Assessment of Radiation dose from Inhalation of Outdoor Dust Containing Natural Radionuclides

The 238U, 232Th and 40K concentrations were estimated in the size-fractionated urban surface deposited sediments in Ekaterinburg, Russia. The average concentrations of 238U, 232Th and 40K in dust fraction (0.002–0.05 mm) are 48 ± 7, 28 ± 1 and 510 ± 20 Bq/kg, respectively. The effective dose is estimated depending on the suggested daily scenarios of different exercises which can be assigned to light, moderate and vigorous activity. The results show that the total effective dose received during 20 years by an adult with the light activity is 5.6 μSv under exposure to air dust concentration 1 × 10−4 g/m3, which is typical for the city of Ekaterinburg. Although for the moderate and vigorous activities the total effective dose is 9.9 μSv and 48.8 μSv, respectively, during 20 years at air dust concentration equal to the diurnal Maximum Permissible Limit (1.5 × 10−4 g/m3). Thus, the effective doses due to natural radionuclides in the dust fraction are relatively low in comparison ICRP reference level.

Tropical Outgoing Longwave Radiation and Longwave Cloud Forcing Diurnal Cycles from CERES

The diurnal cycle is a fundamental earth system variability driven by daily variations in solar insolation. Understanding diurnal variability is important for characterizing top-of-atmosphere and surface energy budgets. Climatological and seasonal first diurnal cycle harmonics of outgoing longwave radiation (OLR) and longwave cloud forcing (LWCF) are investigated using the Clouds and the Earth’s Radiant Energy System (CERES) synoptic 3-hourly data. A comparison with previous studies indicates generally similar results. However, the results indicate that the CERES OLR diurnal cycle amplitudes are 10%–20% larger in desert regions than previous analyses. This difference results from the temporal interpolation technique overestimating the daily maximum OLR. OLR diurnal cycle amplitudes in other tropical regions agree with previous work. Results show that the diurnal maximum and minimum OLR variability contributes equally to the total OLR variance over ocean; however, over land the diurnal maximum OLR variance contributes at least 50% more to the total OLR variability than the minimum OLR. The differences in maximum and minimum daily OLR variability are largely due to differences in surface temperature standard deviations at these times, about 5–6 and 3–4 K, respectively. The OLR variance at diurnal maximum and minimum is also influenced by negative and positive correlations, respectively, between LWCF and clear-sky OLR. The anticorrelation between LWCF and clear-sky OLR at diurnal OLR maximum indicates smaller cloud fractions at warmer surface temperatures. The relationship between LWCF and clear-sky OLR at diurnal minimum OLR appears to result from a preference for deep convection, more high clouds, and larger LWCF values to occur with warmer surface temperatures driving a narrower diurnal minimum OLR distribution.

Analysis of the Urban Thermal Fingerprint of the City of Trento in the Alps

The temperature contrasts typically marking urban heat island (UHI) effects in the city of Trento, Italy, located in an Alpine valley and inhabited in its inner urban area by a population of about 56 000, are investigated. Time series of air temperature data, collected at an urban weather station, in the city center, and at five extraurban stations are compared. The latter are representative of rural and suburban areas, both on the valley floor and on the valley sidewalls. It is found that the extraurban weather stations, being affected by different local-scale climatic conditions, display different temperature contrasts with the urban site. However, the diurnal cycle of the UHI is characterized by similar patterns of behavior at all of the extraurban weather stations: the UHI intensity is stronger at night, whereas during the central hours of the day an “urban cool island” is likely to occur. The diurnal maximum UHI intensity turns out to be typically of order 3°C, but under particularly favorable conditions it may be higher than 6°C. An urban cool island effect is also detected, which is probably caused by the compactness of the inner urban area, and displays typical diurnal maximum intensities of order 1.5°C. As to the seasonal dependence, at the extraurban weather stations on the valley floor the UHI intensity tends to be slightly stronger during dry months, whereas on the valley sidewalls it is mainly influenced by the seasonal lapse-rate changes. Further weather factors, such as wind speed and cloud cover, also affect urbanization effects, making them weaker with stronger winds and cloudier skies.

Multiflash whistlers in ELF-band observed at low latitude

Multiflash whistler-like event in the ELF-band, observed during March 1998 at low latitude station Jammu, is reported. The most prominent feature of these events is the multiflash nature along with the decrease in frequency within a very short span of time resembling similar to terrestrial whistlers. The events have a significantly smaller time duration (0.5–3.5 s) than those reported earlier from high, mid and low latitudes and also display a diurnal maximum occurring around 09:30 h (IST). There have been similar reportings from other latitudes, but whistlers in the ELF-band with a multiflash nature along with a precursor emission have never been reported. Lightning seems to be the dominant source for the ELF whistlers reported here.

Short term variations of tracer transit speed on alpine glaciers

We first present the results of a series of tracer experiments conducted on an alpine glacier (Gornergletscher, Switzerland) over a diurnal discharge cycle. For these injections, a moulin was used into which an ice marginal lake was draining, providing a relatively constant discharge. The measured tracer transit speeds show two diurnal maxima and minima. These findings are qualitatively different to existing observations from two series of injections conducted at Unteraargletscher (Switzerland) using a moulin fed by supraglacial meltwater having a high diurnal variability, which displayed one diurnal maximum and minimum. We then develop and use a simple two-component model of the glacier drainage system, comprising a moulin and a channel element, to simulate the measured transit speeds for all three injection series. The model successfully reproduces all the observations and shows that the same underlying processes can produce the qualitatively different behaviour depending on the different moulin input discharge regimes. Using the model, we assess the relative importance of the different measurement quantities, show that frequent measurements of moulin input discharge are indispensable and propose an experiment design to monitor the development of the drainage system over several weeks.

