scholarly journals Characterizing water vapour concentration dependence of commercial cavity ring-down spectrometers for continuous on-site atmospheric water vapour isotope measurements in the tropics

2021 ◽  
Vol 14 (2) ◽  
pp. 1439-1455
Author(s):  
Shujiro Komiya ◽  
Fumiyoshi Kondo ◽  
Heiko Moossen ◽  
Thomas Seifert ◽  
Uwe Schultz ◽  
...  
Keyword(s):  
Water Vapour ◽  
Concentration Dependence ◽  
Central Amazon ◽  
Water Vapour Concentration ◽  
Fitting Method ◽  
In Situ Calibration ◽  
Significant Difference ◽  
Calibration Interval ◽  
Cavity Ring Down

Abstract. The recent development and improvement of commercial laser-based spectrometers have expanded in situ continuous observations of water vapour (H2O) stable isotope compositions (e.g. δ18O and δ2H) in a variety of sites worldwide. However, we still lack continuous observations in the Amazon, a region that significantly influences atmospheric and hydrological cycles on local to global scales. In order to achieve accurate on-site observations, commercial water isotope analysers require regular in situ calibration, which includes the correction of H2O concentration dependence ([H2O] dependence) of isotopic measurements. Past studies have assessed the [H2O] dependence for air with H2O concentrations of up to 35 000 ppm, a value that is frequently surpassed in tropical rainforest settings like the central Amazon where we plan continuous observations. Here we investigated the performance of two commercial analysers (L1102i and L2130i models, Picarro, Inc., USA) for measuring δ18O and δ2H in atmospheric moisture at four different H2O levels from 21 500 to 41 000 ppm. These H2O levels were created by a custom-built calibration unit designed for regular in situ calibration. Measurements on the newer analyser model (L2130i) had better precision for δ18O and δ2H and demonstrated less influence of H2O concentration on the measurement accuracy at each concentration level compared to the older L1102i. Based on our findings, we identified the most appropriate calibration strategy for [H2O] dependence, adapted to our calibration system. The best strategy required conducting a two-point calibration with four different H2O concentration levels, carried out at the beginning and end of the calibration interval. The smallest uncertainties in calibrating [H2O] dependence of isotopic accuracy of the two analysers were achieved using a linear surface fitting method and a 28 h calibration interval, except for the δ18O accuracy of the L1102i analyser for which the cubic fitting method gave the best results. The uncertainties in [H2O] dependence calibration did not show any significant difference using calibration intervals from 28 up to 196 h; this suggested that one [H2O] dependence calibration per week for the L2130i and L1102i analysers is sufficient. This study shows that the cavity ring-down spectroscopy (CRDS) analysers, appropriately calibrated for [H2O] dependence, allow the detection of natural signals of stable water vapour isotopes at very high humidity levels, which has promising implications for water cycle studies in areas like the central Amazon rainforest and other tropical regions.

scholarly journals Characterising water vapour concentration dependence of commercial cavity ring-down spectrometers for continuous onsite atmospheric water vapour isotope measurements in the tropics

2020 ◽  
Author(s):  
Shujiro Komiya ◽  
Fumiyoshi Kondo ◽  
Heiko Moossen ◽  
Thomas Seifert ◽  
Uwe Schultz ◽  
...  
Keyword(s):  
Water Vapour ◽  
Concentration Dependence ◽  
Water Vapour Concentration ◽  
Fitting Method ◽  
Vapour Concentration ◽  
In Situ Calibration ◽  
Significant Difference ◽  
Hydrological Cycles ◽  
The Tropics

