scholarly journals Precipitable water vapour content from ESR/SKYNET sun–sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe

2018 ◽  
Vol 11 (1) ◽  
pp. 81-94 ◽  
Author(s):  
Monica Campanelli ◽  
Alessandra Mascitelli ◽  
Paolo Sanò ◽  
Henri Diémoz ◽  
Victor Estellés ◽  
...  
Keyword(s):  
Water Vapour ◽  
Precipitable Water ◽  
Climatic Conditions ◽  
Atmospheric Parameter ◽  
High Temporal Resolution ◽  
Precipitable Water Vapour ◽  
Water Vapour Content ◽  
Photometric Calibration ◽  
Wide Range ◽  
Calibration Parameters

Abstract. The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W, from independent sources, taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NETwork (AERONET) W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in terms of % bias, bringing the agreement with the GPS (considered the reference one) from a % bias of 5.76 to 0.52.

scholarly journals Precipitable water vapor content from ESR/SKYNET Sun-sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe

2017 ◽  
Author(s):  
Monica Campanelli ◽  
Alessandra Mascitelli ◽  
Paolo Sanò ◽  
Henri Diémoz ◽  
Victor Estellés ◽  
...  
Keyword(s):  
Water Vapor ◽  
Precipitable Water ◽  
Climatic Conditions ◽  
Precipitable Water Vapor ◽  
Water Vapor Content ◽  
Atmospheric Parameter ◽  
High Temporal Resolution ◽  
Photometric Calibration ◽  
Wide Range ◽  
Calibration Parameters

Abstract. The estimation of the precipitable water vapor content (W) with high temporal and spatial resolution is of great interest in both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed, in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun-sky radiometers, or sun-photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal independent measurements of W taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS dataset were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol Robotic NETwork (AERONET) W estimations. In both the validations the agreement was very high with a percentage RMSD of about 6 %, 13 % and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in term of %Bias, bringing the agreement with the GPS (considered the reference one), from a %Bias of 5.76 to 0.52.

Precipitable water vapour content above the Roque de los Muchachos Observatory from GPS estimations

2009 ◽  
Author(s):  
B. García-Lorenzo ◽  
J. A. Castro-Almazán ◽  
A. Eff-Darwich ◽  
C. Muñoz-Tuñón ◽  
N. Pinilla-Alonso ◽  
...  
Keyword(s):  
Water Vapour ◽  
Precipitable Water ◽  
Precipitable Water Vapour ◽  
Water Vapour Content

Diurnal cycle of GNSS-derived precipitable water vapour in tropical regions

2020 ◽  
Author(s):  
Zofia Bałdysz ◽  
Grzegorz Nykiel ◽  
Dariusz Baranowski ◽  
Beata Latos ◽  
Mariusz Figurski
Keyword(s):  
Water Vapour ◽  
Diurnal Cycle ◽  
Asian Summer Monsoon ◽  
Precipitable Water ◽  
Tropical Atmosphere ◽  
International Gnss Service ◽  
Precipitable Water Vapour ◽  
Water Vapour Content ◽  
Inter Tropical Convergence Zone ◽  
Tropical Regions

