Standard Pressure Levels Research Articles

Influence of air temperature and interrelationship with greenhouse gases (CO2 and CH4) over Iraq using AIRS data

Global and regional observations of air temperature (AT) and specific atmospheric greenhouse gases (GHGs) such as methane (CH4) and carbon dioxide (CO2) are required for a variety of applications, including constraining global or regional estimates of their significant impacts on the climate system. The present study employs Atmospheric Infrared Sounder (AIRS) -Level3 monthly products for AT, CH4, and CO2, at two standard pressure levels (925 and 500 hPa) over Iraq during 2010–2016. Both CO2 and CH4 shows significant seasonal variation, with maximum (minimum) CO2 observed in June (October), while CH4 recorded three maximum peaks during April, August, and November, and a minimum in February. CH4 shows a negative correlation during winter (DJF), spring (MAM), summer (JJA), and autumn (SON) with correlation coefficients (R) −0.627, −0.734, −0.491, and −0.688, respectively. The P-value is below 0.05 (4.14 × 10−15, 2.13 × 10−22, 1.1 × 10−8, and 5.2 × 10−19) for the four seasons, indicating a negative linear relationship. CO2 shows a low negative correlation in DJF and SON, and a low positive correlation in MAM and JJA seasons, with R values equal to −0.315, −0.221, 0.059, and 0.079, for DJF, SON, MAM and JJA seasons, respectively. The P-value was greater than 0.05 (0.061, 0.728, 0.647, and 0.195) for the four seasons, respectively, indicating a nonlinear relationship with AT. The monthly averaged time-series for CH4 and CO2 shows an evident increase, with an annual average increase of 1.81% (4.75) ppbv/year and 3.31% (1.84) ppm/year, respectively. Analysis reveals that the major sink and sources for CH4 are the presence of hydroxyl (OH) radicals and vegetation, whereas the major sources for CO2 are anthropogenic emissions, burning fossil fuels, and land-use change. The satellite observations of AIRS can efficiently show the spatiotemporal variations of air temperature versus CH4 and CO2 for the study area.

Comparison of measurement methods of room sound energy for sound insulation performance evaluation at low frequencies

In the field measurement of acoustic performances, such as sound insulation and floor impact sound insulation, sound pressure level is usually measured to find the sound energy in a closed space. However, the sound pressure level at low frequencies such as the 63 Hz band depends on the measurement position due to the influence of the room eigenmodes, which leads to large uncertainties of the measured average sound pressure levels in rooms. In this study, several measurement methods of sound energy were applied to the low-frequency sound field of a mock-up room that simulates a source room in an RC apartment. Along with the standard sound pressure level measurement, the low-frequency procedure according to ISO 16283 series and acoustic energy density measurement using the combined particle velocity-pressure sensor were conducted, and their accuracies were evaluated based on the average sound pressure obtained by the grid-point measurement over the entire room.

Modeling field measurements of sound insulation for multi-layered CLT-based floor systems: A means of a prediction model using artificial neural networks

A neural network-based prediction tool is developed to calculate the standardized sound level differences and the standardized impact sound pressure levels for multi-layered CLT-floor systems. The data for this model is derived from 104 sound insulation measurements in one-third-octave bands from 50 Hz to 5 kHz taken from 15 buildings in Europe with different room sizes and functions. The network model is developed using various structural parameters such as floor components, wall types, junction types and interlayers, receiving room volume, surface separating area, and more. The network developed shows good performance in predicting standardized airborne and impact sound insulation curves over all frequencies. The weighted standardized level differences DnTw are estimated with an accuracy of 1 dB, while the standard impact sound pressure level LnTw′ is accurate up to 2 dB. The airborne predictions are correlated in the middle-frequency range (200–1000 Hz), while some deviations may occur in higher frequencies. Impact insulation estimations, on the other hand, are more accurate in the high-frequency range (1.25–5 kHz). A sensitivity study is conducted to understand the model’s dependence on parameters. In both types of estimations, the direct sound path through the floor is the most influential factor, with the flanking paths affecting the results in the second order. Additionally, the volume of the receiving room significantly affects impact estimations at low frequencies. The study’s results also emphasize the importance of a visco-elastic interlayer for accurate airborne predictions in all frequency ranges.

