On the relation between the wet delay and the integrated precipitable water vapour in the European atmosphere

Emardson, T. Ragne; Derks, H.

doi:10.1017/s1350482700001377

Cited by 114 publications

(88 citation statements)

References 5 publications

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“…The standard procedure for GPS data analysis assumes that the delay in any direction can be mapped from the delay at zenith. From the ZTD, the component due to the dry atmosphere is removed and the remainder is converted into IWV using an empirical equation that uses the surface pressure and temperature (Bevis et al, 1992;Emardson and Derks, 1999). The impact of the terrain heterogeneity (and then of the surface temperature) on the accuracy of the GPS products is probably small as the conversion between ZTD and IWV is mainly sensitive to the surface pressure measurement.…”

Section: Description Of the Datasetmentioning

confidence: 99%

Water vapour variability induced by urban/rural surface heterogeneities during convective conditions

Champollion

Drobinski

Haeffelin

et al. 2009

Quart J Royal Meteoro Soc

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Scientific interest in urban meteorology has increased because highly populated areas experience high vulnerability to pollution or heavy rain. However, compared to urban air quality or urban heat island (UHI) processes, the urban water vapour cycle is poorly understood because it has been investigated less due to the lack of upper-air measurements and the high sensitivity of surface measurements to local heterogeneities. In this paper, surface measurements of wind, temperature, pressure and humidity, as well as integrated water vapour (IWV) from GPS and MODIS and numerical simulations, have been used to investigate the urban cycle of water vapour in May and June 2004 during the VAPIC field experiment in the Paris area.The surface data show the typical characteristics of an urban area with the absence of water vapour sources and a UHI of about 6 • C at night. The urban IWV distribution differs completely, with an urban IWV excess on average between 1600 and 0600 UTC (with a maximum of about 1.5 kg m −2 at 0600 and 1700 UTC). No IWV difference between the urban and rural areas is found in the middle of the day. The numerical simulations reproduce accurately the urban IWV anomaly.Shallow surface wind convergence associated with the UHI during nighttime provides moisture from the rural areas. Urban areas are therefore under wind convergence for most of the time. The rural water vapour sources and the depth of the convergence control the amplitude of the urban IWV excess. At about 1200 UTC, entrainment at the top of the urban boundary layer is the key process that inhibits the urban IWV excess observed at night.

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Section: Description Of the Datasetmentioning

confidence: 99%

Water vapour variability induced by urban/rural surface heterogeneities during convective conditions

Champollion

Drobinski

Haeffelin

et al. 2009

Quart J Royal Meteoro Soc

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“…The ZHD is not estimated, but is corrected a priori using the Saastamoinen formula (1972). ZWD is, thus, converted into IWV (Integrated Water Vapor), using simply surface temperature and empirical formulas (Bevis et al, 1992;Emardson and Derks, 1999). The accuracy in GPS, IWV has been assessed by a number of authors, using intercomparisons with radiosondes, microwave radiometers, sun photometers, lidars, and very long interferometry baseline (Foelsche and Kirchengast, 2001;Niell et al, 2001;Bock et al, 2004).…”

Section: Radiosonde Sensors and Gps Receiversmentioning

confidence: 99%

Water vapor observations up to the lower stratosphere through the Raman lidar during the Maïdo Lidar Calibration Campaign

