Atmospheric Temperature Inversion Research Articles

Temporal Analysis of Airborne Particulate Matter Reveals a Dose-Rate Effect on Mortality in El Paso: Indications of Differential Toxicity for Different Particle Mixtures

One of two topics explored is the limitations of the daily average in summarizing pollutant hourly profiles. The daily average of hourly measurements of air pollutant constituents provides continuity with previous studies using monitoring technology that only provided the daily average. However, other summary statistics are needed that make better use of all available information in 24-hr profiles. The daily average reflects the total daily dose, obscuring hourly resolution of the dose rate. Air pollutant exposures with comparable total daily doses may have very different effects when occurring at high levels over a few hours as opposed to low levels over a longer time. Alternative data-based choices for summary statistics are provided using principal component analysis to capture the exposure dose rate, while preserving ease of interpretation. This is demonstrated using the earliest hourly particle concentration data available for El Paso from archived records of particulate matter (PM)10. In this way, a significant association between evening PM10 exposures and nonaccidental daily mortality is found in El Paso from 1992 to 1995, otherwise missed using the daily average. Secondly, the nature and, hence, effects of particles in the ambient aerosol during El Paso sandstorms is believed different from that of particles present during stillair conditions resulting from atmospheric temperature inversions. To investigate this, wind speed (ws) is used as a surrogate variable to label PM10 exposures as Low-ws (primarily fine particles), High-ws (primarily coarse particles), or Mid-ws (a mixture of fine and coarse particles). A High-ws evening is significantly associated with a 10% lower risk of mortality on the succeeding third day, as compared with comparable exposures at Low- or Mid-ws. Although this analysis cannot be used to form firm conclusions because it uses a very small data set, it demonstrates the limitations of the daily average and suggests differential toxicity for different particle compositions.

Satellite remote sounding of atmospheric boundary layer temperature inversions over the subtropical eastern Pacific

We describe atmospheric temperature inversions and height‐resolved water vapor fields over the wintertime subtropical northeastern Pacific Ocean in observations by the satellite‐borne Atmospheric Infrared Sounder (AIRS) experiment. A comparison with model analyses shows good agreement in temperature. Water vapor comparisons with operational radiosondes at four sites in California and Hawaii during December 2002–January 2003 have low biases in the 1000–700 and 700–500 hPa layers. Maps of inversion frequency, and, water vapor at 1000–700 and 700–500 hPa over the subtropical northeast Pacific during 1–16 January 2003–when high pressure and clear conditions prevail–show inversions occurring at a local minimum in water vapor at 1000–700 hPa. Water vapor at 700–500 hPa has a broad minimum extending from Baja California to Hawaii, with inversions found on its eastern half. These observations illustrate the potential of the AIRS data for describing a climatology of temperature and water vapor in subtropical oceanic regions.

Detection and Analysis of Clear-Sky, Low-Level Atmospheric Temperature Inversions with MODIS

The near-surface atmosphere of the polar region is characterized by temperature inversions throughout most of the year. However, radiosonde data are sparse, and numerical weather prediction models have relatively poor vertical resolution for boundary layer studies. A method is developed for detecting and estimating the characteristics of clear-sky, low-level temperature inversions using the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites. The method is based on an empirical relationship between the inversion strength, defined as the temperature difference across the inversion, or depth, defined as the altitude difference, and the difference between brightness temperatures in the 7.2- mm water vapor and 11-mm infrared window bands. Results indicate that inversion strength can be estimated unbiasedly with a root-mean-square error (rmse) of 28‐38C and an R2 of 0.80‐0.97. Inversion depth can be estimated with an rmse of 130‐250 m and an R2 of 0.62‐0.82. With MODIS, temperature inversions can be observed at a spatial resolution as high as 1k m 2 and a temporal sampling of up to 14 times per day, providing an opportunity for detailed studies of the spatial distribution and temporal evolution of the high-latitude boundary layer.

Modelling photochemical NOX production and nitrate loss in the upper snowpack of Antarctica

Experimental observations have shown photochemical production in the upper layers of firn. We use a modeling approach for Antarctica in summer, calculating the actinic flux in snowpack, and estimating NOX production from nitrate photolysis. Assuming nitrate photolysis is about as efficient for ice as for aqueous solution, and that all nitrate in the ice is available for photolysis, we find good agreement with measured fluxes of NOX from the snow surface at Neumayer Station, Antarctica. We estimate fluxes for other sites, and confirm that they could significantly affect boundary layer chemistry, especially where an atmospheric surface temperature inversion is present. We find that there is considerably more NOX production in the upper snowpack than in the entire tropospheric column above it. Photolysis explains a proportion of the nitrate loss observed from snow at some sites, but other processes (sorption/desorption) are necessary to explain the magnitude and depth profiles observed.