Assessment of hearing loss risk due to impact noise in industrial environments

Impact noises are often found in industrial environments and they are predominant in mining, construction, factories, workshops, and shipyards. It is well-known that impact noises are more likely to cause noise-induced hearing loss than continuous noise of equal energy. Impulse noises are characterized by their high intensity over a short period of time and many countries have defined impulse noise exposure limits and criteria in occupational settings. They are based on the sound level measurements made using standard sound pressure level meters and dosemeters. However, because of their metrological limitations, it is not appropriate to use these instruments when dealing with such high peak levels and short duration times. Extensive research on hearing damage produced by impulse noise generated by firearms has been presented, mainly on police and military personnel. These studies have led to damage risk criteria contained in various versions of the standard MIL-STD-1474. Although industrial noises can reach similar peak sound pressure levels, not many results have been published on the subject. In this work, several common sources of industrial impact noise were measured in-situ, at the worker locations, using a specialized system equipped with high-dynamic-range microphones and a very high data acquisition rate. The signals were post-processed to obtain the main metrics defined for impulse noise exposure assessment. Then, occupational hearing loss risk was estimated using different criteria. It is shown that many common industrial processes reported a very high risk of impulsive noise to human hearing.

Monitoring sudden stratospheric warmings under climate change since 1980 based on reanalysis data verified by radio occultation

Abstract. We developed a new approach to monitor sudden stratospheric warming (SSW) events under climate change since 1980 based on reanalysis data verified by radio occultation data. We constructed gridded daily mean temperature anomalies from the input fields at different vertical resolutions (basic-case full resolution, cross-check with reanalysis at 10 stratospheric standard pressure levels or 10 and 50 hPa levels only) and employed the concept of threshold exceedance areas (TEAs), the geographic areas wherein the anomalies exceed predefined thresholds (such as 30 K), to monitor the phenomena. We derived main-phase TEAs, representing combined middle- and lower-stratospheric warming, to monitor SSWs on a daily basis. Based on the main-phase TEAs, three key metrics, including main-phase duration, area, and strength, are estimated and used for the detection and classification of SSW events. An SSW is defined to be detected if the main-phase warming lasts at least 6 d. According to the strength, SSW events are classified into minor, major, and extreme. An informative 42 winters' SSW climatology (1980–2021) was developed, including the three key metrics as well as onset date, maximum-warming-anomaly location, and other valuable SSW characterization information. The results and validation against previous studies underpin that the new method is robust for SSW detection and monitoring and that it can be applied to any quality-assured reanalysis, observational and model temperature data that cover the polar region and winter timeframes of interest, either using high-vertical-resolution input data (preferable basic case), coarser standard-pressure-levels resolution, or (at least) 10 and 50 hPa pressure level data. Within the 42 winters, 43 SSW events were detected for the basic case, yielding a frequency of about 1 event per year. In the 1990s, where recent studies showed gaps, we detected several events. Over 95 % of event onset dates occurred in deep winter (December–January–February timeframe, about 50 % in January), and more than three-quarters have their onset location over northern Eurasia and the adjacent polar ocean. Regarding long-term change, we found a statistically significant increase in the duration of SSW main-phase warmings of about 5(±2) d over the climate change period from the 1980s to the 2010s, raising the average duration by nearly 50 % from about 10 d to 15 d and inducing an SSW strength increase of about 40(±25) million km2 days from about 100 to 140 million km2 days. The results are robust (consistent within uncertainties) across the use of different input data resolutions. They can hence be used as a reference for further climate-change-related studies and as a valuable basis for studying SSW impacts and links to other weather and climate phenomena, such as changes in polar-vortex dynamics and in mid-latitude extreme weather.

