Continuous quality assessment of atmospheric water vapour measurement  techniques: FTIR, Cimel, MFRSR, GPS, and Vaisala RS92

Schneider, Mat­thias; Romero, P. M.; Hase, Frank; Blumenstock, Thomas; Cuevas, E.; Ramos, Ramón

doi:10.5194/amt-3-323-2010

Cited by 122 publications

(195 citation statements)

References 33 publications

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“…In case of the satellite instruments, the lowermost tropospheric layers are probably not sensed correctly for less cloud-free scenes. On the other hand, similar to Wang et al (2007) and Schneider et al (2010), we confirm that the GPS technique seems less sensitive to low IWV values than the other devices.…”

Section: Discussionsupporting

confidence: 81%

“…Moreover, several studies in the literature concentrate on a multi-sensor intercomparison at a single site (e.g. Pałm et al, 2010;Schneider et al, 2010;Buehler et al, 2012). In this paper, we will first focus on the mid-latitude site Brussels (Belgium), as a case study (see Sect.…”

Section: R Van Malderen Et Al: a Multi-site Iwv Intercomparisonmentioning

confidence: 99%

“…For low water vapour amounts, the ZTD is almost completely due to the ZHD. Therefore, small relative errors in these amounts produce a large relative error in their difference (ZWD) and consequently in the retrieved IWV (Schneider et al, 2010).…”

Section: Day-night Differencesmentioning

confidence: 99%

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A multi-site intercomparison of integrated water vapour observations for climate change analysis

et al. 2014

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Abstract. Water vapour plays a dominant role in the climate change debate. However, observing water vapour over a climatological time period in a consistent and homogeneous manner is challenging. On one hand, networks of groundbased instruments able to retrieve homogeneous integrated water vapour (IWV) data sets are being set up. Typical examples are Global Navigation Satellite System (GNSS) observation networks such as the International GNSS Service (IGS), with continuous GPS (Global Positioning System) observations spanning over the last 15+ years, and the AErosol RObotic NETwork (AERONET), providing long-term observations performed with standardized and well-calibrated sun photometers. On the other hand, satellite-based measurements of IWV already have a time span of over 10 years (e.g. AIRS) or are being merged to create long-term time series (e.g. GOME, SCIAMACHY, and GOME-2).This study performs an intercomparison of IWV measurements from satellite devices (in the visible, GOME/SCIAMACHY/GOME-2, and in the thermal infrared, AIRS), in situ measurements (radiosondes) and ground-based instruments (GPS, sun photometer), to assess their use in water vapour trends analysis. To this end, we selected 28 sites world-wide for which GPS observations can directly be compared with coincident satellite IWV observations, together with sun photometer and/or radiosonde measurements. The mean biases of the different techniques compared to the GPS estimates vary only between −0.3 to 0.5 mm of IWV. Nevertheless these small biases are accompanied by large standard deviations (SD), especially for the satellite instruments. In particular, we analysed the impact of clouds on the IWV agreement. The influence of specific issues for each instrument on the intercomparison is also investigated (e.g. the distance between the satellite ground pixel centre and the co-located ground-based station, the satellite scan angle, daytime/nighttime differences). Furthermore, we checked if the properties of the IWV scatter plots between these different instruments are dependent on the geography and/or altitude of the station. For all considered instruments, the only dependency clearly detected is with latitude: the SD of the IWV observations with respect to the GPS IWV retrievals decreases with increasing latitude and decreasing mean IWV.

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Section: Discussionsupporting

confidence: 81%

Section: R Van Malderen Et Al: a Multi-site Iwv Intercomparisonmentioning

confidence: 99%

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A multi-site intercomparison of integrated water vapour observations for climate change analysis

et al. 2014

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“…It is much larger than the scatter in the difference with the FTIR profiles meaning that the FTIR well follows the ISOWAT reference, which confirms previous empirical validation exercises made for H 2 O (e.g. Schneider et al, 2006a;Schneider and Hase, 2009;Schneider et al, 2010a). Please note that the depicted red dashed line represents the combined uncertainty of the convolved ISOWAT data and the FTIR data.…”

