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| Titel |
Validation of middle-atmospheric campaign-based water vapour measured by the ground-based microwave radiometer MIAWARA-C |
| VerfasserIn |
B. Tschanz, C. Straub, D. Scheiben, K. A. Walker, G. P. Stiller, N. Kämpfer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 6, no. 7 ; Nr. 6, no. 7 (2013-07-23), S.1725-1745 |
| Datensatznummer |
250017923
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| Publikation (Nr.) |
 copernicus.org/amt-6-1725-2013.pdf |
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| Zusammenfassung |
| Middle atmospheric water vapour can be used as a tracer for dynamical
processes. It is mainly measured by satellite instruments and ground-based
microwave radiometers. Ground-based instruments capable of measuring
middle-atmospheric water vapour are sparse but valuable as they complement satellite
measurements, are relatively easy to maintain and have a long lifetime.
MIAWARA-C is a ground-based microwave radiometer for middle-atmospheric water
vapour designed for use on measurement campaigns for both atmospheric case
studies and instrument intercomparisons. MIAWARA-C's retrieval version 1.1
(v1.1) is set up in a such way as to provide a consistent data set even if the
instrument is operated from different locations on a campaign basis. The
sensitive altitude range for v1.1 extends from 4 hPa (37 km) to 0.017 hPa
(75 km). For v1.1 the estimated systematic error is approximately 10% for
all altitudes. At lower altitudes it is dominated by uncertainties in the
calibration, with altitude the influence of spectroscopic and temperature
uncertainties increases. The estimated random error increases with altitude
from 5 to 25%. MIAWARA-C measures two polarisations of the incident
radiation in separate receiver channels, and can therefore provide two
measurements of the same air mass with independent instrumental noise. The
standard deviation of the difference between the profiles obtained from the
two polarisations is in excellent agreement with the estimated random
measurement error of v1.1. In this paper, the quality of v1.1 data is
assessed for measurements obtained at two different locations: (1) a total of
25 months of measurements in the Arctic (Sodankylä,
67.37° N, 26.63° E) and (2) nine months of measurements at
mid-latitudes (Zimmerwald, 46.88° N, 7.46° E). For both
locations MIAWARA-C's profiles are compared to measurements from the
satellite experiments Aura MLS and MIPAS. In addition, comparisons to ACE-FTS
and SOFIE are presented for the Arctic and to the ground-based radiometer
MIAWARA for the mid-latitude campaigns. In general, all intercomparisons show
high correlation coefficients, confirming the ability of MIAWARA-C to monitor
temporal variations of the order of days. The biases are generally below
13% and within the estimated systematic uncertainty of MIAWARA-C. No
consistent wet or dry bias is identified for MIAWARA-C. In addition,
comparisons to the reference instruments indicate the estimated random error
of v1.1 to be a realistic measure of the random variation on the retrieved
profile between 45 and 70 km. |
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