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| Titel |
Assessment of small-scale integrated water vapour variability during HOPE |
| VerfasserIn |
S. Steinke, S. Eikenberg, U. Löhnert, G. Dick, D. Klocke, P. Di Girolamo, S. Crewell |
| 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 ; 15, no. 5 ; Nr. 15, no. 5 (2015-03-09), S.2675-2692 |
| Datensatznummer |
250119508
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| Publikation (Nr.) |
 copernicus.org/acp-15-2675-2015.pdf |
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| Zusammenfassung |
The spatio-temporal variability of integrated water vapour (IWV) on
small scales of less than 10 km and hours is assessed with data from the
2 months of the High Definition Clouds and Precipitation for advancing
Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE).
The statistical intercomparison of the unique set of observations during HOPE
(microwave radiometer (MWR), Global Positioning System (GPS), sun photometer,
radiosondes, Raman lidar, infrared and near-infrared Moderate Resolution
Imaging Spectroradiometer (MODIS) on the satellites Aqua and Terra) measuring
close together reveals a good agreement in terms of random differences
(standard deviation ≤1 kg m−2) and correlation coefficient
(≥ 0.98). The exception is MODIS, which appears to suffer from
insufficient cloud filtering.
For a case study during HOPE featuring a typical boundary layer development,
the IWV variability in time and space on scales of less than 10 km and
less than 1 h is investigated in detail. For this purpose, the
measurements are complemented by simulations with the novel ICOsahedral
Nonhydrostatic modelling framework (ICON), which for this study has a
horizontal resolution of 156 m. These runs show that differences in
space of 3–4 km or time of 10–15 min induce IWV variabilities on the
order of 0.4 kg m−2. This model finding is confirmed by observed
time series from two MWRs approximately 3 km apart with a comparable
temporal resolution of a few seconds.
Standard deviations of IWV derived from MWR measurements reveal a high
variability (> 1 kg m−2) even at very short time scales of
a few minutes. These cannot be captured by the temporally lower-resolved
instruments and by operational numerical weather prediction models such as
COSMO-DE (an application of the Consortium for Small-scale Modelling covering
Germany) of Deutscher Wetterdienst, which is included in the comparison.
However, for time scales larger than 1 h, a sampling resolution of
15 min is sufficient to capture the mean standard deviation of IWV. The
present study shows that instrument sampling plays a major role when
climatological information, in particular the mean diurnal cycle of IWV, is
determined. |
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