scholarly journals Measuring variations of δ<sup>18</sup>O and δ<sup>2</sup>H in atmospheric water vapour using laser spectroscopy: an instrument characterisation study

2012 ◽  
Vol 5 (1) ◽  
pp. 1597-1655 ◽  
Author(s):  
F. Aemisegger ◽  
P. Sturm ◽  
P. Graf ◽  
H. Sodemann ◽  
S. Pfahl ◽  
...  
Keyword(s):  
Water Vapour ◽  
Laboratory Experiments ◽  
Water Cycle ◽  
Field Measurements ◽  
Detailed Knowledge ◽  
Spectroscopic Techniques ◽  
Mixing Ratio ◽  
Atmospheric Water ◽  
Uncertainty Estimates ◽  
Laser Spectroscopic

Abstract. Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Research). The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Based on the experience from our laboratory experiments we set up a one-week field campaign for comparing measurements of the ambient isotope signals of the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric water cycle and the land-atmosphere moisture fluxes.

scholarly journals Measuring variations of δ<sup>18</sup>O and δ<sup>2</sup>H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study

2012 ◽  
Vol 5 (7) ◽  
pp. 1491-1511 ◽  
Author(s):  
F. Aemisegger ◽  
P. Sturm ◽  
P. Graf ◽  
H. Sodemann ◽  
S. Pfahl ◽  
...  
Keyword(s):  
Water Vapour ◽  
Laboratory Experiments ◽  
Water Cycle ◽  
Field Measurements ◽  
Detailed Knowledge ◽  
Spectroscopic Techniques ◽  
Mixing Ratio ◽  
Atmospheric Water ◽  
Uncertainty Estimates ◽  
Laser Spectroscopic

Abstract. Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic and mesoscale meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro) and off-axis integrated cavity output spectroscopy (Los Gatos Research). The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the effects of (i) water vapour mixing ratio, (ii) measurement stability, (iii) uncertainties due to calibration and (iv) response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Based on the experience from our laboratory experiments, we set up a one-week field campaign for comparing measurements of the ambient isotope signals from the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric water cycle and the land-atmosphere moisture fluxes.

Estimation of fine-scale relative humidity profiles: an issue for understanding the atmospheric water cycle

2020 ◽  
Author(s):  
Veronique Michot ◽  
Helene Brogniez ◽  
Mathieu Vrac ◽  
Soulivanh Thao ◽  
Helene Chepfer ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Quantile Regression ◽  
Water Vapour ◽  
Climate Models ◽  
Water Cycle ◽  
Skill Score ◽  
Horizontal Resolution ◽  
Atmospheric Water ◽  
Global Knowledge ◽  
Humidity Profiles

&lt;p&gt;The multi-scale interactions at the origin of the links between clouds and water vapour are essential for the Earth's energy balance and thus the climate, from local to global. Knowledge of the distribution and variability of water vapour in the troposphere is indeed a major issue for the understanding of the atmospheric water cycle. At present, these interactions are poorly known at regional and local scales, i.e. within 100km, and are therefore poorly represented in numerical climate models. This is why we have sought to predict cloud scale relative humidity profiles in the intertropical zone, using a non-parametric statistical downscaling method called quantile regression forest. The procedure includes co-located data from 3 satellites: CALIPSO lidar and CloudSat radar, used as predictors and providing cloud properties at 90m and 1.4km horizontal resolution respectively; SAPHIR data used as a predictor and providing relative humidity at an initial horizontal resolution of 10km. Quantile regression forests were used to predict relative humidity profiles at the CALIPSO and CloudSat scales. These predictions are able to reproduce a relative humidity variability consistent with the cloud profiles and are confirmed by values of coefficients of determination greater than 0.7, relative to observed relative humidity, and Continuous Rank Probability Skill Score between 0 and 1, relative to climatology. Lidar measurements from the NARVAL 1&amp;2 campaigns and radiosondes from the EUREC4A campaigns were also used to compare Relative Humidity profiles at the SAPHIR scale and at the scale of forest regression prediction by quantile regression.&lt;/p&gt;

scholarly journals Developing a western Siberia reference site for tropospheric water vapour isotopologue observations obtained by different techniques (in situ and remote sensing)

2014 ◽  
Vol 14 (12) ◽  
pp. 5943-5957 ◽  
Author(s):  
K. Gribanov ◽  
J. Jouzel ◽  
V. Bastrikov ◽  
J.-L. Bonne ◽  
F.-M. Breon ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
General Circulation ◽  
Western Siberia ◽  
Water Cycle ◽  
General Circulation Models ◽  
Forest Site ◽  
Atmospheric Water ◽  
Local Measurements