Associations between atmospheric temperature inversions and vertical wind profiles: a preliminary assessment

AbstractDespite the potential importance for air pollution, the association between temperature inversions and vertical wind profiles has been paid scant attention. A preliminary statistical assessment is made, using message data from radiosonde soundings at a station in eastern England for the period 1976–1980, from the surface up to 700 mb. In spite of an expectation among many air pollution meteorologists that inversions and local wind maxima (or vertical wind shears) are ‘typically’ associated, no such typical association between inversions and significant wind levels was identified. This conclusion extended to nocturnal surface inversions and low level jets. This does not mean that there are not clear cases of association, but that either (a) the dataset does not discriminate the associations, and/or (b) the associations are not evident on a climatological, or statistical, basis. Copyright © 2002 Royal Meteorological Society

Turbulent transport of atmospheric aerosols and formation of large-scale structures

Turbulent transport of aerosols and droplets in a random velocity field with a finite correlation time is studied. We derived a mean-field equation and an equation for the second moment for a number density of aerosols. The finite correlation time of random velocity field results in the appearance of the high-order spatial derivatives in these equations. The finite correlation time and compressibility of the velocity field can cause a depletion of turbulent diffusion and a modification of an effective mean drift velocity. The coefficient of turbulent diffusion in the vertical direction can be depleted by 25 % due to the finite correlation time of a turbulent velocity field. The latter result is in compliance with the known anisotropy of the coefficient of turbulent diffusion in the atmosphere. The effective mean drift velocity is caused by a compressibility of particles velocity field and results in formation of large-scale inhomogeneities in spatial distribution of aerosols in the vicinity of the atmospheric temperature inversion. Results obtained by Saffman (1960) for the effect of molecular diffusivity in turbulent diffusion are generalized for the case of compressible and anisotropic random velocity field. A mechanism of formation of small-scale inhomogeneities in particles spatial distribution is also discussed. This mechanism is associated with an excitation of a small-scale instability of the second moment of number density of particles. The obtained results are important in the analysis of various atmospheric phenomena, e.g., atmospheric aerosols, droplets and smog formation.

RoAp Stars through Theorists' Eyes - Excitation Mechanism

This exposition focuses on the still elusive excitation mechanism of the rapid oscillations in some Ap stars. We visit the domain of overstable magnetic convection which was conjectured as the origin of the observed high radial-order p modes. Mostly we dwell, however, on the classical k-mechanism. In roAp stars, the zone of partial hydrogen ionization is driving rather effectively. Furthermore, we argue that an atmospheric temperature inversion supports the κ-mechanism driving by preventing oscillation energy from leaking into the atmosphere.

Occupational contact dermatitis from carnosol

Hourly atmospheric measurements of halocarbons and chlorofluorocarbon (CFC) replacements were conducted at an urban site of Lukang, Changhua, in central Taiwan from May to August, 2013. The temporal distribution of different groups of halocarbons in the Lukang urban atmosphere, including chlorofluorocarbons (CFCs), Chlorodifluoromethane (HCFC-22), Bromochlorodifluoromethane (Halon-1211), and other chlorinated compounds, is presented and discussed. The concentrations (mixing ratios) of HCFC-22, Dichlorodifluoromethane (CFC-12), Halon-1211, Trichlorofluoromethane (CFC-11), Dichloromethane (CH2Cl2), and Trichloroethylene (TCE) were enhanced with respect to the local background levels; the atmospheric mixing ratio of carbon tetrachloride (CCl4) was slightly higher than its local background level; on the other hand, 1,1,2-Trichlorotrifluoroethane (CFC-113) was relatively uniform and not very different from background atmospheric level in non-urban areas. Among these compounds, HCFC-22, Halon-1211 and the halogenated compounds, CH2Cl2 and TCE, used as solvents were strongly enhanced. The average mixing ratio of Halon-1211 was higher than the local background of ∼4.5 ppt by ∼60% although Halon-1211 production had been phased out by 1996.Hourly average mixing ratios of halocarbons (HCFC-22, CFC-12, Halon-1211, CFC-11, CH2Cl2, and TCE) illustrated a distinct diurnal cycle characterized with a pattern of elevated mixing ratio and large mixing ratio variability amplitude at night relative to that in daytime. Although emission sources of these halocarbons were complex, hourly average mixing ratios for most of these high variability halocarbons peaked at ∼5:00 AM when the hourly average wind speed reached the minimum value of the day; by contrast, the hourly average mixing ratio of CO peaked at ∼8:30 AM when the ambient atmospheric wind condition was strongly influenced by sea breezes during the traffic rush hours. This phenomenon revealed that meteorological factors predominated the distribution of halocarbon mixing ratio in the urban atmosphere and the traffic emission of CFC-12 derived from old vehicles manufactured before 1994 was insignificant to the CFC-12 mixing ratio in the urban atmosphere. The meteorological condition of nighttime atmospheric temperature inversion and low wind speed facilitated the accumulation of terrestrial airborne pollutants near the ground; consequently the hourly average mixing ratios at night were higher than those in daytime by up to ∼2% (CFC-11), ∼7% (CFC-12), ∼75% (HCFC-22), ∼72% (Halon-1211), ∼280% (CH2Cl2), and ∼155% (TCE).

