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- Forkman, Peter, 1959, et al.
(författare)
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Longest continous ground-based measurements of mesospheric CO
- 2003
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 30:10
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Tidskriftsartikel (refereegranskat)abstract
- The longest continuous series of ground-based measurements of mesospheric CO is presented. The continuous data cover the period September 2000 to September 2002. Sporadic measurements from 1988 and 1989 are also reported. The results show a large CO accumulation in the winter mesosphere, which is consistent with generally accepted ideas about the seasonally-varying mean meridional circulation. Comparison of the observations with simulations by the Whole Atmosphere Community Climate Model (WACCM) indicate that the model can reproduce the observed seasonal cycle as well as much of its variability, although calculated columns amounts are smaller than the largest values seen in the data.
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- Forkman, Peter, 1959, et al.
(författare)
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The 22 GHz radio-aeronomy receiver at Onsala Space Observatory
- 2003
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - 0022-4073. ; 77:1, s. 23-42
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Tidskriftsartikel (refereegranskat)abstract
- We present a radiometer system for regular long-term measurements of water vapour in the middle atmosphere. To be able to do continuous and long-term measurements a simple, robust, reliable and automatic system is needed. Our system therefore is based on a stable, uncooled, HEMT amplifier frontend and on a digital spectrometer backend. In order to minimise reflections in the frontend transmission line, which distort the signal due to standing waves, we have designed a corrugated receiver horn, which combines good characteristics (low return loss and sidelobes) and narrow beamwidth to simplify the receiver optics. In order to make the radiometer system as simple as possible, we use the sky as the calibration cold load. This is possible since we use the observed brightness temperatures of an already existing broadband dual-channel 21.0/31.4-GHz radiometer, at the observation site, to estimate the brightness temperature of the sky at . However, we have developed a calibration method, which makes it possible to estimate the sky brightness temperature even if we cannot use the dual-channel radiometer. Despite new measurements, which became available in recent years, the determination of middle atmospheric water vapour distribution still remains a challenge due to the fact that there is a large dispersion among the different measurement methods and data sets, which are obtained on a sparse and sporadic basis. This is the reason why several instruments similar to ours currently are developed in Europe.
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| 7. |
- Winnberg, Anders, 1937
(författare)
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How does the Galactic Bulge rotate?
- 2003
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Ingår i: Mass-losing pulsating stars and their circumstellar matter; eds. Y. Nakada, M. Honma and M. Seki. ; Astrophysics and Space Science Library, Vol. 283, s. 367-371
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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