Impacts of Urban Albedo Increase on Local Air Temperature at Daily–Annual Time Scales: Model Results and Synthesis of Previous Work

The authors combine urban and soil–vegetation surface parameterization schemes with one-dimensional (1D) boundary layer mixing and radiation parameterizations to estimate the maximum impact of increased surface albedo on urban air temperatures. The combined model is evaluated with measurements from an urban neighborhood in Basel, Switzerland, and the importance of surface–atmosphere model coupling is demonstrated. Impacts of extensive albedo increases in two Chicago, Illinois, neighborhoods are modeled. Clear-sky summertime reductions of diurnal maximum air temperature for the residential neighborhood (λp = 0.33) are −1.1°, −1.5°, and −3.6°C for uniform roof albedo increases of 0.19, 0.26, and 0.59, respectively; reductions are about 40% larger for the downtown core (λp = 0.53). Realistic impacts will be smaller because the 1D modeling approach ignores advection; a lake-breeze scenario is modeled and temperature reductions decline by 80%. Assuming no advection, the analysis is extended to seasonal and annual time scales in the residential neighborhood. Yearly average temperature decreases for a 0.59 roof albedo increase are about −1°C, with summer (winter) reductions about 60% larger (smaller). Annual cooling degree-day decreases are approximately offset by heating degree-day increases and the frequency of very hot days is reduced. Despite the variability of modeling approaches and scenarios in the literature, a consistent range of air temperature sensitivity to albedo is emerging; a 0.10 average increase in neighborhood albedo (a 0.40 roof albedo increase for λp = 0.25) generates a diurnal maximum air temperature reduction of approximately 0.5°C for “ideal” conditions, that is, a typical clear-sky midlatitude summer day.

Short term variations of tracer transit speed on Alpine glaciers

We present and interpret the results of a series of tracer experiments conducted on an Alpine glacier over a diurnal discharge cycle. For these injections, a moulin was used into which an ice marginal lake was draining, providing a relatively constant discharge. Measured tracer transit speeds show two diurnal maxima and minima. These findings are qualitatively different from existing observations from two series of injections at another site using a moulin fed by supraglacial meltwater with a high diurnal variability, which displayed one diurnal maximum and minimum. We use a simple two-component model of the glacier drainage system, comprising a moulin and a channel element, to simulate the measured transit speeds for all three injection series. The model successfully reproduces all the observations and shows that the same underlying processes can produce the qualitatively different behaviour depending on the different moulin input discharge regimes. Using the model, we asses the relative importance of the different measurement parameters, show that frequent measurements of moulin input discharge are indispensable and propose an experiment design to monitor the development of the drainage system over several weeks.

A Five-Year Climatology of Elevated Severe Convective Storms in the United States East of the Rocky Mountains

A 5-yr climatology of elevated severe convective storms was constructed for 1983–87 east of the Rocky Mountains. Potential cases were selected by finding severe storm reports on the cold side of surface fronts. Of the 1826 days during the 5-yr period, 1689 (91%) had surface fronts east of the Rockies. Of the 1689 days with surface fronts, 129 (8%) were associated with elevated severe storm cases. Of the 1066 severe storm reports associated with the 129 elevated severe storm cases, 624 (59%) were hail reports, 396 (37%) were wind reports, and 46 (4%) were tornado reports. A maximum of elevated severe storm cases occurred in May with a secondary maximum in September. Elevated severe storm cases vary geographically throughout the year, with a maximum over the south-central United States in winter to a central and eastern U.S. maximum in spring and summer. A diurnal maximum of elevated severe storm cases occurred at 2100 UTC, which coincided with the diurnal maximum of hail reports. The wind reports had a broad maximum during the daytime. Because the forecasting of hail from elevated storms typically does not pose as significant a forecast challenge as severe wind for forecasters and tornadoes from elevated storms are relatively uncommon, this study focuses on the occurrence of severe wind from elevated storms. Elevated severe storm cases that produce only severe wind reports occurred roughly 5 times a year. To examine the environments associated with cases that produced severe winds only, five cases were examined in more detail. Common elements among the five cases included elevated convective available potential energy, weak surface easterlies, and shallow near-surface stable layers (less than 100 hPa thick).

The global behavior of the March 1989 ionospheric storm

By any measure the magnetic storm beginning with a sudden storm commencement at 0128 UT March 13, 1989 must be classified historically as a great storm. Associated with this great magnetic storm was the drastic modification of the normal ionosphere lasting for several days. To study this abnormal behavior, ionospheric data collected at 52 ionosonde stations and 12 total electron content observing stations have been analyzed. The global data show a longitudinal dependence on the storm behavior; a pronounced worldwide depression in the diurnal maximum values of f0F2; the extreme depression of the diurnal-minimum in f0F2 to a frequency less than 2 MHz at many stations, sometimes accompanied by an unprecedented rise in h'F to 700 km or more; the presence of traveling ionospheric disturbances; the presence of large-scale standing oscillations; the development of hemispheric asymmetry; and the suppression of the equatorial anomaly. These and other unusual phenomena are described in this paper.