Effects of Climate on the Active Layer and Permafrost on the North Slope of Alaska, U.S.A.

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Some Characteristics of the Climate in Northern Alaska, U.S.A.

The climate of northern Alaska is strongly influenced by the ocean, not only during the summer months, as reported in the early literature, but also during the winter months as a result of the increased heat flux to the atmosphere from sea ice and leads over the ocean compared to the land. The air temperature remains below the freezing point through most of the year. National Weather Service records have underestimated annual total precipitation, on average, by 75%, varying from 20% to 180%, and snowfall by a factor of 2.6, ranging from 1.0 to 6.0, compared with the true values measured by Wyoming gauges. Precipitation, measured by Wyoming gauges in the eastern part of the region, increases with distance from the ocean and with elevation. Snow covers the ground surface for more than 8 mo yr-1. The climate of northern Alaska can be divided into three different zones: Arctic Coastal, Arctic Inland, and Arctic Foothills. The Arctic Coastal zone is characterized by cool summers and relatively warm winters, due to the impact of the ocean. Precipitation is the lowest in the region, and more than 50% falls as snow. The Arctic Inland zone has the warmest summers and coldest winters in the region although its mean annual air temperature is very close to the values of the Arctic Coastal zone to the north. Precipitation is higher than in the Arctic Coastal zone and about 40 to 45% occurs as snow. The Arctic Foothills zone has the warmest winters in the region, due to the influence of the weaker atmospheric temperature inversion compared with the coast, but its summer temperature is slightly colder than that of the Arctic Inland zone. Precipitation is the highest in the region and snowfall accounts for about 40% of it.

The classification of Arctic sea ice types and the determination of surface temperature using advanced very high resolution radiometer data

The accurate quantification of new ice and open water areas and surface temperatures within the sea ice packs is a key to the realistic parameterization of heat, moisture, and turbulence fluxes between ocean and atmosphere in the polar regions. Multispectral NOAA advanced very high resolution radiometer/2 (AVHRR/2) satellite images are analyzed to evaluate how effectively the data can be used to characterize sea ice in the Bering and Greenland seas, both in terms of surface type and physical temperature. The basis of the classification algorithm, which is developed using a late wintertime Bering Sea ice cover data, is that frequency distributions of 10.8‐μm radiances provide four distinct peaks, representing open water, new ice, young ice, and thick ice with a snow cover. The results are found to be spatially and temporally consistent. Possible sources of ambiguity, especially associated with wider temporal and spatial application of the technique, are discussed. An ice surface temperature algorithm is developed for the same study area by regressing thermal infrared data from 10.8‐ and 12.0‐μm channels against station air temperatures, which are assumed to approximate the skin temperatures of adjacent snow and ice. The standard deviations of the results when compared with in situ data are about 0.5 K over leads and polynyas to about 0.5–1.5 K over thick ice. This study is based upon a set of in situ data limited in scope and coverage. Cloud masks are applied using a thresholding technique that utilizes 3.74‐ and 10.8‐μm channel data. The temperature maps produced show coherence with surface features like new ice and leads, and consistency with corresponding surface type maps. Further studies are needed to better understand the effects of both the spatial and temporal variability in emissivity, aerosol and precipitable atmospheric ice particle distribution, and atmospheric temperature inversions.