The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere

Abstract. In this paper, the effects of ice-supersaturated regions and thin, subvisual cirrus clouds on lapse rates are examined. For that, probability distribution and density functions of the lapse rate and the potential temperature gradients from 10 years of measurement data from the MOZAIC/IAGOS project and ERA5 reanalysis data were produced, and an analysis of an example case of an ice-supersaturated region with a large vertical extent is performed. For the study of the probability distribution and density functions, a distinction is made between ice-subsaturated and ice-supersaturated air masses (persistent contrails) and situations of particularly high ice supersaturation that allow the formation of optically thick and strongly warming contrails. The estimation of the lapse rates involves two adjacent standard pressure levels of the reanalysis surrounding MOZAIC's measurement/flight points. If the upper of these levels is in the stratosphere, the distribution function for subsaturated cases shows much lower lapse rates than those of supersaturated cases. If all levels are in the troposphere, the distributions become more similar, but the average lapse rates are still higher in supersaturated than in subsaturated cases, and the distributions peak at higher values and are narrower in ice-supersaturated regions (ISSRs) than elsewhere. This narrowing is particularly pronounced if there is substantial supersaturation. For the examination of an example case, ERA5 data and forecasts from ICON-EU (DWD) are compared. ERA5 data, in particular, show a large ice-supersaturated region below the tropopause, which was pushed up by uplifting air, while the data of ICON-EU indicate areas of saturation. The lapse rate in this ice-supersaturated region (ISSR), which is large, is associated with clouds and high relative humidity. Supersaturation and cloud formation result from uplifting of air layers. The temperature gradient within an uplifting layer steepens, for both dry and moist air. As soon as condensation or ice formation starts in the upper part of a lifting layer, the release of latent heat begins to decrease the lapse rate, but radiation starts to act in the opposite direction, keeping the lapse rate high. The highest lapse rates close to the stability limit can only be reached in potentially unstable situations.

The Vertical variations of Atmospheric Methane (CH4) concentrations over selected cities in Iraq based on AIRS data

The Atmospheric Infrared Sounder (AIRS) on EOS/Aqua satellite provides diverse measurements of Methane (CH4) distribution at different pressure levels in the Earth's atmosphere. The focus of this research is to analyze the vertical variations of (CH4) volume mixing ratio (VMR) time-series data at four Standard pressure levels SPL (925, 850, 600, and 300 hPa) in the troposphere above six cities in Iraq from January 2003 to September 2016. The analysis results of monthly average CH4VMR time-series data show a significant increase between 2003 and 2016, especially from 2009 to 2016; the minimum values of CH4 were in 2003 while the maximum values were in 2016. The vertical distribution of CH4 was relatively high in the cities located in the north of Iraq (Sulaymaniyah and Mosul) more than other cities, especially these in western Iraq (Rutba and Najaf). The highest monthly mean of CH4VMR and standard deviation (SD) was in Sulaymaniyah (1871.11±21.92) ppbv at 925 hPa, while the lowest was in Rutba (1812.81±37.3) ppbv at 300 hPa. Mosul has the second-highest mean and SD next to Sulaymaniyah, especially at the lower levels SPL (925 and 850 hPa) of troposphere more than the rest of selected cities. The seasonal variation of monthly CH4VMR, averaged from 2003 to 2016, shows high values between January and August with a peak between August and September and it declines significantly between October and December with a slight increase in November. Long term trend analysis of monthly CH4VMR at each SPL (925, 850, 600, and 300) hPa above the six cities shows positive values with average growth rates for each SPL equal to (2.9 %, 3.1%, 3.6 %, and 3.9%), respectively. These results indicate that satellite measurements were effective in determining the magnitude of increased CH4 over Iraq that may contribute to the global increase of CH4 in the earth’s Atmosphere.

Mediterranean contemporary winter and summer air mass climatology with respect to temperature and moisture flux

