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| Titel |
HAMP - the microwave package on the upcoming High Altitude and LOng range aircraft HALO |
| VerfasserIn |
M. Mech, S. Crewell, G. Peters, L. Hirsch |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029436
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| Zusammenfassung |
| New cloud observation techniques are needed to improve our understanding of the impact of
clouds on the earth’s water cycle and radiation budget, which represents still one of the
largest uncertainties in global and regional climate modeling. An airborne platform for
such observation techniques will be provided by the new German research aircraft
HALO (High Altitude Long Range) that will be commissioned in 2009. HALO will
open a new dimension for climate and atmospheric research. By HALO it will
be possible to survey the atmosphere on continental scales but with much finer
resolution and with more powerful instrumentation than feasible on space borne
platforms.
An advanced set of microwave remote cloud sensing instruments (HAMP - HALO
Microwave Package) will be operated on board of HALO. It consists of a cloud radar and
a suite of passive radiometers in different frequency bands. The radar MIRA-36
operates at 36.5 GHz. Although this is an unusual low frequency, it benefits from the
wider range of applications due to less signal attenuation in deep clouds and rain,
compared to the 94 GHz radar operated on CloudSat. The frequencies for the passive
microwave radiometers were selected in allusion to the AMSU-A and -B sounder.
Thereby the 150 GHz channel of AMSU-B has been replaced by frequencies in the
118 GHz oxygen band. In combination with the 60 GHz oxygen complex channels, this
frequencies can be used for precipitation retrieval after Bauer and Mugnai (2003).
Furthermore by including channels in the water vapor lines at 22.235 GHz and
183.31 GHz and higher microwave channels sensitive to scattering in the ice phase,
various precipitation retrieval algorithms can be compared by measurements with
HAMP.
This presentation introduces the microwave package on HALO. It further shows the
potential of the observations by presenting results of a simulation study for the selected
microwave frequencies and the cloud radar. The potential of the selected frequencies for
hydrometeor observations and their retrieval has been investigated by developing
simple algorithms based on a data set of simulated brightness temperatures and
concurrent hydrometeor contents and profiles. These were achieved by cloud resolving
model simulations and forward radiative transfer calculations for a set of midlatitude
precipitation events. The different sensitivities of the various passive microwave
frequencies to varying hydrometeor contents and surface properties can be clearly seen.
Even for very simple retrieval algorithms, good retrieval capabilities for frozen
hydrometeors over both surfaces (land/ocean) and for rain over ocean surfaces are
found.
References:
Bauer, P., and A. Mugnai (2003), Precipitation profile retrievals using temperaturesounding
microwave observations, J. Geophys. Res., p. 4730. |
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