The L-WAIVE campaign over the Annecy lake: An analysis of water vapor variability in complex terrain

2020 ◽  
Author(s):  
Patrick Chazette ◽  
Elsa Dieudonné ◽  
Anne Monod ◽  
Harald Sodemann ◽  
Julien Totems ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Vapour ◽  
Vertical Structure ◽  
Isotope Composition ◽  
Lower Troposphere ◽  
Cloud Water ◽  
Mountainous Regions ◽  
Isotopic Analyses ◽  
Ground Based Lidar

<p>The vertical structure of the water vapor field in the lower troposphere is only sparsely documented in mountainous regions and particularly above Alpine lakes. This may in part due to the complexity of the system, being intimately linked to the orography surrounding the lakes and the forcing of the topography-induced winds. The question arises as to how the vertical extent of evaporation processes over the lakes and how these are influenced by larger scale forcing, in particularly with regard to the vertical dimension.</p><p>In order to gain understanding on the vertical structure of atmospheric water vapour above mountain lakes, the L-WAIVE (Lacustrine-Water vApor Isotope inVentory Experiment) field campaign was conducted in the Annecy valley in the French Alps in June 2019. This campaign was based on a synergy between ground-based lidar measurements and ship-borne as well as airborne observations. Two ultra-light aircraft (ULA) were equipped with remote sensing and in-situ instruments to characterize the vertical distribution of the main water vapour isotopes. One ULA embarked a backscatter lidar to monitor the horizontal evolution of the vertical structure of the lower troposphere above and around the lake, and the other one carried an L2130-i Picarro isotope analyser for the in-situ measurement of the H<sub>2</sub><sup>16</sup>O, H<sub>2</sub><sup>18</sup>O and HDO concentrations, an iMet probe for the measurement of thermodynamic properties (T, RH, p), as well as a pre-cleaned Caltech Active Strand Cloud Water Collector which was modified to efficiently collect cloud water at the speed of the ULA. Offset calibration of the Picarro analyser was carried out for each flight before take-off and after landing. Three-dimensional explorations of the lake environment up to 4 km above the mean sea level (~3.5 km above the ground level) were conducted with the ULAs. Simultaneous vertical profiles of water vapour, temperature, aerosols and winds were acquired from two co-located ground-based lidars installed on the shore of the southern part of the Annecy Lake named “petit lac”, in the commune of Lathuile (45°47' N, 6°12' E). Finally, ship-borne profile measurements of the lake water temperature, pH, conductivity and dissolved O<sub>2</sub> as well as water sampling for isotopic analyses were accrued out across the lake of Annecy.</p><p>The campaign period included several cases of weather events leading to variability between dry and humid conditions, cloudy and cloud-free conditions, and regimes dominated by weak and strong winds. Flight patterns have been repeated at several times in the day to capture the diurnal evolution as well as variation between different weather regimes. Additional flights have been conducted to map the spatial variability of the water vapour isotope composition with regard to the lake and topography. The scientific strategy of the experiment will be presented, and the first observational results will be described with emphasis on the vertical structure of the lower troposphere and its relationship to orography, including the characterisation of the water vapour isotopologues variability in, above and around the Annecy lake.</p>

scholarly journals The lacustrine-water vapor isotope inventory experiment L-WAIVE

2020 ◽  
Author(s):  
Patrick Chazette ◽  
Cyrille Flamant ◽  
Harald Sodemann ◽  
Julien Totems ◽  
Anne Monod ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Vapour ◽  
Liquid Water ◽  
Isotope Composition ◽  
Lower Troposphere ◽  
Ground Level ◽  
Atmospheric Water ◽  
Atmospheric Water Vapour ◽  
Weather Events ◽  
Water Vapor Mixing Ratio