Large-scale moisture fluxes and backward air mass trajectories and frequencies were investigated to explain the mechanisms of synoptic-scale seasonal variability of air masses in the Mediterranean basin. For this aim, reanalysis data were used to calculate variations in moisture flux with respect to temperature and stability according to the 8 standard pressure levels between 1000 and 300 hPa. Investigating air mass characteristics changing with pressure levels provided new information in terms of air mass climatology for the Mediterranean basin. Results show that due to the influence of westerly flows, the Atlantic is the main source of moisture higher than 700 hPa. Turbulent transport of moisture from the Mediterranean Sea is the source of moisture close to the surface, which corresponds to levels lower than 700 hPa. According to the trajectory analysis, the continental Arctic (cA) air mass can reach the Mediterranean basin and provide very wet conditions over the Mediterranean basin during winter. In addition, during very dry conditions in summer, all air mass currents originate from surface pressure levels between 1000 and 850 hPa. These relatively warm and dominant air masses cause cloud-free conditions with very low precipitation over the Mediterranean basin. This study showed that air masses should be analyzed not only according to their source and path but also according to pressure levels. Therefore, more studies are needed investigating the contemporary air mass climatology of a specific region.

Temperature inversions in the atmospheric boundary layer and lower troposphere over the Sichuan Basin, China: Climatology and impacts on air pollution

The Sichuan Basin (SB) is one of the four most severely polluted regions in China in terms of air quality, and the frequent generation of temperature inversions is a key factor. The deep mountain-basin topography and the geographical location adjacent to the Tibetan Plateau combine to make the inversion characteristics of this region unique. Knowledge regarding these characteristics remains limited, however. In this study, the radiosonde data at standard pressure levels and significant levels from all SB operational radiosonde stations over 2015–2018 were used to document the climatological features of the inversions from the surface to a height of 5500 m and to evaluate the impact on local air pollutant concentrations.Results revealed that the temperature inversion in the SB is a common and year-round phenomenon. The annual inversion frequency, depth, and strength values are 74.4%, 252.2 m, and 1.3 °C/100 m, respectively. The inversions are most frequent (95.4%), deepest (289.4 m), and strongest (1.6 °C/100 m) in winter. They tend to occur at one of two heights, either below 600 m or between 2200 and 3500 m. Based on their bottom heights, the inversions were divided into three groups: surface-based inversions (SIs), elevated inversions (EIs), and lower-troposphere inversions (LTIs). Annual LTI is most frequent (63.0%) and deepest (264.7 m), while annual SI is strongest (1.8 °C/100 m). Extreme contrasts exist in the seasonal properties of different inversion types. All types of inversions play a considerable role in air pollution, resulting in a high probability of severe and very serious pollution in winter. SI has a greater impact on pollutant concentrations than EI and LTI. The frequent generation of LTIs is a unique feature of the deep SB. LITs exert a significant impact on the formation of local heavy air pollution, but have not been given sufficient attention.

Analysis of the dietary factors associated with suspected pediatric nonalcoholic fatty liver disease and potential liver fibrosis: Korean National Health and Nutrition Examination Survey 2014-2017

BackgroundThe prevalence of nonalcoholic fatty liver disease (NAFLD) has increased as the obese pediatric population has increased. NAFLD causes progressive liver injury and the only effective treatment is lifestyle modifications. However, few studies have examined the dietary risk factors for pediatric NAFLD or liver fibrosis. Here, we evaluated the dietary factors associated with suspected NAFLD and potential liver fibrosis in Korean children.MethodsData collected from 1674 children and adolescents aged 10–18 years during the 2014–2017 Korean National Health and Nutrition Examination Surveys analyzed. The 24-h recall method measured the food consumed 1 day before the survey. The “suspected NAFLD” group included excessive body mass index (BMI) subjects ≥ 85th percentile) with alanine aminotransferase (ALT) levels exceeding the upper normal limit (24.1 U/L for boys and 17.7 U/L for girls); the “healthy control” group included subjects with a BMI and ALT level below these thresholds. Sodium intake was assessed by the urinary sodium-to-urinary specific gravity unit ratio (U-Na-to-SGU ratio). A pediatric NAFLD index (PNFI) higher than 3 indicated potential liver fibrosis.ResultsThe overall prevalence of suspected NAFLD and potential liver fibrosis was 8.2 and 4.5%, respectively. The suspected NAFLD group had a larger proportion of males and subject with a greater height, BMI standard deviation score (BMI-SDS), systolic and diastolic blood pressure SDS, waist circumference, hemoglobin A1c, and levels of total cholesterol, triglycerides, aspartate aminotransferase (AST) and ALT than the control group. The suspected NAFLD group presented significantly higher U-Na-to-SGU ratios and cholesterol intake. The PNFI > 3 subgroup included a significantly larger proportion of males and subjects with higher BMI-SDS, AST and ALT values, and intake of water, carbohydrate, protein, calcium, phosphorus, iron and vitamin B2. After adjusting for confounders, male, BMI-SDS, AST, and protein and carbohydrate intake were independent risk factors for potential liver fibrosis. Niacin intake was an independent protective factor for potential liver fibrosis.ConclusionsChildren with suspected NAFLD had higher urinary sodium level and cholesterol intake than healthy controls. Protein and carbohydrate intake were independent risk factors for potential liver fibrosis; niacin was an independent protective factor.