Section: Ndacc/ftirsupporting

confidence: 68%

“…It describes the response of the retrieval on actual Schneider et al, 2012), which have been empirically validated in a variety of previous studies (e.g. Schneider et al, 2006a;Schneider and Hase, 2009;Schneider et al, 2010a). A further validation of product type 1 is not the subject of this paper.…”

Section: Ground-based Ndacc/ftirmentioning

confidence: 99%

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

et al. 2015

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Abstract. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) integrates tropospheric water vapour isotopologue remote sensing and in situ observations. This paper presents a first empirical validation of MUSICA's H 2 O and δD remote sensing products, generated from groundbased FTIR (Fourier transform infrared), spectrometer and space-based IASI (infrared atmospheric sounding interferometer) observation. The study is made in the area of the Canary Islands in the subtropical northern Atlantic. As reference we use well calibrated in situ measurements made aboard an aircraft (between 200 and 6800 m a.s.l.) by the dedicated ISOWAT instrument and on the island of Tenerife at two different altitudes (at Izaña, 2370 m a.s.l., and at Teide, 3550 m a.s.l.) by two commercial Picarro L2120-i water isotopologue analysers.The comparison to the ISOWAT profile measurements shows that the remote sensors can well capture the variations in the water vapour isotopologues, and the scatter with respect to the in situ references suggests a δD random uncertainty for the FTIR product of much better than 45 ‰ in the lower troposphere and of about 15 ‰ for the middle troposphere. For the middle tropospheric IASI δD product the study suggests a respective uncertainty of about 15 ‰. In both remote sensing data sets we find a positive δD bias of 30-70 ‰.Complementing H 2 O observations with δD data allows moisture transport studies that are not possible with H 2 O observations alone. We are able to qualitatively demonstrate the added value of the MUSICA δD remote sensing data. We document that the δD-H 2 O curves obtained from the different in situ and remote sensing data sets (ISOWAT, Picarro at Izaña and Teide, FTIR, and IASI) consistently identify two different moisture transport pathways to the subtropical north eastern Atlantic free troposphere.

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Solar radiation measurements compared to simulations at the BSRN Izaña station. Mineral dust radiative forcing and efficiency study

García

Cuevas

et al. 2014

JGR Atmospheres

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[1] This paper presents a comparative study of shortwave downward radiation (SDR) measurements and simulations, obtained with the radiative transfer model LibRadtran, at the Baseline Surface Radiation Network (BSRN) site of Izaña Atmospheric Observatory (IZA, Spain). The analysis is based on cloud-free days between March 2009 and August 2012 (386 days), including aerosol-free and Saharan mostly pure mineral dust conditions and comparing the day-to-day, annual, and interannual variability. The observed agreement between simulations and measurements is excellent: the variance of daily measurements overall agrees within 99% with the variance of daily simulations, and the mean bias (simulations-measurements) is -0.30˙0.24 MJm -2 (-1.1˙0.9%) for global, -0.16˙0.34 MJm -2 (-0.4˙0.9%) for direct, and +0.02˙0.25 MJm -2 (+0.9˙9.2%) for diffuse SDR. Furthermore, the diurnally averaged aerosol radiative forcing (DF) and radiative forcing efficiency (DF eff ) due to Saharan mostly pure mineral dust events has been computed at Izaña Observatory. The mean DF values are -7˙1, -96˙5, and 44˙2 Wm -2 for global, direct, and diffuse BSRN SDR, respectively (mean aerosol optical depth, AOD, at 500 nm of 0.18˙0.01), whereas the mean DF eff values are -59˙6, -495˙11, and 230˙8 Wm -2 per unit of AOD at 500 nm for global, direct, and diffuse BSRN SDR, respectively. These values highlight the importance of scattering processes for mineral dust aerosols: the ratio between DF and the corresponding SDR without aerosols is 2.5% for diffuse SDR versus 0.2% for direct SDR. This illustrates the significant potential of mineral dust particles to cool the Earth-atmosphere system.

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Continuous quality assessment of atmospheric water vapour measurement techniques: FTIR, Cimel, MFRSR, GPS, and Vaisala RS92

Cited by 122 publications

References 33 publications

A multi-site intercomparison of integrated water vapour observations for climate change analysis

A multi-site intercomparison of integrated water vapour observations for climate change analysis

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

Solar radiation measurements compared to simulations at the BSRN Izaña station. Mineral dust radiative forcing and efficiency study

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