Correcting Breaks in Temperature and Humidity Observations: Implications for Climate Variability Analysis in Austria

Urbanization modifies the heat balance in urban areas and has negative effects on landscape, aesthetics, energy efficiency, human health and the inhabitants’ quality of life. This work evaluated future scenarios of bioclimatic conditions for João Pessoa, a humid tropical city in Northeast Brazil. The scenarios were determined based on trends in air temperature, relative humidity and wind speed for the time period from 1968 to 2015. The study was performed for two distinct periods of three months each (dry and wet seasons) using data from weather stations equipped with thermo-hygrometers and cup anemometers located in nine representative areas of the city. Trends in air temperature, relative humidity, wind speed, and effective temperature index (ET index) time series were evaluated using the Mann-Kendall test. Results indicated that the air temperature showed an increasing trend of 0.34°C/decade, whereas the relative humidity showed a decreasing trend of 0.49%/decade and the wind speed values ranged from 1.3 ms-1 to 3.80 ms-1. These trends are statistically significant according to the Mann-Kendall test (p<0.05). The air temperature increased between the 1980s and 2010s, which corresponds to a period of rapid urbanization of the city. Future environmental conditions in João Pessoa will be determined in accordance with the urbanization processes.

Hourly summary data at NPP T-TAYL met station. Average/maximum/minimum air temperature; average relative humidity and wind direction; average/maximum wind speed. These are measured and calculated based on 1-second scan rate of all sensors located at an automated meteorological station installed at Jornada LTER NPP T-TAYL site. Wind speed is measured at 75 cm, 150 cm, and 300 cm, wind direction at approximately 3m, and air temperature and relative humidity at approximate 2.5m. This climate station is operated by the Jornada LTER Program. This is an ONGOING dataset.

<p indent="0mm">The existence of either a long-term cooling or warming trend during the Holocene has been much debated over the last decade, and seasonality has been proposed as a possible cause for this so-called “Holocene temperature conundrum”. A long-term trend of increasing winter insolation during the Holocene is well documented and accepted, and hence there is the need to find a reliable proxy to reconstruct the long-term trend in summer temperature during the Holocene. In this context, we measured the stable carbon isotope compositions of extracted α-cellulose (<italic>δ</italic>¹³C_cell) from living sedge plants in the sub-alpine Shiwangutian (SWGT) peatland in Chengbu County in Southwest Hunan Province, in the sub-tropical monsoonal humid climate zone of South China. During March 2021 to July 2022, at approximately monthly intervals, we sampled the newly-emergent leaves of sedge plants (SCNY) from three sites in relatively open (SX and ZX) and relatively closed (beneath forest; XX) environments in the SWGT peatland, which were used for <italic>δ</italic>¹³C_cell measurements. During this interval we also conducted <italic>in situ</italic> monitoring of air temperature, water temperature, precipitation amount, and relative humidity in this peatland. The SCNY <italic>δ</italic>¹³C_cell data range from −29.9‰ to −25.4‰, with an average of −27.4‰. The SCNY <italic>δ</italic>¹³C_cell data from the SX and ZX sites, in a relatively open environment, are generally similar and both are systematically ~0.8‰ more positive than the data from the XX site beneath forest. The time series of SCNY <italic>δ</italic>¹³C_cell data from the SX and ZX sites consistently show seasonal characteristics, with more positive values in summer/autumn and more negative values in winter/spring. However, the SCNY <italic>δ</italic>¹³C_cell data from the XX site do not show seasonal characteristics. We conducted linear correlation analyses between the SCNY <italic>δ</italic>¹³C_cell data and the <italic>in-situ</italic> monitoring data of air temperature, water temperature, precipitation amount, and relative humidity of the month prior to the sampling day. The results show that: (1) At both the SX and ZX sites, SCNY <italic>δ</italic>¹³C_cell has significant positive correlations with both the air and water temperature, but there are no significant correlations with precipitation amount and relative humidity. This indicates that temperature is the major factor influencing sedge <italic>δ</italic>¹³C_cell in relatively open environments in the SWGT peatland. (2) At the XX site, SCNY <italic>δ</italic>¹³C_cell is not significantly correlated with air temperature, water temperature, precipitation amount, and relative humidity, which highlights the influence of site-specific environmental factors on sedge <italic>δ</italic>¹³C_cell. Our sedge <italic>δ</italic>¹³C_cell data from a relatively open environment in the sub-tropical monsoonal humid climate zone in South China are consistent with previously reported sedge <italic>δ</italic>¹³C_cell values from the Sahara sand peatland (above the tree line and therefore in an open environment) in the Altai Mountains in arid Northwest China. These observations demonstrate the potential of <italic>δ</italic>¹³C_cell in peatland sedge plants as an indicator of temperature changes. Sedges are common plants in peatlands and therefore we suggest that sedge <italic>δ</italic>¹³C_cell in peat cores is a potentially valuable proxy for obtaining reliable Holocene summer temperature reconstructions, especially in high northern latitude and high-altitude peatlands, because sedges in those peatlands only grow in summer. We conclude that <italic>δ</italic>¹³C_cell in both modern sedges and sedge residues in peat cores warrants further detailed investigations, especially in high-altitude and high-latitude peatlands.

