INSAT-K1 VHR WATER VAPOUR BRIGHTNESS TEMPERATURE PRODUCT

2016 ◽  
Author(s):  
Nikunj Darji
Keyword(s):  
Brightness Temperature ◽  
Water Vapour

scholarly journals Simulation of sub-millimetre atmospheric spectra for characterizing potential ground-based remote sensing observations

2016 ◽  
Author(s):  
Emma C. Turner ◽  
Stafford Withington ◽  
David A. Newnham ◽  
Peter Wadhams ◽  
Anna E. Jones ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Brightness Temperature ◽  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Hydrogen Bromide ◽  
Electromagnetic Spectrum ◽  
Polar Regions ◽  
Additional Species ◽  
Trace Species ◽  
Instrumental Methods

Abstract. The sub-millimetre is an understudied region of the Earth's atmospheric electromagnetic spectrum. Prior technological gaps and relatively high opacity due to the prevalence of rotational water vapour lines at these wavelengths have slowed progress from a ground-based remote sensing perspective; however, emerging superconducting detector technologies in the fields of astronomy offer the potential to address key atmospheric science challenges with new instrumental methods. A site study, with a focus on the polar regions, is performed to assess theoretical feasibility by simulating the downwelling clear-sky sub-millimetre spectrum from 30 mm (10 GHz) to 150 μm (2000 GHz) at six locations under annual mean, summer, winter, daytime, nighttime and low humidity conditions. Vertical profiles of temperature, pressure and 28 atmospheric gases are constructed by combining radiosonde, meteorological reanalysis, and atmospheric chemistry model data. The sensitivity of the simulated spectra to the choice of water vapour continuum model and spectroscopic line database is explored. For the atmospheric trace species hypobromous acid (HOBr), hydrogen bromide (HBr), perhydroxyl radical (HO2) and nitrous oxide (N2O) the emission lines producing the largest change in brightness temperature are identified. Signal strengths, centre frequencies, bandwidths, estimated minimum integration times and maximum receiver noise temperatures are determined for all cases. HOBr, HBr and HO2 produce brightness temperature peaks in the mK to K range, whereas the N2O peaks are in the K range. The optimal sub-millimetre remote sensing lines for the four species are shown to vary significantly between location and scenario, strengthening the case for future hyperspectral instruments that measure over a broad wavelength range. The techniques presented here provide a framework that can be applied to additional species of interest and taken forward to simulate retrievals and guide the design of future sub-millimetre instruments.

scholarly journals Assimilation of INSAT-3D imager water vapour clear sky brightness temperature in the NCMRWF’s assimilation and forecast system

2019 ◽  
Vol 128 (7) ◽  
Author(s):  
S Indira Rani ◽  
Ruth Taylor ◽  
Priti Sharma ◽  
M T Bushair ◽  
Buddhi Prakash Jangid ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Water Vapour ◽  
Forecast System ◽  
Clear Sky ◽  
Sky Brightness

scholarly journals Stratospheric water vapour budget and convection overshooting the tropopause: modelling study from SCOUT-AMMA

2010 ◽  
Vol 10 (17) ◽  
pp. 8267-8286 ◽  
Author(s):  
X. M. Liu ◽  
E. D. Rivière ◽  
V. Marécal ◽  
G. Durry ◽  
A. Hamdouni ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Water Vapour ◽  
Temperature Difference ◽  
Water Distribution ◽  
Lower Stratosphere ◽  
Background Level ◽  
Convective System ◽  
Regional Atmospheric Modelling System ◽  
Initial Location ◽  
The Impact