et al. 2015

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Abstract.A new lidar system devoted to tropospheric and lower stratospheric water vapor measurements has been installed at the Maïdo altitude station facility of Réunion island, in the southern subtropics.To evaluate the performances and the capabilities of the new system with a particular focus on UTLS (Upper Troposphere Lower Stratosphere) measurements, the Maïdo Lidar Calibration Campaign (MALICCA) was performed in April 2013.Varying the characteristics of the transmitter and the receiver components, different system configuration scenarios were tested and possible parasite signals (fluorescent contamination, rejection) were investigated. A hybrid calibration methodology has been set up and validated to insure optimal lidar calibration stability with time. In particular, the receiver transmittance is monitored through the calibration lamp method that, at the moment, can detect transmittance variations greater than 10-15 %. Calibration coefficients are then calculated through the hourly values of IWV (Integrated Water Vapor) provided by the co-located GPS. The comparison between the constants derived by GPS and Vaisala RS92 radiosondes launched at Maïdo during MALICCA, points out an acceptable agreement in terms of accuracy of the mean calibration value (with a difference of approximately 2-3 %), but a significant difference in terms of variability (14 % vs. 7-9 %, for GPS and RS92 calibration procedures, respectively).We obtained a relatively good agreement between the lidar measurements and 15 co-located and simultaneous RS92 radiosondes. A relative difference below 10 % is measured in the low and middle troposphere (2-10 km). The upper troposphere (up to 15 km) is characterized by a larger spread (approximately 20 %), because of the increasing distance between the two sensors.To measure water vapor in the UTLS region, nighttime and monthly water vapor profiles are presented and compared. The good agreement between the lidar monthly profile and the mean WVMR profile measured by satellite MLS (Microwave Limb Sounder) has been used as a quality control procedure of the lidar product, attesting the absence of significant wet biases and validating the calibration procedure.Due to its performance and location, the MAIDO H 2 O lidar will become a reference instrument in the southern subtropics, insuring the long-term survey of the vertical distribution of water vapor. Furthermore, this system allows the investigation of several scientific themes, such as stratospheretroposphere exchange, tropospheric dynamics in the subtropics, and links between cirrus clouds and water vapor.

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“…Bevis et al [1992] established such a relation depending on surface temperature from a global climatology of radiosoundings (referred to as k Bevis ), while Emardson and Derks [1999] determined site-and region-dependent relations taking into account more than 120000 radiosoundings from 38 sites in The second column shows ZHD from equation (1) with k 1 (P d , T) given by equation (3). The third column shows ZHD P S from equation (2), with g m from Saastamoinen [1972].…”

Section: Relationship Between Zwd and Iwvmentioning

confidence: 99%

GPS zenith delay sensitivity evaluated from high‐resolution numerical weather prediction simulations of the 8–9 September 2002 flash flood over southeastern France

Brenot¹,

Ducrocq²,

Walpersdorf³

et al. 2006

J. Geophys. Res.

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[1] Estimations of zenith total delays (ZTD) were obtained during postprocessing of a high-resolution (2.4 km) nonhydrostatic atmospheric model (Méso-NH). These estimations were used to determine their sensitivity with respect to formulations of atmospheric refractivity, the approximation of zenith hydrostatic delays (ZHD) deduced from ground pressure, and the contributions of hydrometeors. The factor k for the conversion of zenith wet delay (ZWD) to integrated water vapor (IWV) was examined. Méso-NH is applied here to the extreme flash flood event of 8-9 September 2002 in southeastern France. The use of the hydrostatic formulation (to infer ZHD) leads to an overestimation of up to 18 mm with respect to the vertical integration of refractivity. Delay contributions of hydrometeors simulated by the high-resolution model reached more than 70 mm (%11 kg/m 2 IWV) in the heart of the convective cells in the case of the extreme flood event. The mean variations of IWV due to the use of different conversion factors (k used to transform ZWD to IWV) are evaluated to be less than 0.3 kg/m 2 . This is less than the mean underestimation of IWV by 0.6 kg/m 2 relative to the GPS-like evaluation of IWV using the hydrostatic formulation and the ground temperature. In this study we also use GPS ZTD observations to validate three different numerical simulations of this extreme flood event. The simulation with the best fit to the GPS observations is also in best agreement with the surface rainfall measurements.

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On the relation between the wet delay and the integrated precipitable water vapour in the European atmosphere

Abstract: A ground-based network of Global Positioning System (GPS) receivers can be used to determine the

Cited by 114 publications

References 5 publications

Water vapour variability induced by urban/rural surface heterogeneities during convective conditions

Water vapour variability induced by urban/rural surface heterogeneities during convective conditions

Water vapor observations up to the lower stratosphere through the Raman lidar during the Maïdo Lidar Calibration Campaign

GPS zenith delay sensitivity evaluated from high‐resolution numerical weather prediction simulations of the 8–9 September 2002 flash flood over southeastern France

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