Abstract. Water stable isotopologues provide integrated tracers of the atmospheric water cycle, affected by changes in air mass origin, non-convective and convective processes and continental recycling. Novel remote sensing and in situ measuring techniques have recently offered opportunities for monitoring atmospheric water vapour isotopic composition. Recently developed infrared laser spectrometers allow for continuous in situ measurements of surface water vapour δDv and δ18Ov. So far, very few intercomparisons of measurements conducted using different techniques have been achieved at a given location, due to difficulties intrinsic to the comparison of integrated with local measurements. Nudged simulations conducted with high-resolution isotopically enabled general circulation models (GCMs) provide a consistent framework for comparison with the different types of observations. Here, we compare simulations conducted with the ECHAM5-wiso model with two types of water vapour isotopic data obtained during summer 2012 at the forest site of Kourovka, western Siberia: hourly ground-based FTIR total atmospheric columnar δDv amounts, and in situ hourly Picarro δDv measurements. There is an excellent correlation between observed and predicted δDv at surface while the comparison between water column values derived from the model compares well with FTIR estimates.

scholarly journals ECHAM5-wiso water vapour isotopologues simulation and its comparison with WS-CRDS measurements and retrievals from GOSAT and ground-based FTIR spectra in the atmosphere of Western Siberia

2013 ◽  
Vol 13 (1) ◽  
pp. 2599-2640 ◽  
Author(s):  
K. Gribanov ◽  
J. Jouzel ◽  
V. Bastrikov ◽  
J.-L. Bonne ◽  
F.-M. Breon ◽  
...  
Keyword(s):  
Water Vapour ◽  
Western Siberia ◽  
Water Cycle ◽  
Forest Site ◽  
Atmospheric Water ◽  
Russian Government ◽  
Measuring Techniques ◽  
Local Measurements ◽  
Air Mass Origin

Abstract. Water stable isotopes provide integrated tracers of the atmospheric water cycle, affected by changes in air mass origin, non-convective and convective processes and continental recycling. Novel remote sensing and in situ measuring techniques have recently offered opportunities for monitoring atmospheric water vapour isotopic composition. Recently developed infrared laser spectrometers allow for continuous in situ measurements of surface water vapour δDv and δ18Ov. So far, very few intercomparison of measurements conducted using different techniques have been achieved at a given location, due to difficulties intrinsic to the comparison of integrated with local measurements. Nudged simulations conducted with high resolution isotopically enabled GCMs provide a consistent framework for comparison with the different types of observations. Here, we compare simulations conducted with the ECHAM5-wiso model with three types of water vapour isotopic data obtained during summer 2012 at the forest site of Kourovka, Western Siberia: daily mean GOSAT δDv soundings, hourly ground-based FTIR total atmospheric columnar δDv amounts, and in situ hourly Picarro δDv measurements. There is an excellent correlation between observed and predicted δDv at surface while the comparison between water column values derived from the model compares well with FTIR and GOSAT estimates. This research was supported by the grant of Russian government under the contract 11.G34.31.0064.

End-to-end Simulator of a space-borne Raman Lidar for the thermodynamic profiling of the atmosphere

2021 ◽  
Author(s):  
Noemi Franco ◽  
Paolo Di Girolamo ◽  
Donato Summa ◽  
Benedetto De Rosa ◽  
Andreas Behrendt ◽  
...  
Keyword(s):  
Numerical Model ◽  
Water Vapour ◽  
Vertical Profile ◽  
Molecular Nitrogen ◽  
Reference Signal ◽  
Temperature Measurements ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Atmospheric Water ◽  
Atmospheric Water Vapour