Abstract. In order to gain understanding on the vertical structure of atmospheric water vapour above mountain lakes and to assess the respective influence of evaporation and advection processes, the L-WAIVE (Lacustrine-Water vApor Isotope inVentory Experiment) field campaign was conducted in the Annecy valley in the French Alps in June 2019. This campaign was based on a synergy between a suite of ground-based, boat-borne, and airborne measuring platforms implemented to characterise the thermodynamic and isotopic state above the lake environment using both in-situ and remote sensing instruments. Two ultra-light aircrafts (ULA), one equipped with a Rayleigh-Mie lidar, solar fluxmeters and an optical counter, and one equipped with a Cavity Ring-down Spectrometer (CRDS) and an in-cloud liquid water collector, were deployed to characterize the vertical distribution of the main stable water vapour isotopes (H216O, H218O and H2H16O), and their potential interactions with clouds and aerosols. ULA flight patterns were repeated several times per day to capture the diurnal evolution as well as variability associated with different weather events. ULA flights were anchored to continuous water vapour and wind profiling of the lower troposphere performed by two dedicated ground-based lidars. Additional flights have been conducted to map the spatial variability of the water vapour isotope composition regarding the lake and surrounding topography. Throughout the campaign, ship-borne lake temperature profiles as well as liquid water samples at the air-water interface and at 2 m depth were made, supplemented on one occasion by atmospheric water vapour isotope measurements from the ship. The campaign period included a variety of weather events leading to contrasting humidity and cloud conditions, slope wind regimes and aerosol contents in the valley. The water vapor mixing ratio values in the valley atmospheric boundary layer were found to range from 3–4 g kg−1 to more than 10 g kg−1 and to be strongly influenced by the subsidence of higher altitude air masses as well as slope winds. A significant variability of the isotopic composition was observed within the first 3 km above ground level. The influence of the lake evaporation was mainly detected in the first 500 m of the atmosphere. Well-mixed conditions prevailed in the lower free troposphere, mainly above the mean altitude of the mountain tops surrounding the lake.

scholarly journals Aircraft validation of Aura Tropospheric Emission Spectrometer retrievals of HDO / H<sub>2</sub>O

2014 ◽  
Vol 7 (9) ◽  
pp. 3127-3138 ◽  
Author(s):  
R. L. Herman ◽  
J. E. Cherry ◽  
J. Young ◽  
J. M. Welker ◽  
D. Noone ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Standard Deviation ◽  
Lower Troposphere ◽  
Temporal Variations ◽  
Observation Error ◽  
Free Troposphere ◽  
Data Set ◽  
Airborne Measurements

Abstract. The EOS (Earth Observing System) Aura Tropospheric Emission Spectrometer (TES) retrieves the atmospheric HDO / H2O ratio in the mid-to-lower troposphere as well as the planetary boundary layer. TES observations of water vapor and the HDO isotopologue have been compared with nearly coincident in situ airborne measurements for direct validation of the TES products. The field measurements were made with a commercially available Picarro L1115-i isotopic water analyzer on aircraft over the Alaskan interior boreal forest during the three summers of 2011 to 2013. TES special observations were utilized in these comparisons. The TES averaging kernels and a priori constraints have been applied to the in situ data, using version 5 (V005) of the TES data. TES calculated errors are compared with the standard deviation (1σ) of scan-to-scan variability to check consistency with the TES observation error. Spatial and temporal variations are assessed from the in situ aircraft measurements. It is found that the standard deviation of scan-to-scan variability of TES δD is ±34.1‰ in the boundary layer and ± 26.5‰ in the free troposphere. This scan-to-scan variability is consistent with the TES estimated error (observation error) of 10–18‰ after accounting for the atmospheric variations along the TES track of ±16‰ in the boundary layer, increasing to ±30‰ in the free troposphere observed by the aircraft in situ measurements. We estimate that TES V005 δD is biased high by an amount that decreases with pressure: approximately +123‰ at 1000 hPa, +98‰ in the boundary layer and +37‰ in the free troposphere. The uncertainty in this bias estimate is ±20‰. A correction for this bias has been applied to the TES HDO Lite Product data set. After bias correction, we show that TES has accurate sensitivity to water vapor isotopologues in the boundary layer.

scholarly journals Validation of INSAT-3D sounder data with in-situ measurements and other similar satellite observations over Indian region