This study aimed to determine the most frequent occurrence times of daily extremes of air temperature and relative humidity in Santa Maria, RS, Brazil. Hourly data from 2002 to 2019 were obtained from an automatic weather station belonging to INMET. The relative frequencies of the times of occurrence of the daily minimum and maximum air temperatures were calculated for each month. The results allowed knowing the times of occurrence of the daily maximum and minimum air temperatures and relative humidity in Santa Maria, RS, Brazil. Thus, it is possible to obtain greater accuracy in the estimation of chill hours, duration of vernalization periods, and in the quantification of stresses caused by inadequate values of these variables in agriculture. The daily minimum air temperature is most frequently recorded at 7:00 a.m., varying from 6:00 a.m. to 8:00 a.m. throughout the year. The daily maximum air temperature occurs most frequently at 4:00 p.m., while in December and January, it is delayed to 5:00 p.m. The daily maximum relative air humidity occurs most frequently at 7:00 a.m., varying from 7:00 a.m. to 9:00 a.m. throughout the year. The daily minimum relative air humidity, on the other hand, occurs most frequently at 5:00 p.m., varying from 4:00 p.m. to 6:00 p.m. in the different months of the year.

Past and recent changes in air and permafrost temperatures in eastern Siberia

Forecasts of increased frequency of meteorological extremes have received considerable attention due to their potential impact on the integrity of biotic communities, stability of terrestrial and aquatic environments, availability of ecosystem services, and broader societal prosperity. Canada is projected to experience greater warming rates than many other regions of the world and changes in meteorological extremes are predicted to be variable across the country. In this context, our goal is to evaluate the long-term trends of extreme meteorological variables (air and dew point temperature, relative humidity, wind speed, and precipitation) in southern and central Ontario (from 42°N to 50°N), while considering the role dynamics of large-scale atmospheric oscillations (El Niño–Southern Oscillation, North Atlantic Oscillation, Arctic Oscillation, and Pacific Decadal Oscillation). Air temperature minima increased year-round, while temperature maxima mainly increased during the cooler months of the year. Consistent with recent evidence from the literature, our study identified an increase in the amount of atmospheric water since the 1950s, as shown by the rising trends in dew point temperature maxima and minima during winter and mid-summer/early-autumn, respectively. Likewise, we found a weak decline in the relative humidity during the warm season, and a more discernible declining trend during the cooler part of the year, which could be in turn reflective of the moderate change of temperature maxima and rising minima, respectively. Consistent with the broader evidence of a global terrestrial stilling, our analysis showed a declining occurrence of high wind-speed events across the entire study domain, and more frequent slow-wind speeds during both warm and cold periods of the year. Interestingly, a closer examination of temporal trends in calm wind frequency provides evidence of a recent reversal in the latter trend with diminishing prevalence of very calm wind conditions. We generally found a weakly increasing temporal trend with maximum total daily precipitation, but without a coherent spatial pattern within the broader study area. Our analysis showed that large-scale phenomena have a discernible signature mostly on air temperature and humidity variables, but had little impact on low relative humidity, high and low wind-speed, and precipitation variability. Given the modest impact of teleconnections on long-term temporal trends, our study concludes that the meteorological extremes are more directly influenced by regional and local heat and humidity balance processes rather than global-scale atmospheric circulation. The observed trends of air temperature, humidity, and wind speed extremes suggest a profound impact on the phenology of aquatic and terrestrial ecosystems and human experience of weather.