Abstract. The recent development and improvement of commercial laser-based spectrometers have expanded in situ continuous observations of water vapour (H2O) stable isotope ratios (e.g., δ18O, δ2H, etc.) in a variety of sites worldwide. However, we still lack continuous observations in the Amazon, a region that significantly influences atmospheric and hydrological cycles on local to global scales. In order to achieve accurate on-site observations, commercial water isotope analysers require regular in situ calibration, including H2O concentration dependence ([H2O]-dependence) of isotopic accuracy. Past studies have assessed [H2O]-dependence for air with H2O concentrations up to 35,000 ppm, a value that is frequently surpassed in tropical rainforest settings like the central Amazon where we plan continuous observations. Here we investigated the performance of two commercial analysers (L1102i and L2130i models, Picarro, Inc., USA) for measuring δ18O and δ2H in atmospheric moisture at four different H2O levels from 21,500 to 41,000 ppm. These H2O levels were created by a custom-built calibration unit designed for regular in situ calibration. Measurements on the newer analyser model (L2130i) had better precision for δ18O and δ2H and demonstrated less influence of H2O concentration on the measurement accuracy at each moisture level compared to the older L1102i. Based on our findings, we identified the most appropriate calibration strategy for [H2O]-dependence, adapted to our calibration system. The best strategy required using two pairs of a two-point calibration with four different H2O concentration levels. The smallest uncertainties in calibrating [H2O]-dependence of isotopic accuracy of the two analysers were achieved using a linear-surface fitting method and a 28 h calibration interval, except for the δ18O accuracy of the L1102i analyser for which the cubic fitting method gave best results. The uncertainties in [H2O]-dependence calibration did not show any significant difference using calibration intervals from 28 h up to 196 h; this suggested that one [H2O]-dependence calibration per week for the L2130i and L1102i analysers is sufficient.

Laboratory evaluation of water vapour concentration dependence of commercial water vapour isotope cavity ring-down spectrometers for continuous onsite atmospheric measurements in the Amazon rainforest

2021 ◽  
Author(s):  
Shujiro Komiya ◽  
Fumiyoshi Kondo ◽  
Heiko Moossen ◽  
Thomas Seifert ◽  
Uwe Schultz ◽  
...  
Keyword(s):  
Water Vapour ◽  
Concentration Dependence ◽  
Field Measurements ◽  
Amazon Rainforest ◽  
Laboratory Evaluation ◽  
Atmospheric Measurements ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Hydrological Cycles ◽  
Cavity Ring Down

<p>Commercially available laser-based spectrometers permit continuous field measurements of water vapour (H<sub>2</sub>O) stable isotope compositions, yet continuous observations in the Amazon, a region that significantly influences atmospheric hydrological cycles on regional to global scales, are largely missing. In order to achieve accurate on-site observations in such conditions, these instruments will require regular on-site calibration, including for H<sub>2</sub>O concentration dependence ([H<sub>2</sub>O]-dependence) of isotopic accuracy.</p><p>With the aim of conducting accurate continuous δ<sup>18</sup>O and δ<sup>2</sup>H on-site observation in the Amazon rainforest, we conducted a laboratory experiment to investigate the performance and determine the optimal [H<sub>2</sub>O]-dependence calibration strategy for two commercial cavity-ring down (CRDS) analysers (L1102i and L2130i models, Picarro, Inc., USA), coupled to our custom-built automated calibration unit. We particularly focused on the rarely investigated performance of the instruments at atmospheric H<sub>2</sub>O contents above 35,000 ppm, a value regularly reached at our site.</p><p>The later analyser model (L2130i) had better precision and accuracy of δ<sup>18</sup>O and δ<sup>2</sup>H measurements with a less pronounced [H<sub>2</sub>O]-dependence compared to the older L1102i. The [H<sub>2</sub>O]-dependence calibration uncertainties did not significantly change with calibration intervals from 28 h up to 196 h, suggesting that one [H<sub>2</sub>O]-dependence calibration per week for the L2130i and L1102i analysers is enough. This study shows that with both CRDS analysers, correctly calibrated, we should be able to discriminate natural diel, seasonal and interannual signals of stable water vapour isotopes in a tropical rainforest environment.</p><p> </p>

scholarly journals Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign

2009 ◽  
Vol 9 (13) ◽  
pp. 4407-4417 ◽  
Author(s):  
S. Lossow ◽  
M. Khaplanov ◽  
J. Gumbel ◽  
J. Stegman ◽  
G. Witt ◽  
...  
Keyword(s):  
Water Vapour ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
The Arctic ◽  
Small Scale ◽  
Air Masses ◽  
Mixing Ratios ◽  
Water Vapour Concentration ◽  
Wind Shears

