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.

scholarly journals Atmospheric water vapour content over La Silla Paranal Observatory

2009 ◽  
Vol 5 (H15) ◽  
pp. 537-537
Author(s):  
R. Querel ◽  
F. Kerber ◽  
R. Hanuschik ◽  
G. Lo Curto ◽  
D. Naylor ◽  
...  
Keyword(s):  
Real Time ◽  
Water Vapour ◽  
Atmospheric Water ◽  
Water Vapour Content ◽  
Atmospheric Water Vapour ◽  
Infrared Wavelengths ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
Principle Source

Water vapour is the principle source of opacity at infrared wavelengths in the earth's atmosphere. Measurements of atmospheric water vapour serve two primary purposes when considering operation of an observatory: long-term monitoring of precipital water vapour (PWV) is useful for characterizing potential observatory sites, and real-time monitoring of PWV is useful for optimizing use, in particular for mid-IR observations.

scholarly journals Comparison of GNSS and INSAT-3D sounder retrieved precipitable water vapour and validation with the GPS Sonde data over Indian Subcontinent

MAUSAM ◽  
2021 ◽  
Vol 71 (1) ◽  
pp. 1-10
Author(s):  
YADAV RAMASHRAY ◽  
PUVIARASAN N ◽  
GIRI R K ◽  
TOMAR C S ◽  
SINGH VIRENDRA
Keyword(s):  
Water Vapour ◽  
Indian Subcontinent ◽  
India Meteorological Department ◽  
Precipitable Water ◽  
Satellite System ◽  
Atmospheric Water ◽  
Precipitable Water Vapour ◽  
Vertical Column ◽  
Atmospheric Water Vapour ◽  
Channel Sounder

Precipitable water vapour (PWV) plays a key role in the atmospheric processes from climate change to micrometeorology. Its distribution and quantity are critical for the description of state and evaluation of the atmosphere in NWP model. Lack of precise and continuous water vapour data is one of the major error sources in short term forecast of precipitation. The task of accurately measuring atmospheric water vapour is challenging. Conventional in situ measurements of atmospheric water vapour is provided by GPS Sonde humidity sensors profile twice a day at 0000 and 1200 UTC mainly from limited land regions. In recent years India Meteorological Department (IMD) is computing PWV from 19 channel sounder of INSAT-3D in three layers 1000-900 hPa, 900-700 hPa and 700-300 hPa and total PWV in the vertical column of atmosphere stretching from surface to about 100 hPa under cloud free condition. These data most commonly were validated using spatially and temporally collocated GPS Sonde measurements. In this paper, INSAT-3D satellite retrieved PWV data are validated with column integrated PWV estimates from a network of ground based Global Navigation Satellite System (GNSS) over Indian subcontinent. The PWV retrieved by INSAT-3D sounder platform is very promising, being in a good agreement with the GNSS data recorded over India for the period June, 2017 to May, 2018. The root-mean-square (rms) differences of 5.4 to 7.1 mm, bias of -4.7 to +2.1 mm and correlations coefficient of 0.79 to 0.92 was observed between INSAT-3D and GNSS PWV. The correlations coefficient between GPS Sonde and GNSS derived PWV ranges from 0.85 to 0.98.

scholarly journals Effect of water vapour absorption on hydroxyl temperatures measured from Svalbard

2017 ◽  
Vol 35 (3) ◽  
pp. 481-491 ◽  
Author(s):  
Joshua M. Chadney ◽  
Daniel K. Whiter ◽  
Betty S. Lanchester
Keyword(s):  
Water Vapour ◽  
Atmospheric Water ◽  
Echelle Spectrograph ◽  
Water Vapour Content ◽  
Atmospheric Water Vapour ◽  
Transmission Coefficients ◽  
Hydroxyl Airglow ◽  
Water Vapour Absorption ◽  
Vibrational Bands ◽  
High Throughput Imaging

Abstract. We model absorption by atmospheric water vapour of hydroxyl airglow emission using the HIgh-resolution TRANsmission molecular absorption database (HITRAN2012). Transmission coefficients are provided as a function of water vapour column density for the strongest OH Meinel emission lines in the (8–3), (5–1), (9–4), (8–4), and (6–2) vibrational bands. These coefficients are used to determine precise OH(8–3) rotational temperatures from spectra measured by the High Throughput Imaging Echelle Spectrograph (HiTIES), installed at the Kjell Henriksen Observatory (KHO), Svalbard. The method described in this paper also allows us to estimate atmospheric water vapour content using the HiTIES instrument.

