (HR) events and the limited understanding of the physical mechanisms governing the initiation and organization of the associated mesoscale convective systems (MCSs), a composite analysis of 58 HR events over the warm sector (i.e., far ahead of the surface cold front), referred to as WSHR events, over South China during the months of April to June 2008~2014 is performed in terms of precipitation, large-scale circulations, pre-storm environmental conditions, and MCS types. Results show that the large-scale circulations of the WSHR events can be categorized into pre-frontal, southwesterly warm and moist ascending airflow, and low-level vortex types, with higher frequency occurrences of the former two types. Their pre-storm environments are characterized by a deep moist layer with >50 mm column-integrated precipitable water, high convective available potential energy with the equivalent potential temperature of ≥340 K at 850 hPa, weak vertical wind shear below 400 hPa, and a low-level jet near 925 hPa with weak warm advection, based on atmospheric parameter composite. Three classes of the corresponding MCSs, exhibiting peak convective activity in the afternoon and the early morning hours, can be identified as linear-shaped, a leading convective line adjoined with trailing stratiform rainfall, and comma-shaped, respectively. It is found that many linear-shaped MCSs in coastal regions are triggered by local topography, enhanced by sea breezes, whereas the latter two classes of MCSs experience isentropic lifting in the southwesterly warm and moist flows. They all develop in large-scale environments with favorable quasi-geostrophic forcing, albeit weak. Conceptual models are finally developed to facilitate our understanding and prediction of the WSHR events over South China.

Air quality in cities of the extreme south of Brazil

The region comprised of cities located in the extreme south of Brazil has numerous potential sources of pollution, such as industries, mining and agricultural activities. Despite this, they do not have detailed scientific information regarding air quality. The present study aimed to evaluate air quality in nine municipalities in the extreme south of Brazil, based on the monitoring of six pollutants (O3 , NO2, SO2, PM2.5, PM10 and CO) present in Brazilian environmental legislation and the relationship of these pollutants with meteorological parameters. Information on air pollutants and meteorological parameters was collected from satellite data from the European Centre for Medium-Range Weather Forecasts “Copernicus Atmospheric Monitoring Service”, extracted using The Wealther Channel (IBM, USA) during the period ranged from April 25, 2020 to July 4, 2020 in Rio Grande, Pelotas, Bagé, Candiota, Hulha Negra, Pedras Altas, Aceguá and Herval. The concentration of pollutants was below Brazilian limits, with the exception of a single episode in the municipality of Rio Grande. Temperature was the meteorological parameter most correlated with air pollutants, except for SO2, but in general, all pollutants correlated (positive or negative) with at least one atmospheric parameter. Finally, the composition of air pollutants in each municipality seems to be related to its local economic activity. We encourage the continuity of studies in the region aiming at a complete temporal analysis that encompasses all seasons.