Abstract. The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden (68° N, 21° E) with the aim to investigate the small scale distribution of water vapour in the middle atmosphere in the vicinity of the Arctic polar vortex. In situ balloon and rocket-borne measurements of water vapour were performed by means of OH fluorescence hygrometry. The combined measurements yielded a high resolution water vapour profile up to an altitude of 75 km. Using the characteristic of water vapour being a dynamical tracer it was possible to directly relate the water vapour data to the location of the polar vortex edge, which separates air masses of different character inside and outside the polar vortex. The measurements probed extra-vortex air in the altitude range between 45 km and 60 km and vortex air elsewhere. Transitions between vortex and extra-vortex usually coincided with wind shears caused by gravity waves which advect air masses with different water vapour volume mixing ratios. From the combination of the results from the Hygrosonde-2 campaign and the first flight of the optical hygrometer in 1994 (Hygrosonde-1) a clear picture of the characteristic water vapour distribution inside and outside the polar vortex can be drawn. Systematic differences in the water vapour concentration between the inside and outside of the polar vortex can be observed all the way up into the mesosphere. It is also evident that in situ measurements with high spatial resolution are needed to fully account for the small-scale exchange processes in the polar winter middle atmosphere.

scholarly journals Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign

2008 ◽  
Vol 8 (3) ◽  
pp. 12227-12252 ◽  
Author(s):  
S. Lossow ◽  
M. Khaplanov ◽  
J. Gumbel ◽  
J. Stegman ◽  
G. Witt ◽  
...  
Keyword(s):  
Water Vapour ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
The Arctic ◽  
Small Scale ◽  
Water Vapour Concentration ◽  
Exchange Processes ◽  
Vapour Concentration ◽  
Wind Shears

Abstract. The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden, with the aim to investigate the small scale distribution of water vapour in the middle atmosphere in the vicinity of the Arctic polar vortex. In-situ balloon and rocket-borne measurements of water vapour were performed by means of OH fluorescence hygrometry. The combined measurements yielded a high resolution water vapour profile up to an altitude of 75 km. Using water vapour as a dynamical tracer it was possible to directly relate the water data to the position of the polar vortex. The measurement probed extra-vortex air below 19 km and in the altitude range between 45 km and 60 km and vortex air elsewhere. Transitions between vortex and extra-vortex usually coincided with wind shears caused by gravity waves which advect air masses with different water vapour characteristics. From the combination of the results from the Hygrosonde-2 campaign and the first flight of the optical hygrometer in 1994 (Hygrosonde-1) a clear picture of the characteristic water vapour distribution inside and outside the polar vortex can be drawn. Systematic differences in the water vapour concentration between the inside and outside of the polar vortex can be observed all the way up into the mesosphere and are consistent with efficient downward transport of air inside the vortex. It is evident that in-situ measurements with high spatial resolution are needed to fully account for the small-scale exchange processes in the polar winter middle atmosphere.

scholarly journals Evaluation of balloon and satellite water vapour measurements in the Southern tropical and subtropical UTLS during the HIBISCUS campaign

2009 ◽  
Vol 9 (14) ◽  
pp. 5299-5319 ◽  
Author(s):  
N. Montoux ◽  
A. Hauchecorne ◽  
J.-P. Pommereau ◽  
F. Lefèvre ◽  
G. Durry ◽  
...  
Keyword(s):  
Water Vapour ◽  
Lower Stratosphere ◽  
Tunable Diode Laser ◽  
Absorption Bands ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Remote Measurements

