Quarterly Journal of the Royal Meteorological Society
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On the nitrogen budget for the United Kingdom and north‐west Europe Abstract The application of a simple trajectory model approach to the emission, transformation and deposition of a coupled series of atmospheric pollutants including SO2 , NOx and ammonia is described. A detailed comparison of the model results with observations is provided using United Kingdom monitoring data. Whilst reasonable agreement can justifiably be claimed for some species, whether in the gas phase, aerosol or precipitation, it is clear that for the others there are either severe disagreements or a lack of suitable data for comparison purposes. Background sources of these pollutants are assessed by applying wind sector analysis to precipitation measurements at remote sites. The budgets for the United Kingdom and north‐west Europe have a similar balance between wet and dry deposition to that given in the literature for the global nitrogen budget. This is in conflict with some literature budgets for Europe as a whole which have apparently overestimated the dry deposition terms.
Quarterly Journal of the Royal Meteorological Society - Tập 114 Số 482 - Trang 1127-1152 - 1988
The influence of nitrogen oxides on the atmospheric ozone content Abstract The probable importance of NO and NO2 in controlling the ozone concentrations and production rates in the stratosphere is pointed out. Observations on and determinations of nitric acid concentrations in the stratosphere by Murcray, Kyle, Murcray and Williams (1968) and Rhine, Tubbs and Dudley Williams (1969) support the high NO and NO2 concentrations indicated by Bates and Hays (1967). Some processes which may lead to production of nitric acid are discussed. The importance of O (1 S), possibly produced in the ozone photolysis below 2340 Å, on the ozone photochemistry is mentioned.
Quarterly Journal of the Royal Meteorological Society - Tập 96 Số 408 - Trang 320-325 - 1970
Solar and terrestrial radiation. Report to the international commission for solar research on actinometric investigations of solar and atmospheric radiation
Quarterly Journal of the Royal Meteorological Society - Tập 50 Số 210 - Trang 121-126 - 1924
Gravity wave and equatorial wave morphology of the stratosphere derived from long‐term rocket soundings Abstract Fluctuations in vertical profiles of atmospheric temperature and horizontal wind in the 20–60 km altitude range have been isolated from meteorological rocket measurements during 1977–87 at 15 widely separated sites. The seasonal, geographical, and vertical variability of the variance of horizontal velocities, u′2 + v′2 , and relative‐temperature perturbations, T′2 , were studied. The bulk of the variance of both quantities in the 2–10 km and 2–20 km vertical‐wavelength bands was associated with gravity‐wave motions, although in‐depth study of the wave polarization shows that planetary‐scale equatorial wave modes contribute to the variance at equatorial sites. Annual mean variances varied widely among the 15 stations, suggesting appreciable geographical variability in stratospheric wave activity. Whereas u′2 + v′2 values generally increased significantly with altitude throughout the stratosphere, T′2 values grew less substantially and often decreased with altitude at upper heights. Rotations of wave‐velocity phasors with height were always more frequently clockwise than anticlockwise in the northern hemisphere, consistent with upward‐propagating wave energy, yet these percentages (>50%) showed a marked semi‐annual variation, with equinoctial maxima and minima at the solstices. At high latitudes (∼50°N–80°N) variances exhibited a strong annual variation, with the minimum in summer and a strong peak during winter at both lower (20–40 km) and upper (40–60 km) heights. The annual variance cycle attenuated somewhat at mid‐latitudes (∼25°N–40°N), and a strong peak in August dominated the u′2 + v′2 variations at 40–60 km. The peak was also evident in T′2 , but was smaller relative to the winter peak. At low latitudes (∼15°N–25°N) the wave morphology was broadly similar to that at mid‐latitudes, apart from an additional upper‐level peak in the variance in May. This peak in May occurred in some years but not in others at mid‐latitude stations. At the equatorial stations (∼10°N–10°S) the low‐level variance showed little systematic seasonal variability, but exhibited clear modulation over a quasi‐two‐year period. Much of this variance was consistent with the Kelvin modes thought to drive the eastward phase of the stratospheric quasi‐biennial oscillation (QBO). However, the uniform east‐west alignment of waves was inconsistent with the expected polarization of the mixed Rossby‐gravity wave mode which is believed to drive the westward phase of the QBO. At 40–60 km, the variance was strongly attenuated around April‐May and November, when both u′2 + v′2 and T′2 decreased with height around the 40–45 km range, indicating that wave dissipation occurs here. This produced a semi‐annual variation at upper heights, with maxima around January and July, which may contribute significantly to the semi‐annual wave driving of the equatorial upper stratosphere. Polarization studies showed that this variance in the 2–10 km band was mostly due to gravity waves, although equatorial modes contributed during December–February.
Quarterly Journal of the Royal Meteorological Society - Tập 121 Số 521 - Trang 149-186 - 1995
The propagation of groups of internal gravity waves in a shear flow Abstract The propagation in a shear flow of travelling internal gravity waves of short wavelength is investigated by the W.K.B. approximation. This implies that the Richardson number is large. It is shown that a wave group moves with the local group velocity defined in terms of the dominant wavenumber, the absolute frequency and horizontal components of wavenumber being constant. The wave energy carried by a wave packet varies, being proportional to the frequency relative to a frame moving with the local mean wind. A wave packet, on this approximation, can never pass through a critical level at which its horizontal phase velocity is equal to the mean wind, nor is it reflected there. These results imply restrictions on the propagation of internal gravity waves from the troposphere to the upper atmosphere.