Abstract. The aim of this paper is to study the impacts of overshooting convection at a local scale on the water distribution in the tropical UTLS. Overshooting convection is assumed to be one of the processes controlling the entry of water vapour mixing ratio in the stratosphere by injecting ice crystals above the tropopause which later sublimate and hydrate the lower stratosphere. For this purpose, we quantify the individual impact of two cases of overshooting convection in Africa observed during SCOUT-AMMA: the case of 4 August 2006 over Southern Chad which is likely to have influenced the water vapour measurements by micro-SDLA and FLASH-B from Niamey on 5 August, and the case of a mesoscale convective system over Aïr on 5 August 2006. We make use of high resolution (down to 1 km horizontally) nested grid simulations with the three-dimensional regional atmospheric model BRAMS (Brazilian Regional Atmospheric Modelling System). In both cases, BRAMS succeeds in simulating the main features of the convective activity, as well as overshooting convection, though the exact position and time of the overshoots indicated by MSG brightness temperature difference is not fully reproduced (typically 1° displacement in latitude compared with the overshoots indicated by brightness temperature difference from satellite observations for both cases, and several hours shift for the Aïr case on 5 August 2006). Total water budgets associated with these two events show a significant injection of ice particles above the tropopause with maximum values of about 3.7 ton s−1 for the Chad case (4 August) and 1.4 ton s−1 for the Aïr case (5 August), and a total upward cross tropopause transport of about 3300 ton h−1 for the Chad case and 2400 ton h−1 for the Aïr case in the third domain of simulation. The order of magnitude of these modelled fluxes is lower but comparable with similar studies in other tropical areas based on models. These two estimations exhibit significant differences and highlight variability among the cases of the impact of overshooting convection in hydrating the lower stratosphere. We show that the regional enhancement of water above the tropopause is between 0.21 to 0.67 ppmv between 380 and 400 K, generally in the range of other model estimations. The amount of water which remains in the stratosphere after the overshoot is estimated for both cases. A range of 330 to 507 tons is found for the Chad case and an upper limit of 200 tons is found for the Aïr case. Finally we emphasize that the hydrated area in the LS by overshooting convection can be advected relatively far away from the overshoot initial location, with locally mixing ratios of more than 3 ppmv higher than the background level, which is compatible with the balloon borne measurements performed above Niamey in the same air mass, 30 h after the overshoot.

scholarly journals Water vapour radiometry in geodetic very long baseline interferometry telescopes: assessed through simulations

2021 ◽  
Vol 95 (11) ◽  
Author(s):  
Peter Forkman ◽  
Jonas Flygare ◽  
Gunnar Elgered
Keyword(s):  
Brightness Temperature ◽  
Water Vapour ◽  
Very Long Baseline Interferometry ◽  
Signal Propagation ◽  
Long Baseline ◽  
Vlbi Data ◽  
Sky Brightness ◽  
Microwave Radiometers ◽  
Ground Noise ◽  
The Impact

AbstractThe accuracy of geodetic Very Long Baseline Interferometry (VLBI) is affected by water vapour in the atmosphere in terms of variations in the signal propagation delay at the different stations. This “wet” delay may be estimated directly from the VLBI data, as well as from independent instruments, such as collocated microwave radiometers. Rather than having stand-alone microwave radiometers we have, through simulations, evaluated the possibility to use radiometric data from the VLBI receiver in the VGOS telescopes at the Onsala Space Observatory. The advantage is that the emission from water vapour, as sensed by the radiometer, originates from the same atmospheric volume that delays the VLBI signal from the extra-galactic object. We use simulations of the sky brightness temperature and the wet delay together with an assumption of a root-mean-square (rms) noise of the receiver of 1 K, and observations evenly spread between elevation angles of 10$$^\circ $$ ∘ –90$$^\circ $$ ∘ . This results in an rms error of the estimated equivalent zenith wet delay of the order of 3 mm for a one frequency algorithm, used under cloud free conditions, and 4 mm for a two frequency algorithm, used during conditions with liquid water clouds. The results exclude rainy conditions when the method does not work. These errors are reduced by a factor of 3 if the receiver error is 0.1 K meaning that the receivers’ measurements of the sky brightness temperature is the main error source. We study the impact of ground-noise pickup by using a model of an existing wideband feed. Taking the algorithm uncertainty and the ground noise pickup into account we conclude that the method presented will be useful as an independent estimate of the wet delay to assess the quality of the wet delays and linear horizontal gradients estimated from the VLBI data themselves.

scholarly journals Water vapor budget associated to overshoots in the tropical stratosphere: mesoscale modelling study of 4–5 August 2006 during SCOUT-AMMA

2010 ◽  
Vol 10 (2) ◽  
pp. 3975-4025 ◽  
Author(s):  
X. M. Liu ◽  
E. D. Rivière ◽  
V. Marécal ◽  
G. Durry ◽  
A. Hamdouni ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Water Vapour ◽  
Temperature Difference ◽  
Water Distribution ◽  
Lower Stratosphere ◽  
Background Level ◽  
Convective System ◽  
Regional Atmospheric Modelling System ◽  
Initial Location ◽  
The Impact