Inter-reanalysis differences of the temperature trends in the MERRA-2.0 and ERA-Interim: comparison of the middle and lower atmosphere

Studying the long-term temperature variations and trends helps to understand the role of human activities in climate change. We present the temperature trends (calculated by the linear regression method) in the Northern hemisphere in all seasons for the period of 1980–2016 for the ERA-Interim and MERRA-2.0 reanalyses. The temperature trends are analyzed for the six standard post-processed pressure levels (850, 500, and 250 hPa for the troposphere and 70, 10, and 2 hPa for the stratosphere). In addition, we calculate the non-parametric Mann-Kendall test to detect the statistically significant temperature trends in different pressure levels and seasons. It is found that both reanalyses have a negative temperature trend (cooling) in the stratosphere, and the magnitude of the cooling rates increases with increasing height. While the largest cooling trend (by considering all pressure levels and seasons) occurs in the autumn for the MERRA-2.0 (− 0.167 K/year), the largest cooling trend is in winter for the ERA-Interim (− 0.118 K/year). Furthermore, the results of the MANN-Kendall test reveal considerable differences in terms of statistically significant temperature changes between two reanalyses at 10 hPa where the cooling trends are statistically significant at 99% level in all seasons in MERRA-2.0 reanalysis while the temperature changes are only significant at 99% level in autumn in ERA-Interim. In general, the magnitude of the cooling trends in the middle and upper stratosphere is higher for the MERRA-2.0 than ERA-Interim. Positive temperature trends (warming) are found for the bulk of troposphere, though the magnitude of the temperature changes over the study period is higher in the lower troposphere (at 850 hPa at 99% confidence level) for both reanalyses. The largest warming rates are found during autumn season where the magnitude of the temperature changes are + 0.031 (K/year) and + 0.033 (K/year) for the MERRA-2.0 and ERA-Interim, respectively. Our results suggest a high level of uncertainty in the temperature trends in the middle and upper stratosphere and a reasonable agreement between ERA-Interim and MERRA-2.0 warming trend in the troposphere. We also briefly discuss the role of different sources of uncertainty of the temperature trends in the middle and upper stratosphere.

Temperature inversions in severe polluted days derived from radiosonde data in North China from 2011 to 2016

Temperature inversion tends to inhibit the transfer of momentum, heat and moisture in the atmospheric boundary layer, which is often accompanied by severe air pollution. Recently, severe haze pollution has frequently occurred in North China. In this study, the characteristics of temperature inversion on severe polluted days (SPDs) in Beijing were investigated by using radiosonde data with standard pressure levels from 2011 to 2016. Both surface-based inversion (SI) and elevated inversion (EI) were analyzed. 93% of the SPDs were accompanied by temperature inversion, most of which occurred in wintertime. Annual frequency of SI (FSI) and EI (FEI) showed slight fluctuations with mean value of 0.18 and 0.67, respectively. Overall, the annual SI was stronger and deeper than annual EI. Seasonally, the SI was most frequent (0.39) in autumn, in contrast to EI that occurred most frequently (0.95) in summer. Both SI and EI were weakest in summer and strongest in winter. Average monthly SI strength was about 0.38 °C in summer and 2.40 °C in winter, average monthly EI strength was about 0.64 °C in summer and 2.20 °C in winter. The average monthly SI and EI were deepest in winter and shallowest in summer. SI depth were 778 m and 221 m in winter and summer, EI were 630 m and 336 m in winter and summer. The substantially strong liner relationship was found between seasonal inversion strength and PM2.5 concentration, and the inversion strength was found to be better compared with the inversion depth at predicting the PM2.5 concentration during SPDs. Obvious lower air outflow and turbulent kinetic energy were found in SPDs compared to non-SPDs, which indicated weaker turbulence in SPDs. Future efforts should focus on accurate model simulations of temperature inversions in SPDs.

