Survey of Intercomparisons of Water Vapour Measurements

Hocke, Klemens; Martin, Lorenz; Kämpfer, Niklaus

doi:10.1007/978-1-4614-3909-7_11

Cited by 5 publications

(4 citation statements)

References 238 publications

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“…The extended GPV datasets were provided by the Japan Meteorological Agency. We are grateful to Y. Yoshida of NIES for helpful discussions about screening of TANSO-FTS SWIR XH 2 …”

Section: Discussionmentioning

confidence: 99%

“…Intercomparison of IWV derived from different techniques or instruments is a commonly used method for assessing the bias and relative precision of the data [2]. The standard deviation of the mean difference between the IWV, which is obtained from the intercomparison, includes the spatial and temporal representativeness (variability) and the effect of difference in the vertical resolution between the two measurements, in addition to the respective measurement precisions.…”

Section: Introductionmentioning

confidence: 99%

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Intercomparison of XH2O Data from the GOSAT TANSO-FTS (TIR and SWIR) and Ground-Based FTS Measurements: Impact of the Spatial Variability of XH2O on the Intercomparison

et al. 2017

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Spatial and temporal variability of atmospheric water vapor (H 2 O) is extremely high, and therefore it is difficult to accurately evaluate the measurement precision of H 2 O data by a simple comparison between the data derived from two different instruments. We determined the measurement precisions of column-averaged dry-air mole fractions of H 2 O (XH 2 O) retrieved independently from spectral radiances in the thermal infrared (TIR) and the short-wavelength infrared (SWIR) regions measured using a Thermal And Near-infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT), by an intercomparison between the two TANSO-FTS XH 2 O data products and the ground-based FTS XH 2 O data. Furthermore, the spatial variability of XH 2 O was also estimated in the intercomparison process. Mutually coincident XH 2 O data above land for the period ranging from April 2009 to May 2014 were intercompared with different spatial coincidence criteria. We found that the precisions of the TANSO-FTS TIR and TANSO-FTS SWIR XH 2 O were 7.3%-7.7% and 3.5%-4.5%, respectively, and that the spatial variability of XH 2 O was 6.7% within a radius of 50 km and 18.5% within a radius of 200 km. These results demonstrate that, in order to accurately evaluate the measurement precision of XH 2 O, it is necessary to set more rigorous spatial coincidence criteria or to take into account the spatial variability of XH 2 O as derived in the present study.

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“…The extended GPV datasets were provided by the Japan Meteorological Agency. We are grateful to Y. Yoshida of NIES for helpful discussions about screening of TANSO-FTS SWIR XH 2 …”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intercomparison of XH2O Data from the GOSAT TANSO-FTS (TIR and SWIR) and Ground-Based FTS Measurements: Impact of the Spatial Variability of XH2O on the Intercomparison

et al. 2017

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“…To this finding it may contribute that suspected systematic changes are expected to become visible only in the range of 0.1 %rh or below, and that the present-day marine and atmospheric measurement technology is not accurate enough to resolve such effects. There is also the problem that long-term series of relative humidity are "almost not available" [77,83] in quality and length comparable to those known for temperature and precipitation; this is true in particular for the marine atmosphere [84] and for the Arctic. "The water vapour distribution especially in Arctic regions is only poorly known and suffers from a limited reliability of some observational standard methods like radiosondes" [85].…”

Section: Relative Humidity: Cause and Effect Of Evaporationmentioning

confidence: 99%

Relative Humidity: A Control Valve of the Steam Engine Climate

Feistel

Hellmuth

2021

J. Hum. Earth Future

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In the words of Heinrich Hertz in 1885, the Earth is a “gigantic steam engine”. On average, of the planet’s cross section exposed to sunlight, 72 % belong to the global ocean. With a delay of only 2-3 months, most of the heat absorbed there is released by evaporation rather than by thermal radiation. Water vapour is the dominating “greenhouse gas” of the marine troposphere with a typical relative humidity (RH) of 80 % at the surface. Observing the heat transport across the ocean surface permits insight in the powerhouse of the “steam engine”, controlled by the RH at the surface, a quantity that is often considered the “Cinderella” among the climate data. RH of the troposphere also controls cloud formation that is equally fundamental as challenging for climate research. As a precise and perfectly consistent thermodynamic basis for the description of such processes, the new oceanographic standard TEOS-10 was introduced by UNESCO/IOC in 2010 and IUGG in 2011. Its equations cover all thermodynamic properties of liquid water, seawater, ice and humid air, as well as their mutual equilibria and phase transitions. For harmonisation of the inconsistent RH definitions of humid air between meteorology and climatology, the relative fugacity has been defined as a physically more reasonable RH substitute that does not rely on the approximation of ideal gases. Doi: 10.28991/HEF-2021-02-02-06 Full Text: PDF

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“…For example, records between 1849 and 1868 of dry-bulb and wet-bulb thermometers at the Royal Observatory at Greenwich were analysed by Ellis (1878), and at the German weather station Hohenpeissenberg, where continuous RH records began in 1879 (DWD, 2012), different hygrometers and a psychrometer (in 1841) had been used since 1781 5 . Nevertheless, long-term series of RH comparable in length and quality to historical records of temperature and precipitation are “almost not available” (Hocke et al, 2013) for modern climate research.…”

Section: Brief Historymentioning

confidence: 99%

Metrological challenges for measurements of key climatological observables. Part 4: atmospheric relative humidity

et al. 2015

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Water in its three ambient phases plays the central thermodynamic role in the terrestrial climate system. Clouds control Earth’s radiation balance, atmospheric water vapour is the strongest “greenhouse” gas, and non-equilibrium relative humidity at the air-sea interface drives evaporation and latent heat export from the ocean. In this paper, we examine the climatologically relevant atmospheric relative humidity, noting fundamental deficiencies in the definition of this key observable. The metrological history of this quantity is reviewed, problems with its current definition and measurement practice are analysed, and options for future improvements are discussed in conjunction with the recent seawater standard TEOS-10. It is concluded that the International Bureau of Weights and Measures, (BIPM), in cooperation with the International Association for the Properties of Water and Steam, IAPWS, along with other international organisations and institutions, can make significant contributions by developing and recommending state-of-the-art solutions for this long standing metrological problem, such as are suggested here.

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Survey of Intercomparisons of Water Vapour Measurements

Cited by 5 publications

References 238 publications

Intercomparison of XH2O Data from the GOSAT TANSO-FTS (TIR and SWIR) and Ground-Based FTS Measurements: Impact of the Spatial Variability of XH2O on the Intercomparison

Intercomparison of XH2O Data from the GOSAT TANSO-FTS (TIR and SWIR) and Ground-Based FTS Measurements: Impact of the Spatial Variability of XH2O on the Intercomparison

Relative Humidity: A Control Valve of the Steam Engine Climate

Metrological challenges for measurements of key climatological observables. Part 4: atmospheric relative humidity

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