MICROCLIMATE CONTROL IN GREENHOUSES BASED ON PHYTOMONITORING DATA AND MOLLIER PHASE DIAGRAM

SUMMARYThe production of winter wheat (Triticum aestivumL.) is affected by crop population structures and field microclimates. This 3-year study assessed the effect of different precision planting patterns and irrigation conditions on relative humidity (RH), air and soil temperature within the canopy, intercepted photosynthetically active radiation (iPAR), evapotranspiration (ET), water productivity (WP) and grain yields. Field experiments were conducted from 2011 to 2014 on a two-factor split-plot design with three replicates. The experiments involved three precision planting patterns (single row, alternating single and twin rows [hereafter ‘single–twin’] and twin row) and three irrigation treatments (0 mm (I0), 90 mm (I90) and 180 mm (I180)). Planting patterns and irrigation treatments exerted a significant effect on RH, air and soil temperature, iPAR,ET,WPand grain yield. The lowest RH and iPAR levels were detected in the single row pattern. When the irrigation treatment was identical, the highest soil and air temperatures were detected in the single row pattern, followed by the single–twin row and twin row patterns. Compared with the single row, the single–twin and twin row patterns increasedETby 0·3 and 1·4,WPby 4·7 and 5·7% and yields by 6·0 and 7·9%, respectively. Compared with I0, the I90and I180irrigation treatments increasedETby 0·3 and 1·4%, andWPby 4·7 and 5·7%, respectively. The grain yields of the twin row pattern were 5·8 and 1·7% higher than those of the single row and single–twin row patterns, respectively. Compared with I0, I90increased yield by 19·3%. The twin row pattern improved crop structure and farmland microclimate by increasing RH and iPAR, and reducing soil and air temperatures, thus increasing grain yield. These results indicated that a twin row pattern effectively improved grain yield at I0. On the basis of iPAR,WPand grain yield, it was concluded that a twin row pattern combined with an I90irrigation treatment provided optimal cropping conditions for the North China plain.

During the total solar eclipse on March 29, 2006 [1], researchers in Kislovodsk measured variations in the flux of the total shortwave radiation, meteorological elements (wind speed and direction and relative air humidity), and turbulence parameters in the surface atmospheric layer, vertical profiles of air temperature in the layer 0‐600 m, functions of particle size distribution (0.20‐1.50 µ m), and concentrations of light ions. It was found that the decrease in the maximum air temperature caused by the eclipse reached 3.5°C in the surface atmospheric layer and approximately 2°C at an altitude of 600 m a.s.l. After the full phase of the eclipse, turbulent kinetic energy decreased by a factor of 2.5, dispersion of the vertical component of the wind speed decreased by a factor of 2.3, turbulent heat flux decreased by a factor of 3.5, and dispersion of turbulent pulsations of air temperature decreased by a factor of 10. Despite the long history of investigations of eclipses [2], the influence of the solar eclipses on processes in the boundary atmospheric layer has not yet been studied sufficiently enough [3‐5]. It is clear that a solar eclipse should lead to variations in the thermal regime of the boundary atmospheric layer, increase in the relative air humidity, and consequent increase in the size of aerosol particles. Variations in the parameters of aerosol along with other factors can change notably the electric characteristics of the surface atmosphere [6]. Decrease in the near-surface air temperature can also lead to variations in the turbulence regime. In order to study the quantitative variations in the above-mentioned parameters of the lower atmosphere during the total solar eclipse in the last decade of March in Kislovodsk (altitude ~900 m a.s.l.), the following measurements were carried out at the urban meteorological station: flux F of total shortwave radiation (CNR1 net radiometer (Kipp and Zonen, Netherlands); accuracy ± 10 W/m 2 ), meteorological parameters (accuracy of measurements: air temperature ± 0.3°C , relative humidity ± 5% , components of wind speed ± 0.15 m/s), turbulent pulsations (digitization step 0.1 s) of three components of wind speed and air temperature using a Meteo-2M acoustic meteorological station (Institute of Atmospheric Optics, Tomsk), vertical profiles of air temperature (time averaging 5 min, spatial averaging 50 m, accuracy of measurements ± 0.5°C ) in layer 0‐ 600 m (MTP-5 UHF microwave profiler of the Central Aerological Observatory [8]), concentrations of negative light ions using a SIGMA-1 counter of aeroions (accuracy of each measurement ± 30% , time constant 1.5 s, mobility of ions >0.4 cm 2 / W · s), and distribution function of the dry base of aerosol particles in the size range 0.20‐1.50 µ m (LAS-P laser spectrometer of aerosols, averaging time of differential countable concentrations of particles 15 s, and random error of measurements of countable concentrations 20%). Calibration of the laser spectrometer was carried out using nuclear filters, which allowed us to increase the accuracy of determination of the boundaries of the particle size ranges determined by the spectrometer.