Effects of Different Spectral Shapes and Amplitude Modulation of Broadband Noise on Annoyance Reactions in a Controlled Listening Experiment.

Environmental noise from transportation or industrial infrastructure typically has a broad frequency range. Different sources may have disparate acoustical characteristics, which may in turn affect noise annoyance. However, knowledge of the relative contribution of the different acoustical characteristics of broadband noise to annoyance is still scarce. In this study, the subjectively perceived short-term (acute) annoyance reactions to different broadband sounds (namely, realistic outdoor wind turbine and artificial, generic sounds) at 40 dBA were investigated in a controlled laboratory listening experiment. Combined with the factorial design of the experiment, the sounds allowed for separation of the effects of three acoustical characteristics on annoyance, namely, spectral shape, depth of periodic amplitude modulation (AM), and occurrence (or absence) of random AM. Fifty-two participants rated their annoyance with the sounds. Annoyance increased with increasing energy content in the low-frequency range as well as with depth of periodic AM, and was higher in situations with random AM than without. Similar annoyance changes would be evoked by sound pressure level changes of up to 8 dB. The results suggest that besides standard sound pressure level metrics, other acoustical characteristics of (broadband) noise should also be considered in environmental impact assessments, e.g., in the context of wind turbine installations.

Pressure comfort sensation and discrimination on female body below waistline

The garment pressure comfort sensation and discrimination were studied in the paper. The garment pressure comfort threshold and difference threshold were defined and calculated according to staircase method of psychophysics. In experiment, 10 subjects were employed in sensory tests and pressure measurements. A novel stretchable compressive belt was developed, which was used to control the pressure applied on separate body parts by its extension and intention, and the subjects judgement and pressure monitor were recorded in times. Finally, the comfort thresholds at nine separate body parts below waistline and difference thresholds at three parts & three varied standard pressure levels were investigated. This study provided proper comfort pressure range to human body for developing compression wear.Practitioner summary: Garment pressure comfort and difference threshold were firstly defined and calculated according to staircase method of psychophysics. The comfort thresholds at nine body parts and difference thresholds at three parts & three varied standard pressure levels were investigated. This study provided proper comfort pressure range to human body for developing compression wear.

Near real-time tropospheric water vapour profiling using a ground-based GPS receiver

ABSTRACTThis article presents a remote-sensing tool employing an artificial neural networks algorithm for near real-time determination of the relative humidity (RH) profile above a site using global positioning system (GPS) data recorded by a ground-based GPS receiver. GPS data were processed to obtain Integrated Water Vapour. The integrated water vapour in conjunction with ground level information for temperature, pressure, and RH was fed as inputs to the developed neural network which in turn generated the instantaneous RH profile, at six standard pressure levels of 100, 150, 200, 300, 500, and 700 hPa, as output. GPS and radiosonde data for the years 2009 and 2010 were used to train the system while the same data for 2011 were used to validate the system. The relative humidity profile results for 2011 generated using GPS data and the neural network, upon comparison with recorded in situ radiosonde RH profile measurements for the same days and times in the year 2011, had root mean square error of less than 4%, which falls within the margin of error of the Vaisala RS92 Radiosonde’s humidity measurement regime.