&lt;p&gt;An end-to-end model has been developed in order to simulate the expected performance of a space-borne Raman Lidar, with a specific focus on the Atmospheric Thermodynamics LidAr in Space &amp;#8211; ATLAS proposed as a &amp;#8220;mission concept&amp;#8221; to the ESA in the frame of the &amp;#8220;Earth Explorer-11 Mission Ideas&amp;#8221; Call. The numerical model includes a forward module, which simulates the lidar signals with their statistical uncertainty, and a retrieval module able to provide vertical profiles of atmospheric water vapour mixing ratio and temperature based on the analyses of the simulated signals. Specifically, the forward module simulates the interaction mechanisms of laser radiation with the atmospheric constituents and the behavior of all the devices present in the experimental system(telescope, optical reflecting and transmitting components, avalanche photodiodes, ACCDs). An analytical expression of the lidar equation for the water vapour and molecular nitrogen roto-vibrational Raman signals and the pure rotational Raman signals from molecular oxygen and nitrogen is used. The analytically computed signals are perturbed by simulating their shot-noise through Poisson statistics. Perturbed signals thus take into account the fluctuations in the number of photons reaching the detector over a certain time interval.&amp;#160;The simulator also provides an estimation of the background due to the solar contribution. Daylight background includes three distinct terms: a cloud-free atmospheric contribution, a surface contribution and a cloud contribution[1]. Background is calculated as a function of the solar zenith angle. In order to better estimatethe background contribution, an integration on slant path is performed instead of a classical parallel-planes approximation. The proposed numerical model allows to better simulate solar background for high solar zenith angles, even higher than 90 degrees.&amp;#160;Signals simulated through the forward model are then fed into the retrieval module. A background subtraction scheme is used to remove the solar contribution and a vertical averaging is performed to smooth the signals. Based on the application of the roto-vibrational Raman lidar technique, the vertical profile of atmospheric water vapour mixing ratio is obtained from the power ratio of the water vapour to a reference signal, such as molecular nitrogen roto-vibrational Raman signal or an alternative temperature-independent reference signal. A vertical profile of temperature is then obtained through the ratio of high-to-low quantum number rotational Raman signals by the application of the pure rotational Raman lidar technique. Both atmospheric water vapour mixing ratio and temperature measurements require the determination of calibration constants, which can be obtained from the comparison with simultaneous and co-located measurements from a different sensor [2].&amp;#160;The simulator finally provides statistical (RMS) and systematic (bias) uncertainties. Estimates are provided in terms of percentage and absolute (g/kg) uncertainty for water vapour mixing ratio measurements and in terms of absolute uncertainty (K) for temperature measurements.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;1 - P.Di Girolamo et al., &quot;Spaceborne profiling of atmospheric temperature and particle extinction with pure rotational Raman lidar and of relative humidity in combination with differential absorption lidar: performance simulations&quot;Appl.Opt.&amp;#160;45, 2474-2494(2006)&lt;/p&gt;&lt;p&gt;2 - P.Di Girolamo et al., &quot;Space-borne profiling of atmospheric thermodynamic variables with Raman lidar: performance simulations,&quot;Opt.Express&amp;#160;26, 8125-8161(2018)&lt;/p&gt;

scholarly journals The Observed State of the Water Cycle in the Early Twenty-First Century

2015 ◽  
Vol 28 (21) ◽  
pp. 8289-8318 ◽  
Author(s):  
M. Rodell ◽  
H. K. Beaudoing ◽  
T. S. L’Ecuyer ◽  
W. S. Olson ◽  
J. S. Famiglietti ◽  
...  
Keyword(s):  
Water Budget ◽  
Water Cycle ◽  
First Century ◽  
The Arctic ◽  
Atmospheric Water ◽  
Satellite Measurements ◽  
Satellite Systems ◽  
Variational Framework ◽  
Early Twenty ◽  
Uncertainty Estimates

Abstract This study quantifies mean annual and monthly fluxes of Earth’s water cycle over continents and ocean basins during the first decade of the millennium. To the extent possible, the flux estimates are based on satellite measurements first and data-integrating models second. A careful accounting of uncertainty in the estimates is included. It is applied within a routine that enforces multiple water and energy budget constraints simultaneously in a variational framework in order to produce objectively determined optimized flux estimates. In the majority of cases, the observed annual surface and atmospheric water budgets over the continents and oceans close with much less than 10% residual. Observed residuals and optimized uncertainty estimates are considerably larger for monthly surface and atmospheric water budget closure, often nearing or exceeding 20% in North America, Eurasia, Australia and neighboring islands, and the Arctic and South Atlantic Oceans. The residuals in South America and Africa tend to be smaller, possibly because cold land processes are negligible. Fluxes were poorly observed over the Arctic Ocean, certain seas, Antarctica, and the Australasian and Indonesian islands, leading to reliance on atmospheric analysis estimates. Many of the satellite systems that contributed data have been or will soon be lost or replaced. Models that integrate ground-based and remote observations will be critical for ameliorating gaps and discontinuities in the data records caused by these transitions. Continued development of such models is essential for maximizing the value of the observations. Next-generation observing systems are the best hope for significantly improving global water budget accounting.

Atmospheric water vapour processing

Waterlines ◽  
1993 ◽  
Vol 12 (2) ◽  
pp. 20-22 ◽  
Author(s):  
Roland Wahlgren
Keyword(s):  
Water Vapour ◽  
Atmospheric Water ◽  
Atmospheric Water Vapour
Sign in / Sign up

Export Citation Format

Share Document