Global warming can cause deep and extensive changes in the Earth’s climate and changes in the time and place of climatic phenomena. The present trend analysis study assesses cold stress using the thermo-hygrometric index (THI) in the two seasons of autumn and winter in outdoor environments in Iran. The data related to the average of the two variables of daily air temperature and relative humidity from 60 synoptic meteorological stations for a statistical period of 30 years were obtained from the Iranian Meteorological Organization. The THI index was calculated for autumn and winter, and the level of thermal discomfort was determined for each station. The Mann–Kendall statistical test with the help of Minitab ver17.1.0 software was also used to investigate the changes in air temperature, relative humidity and THI index. The THI for autumn increased in 68% of the stations, and this increasing trend is statistically significant in 51% of these stations. The THI for winter increased in 83% of the stations, and this increasing trend is statistically significant in 51% of these stations. In autumn, 53% of the stations were in the range of thermal discomfort, and in winter only 5% were in the range of thermal comfort. The decreasing trend in THI in some climatic types, along with the increasing trend in air temperature, can indicate the decrease in relative humidity in the monitored stations during the studied years. It is recommended to know the temporal and spatial distribution and the probability of occurrence of cold stress through the use of THI in order to adopt preventive measures and policies in the outdoors in Iran.

Assessment of the risks posed by severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) on surfaces requires data on survival of this virus on environmental surfaces and on how survival is affected by environmental variables, such as air temperature (AT) and relative humidity (RH). The use of surrogate viruses has the potential to overcome the challenges of working with SARS-CoV and to increase the available data on coronavirus survival on surfaces. Two potential surrogates were evaluated in this study; transmissible gastroenteritis virus (TGEV) and mouse hepatitis virus (MHV) were used to determine effects of AT and RH on the survival of coronaviruses on stainless steel. At 4 degrees C, infectious virus persisted for as long as 28 days, and the lowest level of inactivation occurred at 20% RH. Inactivation was more rapid at 20 degrees C than at 4 degrees C at all humidity levels; the viruses persisted for 5 to 28 days, and the slowest inactivation occurred at low RH. Both viruses were inactivated more rapidly at 40 degrees C than at 20 degrees C. The relationship between inactivation and RH was not monotonic, and there was greater survival or a greater protective effect at low RH (20%) and high RH (80%) than at moderate RH (50%). There was also evidence of an interaction between AT and RH. The results show that when high numbers of viruses are deposited, TGEV and MHV may survive for days on surfaces at ATs and RHs typical of indoor environments. TGEV and MHV could serve as conservative surrogates for modeling exposure, the risk of transmission, and control measures for pathogenic enveloped viruses, such as SARS-CoV and influenza virus, on health care surfaces.

Emergence from the water ofAnax juniusDrury normally occurred after sunset. The onset was affected independently by water temperature and air temperature; low water temperature and high air temperature delayed the onset of emergence. In the field, the net vrtical distance travelled above the water, before ecdysis, was positively correlated with air temperature. In the laboratory, the vertical distance travelled above the water was greatest when air and water temperatures were approximately the same. The average speed of climbing to the first resting position above the water surface was faster at high than low water temperature, but the average speed of climbing from there to the final position, where ecdysis occurred, was reduced due to the effects of air temperature and humidity. Air temperatures below 12.6 °C were found to retard ecdysis and larvae returned to the water and emerged early the following day making the final process of emergence and ecdysis diurnal instead of nocturnal. The duration of ecdysis was shorter at high than low air temperatures and only the first three stages, as arbitrarily defined, were longer at low than high relative humidity; stage 4, shortened with low relative humidity. This study shows thatA.Junius, emerging from the water is affected at first by the temperature experienced when submerged, but it becomes gradually and cumulatively affected by air temperature and humidity while climbing to the ecdysial position and moulting.

