Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS

Müller, Stefan; Kämpfer, Niklaus; Feist, Dietrich G.; Haefele, Alexander; Milz, M.; Sitnikov, N.; Schiller, C.; Kiemle, Christoph; Urban, Joachim

doi:10.5194/acp-8-3169-2008

Cited by 20 publications

(10 citation statements)

References 27 publications

(29 reference statements)

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“…This result is in broad agreement with the findings from the balloon comparisons when taking into account that AMSOS data have been assigned with a dry bias of 0-20 % in comparisons to other data sets (cf. Müller et al, 2008).…”

Section: Intercomparison Of Aircraft Observationsmentioning

confidence: 99%

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Validation of MIPAS-ENVISAT H<sub>2</sub>O operational data collected between July 2002 and March 2004

et al. 2013

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Abstract. Water vapour (H2O) is one of the operationally retrieved key species of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument aboard the Environmental Satellite (ENVISAT) which was launched into its sun-synchronous orbit on 1 March 2002 and operated until April 2012. Within the MIPAS validation activities, independent observations from balloons, aircraft, satellites, and ground-based stations have been compared to European Space Agency (ESA) version 4.61 operational H2O data comprising the time period from July 2002 until March 2004 where MIPAS measured with full spectral resolution. No significant bias in the MIPAS H2O data is seen in the lower stratosphere (above the hygropause) between about 15 and 30 km. Differences of H2O quantities observed by MIPAS and the validation instruments are mostly well within the combined total errors in this altitude region. In the upper stratosphere (above about 30 km), a tendency towards a small positive bias (up to about 10%) is present in the MIPAS data when compared to its balloon-borne counterpart MIPAS-B, to the satellite instruments HALOE (Halogen Occultation Experiment) and ACE-FTS (Atmospheric Chemistry Experiment, Fourier Transform Spectrometer), and to the millimeter-wave airborne sensor AMSOS (Airborne Microwave Stratospheric Observing System). In the mesosphere the situation is unclear due to the occurrence of different biases when comparing HALOE and ACE-FTS data. Pronounced deviations between MIPAS and the correlative instruments occur in the lowermost stratosphere and upper troposphere, a region where retrievals of H2O are most challenging. Altogether it can be concluded that MIPAS H2O profiles yield valuable information on the vertical distribution of H2O in the stratosphere with an overall accuracy of about 10 to 30% and a precision of typically 5 to 15% – well within the predicted error budget, showing that these global and continuous data are very valuable for scientific studies. However, in the region around the tropopause retrieved MIPAS H2O profiles are less reliable, suffering from a number of obstacles such as retrieval boundary and cloud effects, sharp vertical discontinuities, and frequent horizontal gradients in both temperature and H2O volume mixing ratio (VMR). Some profiles are characterized by retrieval instabilities.

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Section: Intercomparison Of Aircraft Observationsmentioning

confidence: 99%

“…Retrieval method and error analysis are discussed in Müller et al (2008). ENVISAT validation flights were carried out in September 2002 covering a wide latitude range from the tropics to the Arctic, providing a large number of collocations (Fig.…”

Section: Intercomparison Of Aircraft Observationsmentioning

confidence: 99%

Validation of MIPAS-ENVISAT H<sub>2</sub>O operational data collected between July 2002 and March 2004

et al. 2013

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“…Water vapor in the UT/LS region is not only measured by in-situ instrumentation on board of aircraft and balloons but is also monitored by satellite based instruments. In the past, whenever possible, FISH measurements were readily taken to validate these satellite based hygrometers (Thomason et al, 1994;Kanzawa et al, 2002;Offermann et al, 2002;Lumpe et al, 2006;Kiemle et al, 2008;Müller et al, 2008;Milz et al, 2009;Wetzel et al, 2013). Figure 13 exemplarily demonstrates the comparison of the Microwave Limb Sounder (MLS) (Lambert et al, 2007;Read et al, 2007) installed on the NASA Aura satellite with respect to the FISH instrument.…”

Section: Satellite Intercomparisons: Fish -Aura Mlsmentioning

confidence: 99%

Two decades of water vapor measurements with the FISH fluorescence hygrometer: a review