Abstract. Balloon water vapour in situ and remote measurements in the tropical upper troposphere and lower stratosphere (UTLS) obtained during the HIBISCUS campaign around 20° S in Brazil in February–March 2004 using a tunable diode laser (μSDLA), a surface acoustic wave (SAW) and a Vis-NIR solar occultation spectrometer (SAOZ) on a long duration balloon, have been used for evaluating the performances of satellite borne remote water vapour instruments available at the same latitude and measurement period. In the stratosphere, HALOE displays the best precision (2.5%), followed by SAGE II (7%), MIPAS (10%), SAOZ (20–25%) and SCIAMACHY (35%), all of which show approximately constant H2O mixing ratios between 20–25 km. Compared to HALOE of ±10% accuracy between 0.1–100 hPa, SAGE II and SAOZ show insignificant biases, MIPAS is wetter by 10% and SCIAMACHY dryer by 20%. The currently available GOMOS profiles of 25% precision show a positive vertical gradient in error for identified reasons. Compared to these, the water vapour of the Reprobus Chemistry Transport Model, forced at pressures higher than 95 hPa by the ECMWF analyses, is dryer by about 1 ppmv (20%). In the lower stratosphere between 16–20 km, most notable features are the steep degradation of MIPAS precision below 18 km, and the appearance of biases between instruments far larger than their quoted total uncertainty. HALOE and SAGE II (after spectral adjustment for reducing the bias with HALOE at northern mid-latitudes) both show decreases of water vapour with a minimum at the tropopause not seen by other instruments or the model, possibly attributable to an increasing error in the HALOE altitude registration. Between 16–18 km where the water vapour concentration shows little horizontal variability, and where the μSDLA balloon measurements are not perturbed by outgassing, the average mixing ratios reported by the remote sensing instruments are substantially lower than the 4–5 ppmv observed by the μSDLA. Differences between μSDLA and HALOE and SAGE II (of the order of −2 ppmv), SCIAMACHY, MIPAS and GOMOS (−1 ppmv) and SAOZ (−0.5 ppmv), exceed the 10% uncertainty of μSDLA, implying larger systematic errors than estimated for the various instruments. In the upper troposphere, where the water vapour concentration is highly variable, AIRS v5 appears to be the most consistent within its 25% uncertainty with balloon in-situ measurements as well as ECMWF. Most of the remote measurements show less reliability in the upper troposphere, losing sensitivity possibly because of absorption line saturation in their spectral ranges (HALOE, SAGE II and SCIAMACHY), instrument noise exceeding 100% (MIPAS) or imperfect refraction correction (GOMOS). An exception is the SAOZ-balloon, employing smaller H2O absorption bands in the troposphere.

Increse of newly - detected in situ cancers in non-palpable breast lesions

2006 ◽  
Vol 53 (1) ◽  
pp. 73-75
Author(s):  
N. Miletic ◽  
D. Stojiljkovic ◽  
M. Inic ◽  
M. Prekajski ◽  
A. Celebic ◽  
...  
Keyword(s):  
Breast Tissue ◽  
Malignant Disease ◽  
Clinical Stage ◽  
Diagnostic Procedures ◽  
Basal Membrane ◽  
Needle Aspiration ◽  
Screening Mammography ◽  
Significant Difference ◽  
Malignant Lesions

Great importance in detecting cancer in the phase of in situ lays in the fact that the epithelial layer is deprived of blood and lymph vessels, so metastases may develop only when basal membrane has been broken. This paper includes 46 operated women in whom it preoperatively had been verified suspect non-palpable lesion. The preoperative diagnostics included use of high- resolution mammography, aimed mammography, palpatory examination, as well as fine-needle aspiration (FNA), biopsy and cytologic analysis of the sample. The methodology of this work implies the use of stereotaxic marking, specimen mammography and ex-tempore pathohistology analysis. Out of 46 investigated patients in clinical stage T0N0M0, in whom there were no signs of malignant disease, and according to suspect lesion of initial screening mammography, malignant lesions of breast tissue were diagnosed in 19 patients (41%) intraoperatively. Three of these lesions (15,8%) were histopathologically verified as in situ. Comparing our results with data of the Institute of oncology and radiology of Serbia hospital registry (IORS) for the year 2001, from 1173 patients registered with malignant lesions, only 16 ones (1,4%) had in situ cancer, operated on the basis of the suspect mammography of clinical stage T0N0M0. Statistically significant difference was found related to the number of detected cancers in this early phase of the breast malignant disease. This limits surgical intervention to tumorectomy, with preservation of the remaining breast tissue, what brings to healing, justifying in that way, screening examinations and routine application of the most contemporary diagnostic procedures.

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