To determine the effectiveness of rehabilitation on improving ecosystem functions, we examined net photosynthetic rate (P N), tree species composition, soil enzyme activities, and the microclimate (air and soil temperature, relative humidity) of an area on Mt. Makiling that has been rehabilitated and protected from fire for over 12 years. After it was last burned extensively in 1991, restoration was initiated by planting Acacia mangium and Acacia auriculiformis. We selected three areas to study in 2003. Two areas were rehabilitated with A. mangium and A. auriculiformis, and one was still dominated by Imperata cylindrica and Saccharum spontaneum. P N of A. mangium and A. auriculiformis showed significantly lower values than those of I. cylindrica and S. spontaneum. The Acacia plantations had more naturally regenerated tree species than the grassland. Additionally, more tree species appeared in the A. mangium plantation than in the A. auriculiformis plantation. Ficus spetica was present in all of the study sites. Dehydrogenase and phosphatase activities were significantly higher in soil under the Acacia plantations than under grassland. Grassland showed higher air temperature, relative humidity, and soil temperature as well as a larger variation per hour in these parameters compared to the Acacia plantations. The highest air temperature, relative humidity, and soil temperature were measured in April during the dry season. From the regression analysis, soil temperature was significantly correlated with air temperature. Hence plantations, as a rehabilitation activity for grassland, promote natural regeneration and stabilize the microclimate. This stabilization of the microclimate affects establishment and growth of naturally occurring tree species.

Role of street trees in mitigating effects of heat and drought at highly sealed urban sites

The aim of the present study is to assess changes in the Baltic Sea climate based on different available meteorological data sources (ERA40 and ERA-INTERIM) and various published Baltic Sea climate indices. This regional assessment will be presented in relation to global climate change and assessments available from the literature. The climate of the Baltic Sea which is located between 50N and 70N is mainly influenced by the competition of westerly humid air flow and easterly continental type air masses and is therefore highly variable. We are investigating air temperature, wind speed, cloud cover, solar radiation and precipitation. Comparisons to climate indices of general relevance as the Baltic ice cover will be conducted. Using regression analysis we could confirm the following basic trends, increase in air temperature, increase in precipitation, increase in cloudiness. The increase in air temperature in the Baltic Sea area (0.02K/year) is much more rapid then the warming trend for the global air temperature (0.005K/year). The increase in cloudiness has resulted in an effective reduction of incoming solar radiation therefore the accelerated warming is not a result of increased solar radiation, but likely due to an increased net long wave radiation input. Further it has to be mentioned that not all available data sets confirmed the trend in cloudiness, ERA40 data show a nonsignificant decrease instead. No clear trend in the wind velocities could be detected, but wind velocities from ERA40 reanalysis project show an insignificant increase in wind speeds. Results from model runs with the GETM model (General Estuarine Transport Model, http://getm.eu) show sea surface warming consistent with the increase in heat flux forcing and with satellite observations. The warmer sea surface without an adequate warming in the deeper parts results in a much stronger vertical density stratification and consequently to reduced vertical mixing. A more thorough inspection of the available regional and global data provides some reasonable doubt concerning the application of least square regression analysis to the available time series. Indeed it can be shown by a test based on the F statistics that most of the analyzed time series cannot be considered as stationary and therefore drawing simple regression lines trough these datasets is statistically incorrect. Testing for structural breakpoints in these time series reveals for many investigated parameters and also for many tested climate indices the existence of such breakpoints in the 70-80ties of the last century. Therefore it has to be concluded that the simple trend estimation for many climate parameters is statistically incorrect. Instead for statistical investigations it has to be assumed that there exist either 2 different climate states with either 2 different means or alternatively with 2 different trends which have to be estimated separately.