New features in Saturn's atmosphere revealed by high-resolution thermal infrared images

FIFTEEN years ago, it was found1 that Saturn has a very different thermal infrared (7–13 (μm) brightness distribution from that observed at visible wavelengths. Single-detector scans of Saturn at 11.7 μm (ref. 1) showed emission increasing strongly towards the south pole, which was attributed in part to 12-μm ethane (C2H6) emission in the upper atmosphere of Saturn, enhanced by an atmospheric temperature inversion. Subsequently, it was confirmed that the observed brightening in ethane was concentrated towards the pole, and was not simply a general limb-brightening effect2. A similar brightening has been seen in the vibrational ν4 band of methane near 7.8 μm3 and in the hydrogen (3–1) pressure induced rotational line near 17.0 μm. Here we present observations of the stratospheric infrared emission structure on Saturn made using a 58×62 pixel imaging array camera system at 7.8, 11.6 and 12.4 μm. The high-spatial-resolution (1.3-arcsec full width at half maximum) global images show a variety of new features including a narrow equatorial belt of enhanced emission at 7.8 μm, a prominent symmetrical north polar hotspot at all three wavelengths, and a mid-latitude structure which is asymmetrically brightened at the east limb. These results confirm the polar brightening and reversal in position predicted by recent models4,5 for seasonal thermal variations of Saturn's stratosphere.

The formation of ozone and peroxyacetyl nitrate (PAN) in the urban atmospheres of Alberta

Atmospheric temperature inversions frequently trap pollutants in the urban atmospheres of Alberta leading to photochemical air pollution. Peroxyacetyl nitrate (PAN) was monitored, for the first time in Alberta, from November 1980 to August 1981 at the University of Calgary using electron capture gas chromatography. Measurements were made at one-half-hour intervals from July, 1981 to February, 1982 at a downtown location. Maximum PAN concentrations were recorded at the University and downtown sites on August 14 at 1400 h, 1981 and the values were 2.4 and 6.6 ppb, respectively. In each case the maximum PAN peak coincided with the afternoon peak in ozone concentrations, 79 ppb at the University and 59 ppb at the downtown site. Surprisingly, a high value of 2.3 ppb PAN was recorded at the University during January of 1981 giving rise to questions regarding the influence of low temperatures and solar radiation on the photochemical formation of PAN. Calculations employing a simple photochemical model for PAN and ozone formation have been carried out and comparisons made between the observed and the computed values.

Absolute Movements, Mass Balance, and Snow Temperatures of the Riiser-Larsenisen (Abstract only)

During the Norwegian Antarctic Research Expeditions 1967–77 and 1978–79 a land party worked on Riiser-Larsenisen, an ice shelf 120 km wide on the coast of Dronning Maud Land (15° to 20°W). In February 1977 three patterns of six stakes each were laid out over areas of about 4 km2 as part of a combined investigation into absolute movements and strain-rates. Eight stakes for absolute movement were also laid out. The stakes were also used for determination of mean snow accumulation together with a stake line across the ice shelf. The positions of the stakes were determined by theodolite observations from the stake points and from trigonometric stations located on land and on an ice rise near the ice front. In February 1979 all these measurements were repeated, and absolute movement, deformation, and mean accumulation were calculated. The absolute velocity of the ice shelf varied from 30 m a−1 near the grounding line to 130 m a−1 near the ice front. The mean annual accumulation was 510 mm water equivalent on the outer part of the ice shelf and 580 mm at the grounding line. Based on these measurements, together with snow-density measurements down to 16 m and measurements of the height of the ice shelf, the mass balance of the ice shelf was studied. The stake pattern across the grounding line showed considerable expansion. This is interpreted as a result of water freezing in bottom crevasses made by the tides. In 1979 snow temperatures were measured in eight bore holes down to 10 m depth. The snow temperatures at 10 m depth were used as a measure of the annual mean air temperature. The annual mean air temperature ranged from -16.8°C near the ice front to -19.2°C at the grounding line. Snow temperatures in bore holes on the slope of the ice rise and inland indicate a mean atmospheric temperature inversion of 0.28°C 100 m−1 for a 440 m layer near the grounding line, and 0.30°C 100 m−1 for a 160 m layer near the ice front. Here a mean inversion of 2.8°C 100 m−1 was found for the lowest 40 m layer of the atmosphere.