Trends and annual cycles in soundings of Arctic tropospheric ozone

Abstract. Ozone soundings from nine Nordic stations have been homogenized and interpolated to standard pressure levels. The different stations have very different data coverage; the longest period with data is from the end of the 1980s to 2014. At each pressure level the homogenized ozone time series have been analysed with a model that includes both low-frequency variability in the form of a polynomial, an annual cycle with harmonics, the possibility for low-frequency variability in the annual amplitude and phasing, and either white noise or noise given by a first-order autoregressive process. The fitting of the parameters is performed with a Bayesian approach not only giving the mean values but also confidence intervals. The results show that all stations agree on a well-defined annual cycle in the free troposphere with a relatively confined maximum in the early summer. Regarding the low-frequency variability, it is found that Scoresbysund, Ny Ålesund, Sodankylä, Eureka, and Ørland show similar, significant signals with a maximum near 2005 followed by a decrease. This change is characteristic for all pressure levels in the free troposphere. A significant change in the annual cycle was found for Ny Ålesund, Scoresbysund, and Sodankylä. The changes at these stations are in agreement with the interpretation that the early summer maximum is appearing earlier in the year. The results are shown to be robust to the different settings of the model parameters such as the order of the polynomial, number of harmonics in the annual cycle, and the type of noise.

Evaluation of model‐generated vertical profiles of meteorological variables: method and initial results

ABSTRACTMeteorological centres compare global and large‐scale regional model output versus radiosonde data more or less continuously for specific models and also make inter‐model comparisons. They normally provide comparisons of meteorological variables at standard pressure levels, and similar comparisons for finer‐scale models may be found as output from field tests and other experiments. Additional means to evaluate vertical profiles derived from model output more fully should help provide a more complete evaluation of model output compared with observations. Here, two versions of a program to produce vertical profiles of meteorological variables in terms of user input heights or pressure levels are developed, and integrated mean value profiles of the variables for layers defined by those heights or pressures are generated. Output profiles were entered into spreadsheets for calculation of the derived variables of density and vector wind speed. The level and mean layer values from the Weather Research and Forecasting model (version 3.6.1) were compared with co‐incident World Meteorological Organization radiosonde observation data and the differences were computed for several variables. The methods developed here may be used for a variety of model‐generated and observed vertical profiles with only minimal changes, primarily to the input function.

Atmospheric circulation characteristics favouring extreme precipitation in Turkey

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 71:139-153 (2016) - DOI: https://doi.org/10.3354/cr01433 Atmospheric circulation characteristics favouring extreme precipitation in Turkey C. J. Lolis1,*, M. Türkeş2 1Laboratory of Meteorology, Department of Physics, University of Ioannina, 45110 Ioannina, Greece 2Bogazici University Center for Climate Change and Policy Studies, 34342 İstanbul, Turkey *Corresponding author: chlolis@uoi.gr ABSTRACT: The atmospheric circulation characteristics over Europe and the Mediterranean that favour extreme precipitation in Turkey are analysed. In total, 326 extreme precipitation events in Turkey are defined using a criterion involving the upper 1 and 5% percentiles of daily precipitation at 70 meteorological stations for the period 1979 to 2011. The 500 and 1000 hPa standard pressure level geopotential heights, 850 hPa level air temperature and relative humidity, 500 hPa level relative vorticity, 925 hPa level divergence and convective available potential energy obtained from the ERA-Interim data set are examined for the days before, during and after the events. A multivariate statistical approach including factor analysis and k-means cluster analysis is followed, and the events are classified into 7 clusters according to the corresponding atmospheric circulation characteristics. The results show that in most cases, a west to east movement of strong upper air disturbances (mainly troughs with strong gradient toward or over Turkey) and low-pressure systems over the Eastern Mediterranean Basin, particularly south of Turkey, play a significant role for the occurrence of extreme precipitation events. The details referring to the areas of low level convergence, positive vorticity advection, high relative humidity and instability play a dominant role in the spatial and temporal distribution of the events. KEY WORDS: Turkey · Mediterranean · Extreme precipitation · Atmospheric circulation · Factor analysis · k-means cluster analysis Full text in pdf format Supplementary material PreviousNextCite this article as: Lolis CJ, Türkeş M (2016) Atmospheric circulation characteristics favouring extreme precipitation in Turkey. Clim Res 71:139-153. https://doi.org/10.3354/cr01433 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 71, No. 2. Online publication date: December 28, 2016 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2016 Inter-Research.

