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| Titel |
Diurnal variations of humidity and ice water content in the tropical upper troposphere |
| VerfasserIn |
P. Eriksson, B. Rydberg, M. Johnston, D. P. Murtagh, H. Struthers, S. Ferrachat, U. Lohmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 23 ; Nr. 10, no. 23 (2010-12-06), S.11519-11533 |
| Datensatznummer |
250008937
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| Publikation (Nr.) |
 copernicus.org/acp-10-11519-2010.pdf |
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| Zusammenfassung |
| Observational results of diurnal variations of humidity from Odin-SMR and
AURA-MLS, and cloud ice mass from Odin-SMR and CloudSat are presented for the
first time. Comparisons show that the retrievals of humidity and cloud ice
from these two satellite combinations are in good agreement. The retrieved
data are combined from four almost evenly distributed times of the day
allowing mean values, amplitudes and phases of the diurnal variations around
200 hpa to be estimated. This analysis is applied to six climatologically
distinct regions, five located in the tropics and one over the subtropical
northern Pacific Ocean. The strongest diurnal cycles are found over tropical
land regions, where the amplitude is ~7 RHi for humidity and ~50%
for ice mass. The greatest ice mass for these regions is found during the
afternoon, and the humidity maximum is observed to lag this peak by
~6 h. Over tropical ocean regions the variations are smaller and
the maxima in both ice mass and humidity are found during the early
morning. Observed results are compared with output from three climate models
(ECHAM, EC-EARTH and CAM3). Direct measurement-model comparisons were not
possible because the measured and modelled cloud ice masses represent
different quantities. To make a meaningful comparison, the amount of snow had
to be estimated from diagnostic parameters of the models. There is a high
probability that the models underestimate the average ice mass (outside the
1-σ uncertainty). The models also show clear deficiencies when it
comes to amplitude and phase of the regional variations, but to varying
degrees. |
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