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

Radiosonde is extensively used for understanding meteorological parameters in the vertical direction. Four typhoon events, including three landfalls (MERANTI, NEPARTAK, and MEGI) and one non-landfall (MALAKAS), were chosen in analysing the precipitable water vapour (PWV) characteristics in this study. The spatial distribution of the three radiosonde stations in Zhejiang province does not meet the requirement in analysing changes in PWV during typhoon event. Global position system (GPS) observations are an alternative method for deriving the PWV. This enables improvements in the temporal–spatial resolution of PWV computed by the radiosonde measurements. The National Centers for Environmental Prediction (NCEP) re-analysed data were employed for interpolating temperature and atmosphere pressure at the GPS antennas height. The PWV computed from GPS observations and NCEP re-analysed data were then compared with the true PWV. The maximum difference of radiosonde and GPS PWV was not more than 30 mm at Taiz station. The Root-Mean-Square (RMS) of PWV differences between radiosonde and GPS was not more than 5 mm in January, February, March, November, and December. It was slightly greater than 5 mm in April. High RMS in May, June, July, August, September, and October implies that differences in GPS and radiosonde PWVs are evident in these months. Correlation coefficients of GPS and radiosonde PWVs were more than 0.9, indicating that the changes in GPS and radiosonde PWVs are similar. Radiosonde calculated PWVs were used for GPS PWV calibration for understanding the PWV changes during the period of a typhoon event. The results from three landfall typhoons show that the average PWV over Zhejiang province is increasing and approaching China mainland. In contrast, MALAKAS did not make landfall and shows a decreasing PWV trend, although it was heading to China mainland. Generally, the PWV change can be used to predict whether the typhoon will make landfall in these cases. PWV spatial distribution of MERANTI shows that PWV peaks change along the typhoon epicenter over Zhejiang province.

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“…

is the height and is measured in metres. With the assumption of hydrostatic balance (

are the corresponding values for dry air), the PWV can be rewritten as follows [ 33 ]:

…”

Section: Methodsmentioning

confidence: 99%

Precipitable Water Vapour Retrieval from GPS Precise Point Positioning and NCEP CFSv2 Dataset during Typhoon Events

Tang

Hancock

Xiang³

et al. 2018

Sensors

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“…only considered matching data points when at least 5 AERONET PWV retrievals were successful within a 1 h time window centered on the 09:00 LT radiosonde launch time. PWV uncertainty was assumed to be 10% for sunphotometer retrievals (Pérez-Ramírez et al, 2014) and 3% for radiosondes (Castro-Almazán et al, 2016).…”

Section: Aeronet and Radiosonde Pwv Retrievalsmentioning

confidence: 99%

Precipitable water vapor retrievals using a ground infrared sky camera in subtropical South America

Hack

Pauliquevis

Barbosa

et al. 2022

Preprint

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Abstract. The atmospheric precipitable water vapor (PWV) is a critical quantity in fast-changing weather processes. Current retrieval techniques lack the spatial and/or temporal resolution necessary for a full PWV characterization. Here we investigate a retrieval method using an all-sky ground camera comprising a 14-bit 644 x 512-pixel microbolometer sensor array. The radiometrically calibrated infrared downwelling spectral radiance, Lλ, was acquired at rates of up to 3 min−1. For the studied site (23.56° S, 46.74° W, 786 m asl) and spectral interval, Lλ is sensitive to the PWV, the vertical distribution of humidity, and their temporal, spatial, or seasonal variations. By comparing measured and simulated Lλ, we show the PWV can be retrieved from prior knowledge about the local humidity profile. This information can originate from radiosonde data or statistical analysis of past vertical humidity distributions. Comparison with sunphotometer PWV retrievals, for stable atmospheric conditions, showed an agreement of the average PWV within 2.8 % and a precision of subsequent retrievals of 1.9 %. The PWV was also retrieved as a bidimensional array, allowing the investigation of spatial inhomogeneities of humidity distribution. The method can be used for day or nighttime retrievals, under partly cloudy sky conditions. Potential applications include studies on convection initiation processes.

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“…RS provides a direct measure of the actual conditions of the FA and, therefore, is particularly convenient for CR validation in mountainous terrain. Different error sources must be considered for RS (Miloshevich et al 2009), including the sampling error associated with the finite number of levels measured (Castro-Almazán et al 2016). However, these uncertainties are low enough to be neglected in this analysis.…”

Section: Data Processingmentioning

confidence: 99%

Canarian Observatories Meteorology; Comparison of OT and ORM using Regional Climate Reanalysis

Hidalgo

Muñoz–Tuñón

Castro-Almazán

et al. 2021

PASP

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The present work has been carried out as a support for site selection for The European Solar Telescope (EST), a 4 m telescope project that will be located in the Canary Islands Observatories. For such purpose, we present a comparative analysis of a long time-series of 17 yr of climate parameters with significance in astronomical site testing for Teide (OT) and Roque de Los Muchachos (ORM) observatories. The climate parameters have been obtained from a climate reanalyses database with a spatial resolution of 11 km × 11 km, which has been compared with local averaged data using Automatic Weather Stations (AWS) and radiosounding. The results show the reliability of using climate reanalysis databases for site-testing both at the heights of the OT and ORM observatories (boundary layer) and in the free atmosphere. Climate parameters analyzed are relative humidity, temperature, wind velocity, and wind direction. For the boundary layer, we have obtained full time-series, annual behavior, and statistical distributions for each parameter. Monthly averaged values are given by using a 17 yr time period. Statistics are given for two time periods: Summer (June to August) and non-summer (the rest). The summer period has been selected according to the most intense observational period along the year for the EST. Day/night variations of the climate parameters have been also analyzed. Both observatories show values in the range 6%-70% for relative humidity, 2.6°C-19°C for temperature, and 5-12 m s −1 for wind velocity, 95% of the time; median values are around 25%, 10°C, and 5 m s −1 , respectively. The most frequent wind direction (wind blowing from) is West for both observatories (∼20%), with a second peak at Northeast (∼19%) for ORM and Northwest for OT (∼17%). Less frequent wind directions are South and Southeast (5% in both cases). No significant difference between OT and ORM in these climate parameters have been found. Using the relative humidity, temperature, wind, and velocity limits for EST we have estimated an operational time 98%. Our results confirm the quality of ORM and OT observatories with stable and predictable weather conditions.

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

Cited by 8 publications

References 35 publications

Precipitable Water Vapour Retrieval from GPS Precise Point Positioning and NCEP CFSv2 Dataset during Typhoon Events

Precipitable Water Vapour Retrieval from GPS Precise Point Positioning and NCEP CFSv2 Dataset during Typhoon Events

Precipitable water vapor retrievals using a ground infrared sky camera in subtropical South America

Canarian Observatories Meteorology; Comparison of OT and ORM using Regional Climate Reanalysis

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