Abstract. The aim of this paper is to study the impacts of overshooting convection at a local scale on the water distribution in the tropical UTLS. Overshooting convection is likely to be one of the key processes controlling the entry of water vapour amount in the stratosphere by injecting ice crystals above the tropopause which later sublimate and hydrate the lower stratosphere. For this purpose, we quantify the individual impact of two overshooting cases in Africa observed during SCOUT-AMMA: the case of 4 August 2006 over Southern Chad which is likely to have influenced the water vapour measurements by micro-SDLA and FLASH-B from Niamey on 5 August, and the case of a mesoscale convective system over Aϊr on 5 August 2006. We make use of high resolution (down to 1 km horizontally) three nested grid simulations with the three-dimensional regional atmospheric model BRAMS (Brazilian Regional Atmospheric Modelling System). In both cases, BRAMS succeeds in simulating the main features of the convective activity, as well as overshooting convection, thought the exact position and time of the overshoots indicated by MSG brightness temperature difference is not fully reproduced (typically 1° in latitude compared with the overshoots indicated by brightness temperature difference from satellite observations for both cases, and several hours shift the Aϊr case on 5 August 2006). Total water budgets associated with these two events show a significant injection of ice particles above the tropopause with maximum values of about 3.7 ton s−1 for the Chad case (4 August) and 1.4 ton s−1 for the Aϊr case (5 August), and a total cross tropopause transport of about 3300 ton h−1 for the Chad case and 2400 ton h−1 for the Aϊr case in the third domain of simulation. The order of magnitude of these modelled fluxes is lower but comparable with similar studies in other tropical areas based on models. These two estimations exhibit significant differences and highlight variability among the cases of the impact of overshooting convection in hydrating the lower stratosphere. We show that the regional enhancement of water above the tropopause is between 0.21 to 0.67 ppmv between 380 K and 400 K, in the range of other model estimations. Finally we emphasize that as long as the model resolution is high, the hydrated area in the LS by overshooting convection can be advected relatively far away from the overshoot initial location, with locally mixing ratios of more than 3 ppmv higher than the background level, which is compatible with the balloon borne measurements performed above Niamey in the same air mass, 30 h after the overshoot. However, in the model, when exiting the highest resolution grid, the hydrating signal is lost rapidly.

scholarly journals Simulation of submillimetre atmospheric spectra for characterising potential ground-based remote sensing observations

2016 ◽  
Vol 9 (11) ◽  
pp. 5461-5485 ◽  
Author(s):  
Emma C. Turner ◽  
Stafford Withington ◽  
David A. Newnham ◽  
Peter Wadhams ◽  
Anna E. Jones ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Brightness Temperature ◽  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Hydrogen Bromide ◽  
Electromagnetic Spectrum ◽  
Polar Regions ◽  
Night Time ◽  
Additional Species ◽  
Trace Species

Abstract. The submillimetre is an understudied region of the Earth's atmospheric electromagnetic spectrum. Prior technological gaps and relatively high opacity due to the prevalence of rotational water vapour lines at these wavelengths have slowed progress from a ground-based remote sensing perspective; however, emerging superconducting detector technologies in the fields of astronomy offer the potential to address key atmospheric science challenges with new instrumental methods. A site study, with a focus on the polar regions, is performed to assess theoretical feasibility by simulating the downwelling (zenith angle = 0°) clear-sky submillimetre spectrum from 30 mm (10 GHz) to 150 µm (2000 GHz) at six locations under annual mean, summer, winter, daytime, night-time and low-humidity conditions. Vertical profiles of temperature, pressure and 28 atmospheric gases are constructed by combining radiosonde, meteorological reanalysis and atmospheric chemistry model data. The sensitivity of the simulated spectra to the choice of water vapour continuum model and spectroscopic line database is explored. For the atmospheric trace species hypobromous acid (HOBr), hydrogen bromide (HBr), perhydroxyl radical (HO2) and nitrous oxide (N2O) the emission lines producing the largest change in brightness temperature are identified. Signal strengths, centre frequencies, bandwidths, estimated minimum integration times and maximum receiver noise temperatures are determined for all cases. HOBr, HBr and HO2 produce brightness temperature peaks in the mK to µK range, whereas the N2O peaks are in the K range. The optimal submillimetre remote sensing lines for the four species are shown to vary significantly between location and scenario, strengthening the case for future hyperspectral instruments that measure over a broad wavelength range. The techniques presented here provide a framework that can be applied to additional species of interest and taken forward to simulate retrievals and guide the design of future submillimetre instruments.

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