2016 ◽  
Author(s):  
M. Venkat Ratnam ◽  
A. Hemanth Kumar ◽  
A. Jayaraman
Keyword(s):  
Water Vapor ◽  
Lower Troposphere ◽  
India Meteorological Department ◽  
Analysis Data ◽  
Infrared Region ◽  
In Situ Measurements ◽  
Indian Region ◽  
Positive Bias ◽  
3D Data

Abstract. To date, several satellites measurements are available which can provide profiles of temperature and water vapor with reasonable accuracies. However, temporal resolution remained poor, particularly over topics, as most of them are polar orbiting. At this juncture, launch of INSAT-3D (Indian National Satellite) by the Indian Space Research Organization (ISRO) on 26 July 2013 carrying multi-spectral imager covering visible to long wave infrared region made it possible to obtain profiles of temperature and water vapor over Indian region with higher temporal and vertical resolutions and altitude coverage besides the other parameters. The initial validation of INSAT-3D data is made with the high temporal (3 h) resolution radiosonde observations launched over Gadanki (13.5° N, 79.2° E) during a special campaign and routine evening soundings obtained at 12 UTC. We also compared INSAT-3D data with the radiosonde observations obtained from 34 India Meteorological Department stations. Comparisons were also made over Indian region with data from other satellites like AIRS, MLS and SAPHIR and ERA-Interim and NCEP re-analysis datasets. INSAT-3D is able to show a better coverage over Indian region with high spatial and temporal resolutions as expected. Good correlation in temperature between INSAT-3D and in-situ measurements is noticed except in the upper troposphere and lower stratospheric region (positive bias of 2–3 K). There exists mean dry bias of 10–25 % in relative humidity. Similar biases are also noticed when compared to other satellites and re-analysis data sets. INSAT-3D shows large positive bias in temperature above 25° N in the lower troposphere. Thus, caution is advised in using this data at those places for tropospheric studies. Finally it is concluded that temperature data from INSAT-3D is of high quality that can be directly assimilated for better forecast over Indian region.

scholarly journals Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

2014 ◽  
Vol 7 (7) ◽  
pp. 6917-6969 ◽  
Author(s):  
M. Schneider ◽  
Y. González ◽  
C. Dyroff ◽  
E. Christner ◽  
A. Wiegele ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
Lower Troposphere ◽  
Remote Sensing Data ◽  
Added Value ◽  
Empirical Validation ◽  
Transport Pathways ◽  
Sensing Data ◽  
Interferometer Observation

Abstract. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) integrates tropospheric water vapour isototopologue remote sensing and in-situ observations. This paper presents a first empirical validation of MUSICA's H2O and δD remote sensing products (generated from ground-based FTIR, Fourier Transform InfraRed, spectrometer and space-based IASI, Infrared Atmospheric Sounding Interferometer, observation). As reference we use well calibrated in-situ measurements made aboard an aircraft (between 200 and 6800 m a.s.l.) by the dedicated ISOWAT instrument and on the island of Tenerife at two different altitudes (at Izaña, 2370 m a.s.l., and at Teide, 3550 m a.s.l.) by two commercial Picarro L2120-i water isotopologue analysers. The comparison to the ISOWAT profile measurements shows that the remote sensors can well capture the variations in the water vapour isotopologues and the scatter with respect to the in-situ references suggests a δD random uncertainty for the FTIR product of much better than 45‰ in the lower troposphere and of about 15‰ for the middle troposphere. For the middle tropospheric IASI δD product the study suggests a respective uncertainty of about 15‰. In addition, we find indications for a positive δD bias in the remote sensing products. The δD data are scientifically interesting only if they add information to the H2O observations. We are able to qualitatively demonstrate the added value of the MUSICA δD remote sensing data by comparing δD-vs.-H2O curves. First, we show that the added value of δD as seen in the Picarro data is similarly seen in FTIR data measured in coincidence. Second, we document that the δD-vs.-H2O curves obtained from the different in-situ and remote sensing data sets (ISOWAT, Picarro at Izaña and Teide, FTIR, and IASI) consistently identify two different moisture transport pathways to the subtropical north eastern Atlantic free troposphere.

