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

Pérez-Jordán, Gabriel; Castro-Almazán, Julio A.; Muñoz–Tuñón, C.; Codina, Bernat; Vernin, J.

doi:10.1093/mnras/stv1394

Cited by 25 publications

(20 citation statements)

References 11 publications

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“…In this sense, special care is needed when radiosoundings from different sources and with differing characteristics are being discussed, or when working in a particularly dry atmosphere. This was the case in Pérez-Jordán et al (2015), where we used a set of 23 high-vertical-resolution balloons to validate the Weather Research and Forecasting (WRF) mesoscale numerical model for a dry astronomical location (Roque de los Muchachos Observatory, Canary Islands, Spain; ORM hereafter). The possibility of making use of these radiosounding datasets provided a unique opportunity, as no other atmospheric balloons had been launched at the observatory.…”

Section: Rationale and Objectivesmentioning

confidence: 99%

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

2016

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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 (N 0 ) is the reverse. The value of N 0 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 P 90 = 4.6 %. Therefore, whereas a radiosounding samples at least N 0 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.

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Section: Rationale and Objectivesmentioning

confidence: 99%

“…A second sample of 42 radiosoundings were also included in Pérez-Jordán et al (2015) for verification and control. The point selected was the radiosounding operational station located close to sea level in Güímar (GUI, hereafter), in the neighbouring island of Tenerife.…”

Section: Rationale and Objectivesmentioning

confidence: 99%

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

2016

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“…In a previous paper (Pérez-Jordán et al 2015) we validated the Weather Research and Forecasting (WRF) Numerical Weather Prediction (NWP) model for the precipitable water vapour (PWV) at astronomical sites. We used high resolution radiosonde balloon data launched at Roque de los Muchachos Observatory (ORM) in the Canary Islands and, from a comparison, we proposed a calibration for the highest horizontal resolution (3 km) results.…”

Section: Introduction and Objectivesmentioning

confidence: 99%

“…Abundant literature exists addressing the success of mesoscale NWP models in PWV forecasting (Cucurull et al 2000;Memmo et al 2005;Zhu et al 2008;Chacón et al 2010;Pozo et al 2011;González et al 2013;Pozo et al 2016). Some of these studies are centred on the use of WRF at the ORM (Pérez et al 2010;González et al 2013;Pérez-Jordán et al 2015). Giordano et al (2013) also tested ⋆ Visiting fellow.…”

Section: Introduction and Objectivesmentioning

confidence: 99%

“…PWV is commonly expressed in mm, meaning the height that the water would reach if condensed and collected in a vessel of the same unit cross-section. Generally speaking, the vertical distribution of PWV decreases with height but shows high spatial and temporal variability (Otárola et al 2011). It is also important to emphasize that for the ORM, the PWV content cannot be described merely as a function of altitude (Hammersley 1998); other factors, such as the thickness of the troposphere, have also to be considered (García-Lorenzo et al 2004).…”

Section: Introduction and Objectivesmentioning

confidence: 99%

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Precipitable water vapour forecasting: a tool for optimizing IR observations at Roque de los Muchachos Observatory

Pérez-Jordán

Castro-Almazán

Muñoz–Tuñón

2018

Monthly Notices of the Royal Astronomical Society

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We validate the Weather Research and Forecasting (WRF) model for precipitable water vapour (PWV) forecasting as a fully operational tool for optimizing astronomical infrared (IR) observations at Roque de los Muchachos Observatory (ORM). For the model validation we used GNSS-based (Global Navigation Satellite System) data from the PWV monitor located at the ORM. We have run WRF every 24 h for near two months, with a horizon of 48 hours (hourly forecasts), from 2016 January 11 to 2016 March 4. These runs represent 1296 hourly forecast points. The validation is carried out using different approaches: performance as a function of the forecast range, time horizon accuracy, performance as a function of the PWV value, and performance of the operational WRF time series with 24-and 48-hour horizons. Excellent agreement was found between the model forecasts and observations, with R = 0.951 and R = 0.904 for the 24-and 48-h forecast time series respectively. The 48-h forecast was further improved by correcting a time lag of 2 h found in the predictions. The final errors, taking into account all the uncertainties involved, are 1.75 mm for the 24-h forecasts and 1.99 mm for 48 h. We found linear trends in both the correlation and RMSE of the residuals (measurements − forecasts) as a function of the forecast range within the horizons analysed (up to 48 h). In summary, the WRF performance is excellent and accurate, thus allowing it to be implemented as an operational tool at the ORM.

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Precipitable water vapor (PWV) estimations from the site of the Eastern Anatolia Observatory∗ (DAG), a new astronomical observatory in Turkey

et al. 2018

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

Cited by 25 publications

References 11 publications

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

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

Precipitable water vapour forecasting: a tool for optimizing IR observations at Roque de los Muchachos Observatory

Precipitable water vapor (PWV) estimations from the site of the Eastern Anatolia Observatory∗ (DAG), a new astronomical observatory in Turkey

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