scholarly journals Capturing the signature of heavy rainfall events using the 2-d-/4-d water vapour information derived from GNSS measurement in Hong Kong

2018 ◽  
Author(s):  
Qingzhi Zhao ◽  
Yibin Yao ◽  
Wanqiang Yao
Keyword(s):  
Hong Kong ◽  
Water Vapour ◽  
Heavy Rainfall ◽  
Precipitable Water ◽  
Atmospheric Water ◽  
Precipitable Water Vapour ◽  
Rainfall Events ◽  
Atmospheric Water Vapour ◽  
Tomographic Technique ◽  
Heavy Rainfall Events

Abstract. Apart from the well-known applications like positioning, navigation and timing (PNT), Global Navigation Satellite System (GNSS) has manifested its ability in many other areas that are vital to society largely. With the dense setting of the regional continuously operating reference station (CORS) networks, monitoring the variations in atmospheric water vapour using a GNSS technique has become the focus in the field of GNSS meteorology. Most previous studies mainly concentrate on the analysis of relationship between the two-dimensional (2-d) Precipitable Water Vapour (PWV) and rainfall while the four-dimensional (4-d) variations of atmospheric water vapour derived from the GNSS tomographic technique during rainfall events are rarely discussed. This becomes the focus of this work, which investigates the emerging field of GNSS technology for monitoring changes in atmospheric water vapour during rainfall, especially in the vertical direction. This paper includes an analysis of both 2-d, and 4-d, precipitable water vapour profiles. A period with heavy rainfall events in this study was selected to capture the signature of atmospheric water vapour variation using the ground-based GNSS tomographic technique. GNSS observations from the CORS network of Hong Kong were used. Analysed results of the 2-d PWV/4-d water vapour profiles change during the arrival, occurrence, and depression of heavy rainfall show that: (i) the PWV time series shows an increasing trend before the arrival of heavy rainfall and decreases to its average value after the depression of rainfall; (ii) rainfall leads to an anomalous variation in relative humidity and temperature while their trends are totally opposite and show daily periodicity for periods without rain (this is highly correlated with the changes in solar radiation); (iii) atmospheric water vapour presents unstable conditions with intense vertical convective motion and hydrometeors are formed before the arrival of rainfall while returning to relatively stable conditions during heavy rainfall. This study indicates the potential for using GNSS-derived 2-d PWV and 4-d profiles to monitor spatio-temporal variations in atmospheric water vapour during rainfall, which provides a better understanding of the mechanism of convection and rainfall induced by the extreme weather events.

scholarly journals Variation of aerosol optical thickness with atmospheric water vapour : A case study over a continental station Mysore, India

MAUSAM ◽  
2021 ◽  
Vol 62 (3) ◽  
pp. 441-448
Author(s):  
K.E. GANESH ◽  
T.K. UMESH ◽  
B. NARASIMHAMURTHY
Keyword(s):  
Water Vapour ◽  
Optical Thickness ◽  
Near Infrared ◽  
Solar Spectrum ◽  
Aerosol Optical Thickness ◽  
Infrared Range ◽  
Atmospheric Water ◽  
Atmospheric Measurements ◽  
Precipitable Water Vapour ◽  
Atmospheric Water Vapour

Atmospheric measurements in a continental, low latitude station Mysore (12.3° N) has been carried out, for the period December 2003 to June 2006. Measurements were made using a sunphotometer with five bands in the visible and near-infrared range of the solar spectrum. To bring out the wavelength dependence of Aerosol Optical Thickness (AOT) on atmospheric water vapour, typically two wavelength channels are being used, one at 500 nm and the other at 1020 nm. A linear dependence between AOT and water vapour on meteorologically calm days is the important observation made. Growth rate of AOT is found to be larger at shorter wavelength (500 nm) than that of the longer wavelength (1020 nm). A mass-plot representation is followed on monthly basis, which is nothing but the graphical plot of spectral AOT versus water vapour of the scans for all the clear sky days of a particular month. Further investigations reveal that some months exhibit a single trend of growth of AOT with water vapour whereas double trend is the scenario for other months. These results provide insight into the changes in the atmospheric aerosol characteristics with precipitable water vapour, which is the subject matter of this paper.

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.

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