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.

scholarly journals A semi-empirical error estimation for PWV derived from atmospheric radiosonde data at the Canary Islands

2016 ◽  
Author(s):  
Julio~A. Castro-Almazán ◽  
Gabriel Pérez-Jordán ◽  
Casiana Muñoz-Tuñón
Keyword(s):  
Error Estimation ◽  
Sampling Error ◽  
Precipitable Water ◽  
Radiosonde Data ◽  
Optimum Number ◽  
Site Testing ◽  
Precipitable Water Vapour ◽  
Unique Site ◽  
High Vertical Resolution ◽  
Semi Empirical

Abstract. An unbiased method to estimate the error and the optimum number of sampled levels in Precipitable Water Vapour (PWV) determinations from atmospheric radiosoundings is proposed. Two components have been considered, the uncertainties in the measures and the sampling error. The sampling component has been modelled from an empirical dataset of 64 high vertical resolution radiosounding profiles equipped with sondes Vaisala RS80 and RS92. The balloons were launched at the astronomical Roque de los Muchachos Observatory (ORM, ~2200 masl), during intensive and unique site testing runs carried out in 1990 and 1995, and from the neighbour operational station of Güímar, in Tenerife (TFE, ~105 masl) in 2013–2014. The PWV values ranged between ~0.9 mm and ~41 mm. The method takes into account the dependence on the number of samples measured, after sub-sampling the profile for error minimization, and was tested by comparison with a dataset of 42 extremely low resolution profiles only sampling the standard levels (~15 levels). The results show that errors are larger for the wettest atmosphere conditions. On the other hand, drier conditions requires a larger optimum number of samples. The optimum number of samples N0 is less than 200 for PWV ≥ 10 mm. For drier conditions, as in astronomical sites, N0 grows up to ~550 levels. This result may be important forPWV determinations in astronomical observatories. The absolute errors are always < 0.6 mm, with a median relative error of 2.4 &amp;pm; 0.8 % and extreme value of 7.9 % in the driest condition (PWV = 0.89 mm). These errors reduce the uncertainties previously reported in the literature. Nevertheless, errors grow up to 30 % in poorly sampled profiles (the number of samples being less than N0) for dry atmospheres. Alternative equations for direct error estimation, specifically for PWV from radiosoundings equipped with Vaisala RS80 and RS92 sensors, are also provided.

scholarly journals Evaluation of MODIS Water Vapour Products over ALGERIA using Radiosonde Data

2021 ◽  
Vol 44 ◽  
Author(s):  
Houaria Namaoui ◽  
Salem Kahlouche ◽  
Ahmed Hafidh Belbachir
Keyword(s):  
Water Vapour ◽  
Satellite Data ◽  
Correlation Coefficients ◽  
Precipitable Water ◽  
Radiosonde Data ◽  
Precipitable Water Vapour ◽  
Total Precipitable Water ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Remote sensing of atmospheric water vapour using GNSS and Satellite data has become an efficient tool in meteorology and climate research. Many satellite data have been increasingly used to measure the content of water vapour in the atmosphere and to characterize its temporal and spatial variations. In this paper, we have used observations from radiosonde data collected from three stations (Algiers, Bechar and Tamanrasset) in Algeria from January to December 2012 to evaluate Moderate Resolution Imaging Spectroradiometer (MODIS) total precipitable water vapour (PWV) products. Results show strong agreement between the total precipitable water contents estimated based on radiosondes observations and the ones measured by the sensor MODIS with the correlation coefficients in the range 0.69 to 0.95 and a mean bias, which does not exceed 1.5.  

scholarly journals Atmospheric water vapour and its effect on aerosol Extinction at a coastal station – Visakhapatnam

MAUSAM ◽  
2022 ◽  
Vol 44 (3) ◽  
pp. 243-248
Author(s):  
K. NIRANJAN ◽  
Y. RAMESH BABU
Keyword(s):  
Water Vapour ◽  
Solar Flux ◽  
Radiosonde Data ◽  
Aerosol Extinction ◽  
Atmospheric Water ◽  
Precipitable Water Vapour ◽  
Water Vapour Content ◽  
Coastal Station ◽  
Atmospheric Water Vapour ◽  
Flux Measurements

Integrated atmospheric water vapour content. has been evaluated from the spectral optical depths around the PaT band of water vapour by making directly transmitted solar flux measurements at 800, 935 and 1025 nm. The temporal variation of the total precipitable water vapour shows significant seasonal variation with maximum during~ pre-monsoon and monsoon months and minimum during winter months. The integrated content shows a positive correlation with surface humidity parameters and the correlation is better during monsoon months compared to other seasons. The experimentally derived variations of water vapour are compared with the model variations formulated using radiosonde data. The aerosol extinctions derived from the, multi-spectral solar flux measurements in the visible and near IR regions increase with increasing atmospheric water vapour and this increase shows .a seasonal dependence the surface temperature also seems to affect the, aerosol extinction probably through Its effect on the mixing heights.

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

&lt;p&gt;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 &amp;#160;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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;

The pattern of radiative heating and cooling in the troposphere and lower stratosphere

1956 ◽  
Vol 236 (1205) ◽  
pp. 148-156 ◽  
Keyword(s):  
Cooling Rate ◽  
Water Vapour ◽  
Middle Atmosphere ◽  
Precipitable Water ◽  
Radiative Heating ◽  
The Arctic ◽  
Trade Wind ◽  
Water Vapour Content ◽  
Middle Latitudes ◽  
Heating And Cooling

For any meteorological effects of radiation, only those constituents of the air which have a very strong absorption in the infra-red are involved; these are water vapour and carbon dioxide. Several methods have been developed (Mügge & Möller 1932 a, b ; Elsasser 1942; Yamamoto 1952) for computing the radiation flux, and numerous calculations of these fluxes and of the cooling rates have been performed in the last 25 years (Ludwig 1935; Kortiim 1939; Thompson & Neiburger 1955). The results are summarized in figure 1, which shows the distribution of the tem­perature and of the cooling rate by water vapour in some characteristic atmospheres. The lower levels of the tropical atmosphere have a small cooling rate because the higher layers are very humid and the lower layers are thus sheltered from radiation losses. A contrary effect occurs at 30° latitude, where a very dry subsiding middle atmosphere is observed above a very wet trade-wind layer. In the arctic atmosphere a high cooling rate results for 1.5 km as a consequence of the conduction-like effect of radiation. The maximum values of the cooling rate are attained in the higher troposphere; they shift to somewhat lower levels with decreasing temperature and decreasing water-vapour content, from 10.5 km in the tropics to 7 km in middle latitudes and 4 km in the arctic. Apart from the extreme conditions in the arctic, the curves do not show much difference, and it is probable that all the differences may be understood by considering only the different amount of precipitable water.

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.

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