scholarly journals Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

2015 ◽  
Vol 8 (1) ◽  
pp. 483-503 ◽  
Author(s):  
M. Schneider ◽  
Y. González ◽  
C. Dyroff ◽  
E. Christner ◽  
A. Wiegele ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
Moisture Transport ◽  
Lower Troposphere ◽  
Remote Sensing Data ◽  
Added Value ◽  
Data Sets ◽  
Empirical Validation ◽  
Sensing Data

Abstract. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) integrates tropospheric water vapour isotopologue remote sensing and in situ observations. This paper presents a first empirical validation of MUSICA's H2O and δD remote sensing products, generated from ground-based FTIR (Fourier transform infrared), spectrometer and space-based IASI (infrared atmospheric sounding interferometer) observation. The study is made in the area of the Canary Islands in the subtropical northern Atlantic. As reference we use well calibrated in situ measurements made aboard an aircraft (between 200 and 6800 m a.s.l.) by the dedicated ISOWAT instrument and on the island of Tenerife at two different altitudes (at Izaña, 2370 m a.s.l., and at Teide, 3550 m a.s.l.) by two commercial Picarro L2120-i water isotopologue analysers. The comparison to the ISOWAT profile measurements shows that the remote sensors can well capture the variations in the water vapour isotopologues, and the scatter with respect to the in situ references suggests a δD random uncertainty for the FTIR product of much better than 45‰ in the lower troposphere and of about 15‰ for the middle troposphere. For the middle tropospheric IASI δD product the study suggests a respective uncertainty of about 15‰. In both remote sensing data sets we find a positive δD bias of 30–70‰. Complementing H2O observations with δD data allows moisture transport studies that are not possible with H2O observations alone. We are able to qualitatively demonstrate the added value of the MUSICA δD remote sensing data. We document that the δD–H2O curves obtained from the different in situ and remote sensing data sets (ISOWAT, Picarro at Izaña and Teide, FTIR, and IASI) consistently identify two different moisture transport pathways to the subtropical north eastern Atlantic free troposphere.

scholarly journals Moisture Vertical Structure, Column Water Vapor, and Tropical Deep Convection

2009 ◽  
Vol 66 (6) ◽  
pp. 1665-1683 ◽  
Author(s):  
Christopher E. Holloway ◽  
J. David Neelin
Keyword(s):  
Water Vapor ◽  
Vertical Structure ◽  
Deep Convection ◽  
Strong Association ◽  
Lower Troposphere ◽  
Principal Component ◽  
Environmental Water ◽  
Specific Humidity ◽  
Free Troposphere ◽  
Precipitation Gauge

Abstract The vertical structure of the relationship between water vapor and precipitation is analyzed in 5 yr of radiosonde and precipitation gauge data from the Nauru Atmospheric Radiation Measurement (ARM) site. The first vertical principal component of specific humidity is very highly correlated with column water vapor (CWV) and has a maximum of both total and fractional variance captured in the lower free troposphere (around 800 hPa). Moisture profiles conditionally averaged on precipitation show a strong association between rainfall and moisture variability in the free troposphere and little boundary layer variability. A sharp pickup in precipitation occurs near a critical value of CWV, confirming satellite-based studies. A lag–lead analysis suggests it is unlikely that the increase in water vapor is just a result of the falling precipitation. To investigate mechanisms for the CWV–precipitation relationship, entraining plume buoyancy is examined in sonde data and simplified cases. For several different mixing schemes, higher CWV results in progressively greater plume buoyancies, particularly in the upper troposphere, indicating conditions favorable for deep convection. All other things being equal, higher values of lower-tropospheric humidity, via entrainment, play a major role in this buoyancy increase. A small but significant increase in subcloud layer moisture with increasing CWV also contributes to buoyancy. Entrainment coefficients inversely proportional to distance from the surface, associated with mass flux increase through a deep lower-tropospheric layer, appear promising. These yield a relatively even weighting through the lower troposphere for the contribution of environmental water vapor to midtropospheric buoyancy, explaining the association of CWV and buoyancy available for deep convection.

scholarly journals Comparisons of Modeled and Observed Reflectivities and Fall Speeds for Snowfall of Varied Riming Degrees during Winter Storms on Long Island, New York