<p>Convective processes in the tropical atmosphere and their diurnal cycles have important repercussions for the circulations in the tropical regions and beyond. Monitoring of the water vapour content in the tropical atmosphere remains a challenge due to its high temporal and spatial variability. Global models tend to fail to correctly capture the diurnal convection, limiting forecasting accuracy. In this work, we investigated precipitable water vapour (PWV) diurnal cycle, precipitation and infrared  brightness temperature (TB) data over the tropical area. We used in-situ observations from 44 IGS (International GNSS Service) stations covering time span of 18 years, together with satellite-based precipitation and cloudiness data, taken from the Tropical Rainfall Measurement Mission gridded dataset (TRMM 3B42 v7) and the global, merged infrared (IR) dataset, respectively. The data provided an opportunity to examine the characteristics of a diurnal cycle of PWV, precipitation and TB over the study area in greater detail than before.</p><p>In particular, our results show that the diurnal cycle of PWV and TB were almost entirely dominated by mono-modal distributions. The diurnal cycle of precipitation onshore (continental areas or big islands; continental regime) had a single late afternoon peak, and that offshore (small islands; oceanic regime) had both a midday and a nocturnal peak. Daily amplitude phase shift of PWV and precipitation at onshore stations with a continental regime consistently occurred at the same time, while TB maximum peaked about five hours later. Furthermore, results show that the daily mean and the amplitude of the diurnal cycle of PWV, precipitation and TB appeared smaller on offshore stations, exhibited to an oceanic regime, than on onshore, continental stations. Additional analysis of seasonal variations of GNSS-derived PWV shows the usefulness of such measurements for tracking propagation of longer-scale phenomena, such as Inter Tropical Convergence Zone (ITCZ), Southeast Asian monsoon or East Asian summer monsoon.</p>

scholarly journals Forecasting the precipitable water vapour content: validation for astronomical observatories using radiosoundings

2015 ◽  
Vol 452 (2) ◽  
pp. 1992-2003 ◽  
Author(s):  
G. Pérez-Jordán ◽  
J. A. Castro-Almazán ◽  
C. Muñoz-Tuñón ◽  
B. Codina ◽  
J. Vernin
Keyword(s):  
Water Vapour ◽  
Precipitable Water ◽  
Content Validation ◽  
Precipitable Water Vapour ◽  
Water Vapour Content

scholarly journals Infrared and Submillimetre Observing Conditions on the Antarctic Plateau

2000 ◽  
Vol 17 (3) ◽  
pp. 260-269 ◽  
Author(s):  
Marton G. Hidas ◽  
Michael G. Burton ◽  
Matthew A. Chamberlain ◽  
John W. V. Storey
Keyword(s):  
Water Vapour ◽  
Precipitable Water ◽  
Atmospheric Transmission ◽  
Precipitable Water Vapour ◽  
Water Vapour Content ◽  
Antarctic Plateau ◽  
Near Ir ◽  
The Antarctic ◽  
Determining Factor

AbstractThe Antarctic Plateau provides the best terrestrial sites for infrared (IR) and submillimetre (sub-mm) astronomy. In this paper we examine the relative importance of temperature, aerosol content and precipitable water vapour to determine which parameters have the greatest influence on atmospheric transmission and sky brightness. We use the atmospheric modelling program MODTRAN to model the observed sky spectrum at the South Pole from the near-IR to the sub-mm. We find that temperature and aerosol content determine the quality of near-IR observing conditions, aerosol content is the determining factor in the mid-IR up to 20 μm, while at longer wavelengths, including the sub-mm, it is the water vapour content that matters. Finding a location where aerosol levels are minimised is a key constraint in determining the optimum site on the Antarctic Plateau for an IR observatory.

scholarly journals A semiempirical error estimation technique for PWV derived from atmospheric radiosonde data

2016 ◽  
Vol 9 (9) ◽  
pp. 4759-4781 ◽  
Author(s):  
Julio A. Castro-Almazán ◽  
Gabriel Pérez-Jordán ◽  
Casiana Muñoz-Tuñón
Keyword(s):  
Water Vapour ◽  
Sampling Error ◽  
Precipitable Water ◽  
Semiempirical Method ◽  
The Arctic ◽  
Radiosonde Data ◽  
Optimum Number ◽  
Precipitable Water Vapour ◽  
Water Vapour Content ◽  
Covariance Components