COMMUNITY NOISE IN GREATER CAIRO

Noise is unwanted sound. Community (environmental) noise is defined as noise emitted from all sources except noise at the work place. Sources include road traffic; rail and air traffic; industry; construction; public works and neighbourhood noise. LAeq,T is the energy average equivalent level of the A-weighted sound over period T. Hazardous effects of community noise have been known for ages, however, noise problems of the past are not to be compared with those of modern society. Studies in the European Union have indicated that noise is one of the major sources of coronary heart disease. In Egypt, as in other developing countries, community noise is a serious problem. Health effects of community noise include hearing impairment; effects on speech intelligibility; sleep disturbances; effects on blood pressure, heart rate, and other physiological functions; effects on performance and on mental health; behavioural effects and annoyance. Control of noise in Egypt is regulated by environmental law 4/1994 and its executive regulations. A study of community noise in the three Governorates of Greater Cairo indicated that the sound pressure levels in most of the studied areas were above the Egyptian standards. In and around schools, sound pressure levels exceeded the Egyptian standards. On Cairo streets community noise was found to be related to the width of the street, number of lanes and traffic density as well as the behaviour of drivers. Standard sound pressure levels for special environments were also referred to. Sources of community noise in the Egyptian environment were discussed. Control of community noise included measures related to the means of transportation, urban planning, architectural design of buildings, social activities and government actions.

기온감률의 일중 경시변화 예측 가능성

경계층 내에서는 일중 시간대에 따라 기온감률의 변이가 크므로, 복잡지형의 기온분포 추정에 흔히 사용되는 표준기온감률보다 현실성 있는 매시 기온감률 추정 방법을 고안하였다. 이 방법에서는 기온 경시변동의 장기간 평균을 기준으로 하되, 표준등압면 1000-925hPa 층위의 기온감률을 이용하여 기온감률 표준곡선을 작성하고, 여기에 매시 운량에 따라 보정된 기온감률이 모의된다. 신뢰성 검증을 위해 대관령 지역에 적용하여 10개월 간 매시 기온감률을 추정하고 그 결과를 초음파 기온프로파일러로부터 얻은 지상 500-600m 층위 실측 기온감률과 비교한 결과, ME <TEX>$-0.0001^{\circ}C/m$</TEX>, RMSE <TEX>$0.0024^{\circ}C/m$</TEX>였다. 이 방법을 지상 1.5m에서 측정되는 산사면의 고도별 기온감률 추정에 적용할 수 있는지 확인하기 위해 복잡지형인 '하동2수위표' 표준유역의 313-401m 고도구간 매시 기온감률을 계산하였다. 해당 유역 산사면 여러 지점으로부터 실측기온을 얻어 기온감률을 구한 다음 추정값과 비교한 결과 대관령의 연직 프로파일에 비해 오차가 컸지만 하늘상태에 따른 일중 기온감률의 변동경향은 이 방법에 의해 모의할 수 있었다. Temperature lapse rate within the planetary boundary layer shows a diurnal cycle with a substantial variation. The widely-used lapse rate value for the standard atmosphere may result in unaffordable errors if used in interpolating hourly temperature in complex terrain. We propose a simple method for estimating hourly lapse rate and evaluate whether this scheme is better than the conventional method using the standard lapse rate. A standard curve for lapse rate based on the diurnal course of temperature was drawn using upper air temperature for 1000hPa and 925hPa standard pressure levels. It was modulated by the hourly sky condition (amount of clouds). In order to test the reliability of this method, hourly lapse rates for the 500-600m layer over Daegwallyeong site were estimated by this method and compared with the measured values by an ultrasonic temperature profiler. Results showed the mean error <TEX>$-0.0001^{\circ}C/m$</TEX> and the root mean square error <TEX>$0.0024^{\circ}C/m$</TEX> for this vertical profile experiment. An additional experiment was carried out to test if this method is applicable for the mountain slope lapse rate. Hourly lapse rates for the 313-401m slope range in a complex watershed ('Hadong Watermark 2') were estimated by this method and compared with the observations. We found this method useful in describing diurnal cycle and variation of the mountain slope lapse rate over a complex terrain despite larger error compared with the vertical profile experiment.