Absolute Movements, Mass Balance, and Snow Temperatures of the Riiser-Larsenisen (Abstract only)

During the Norwegian Antarctic Research Expeditions 1967–77 and 1978–79 a land party worked on Riiser-Larsenisen, an ice shelf 120 km wide on the coast of Dronning Maud Land (15° to 20°W). In February 1977 three patterns of six stakes each were laid out over areas of about 4 km2 as part of a combined investigation into absolute movements and strain-rates. Eight stakes for absolute movement were also laid out. The stakes were also used for determination of mean snow accumulation together with a stake line across the ice shelf. The positions of the stakes were determined by theodolite observations from the stake points and from trigonometric stations located on land and on an ice rise near the ice front.In February 1979 all these measurements were repeated, and absolute movement, deformation, and mean accumulation were calculated. The absolute velocity of the ice shelf varied from 30 m a−1 near the grounding line to 130 m a−1 near the ice front. The mean annual accumulation was 510 mm water equivalent on the outer part of the ice shelf and 580 mm at the grounding line. Based on these measurements, together with snow-density measurements down to 16 m and measurements of the height of the ice shelf, the mass balance of the ice shelf was studied.The stake pattern across the grounding line showed considerable expansion. This is interpreted as a result of water freezing in bottom crevasses made by the tides.In 1979 snow temperatures were measured in eight bore holes down to 10 m depth. The snow temperatures at 10 m depth were used as a measure of the annual mean air temperature. The annual mean air temperature ranged from -16.8°C near the ice front to -19.2°C at the grounding line. Snow temperatures in bore holes on the slope of the ice rise and inland indicate a mean atmospheric temperature inversion of 0.28°C 100 m−1 for a 440 m layer near the grounding line, and 0.30°C 100 m−1 for a 160 m layer near the ice front. Here a mean inversion of 2.8°C 100 m−1 was found for the lowest 40 m layer of the atmosphere.

Sodar studied atmospheric temperature inversions of the Salt Lake Valley

Inversional temperature phenomena indigenous to Utah's Salt Lake Valley were observed and studied over a continuous time span of 28 days occurring in December-January 1976–1977. The phenomena were combined with local topographical barriers to maintain a situation of marked atmospheric stability in the lowest kilometer. The nonturbulent conditions resulting were commonly neutral in character, but composite conditions retained generally stable patterns of inversion genesis and disintegration. Particular attention was given to comparing available rawinsonde raw data (soundings) with their coincidental sodar counterparts obtained from the continuous record. Results implied a compatibility between two techniques of sensing used, one being a remote sensor, the other in situ. Best agreement was discovered in the inversion cases below 500 m and with those of stronger intensities.

Thermal and albedo mapping of Mars during the Viking primary mission

Measurements of Martian emission and reflection reveal wide variations of surface properties and indicate the presence of a larger atmospheric contribution to the observed radiances than was anticipated. Temperatures observed during the Viking primary mission range from 130 to 290 K. Surface thermal inertias from 1.6 to 11×10−3 cal cm−2 s−1/2 K−1 are mapped, and they correlate with surficial geologic units. An equatorial map of bolometric albedo generally correlates with prior narrowband observations. These albedos range from 0.09 to 0.43; some regional brightenings are atmospheric in origin. The photometric behavior implies quasi-Lambertian surface reflectance plus a strongly forward-scattering atmosphere. Brightness temperatures at large emission angles are strongly influenced by atmospheric infrared opacity and by the presence of rocks on the surface. The correlation and grouping of albedo and thermal inertia indicate that there are two major components of Martian surface material, with bright regions having a fine particulate covering. Winter polar temperatures show spatial and temporal variations, suggesting variation of atmospheric composition; a strong atmospheric temperature inversion exists above the south polar cap during winter. Surface CO2 condensation may also occur locally near the equator before dawn. Rising temperatures before dawn in a region near Arsia Mons imply the presence of daily local water ice fogs.

Internal Gravity Waves Generated by Penetrative Convection

Abstract Penetrative convection is modeled by a series of idealized disturbances at the base of an atmospheric temperature inversion. Internal gravity waves excited in the inversion by the disturbances are theoretically found to drain away a fraction of the initial energy of the disturbances. The portion of energy lost upward is significant when the temperature inversion is weak. Vertical energy fluxes due to internal gravity waves are mathematically described using wave group approaches.

A Method for Translunar Radio Communication

THE increase of human activity on the lunar surface that can be expected to follow the first manned landings will present a special problem in translunar communications. The lack of an ionosphere about the Moon, the lack of any appreciable atmosphere on the lunar surface, and the nearness of the lunar horizon, require solutions to this problem that may be somewhat different from those most easily available on the Earth's surface. Extended radio coverage about the lithosphere, such as occurs on Earth because of the atmospheric density gradient and temperature inversions, will not be possible because of the vanishingly low density of any gaseous envelope that may exist around the Moon.

ATMOSPHERIC POLLUTION, TEMPERATURE INVERSION, AND DEATHS FROM BRONCHITIS

ATMOSPHERIC POLLUTION, TEMPERATURE INVERSION, AND DEATHS FROM BRONCHITIS