scholarly journals Refere comment on "Comparison of total water vapour content in the Arctic derived from GPS, AIRS, MODIS and SCIAMACHY" by Alraddawi et al.

2017 ◽  
Author(s):  
Anonymous
Keyword(s):  
Water Vapour ◽  
The Arctic ◽  
Total Water ◽  
Water Vapour Content

scholarly journals Enhanced MODIS Atmospheric Total Water Vapour Content Trends in Response to Arctic Amplification

Atmosphere ◽  
2017 ◽  
Vol 8 (12) ◽  
pp. 241 ◽  
Author(s):  
Dunya Alraddawi ◽  
Philippe Keckhut ◽  
Alain Sarkissian ◽  
Olivier Bock ◽  
Abdanour Irbah ◽  
...  
Keyword(s):  
Water Vapour ◽  
Arctic Amplification ◽  
Total Water ◽  
Water Vapour Content

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 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.

Measuring Water Vapour in High-Purity Gas

1969 ◽  
Vol 2 (6) ◽  
pp. 236-238
Author(s):  
G. W. Lord
Keyword(s):  
Heat Treatment ◽  
Water Vapour ◽  
High Purity ◽  
Semiconductor Materials ◽  
Direct Reading ◽  
Magnetic Alloys ◽  
Water Vapour Content

The desired properties of magnetic alloys, semiconductor materials and similar products are usually developed by heat treatment in a stream off pure dry gas … the presence of even a few parts per million of water vapour in this gas can cause unwanted changes in such properties … to monitor the water-vapour content, a direct-reading dewpoint meter has been developed which is claimed to be more rapid and sensitive than similar meters

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