Abstract. A semiempirical method for estimating the error and optimum number of sampled levels in precipitable water vapour (PWV) determinations from atmospheric radiosoundings is proposed. Two terms have been considered: the uncertainties in the measurements and the sampling error. Also, the uncertainty has been separated in the variance and covariance components. The sampling and covariance components have been modelled from an empirical dataset of 205 high-vertical-resolution radiosounding profiles, equipped with Vaisala RS80 and RS92 sondes at four different locations: Güímar (GUI) in Tenerife, at sea level, and the astronomical observatory at Roque de los Muchachos (ORM, 2300 m a.s.l.) on La Palma (both on the Canary Islands, Spain), Lindenberg (LIN) in continental Germany, and Ny-Ålesund (NYA) in the Svalbard Islands, within the Arctic Circle. The balloons at the ORM were launched during intensive and unique site-testing runs carried out in 1990 and 1995, while the data for the other sites were obtained from radiosounding stations operating for a period of 1 year (2013–2014). The PWV values ranged between ∼  0.9 and ∼  41 mm. The method sub-samples the profile for error minimization. The result is the minimum error and the optimum number of levels. The results obtained in the four sites studied showed that the ORM is the driest of the four locations and the one with the fastest vertical decay of PWV. The exponential autocorrelation pressure lags ranged from 175 hPa (ORM) to 500 hPa (LIN). The results show a coherent behaviour with no biases as a function of the profile. The final error is roughly proportional to PWV whereas the optimum number of levels (N0) is the reverse. The value of N0 is less than 400 for 77 % of the profiles and the absolute errors are always <  0.6 mm. The median relative error is 2.0 ±  0.7 % and the 90th percentile P90 = 4.6 %. Therefore, whereas a radiosounding samples at least N0 uniform vertical levels, depending on the water vapour content and distribution of the atmosphere, the error in the PWV estimate is likely to stay below ≈  3 %, even for dry conditions.

scholarly journals Water Vapour Assessment Using GNSS and Radiosondes over Polar Regions and Estimation of Climatological Trends from Long-Term Time Series Analysis

2021 ◽  
Vol 13 (23) ◽  
pp. 4871
Author(s):  
Monia Negusini ◽  
Boyan H. Petkov ◽  
Vincenza Tornatore ◽  
Stefano Barindelli ◽  
Leonardo Martelli ◽  
...  
Keyword(s):  
Water Vapour ◽  
Correlation Coefficients ◽  
Arctic Region ◽  
Precipitable Water ◽  
Satellite System ◽  
The Arctic ◽  
Polar Regions ◽  
Precipitable Water Vapour ◽  
Water Vapour Content

The atmospheric humidity in the Polar Regions is an important factor for the global budget of water vapour, which is a significant indicator of Earth’s climate state and evolution. The Global Navigation Satellite System (GNSS) can make a valuable contribution in the calculation of the amount of Precipitable Water Vapour (PW). The PW values retrieved from Global Positioning System (GPS), hereafter PWGPS, refer to 20-year observations acquired by more than 40 GNSS geodetic stations located in the polar regions. For GNSS stations co-located with radio-sounding stations (RS), which operate Vaisala radiosondes, we estimated the PW from RS observations (PWRS). The PW values from the ERA-Interim global atmospheric reanalysis were used for validation and comparison of the results for all the selected GPS and RS stations. The correlation coefficients between times series are very high: 0.96 for RS and GPS, 0.98 for RS and ERA in the Arctic; 0.89 for RS and GPS, 0.97 for RS and ERA in Antarctica. The Root-Mean-Square of the Error (RMSE) is 0.9 mm on average for both RS vs. GPS and RS vs. ERA in the Arctic, and 0.6 mm for RS vs. GPS and 0.4 mm for RS vs. ERA in Antarctica. After validation, long-term trends, both for Arctic and Antarctic regions, were estimated using Hector scientific software. Positive PWGPS trends dominate at Arctic sites near the borders of the Atlantic Ocean. Sites located at higher latitudes show no significant values (at 1σ level). Negative PWGPS trends were observed in the Arctic region of Greenland and North America. A similar behaviour was found in the Arctic for PWRS trends. The stations in the West Antarctic sector show a general positive PWGPS trend, while the sites on the coastal area of East Antarctica exhibit some significant negative PWGPS trends, but in most cases, no significant PWRS trends were found. The present work confirms that GPS is able to provide reliable estimates of water vapour content in Arctic and Antarctic regions too, where data are sparse and not easy to collect. These preliminary results can give a valid contribution to climate change studies.

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