Ground-based measurements

Lack of reliable measurement is the first reason, as reliable ground-based measurements by scientific instruments have been made just in this century. These measure conditions only at the location of each instrument, and they are usually land-based, although 75% of the Earth is covered with water. We have been able to take precise, direct measurements only in the last four decades, and not until the advent of precision space borne instruments in the 1970s were we able to measure global temperatures at a range of altitudes across the entire atmosphere. 

The predictions of this model (normalized to meteoritic abundance for solar metallicity) are illustrated in Fig. 9.6 and compared with observational data for beryllium in stars, based on ground-based measurements of the near-UV Be II doublet A 3130. Assuming that surface Be can suffer some destruction in some of the metal-rich disk stars, there is fair agreement down to about 0.1 of solar abundance, but the secondary trend predicted at still lower metallicities is too steep. 

Wang, T M. A. Carroll, G. M. Albercook, K. R. Owens, K. A. Duderstadt, A. N. Markevitch, D. D. Parrish, J. S. Holloway, F. C. Fehsenfeld, G. Forbes, and J. Ogren, Ground-Based Measurements of NOa. and Total Reactive Oxidized Nitrogen (NOv) at Sable Island, Nova Scotia, during the NARE 1993 Summer Intensive, J. Geophys. Res., 101, 28991-29004 (1996). 

Fried, A., S. Sewell, B. Henry, B. P. Wert, T. Gilpin, and J. R. Drummond, Tunable Diode Laser Absorption Spectrometer for Ground-Based Measurements of Formaldehyde, J. Geophys. Res., 102, 6253-6266 (1997). 

For example, analysis of a combined set of data from ground-based measurements using Dobson spectrometers and related approaches as well as ozonesondes and SBUV from 1979 to 1994 indicates that at midlatitudes in the Northern Hemisphere, the trend in total ozone is as much as -7% per decade in the winter and spring compared to - 3% per decade in the summer and fall in the Southern Hemisphere at midlatitudes, there is less seasonal variation but negative trends in total ozone in the range —3 to —6% per decade are observed (Harris et al., 1997). Trends in the tropics were not clearly statistically significant. 

Krzyscin, J. W UV Controlling Factors and Trends Derived from the Ground-Based Measurements Taken at Belsk, Poland, 1976-1994, J. Geophys. Res., 101, 16797-16805 (1996). 

Evans, W. F. J., C. Reinhart, and E. Puckrin, A Ground Based Measurement of the Anomalous Cloud Absorption Effect, Geophys. Res. Lett., 22, 2135-2138 (1995). 

One of the success stories of in situ measurements in the stratosphere is the confirmation that the rapid loss of ozone over Antarctica each October is indeed caused by photochemistry related to the release of chlorofluoro-carbons at the surface of the earth. Ground-based measurements of the primary chlorine culprit, CIO, and 03 have given a similar picture (4), but not with the fine detail possible from the in situ techniques, as shown in... 

Therefore, ground-based measurements are restricted to atmospheric windows where the water vapour absorptions are relatively small. For limb space-based atmospheric sounding, this is less of a problem but retrieval of trace gases in the upper troposphere are restricted to a limited number of candidates. For many gases such measurements are optimal for sounding the stratosphere and mesosphere. For the lower stratosphere and upper troposphere, some interesting possibilities exist, but the range of application is more restricted. 

Table 3.2 Elemental composition of biomass burning aerosols in the Amazon basin measured during the SCAR-B experiment and comparison with long-term ground-based measurements at Alta Floresta and Cuiaba.

Harrison L. and Michalsky J. (1994) Objective algorithms for the retrieval of optical depths from ground-based measurements. Appl. Optics 33, 5126—5132. 

Comparisons between UV estimates derived from satellite data and ground-based measurements at a few stations in Europe have shown that for daily doses there is only a bias between data sets of about 5%, but the standard deviation is in the order of about 30% [48]. For monthly doses, the scatter becomes signifi-... 

R. McKenzie, G. Seckmeyer, A.F. Bais, J.B. Kerr, S. Madronich (2001). Satellite-retrievals of erythemal UV dose compared with ground-based measurements at Northern and Southern mid-latitudes. J. Geophys. Res., 106, 24051-24062. 

Forkman, P., P. Eriksson, A. Winnberg, R.R. Garcia, and D. Kinnison, Longest continuous ground-based measurements of mesospheric CO. Geophys Res Lett 30, 1532, doi 10.1029/2003GL016931, 2003. 

Kreher, K., J.G. Keys, P.V. Jonston, U. Platt, and X. Liu, Ground-based measurements of OCIO and HC1 in austral spring 1993 at Arrival Heights, Antarctica. Geophys Res Lett 23, 1545, 1996. 

Perner, D., A. Roth, and T. Kliipfel, Ground based measurements of stratospheric OCIO, NO2 and O3 at Sondre Strpmfjord in winter 1991/92. Geophys Res Lett 21, 1367, 1994. 

A-3 of the Appendix lists the numerical data. In the visible and near-infrared spectral regions the fluxes were mainly derived from ground-based measurements at mountain stations supplemented by aircraft and balloons as platforms. The ultraviolet portion of the solar spectrum has been explored with instruments on board rocket sondes and satellites. These data are of special interest here. Measurements before 1980 have been reviewed by Ackerman (1971), Simon (1978), and Nicolet (1981). More recent data have been reported by Mount and Rottman (1981,1983,1985) and Mentall etal. (1985). 

Ground-based measurements of total ozone use the Dobson spectrometer. This instrument measures the column density of ozone in the atmosphere by optical absorption, with the sun or the moon as background source. The data are expressed as an equivalent column height at standard pressure and... 

Table 9-11. Summary of Ground-Based Measurements of NOx at Rural and Mountain-Top Sites ...

Field studies of S02 oxidation have been performed mostly in the downwind regions of sufficiently isolated sources. The favored objects were stacks of electric power plants, whose plumes often are identifiable at distances up to 300 km from the source, and larger cities. S02 and particulate sulfate were measured and the data were analyzed in terms of the concentration ratio (S04-)/(S02) + (S04 ) as a function of time or a combination of wind speed and distance. Sampling was done mostly by aircraft, although urban plumes have also been studied by ground-based measurements. Table 10-11 presents results from a variety of such investigations. 

Meszaros et al. (1977) 7.2-35 Ground-based measurements in a suburban area of Budapest, Hungary, correlation analysis with wind speed, temperature, data grouping. 

Elshout et al. (1978) 0.6-4.4 1.7 2.4 Ground-based measurements in Arnhem, The Netherlands, of polluted air originating in the Ruhr Valley four selected days in winter 1972. 

McMurry and Wilson (1983), dry McMurry and Wilson (1983), r.h. >75% 0-5 ssl 2 — — Urban plume of Columbus, Ohio, ground-based measurements in July and August 1980. 

Direct in-situ atmospheric observations of humidity-induced restructuring are difficult to obtain and remain sparse. Most evidence for humidity processing has come from laboratory and ground-based measurements. Trials on the humidity processing of atmospheric samples attributed a decrease in size to the restructuring of freshly emitted smoke [69]. In the same trials, laboratory experiments indicated that aggregate... 

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