Radiosonde-Based Northern Hemisphere Tropospheric Water Vapor Trends

Ross, Rebecca J.; Elliott, William P.

doi:10.1175/1520-0442(2001)014<1602:rbnhtw>2.0.co;2

Cited by 173 publications

(149 citation statements)

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“…In situ measurements by radiosondes have been used regularly since the 40s to measure the water vapour in the atmosphere and have widely been used to determine IWV trends in the literature (e.g. Ross and Elliott, 2001;Durre et al, 2009;Van Malderen and De Backer, 2010;Mattar et al, 2011). On meteorological satellites, the total precipitable water vapour is sounded using visible, near infrared, thermal infrared, passive microwave, and radio-occultation techniques (Urban, 2013).…”

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

confidence: 99%

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

confidence: 99%

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

et al. 2014

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“…Among them, the atmospheric sounding through weather balloons equipped with pressure, temperature and humidity sensors is an essential technique to monitor the TWVC changes under all weather conditions (e.g. Ross and Elliott, 2001;Durre et al, 2009). Nevertheless, it is well known that radiosonde humidity records can contain sensor-dependent errors that vary notably over time and space (e.g.…”

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confidence: 99%

Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from the GRUAN network

et al. 2015

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Abstract. The main goal of this paper is to validate the total water vapour column (TWVC) measured by the Global Ozone Monitoring Experiment-2 (GOME-2) satellite sensor and generated using the GOME Data Processor (GDP) retrieval algorithm developed by the German Aerospace Centre (DLR). For this purpose, spatially and temporally collocated TWVC data from highly accurate sounding measurements for the period January 2009-May 2014 at six sites are used. These balloon-borne data are provided by the GCOS Reference Upper-Air Network (GRUAN). The correlation between GOME-2 and sounding TWVC data is reasonably good (determination coefficient, R 2 , of 0.89) when all available radiosondes (1400) are employed in the intercomparison. When cloud-free cases (544) are selected by means of the satellite cloud fraction (CF < 5 %), the correlation exhibits a remarkable improvement (R 2 ∼ 0.95). Nevertheless, the analysis of the relative differences between GOME-2 and GRUAN data shows a mean absolute bias error (weighted with the combined uncertainty derived from the estimated errors of both data sets) of 15 % for all-sky conditions (9 % for cloud-free cases). These results evidence a notable bias in the satellite TWVC data against the reference balloon-borne measurements, partially related to the cloudy conditions during the satellite overpass. The detailed analysis of the influence of cloud properties -CF, cloud top albedo (CTA) and cloud top pressure (CTP) -on the satellitesounding differences reveals, as expected, a large effect of clouds in the GOME-2 TWVC data. For instance, the relative differences exhibit a large negative dependence on CTA, varying from −6 to −23 % when CTA rises from 0.3 to 0.8. Furthermore, the satellite-sounding TWVC differences show a strong dependence on the satellite solar zenith angle (SZA) for values above 50 • . Hence the smallest relative differences found in this satellite-sounding comparison are achieved for those cloud-free cases with satellite SZA below 50 • . Finally, the relative differences also show a negative dependence on the reference TWVC values, e.g. changing from +10 % (TWVC below 10 mm) to −10 % (TWVC above 40 mm) when cloud-free conditions with SZA below 50 • are selected. Overall, relative differences within ±10 % with respect to reference sounding data for a large range of TWVC values can be considered as a good result for satellite retrievals.

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“…However, there is a lack of reliable measurements for larger time periods on global scale to support this statement in a quantitative manner. Data for the last three to four decades of the twentieth century indicate an increase of the water vapour content for the lower troposphere of the northern hemisphere [72]. The non-uniform distribution of water vapour in the atmosphere is even more pronounced in the vertical direction.…”

Section: Erca 7 45mentioning

confidence: 98%

“…What do recent observations suggest? Studies based on radiosonde data from the end of the past century, which saw an increase of the mean temperature over land and over the oceans [95], revealed the presence of regional moistening trends for the lower troposphere since the mid-1970s [72,119]. Based on satellite measurements Trenberth et al [120] observed increases in precipitable water over the global oceans since the mid-1980s.…”

Section: Atmospheric Water and Global Changementioning

confidence: 99%

Water in the Earth's atmosphere

Quante¹,

Matthias²

2006

J. Phys. IV France

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Abstract. Water is the key to our existence on this planet and it is involved in nearly all biological, geological, and chemical processes. Life on Earth depends very much on the remarkable properties of water. The availability of freshwater is for many regions one of the key concerns in connection with global climate change. The atmosphere contains only about 0.001% of the water available on our planet. Despite this small amount its horizontal and vertical distribution plays a key role in the global water cycle and the Earth's climate. The atmosphere has direct connections to most of the other reservoirs and steers the redistribution of water between them with an average turnover time of about 10 days. Evaporation over the oceans exceeds precipitation and over land evapotranspiration amounts only to 2/3 of the precipitation reaching the ground. Consequently, there is a net flux of water from the oceans towards the continents, of course via the atmosphere, which has the largest overall volume of fluxes. Water is present in the atmosphere as solid, liquid, or gas. Water vapour is the most important greenhouse gas in the atmosphere and, in addition, changes of water phase and cloud-radiation interaction contribute strongly to the global energy cycle. Water is also a physically and chemically integral part of other biogeochemical cycles. Although there have been large efforts and improvements in recent years, uncertainties in quantifying the components of the atmospheric water cycle still exist. Observational capabilities on the global scale are not satisfactory at present, but the advent of new satellites devoted to the global observation of precipitation and cloud systems along with dedicated modelling projects certainly will improve the situation. Progress is urgently needed to adequately contribute to the answer of one of the central questions in the context of global warming: Is the hydrological cycle accelerating?

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Radiosonde-Based Northern Hemisphere Tropospheric Water Vapor Trends

Cited by 173 publications

References 13 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

Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from the GRUAN network

Water in the Earth's atmosphere

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