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

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.

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Retrieval of δ<sup>18</sup>O and δD in atmospheric water vapour from ground-based FTIR

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-195-2014 ◽

2014 ◽

Vol 7 (1) ◽

pp. 195-231 ◽

Cited By ~ 2

Author(s):

N. V. Rokotyan ◽

V. I. Zakharov ◽

K. G. Gribanov ◽

F.-M. Bréon ◽

J. Jouzel ◽

...

Keyword(s):

Water Vapour ◽

General Circulation ◽

Near Infrared ◽

A Priori ◽

Circulation Model ◽

Infrared Region ◽

Atmospheric Water ◽

Atmospheric Water Vapour ◽

Δ18o And Δd ◽

Atmospheric Transmittance

Abstract. This paper investigates the possibility of retrieving isotopic composition of atmospheric water vapour from high-resolution ground based measurements of atmospheric transmittance spectra in the near-infrared region (4000–11 000 cm−1). Simulated measurements of atmospheric transmittance were analyzed in order to find clear spectral signatures of H218O, HDO and H216O. Appropriate signals of the species of interest were found and also identified in measured spectra recorded by ground-based Fourier transform infrared spectrometer (FTIR) at the Institute of Environmental Physics of Bremen University. A set of H218O, HDO and H216O spectroscopic windows is presented. Theoretical estimations of the retrieval precision indicate that spectra recorded by ground-based FTIR spectrometers can be used to measure the seasonal cycle of δ18O and δD in the atmosphere. Studying the influence of the a priori on retrieval results shows low sensitivity to a priori assumptions. Impact of the uncertainties in spectroscopic line parameters of water isotopologues on precision of the retrieval of δ18O and δD is investigated. Time series of δ18O retrieved from ground-based FTIR spectra are represented for the first time. Comparison with the results of ECHAM5-wiso isotopic general circulation model simulations demonstrates a good agreement for "summer" measurements. Conversely, the comparison of "winter" measurements and modeling result show a discrepancy that demonstrate worse agreement that may be connected with incorrect temperature dependence of spectroscopic parameters.

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

MAUSAM ◽

10.54302/mausam.v44i3.4979 ◽

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.

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

MAUSAM ◽

10.54302/mausam.v71i1.1 ◽

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.

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

10.5194/angeo-2018-76 ◽

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.

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Non-selective absorption by atmospheric water vapour at visible and near infrared wavelengths

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.49710544619 ◽

1979 ◽

Vol 105 (446) ◽

pp. 1027-1040 ◽

Cited By ~ 20

Author(s):

Claudio Tomasi

Keyword(s):

Water Vapour ◽

Near Infrared ◽

Selective Absorption ◽

Atmospheric Water ◽

Atmospheric Water Vapour ◽

Infrared Wavelengths

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A feasibility study for the retrieval of the total column precipitable water vapour from satellite observations in the blue spectral range

Atmospheric Measurement Techniques ◽

10.5194/amt-6-2593-2013 ◽

2013 ◽

Vol 6 (10) ◽

pp. 2593-2605 ◽

Cited By ~ 19

Author(s):

T. Wagner ◽

S. Beirle ◽

H. Sihler ◽

K. Mies

Keyword(s):

Water Vapour ◽

Spectral Range ◽

Precipitable Water ◽

Visible Spectral Range ◽

Atmospheric Water ◽

Ozone Monitoring Instrument ◽

Precipitable Water Vapour ◽

Atmospheric Water Vapour ◽

Water Vapour Absorption ◽

Ozone Monitoring

Abstract. We present a new algorithm for satellite retrievals of the atmospheric water vapour column in the blue spectral range. The water vapour absorption cross section in the blue spectral range is much weaker than in the red spectral range. Thus the detection limit and the uncertainty of individual observations are systematically larger than for retrievals at longer wavelengths. Nevertheless, water vapour retrievals in the blue spectral range have also several advantages: since the surface albedo in the blue spectral range is similar over land and ocean, water vapour retrievals are more consistent than for longer wavelengths. Compared to retrievals at longer wavelengths, the sensitivity for atmospheric layers close to the surface is higher due to the (typically 2 to 3 times) higher ocean albedo in the blue. Water vapour retrievals in the blue spectral range are also possible for satellite sensors, which do not measure at longer wavelengths of the visible spectral range like the Ozone Monitoring Instrument (OMI). We investigated details of the water vapour retrieval in the blue spectral range based on radiative transfer simulations and observations from the Global Ozone Monitoring Experiment 2 (GOME-2) and OMI. It is demonstrated that it is possible to retrieve the atmospheric water vapour column density in the blue spectral range over most parts of the globe. The findings of our study are of importance also for future satellite missions (e.g. Sentinel 4 and 5).

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