Meyer¹,

Rolf²,

Schiller³

et al. 2015

Preprint

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Abstract. The Fast In-situ Stratospheric Hygrometer (FISH) is an airborne Lyman-α photofragment fluorescence hygrometer for accurate and precise measurement of total water mixing ratios (WMR) (gas phase + evaporated ice) in the upper troposphere and lower stratosphere (UT/LS) since almost two decades. Here, we present a comprehensive review of the measurement technique, calibration procedure, accuracy and reliability of FISH. A crucial part for the FISH measurement quality is the regular calibration to a water vapor reference, namely the commercial frostpoint hygrometer DP30. In the frame of this work this frostpoint hygrometer is compared to German and British traceable metrological water standards and its accuracy is found to be 2–4%. Overall, in the range from 4–1000 ppmv, the total accuracy of FISH was found to be 6–8% as stated also in previous publications. For lower mixing ratios down to 1 ppmv, the uncertainty reaches a lower limit of 0.3 ppmv. For specific, non-atmospheric conditions, as set in experiments at the AIDA chamber – namely mixing ratios below 10 and above 100 ppmv in combination with high and low pressure conditions – the need to apply a modified FISH calibration evaluation has been identified. The new evaluation improves the agreement of FISH with other hygrometers to ± 10% accuracy in the respective mixing ratio ranges. Further, a quality check procedure for high total water measurements in cirrus clouds at high pressures (400–500 hPa) is introduced. The performance of FISH in the field is assessed by reviewing intercomparisons of FISH water vapor data with other in-situ and remote sensing hygrometers over the last two decades. We find that the agreement of FISH with the other hygrometers has improved over that time span from overall up to ±30% or more to about ±5–20% @ < 10 ppmv and to ±0–15% @ > 10 ppmv. As presented here, the robust and continuous calibration and operation procedures of the FISH instrument over the last two decades, establish the position of FISH as one of the core instruments for in-situ observations of water vapor in the UT/LS.

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“…[3] AMSOS (Airborne Microwave Stratospheric Observing System) measures the water vapor rotational transition line at a frequency of 183.3 GHz, [Vasic et al, 2005]. The main result of AMSOS are water vapor profiles between 15 and 75 km from polar regions to the tropics as reported by Feist et al [2007] and Müller et al [2008]. AMSOS is flown on board a Swiss Airforce Learjet and measured yearly since 1998 in one week campaigns mainly on meridional flight tracks from midlatitudes to the North pole.…”

Section: Instrumentmentioning

confidence: 99%

First measurements of lower mesospheric wind by airborne microwave radiometry

Flury¹,

Hocke²,

Müller³

et al. 2008

Geophysical Research Letters

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[1] The Institute of Applied Physics operates an airborne microwave radiometer that measures the rotational transition line of water vapor at 183.3 GHz. A narrowband digital FFT spectrometer is used for the detection of the atmospheric signal with a channel resolution of 12 kHz. For the first time we measure lower mesospheric wind using the wind induced Doppler shift of the spectral line at its center. The Doppler frequency shift is calculated by the center of mass method allowing to retrieve the wind speed in the layer 55-70 km with a precision of 14 m/s. A good agreement with ECMWF operational reanalysis is found. We show that microwave remote sensing is an appropriate technique to fill the current experimental data gap in lower mesospheric winds. Precise wind measurements are of need to improve atmosphere circulation models and medium range weather forecasts.

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Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS

Cited by 20 publications

References 27 publications

Validation of MIPAS-ENVISAT H<sub>2</sub>O operational data collected between July 2002 and March 2004

Validation of MIPAS-ENVISAT H<sub>2</sub>O operational data collected between July 2002 and March 2004

Two decades of water vapor measurements with the FISH fluorescence hygrometer: a review

First measurements of lower mesospheric wind by airborne microwave radiometry

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Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS

Cited by 20 publications

References 27 publications

Validation of MIPAS-ENVISAT H&lt;sub&gt;2&lt;/sub&gt;O operational data collected between July 2002 and March 2004

Validation of MIPAS-ENVISAT H&lt;sub&gt;2&lt;/sub&gt;O operational data collected between July 2002 and March 2004

Two decades of water vapor measurements with the FISH fluorescence hygrometer: a review

First measurements of lower mesospheric wind by airborne microwave radiometry

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Validation of MIPAS-ENVISAT H<sub>2</sub>O operational data collected between July 2002 and March 2004

Validation of MIPAS-ENVISAT H<sub>2</sub>O operational data collected between July 2002 and March 2004