2016 ◽  
Vol 144 (11) ◽  
pp. 4327-4347 ◽  
Author(s):  
Andrew L. Molthan ◽  
Brian A. Colle ◽  
Sandra E. Yuter ◽  
David Stark
Keyword(s):  
New York ◽  
Vertical Structure ◽  
Wrf Model ◽  
Cloud Water ◽  
Weather Research And Forecasting ◽  
Winter Storms ◽  
Stereo Microscope ◽  
Fall Speed ◽  
Snow Conditions

Abstract Derived radar reflectivities and fall speeds for four Weather Research and Forecasting (WRF) Model bulk microphysical parameterizations (BMPs) run at 1.33-km grid spacing are compared with ground-based, vertically pointing Ku-band radar, scanning S-band radar, and in situ measurements at Stony Brook, New York. Simulations were partitioned into periods of observed riming degree as determined manually using a stereo microscope and camera during nine winter storms. Simulations were examined to determine whether the selected BMPs captured the effects of varying riming intensities, provided a reasonable match to the vertical structure of radar reflectivity or fall speed, and whether they produced reasonable surface fall speed distributions. Schemes assuming nonspherical mass–diameter relationships yielded reflectivity distributions closer to observed values. All four schemes examined in this study provided a better match to the observed, vertical structure of reflectivity during moderate riming than light riming periods. The comparison of observed and simulated snowfall speeds had mixed results. One BMP produced episodes of excessive cloud water at times, resulting in fall speeds that were too large. However, most schemes had frequent periods of little or no cloud water during moderate riming periods and thus underpredicted the snowfall speeds at lower levels. Short, 1–4-h periods with relatively steady snow conditions were used to compare BMP and observed size and fall speed distributions. These limited data suggest the examined BMPs underpredict fall speeds of cold-type snow habits and underrepresent aggregates larger than 4-mm diameter.

scholarly journals Validation of INSAT-3D sounder data with in situ measurements and other similar satellite observations over India

2016 ◽  
Vol 9 (12) ◽  
pp. 5735-5745 ◽  
Author(s):  
Madineni Venkat Ratnam ◽  
Alladi Hemanth Kumar ◽  
Achuthan Jayaraman
Keyword(s):  
Water Vapour ◽  
Lower Troposphere ◽  
India Meteorological Department ◽  
Satellite System ◽  
Reanalysis Data ◽  
In Situ Measurements ◽  
Data Sets ◽  
Positive Bias ◽  
3D Data

Abstract. To date, several satellites measurements are available which can provide profiles of temperature and water vapour with reasonable accuracies. However, the temporal resolution has remained poor, particularly over the tropics, as most of them are polar orbiting. At this juncture, the launch of INSAT-3D (Indian National Satellite System) by the Indian Space Research Organization (ISRO) on 26 July 2013 carrying a multi-spectral imager covering visible to long-wave infrared made it possible to obtain profiles of temperature and water vapour over India with higher temporal and vertical resolutions and altitude coverage, besides other parameters. The initial validation of INSAT-3D data is made with the high temporal (3 h) resolution radiosonde observations launched over Gadanki (13.5° N, 79.2° E) during a special campaign and routine evening soundings obtained at 12:00 UTC (17:30 LT). We also compared INSAT-3D data with the radiosonde observations obtained from 34 India Meteorological Department stations. Comparisons were also made over India with data from other satellites like AIRS, MLS and SAPHIR and from ERA-Interim and NCEP reanalysis data sets. INSAT-3D is able to show better coverage over India with high spatial and temporal resolutions as expected. Good correlation in temperature between INSAT-3D and in situ measurements is noticed except in the upper tropospheric and lower stratospheric regions (positive bias of 2–3 K). There is a mean dry bias of 20–30 % in the water vapour mixing ratio. Similar biases are noticed when compared to other satellites and reanalysis data sets. INSAT-3D shows a large positive bias in temperature above 25° N in the lower troposphere. Thus, caution is advised when using these data for tropospheric studies. Finally it is concluded that temperature data from INSAT-3D are of high quality and can be directly assimilated for better forecasts over India.

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