Quarterly Journal of the Royal Meteorological Society - Tập 92 Số 394 - Trang 466-480 - 1966
Drop‐size distribution in cloud and fog Abstract Experimental data relating to drop‐size distribution in cloud and fog are examined and it is shown that in many cases the size distribution can be represented by the formula
where F is the fraction of liquid water in the air comprised by drops with diameter less than x. The constant a increases with the liquid water content of the cloud. It is not clear what governs the value of the constant n but a reasonable mean value is about 3.3. It is shown that, if the drop‐size distribution can be described by the equation quoted above the median volume diameter is the most suitable parameter for describing the average size of the cloud particles when the value of n is not known.
Quarterly Journal of the Royal Meteorological Society - Tập 77 Số 333 - Trang 418-426 - 1951
The evaluation of infra‐red radiative fluxes due to atmospheric water vapour Abstract An empirical technique is developed for obtaining the flux transmission, over a narrow spectral interval, of an assembly of layers of varying pressure and temperature. Although verified only for a regular spectrum of the type proposed by Elsasser (1942), the technique should be valid for any type of spectrum. Using this technique as a check, an empirical method of sufficient accuracy is developed for evaluating the integrated flux transmission of an assembly of layers. This latter method enables the radiation‐chart procedures, advocated by Elsasser (1942), Robinson (1947), and Yamamoto (1952), to be tested for simply‐stratified atmospheric models. Such tests reveal that the effects of temperature are inadequately taken into account. A principle advocated by Cowling (1950b) is developed into a radiation‐chart procedure, in which the absorbing mass of each individual layer is corrected to a standard temperature and pressure. The coordinates of such a radiation chart are presented, but unfortunately adequate experimental data for the construction of such a chart are not yet available.
Quarterly Journal of the Royal Meteorological Society - Tập 79 Số 341 - Trang 367-379 - 1953
A statistical model for water‐vapour absorption
Quarterly Journal of the Royal Meteorological Society - Tập 78 Số 338 - Trang 638-640 - 1952
Coastal winds and low‐level jets: Simulations for sea gulfs Abstract The reasons for the relatively strong coastal afternoon surface winds observed along the Gulf of Finland were studied by using a high‐resolution two‐dimensional numerical model in typical summertime conditions. Sea breeze effects were included by defining a clear sky, whereas they were minimized by alternatively defining a thick cloud cover. The geostrophic wind was varied both in speed and direction. A case‐study was made with a three‐dimensional operational forecast model with results that agreed with the two‐dimensional experiments and observations. Strongish afternoon surface winds nearly parallel with the coastline were obtained in the overcast gulf experiments. In these cases, well‐mixed air entering the smooth sea slantwise from over land commenced an inertial oscillation downstream such that the emerging low‐level jet maximum was located just above the opposite coast, causing the strong winds there. If the sky was clear, sea breezes and strong convective mixing further enhanced the coastal surface winds to supergeostrophic speeds. In contrast, weak coastal winds occurred when the sea breeze and the basic flow were nearly opposite. Given the gulf geometry, the sea breeze cell from the opposite coast could be advected over the gulf in a suitable basic flow, which resulted in another minimum in the coastal wind speed as a function of geostrophic wind direction. Copyright © 2005 Royal Meteorological Society.
Quarterly Journal of the Royal Meteorological Society - Tập 131 Số 606 - Trang 625-637 - 2005
Multi‐event analysis of the westerly Greenland tip jet based upon 45 winters in ERA‐40 Abstract The westerly Greenland tip jet is an intense, narrow and intermittent wind phenomenon located southeast of Cape Farewell that occurs frequently during the winter season. Using the ERA‐40 reanalysis dataset, a catalogue of 586 objectively detected westerly tip jet events is compiled for the winters 1957‐2002, and an analysis is undertaken of the character of the jet and its accompanying atmospheric features. It is shown that the tip jet frequency exhibits a significant positive correlation with both the NAO index and the latitude of the Icelandic Low. The peak wind speed and accompanying heat fluxes of the jet have values up to 30 m s−1 and 600 W m−2 , respectively, and are sustained for less than one day. The air parcels constituting the tip jet are shown, based upon a trajectory model and the ERA‐40 dataset, to have a continental origin, and to exhibit a characteristic deflection and acceleration around southern Greenland. The events are almost invariably accompanied both by a notable coherence of the lower‐level tip jet with an overlying upper‐level jet stream, and by a surface cyclone located to the lee of Greenland. It is also shown that the cyclone originates upstream of and is advected to the lee of Greenland, and thereby it both precedes in time and contributes dynamically to the formation of the tip jet. On this basis, it is suggested that the tip jet arises from the interplay of the synoptic‐scale flow evolution and the perturbing effects of Greenland's topography upon the flow. Copyright © 2009 Royal Meteorological Society
Quarterly Journal of the Royal Meteorological Society - Tập 135 Số 645 - Trang 1999-2011 - 2009
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