A Raman lidar at Maïdo Observatory (Reunion Island) to measure water vapor in the troposphere and lower stratosphere: calibration and validation

Abstract. The Maïdo high-altitude observatory located in Reunion Island (21° S, 55.5° E) is equipped with Lidar1200, an innovative Raman lidar designed to measure the water vapor mixing ratio in the troposphere and the lower stratosphere. The calibration methodology is based on a GNSS (Global Navigation Satellite System) IWV (Integrated Water Vapor) dataset and lamp measurements. The mean relative standard error on the calibration coefficient is around 2.7 %. Two years of lidar water vapor measurements from November 2013 to October 2015 are now processed. By comparing CFH (Cryogenic Frost point Hygrometer) radiosonde profiles with the Raman lidar profiles, the ability of the lidar to provide accurate measurements is possible up to 22 km. The ability of measuring water vapor mixing ratios of a few ppmv in the lower stratosphere is demonstrated with a 48-hours integration time period, an absolute error lower than 0.8 ppmv and a relative error less than 20 %. This Raman lidar is dedicated to provide regular profiles of water vapor measurements with a high vertical resolution and low uncertainties to international networks; in the wider interest of research on stratosphere-troposphere exchange processes and on the long-term survey of water vapor in the upper troposphere and lower stratosphere in the Southern Hemisphere. A strategy of data sampling and filtering is proposed to meet these objectives with regard to the altitude range requested. 10-min time integration and 65–90 m vertical resolution ensure a vertical profile reaching 10 km, but more than 2800 minutes and a vertical resolution of 150–1300 m are necessary to reach the lower stratosphere with an uncertainty less than 20 %.

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Validation of the Water Vapor Profiles of the Raman Lidar at the Maïdo Observatory (Reunion Island) Calibrated with Global Navigation Satellite System Integrated Water Vapor

Atmosphere ◽

10.3390/atmos10110713 ◽

2019 ◽

Vol 10 (11) ◽

pp. 713 ◽

Cited By ~ 1

Author(s):

Hélène Vérèmes ◽

Guillaume Payen ◽

Philippe Keckhut ◽

Valentin Duflot ◽

Jean-Luc Baray ◽

...

Keyword(s):

Water Vapor ◽

Global Navigation Satellite System ◽

Satellite System ◽

Navigation Satellite ◽

Reunion Island ◽

Raman Lidar ◽

Réunion Island ◽

Global Navigation ◽

Global Navigation Satellite ◽

Good Agreement

The Maïdo high-altitude observatory located in Reunion Island (21 ∘ S, 55.5 ∘ E) is equipped with the Lidar1200, an innovative Raman lidar designed to measure the water vapor mixing ratio in the troposphere and the lower stratosphere, to perform long-term survey and processes studies in the vicinity of the tropopause. The calibration methodology is based on a GNSS (Global Navigation Satellite System) IWV (Integrated Water Vapor) dataset. The lidar water vapor measurements from November 2013 to October 2015 have been calibrated according to this methodology and used to evaluate the performance of the lidar. The 2-year operation shows that the calibration uncertainty using the GNSS technique is in good agreement with the calibration derived using radiosondes. During the MORGANE (Maïdo ObservatoRy Gaz and Aerosols NDACC Experiment) campaign (Reunion Island, May 2015), CFH (Cryogenic Frost point Hygrometer) radiosonde and Raman lidar profiles are compared and show good agreement up to 22 km asl; no significant biases are detected and mean differences are smaller than 9% up to 22 km asl.

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Water Vapor Profiles up to the UT/LS from Raman Lidar at Reunion Island (21°S, 55°E) : Technical Description, Data Processing and Comparison with Sondes

EPJ Web of Conferences ◽

10.1051/epjconf/201611905004 ◽

2016 ◽

Vol 119 ◽

pp. 05004

Author(s):

Hélène Vérèmes ◽

Philippe Keckhut ◽

Jean-Luc Baray ◽

Jean-Pierre Cammas ◽

Davide Dionisi ◽

...

Keyword(s):

Water Vapor ◽

Data Processing ◽

Reunion Island ◽

Raman Lidar ◽

Technical Description ◽

Réunion Island

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Two-year operation of the lidar1200: from fine-scale tropospheric structures to lower stratospheric water vapor detection

EPJ Web of Conferences ◽

10.1051/epjconf/201817605015 ◽

2018 ◽

Vol 176 ◽

pp. 05015

Author(s):

Hélène Vérèmes ◽

Guillaume Payen ◽

Philippe Keckhut ◽

Valentin Duflot ◽

Jean-Luc Baray ◽

...

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Integration Time ◽

Fine Scale ◽

Vertical Resolution ◽

Vapor Detection ◽

Stratospheric Water Vapor ◽

Frost Point ◽

Time Period ◽

Water Vapor Detection

The 2-year lidar water vapor database (November 2013 - October 2015) of the Maïdo Observatory (Reunion Island / 21°S,55.5°E) is now processed. The performances of the lidar in providing accurate vertical structures are shown to be good. The ability to measure quantities of a few ppmv in the lower stratosphere is demonstrated (based on Cryogenic Frost point Hygrometer sonde/lidar profiles comparisons) for a 48-hour integration time period, up to 22 km (with a vertical resolution of 1.3 km).

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Calibration of a Multichannel Water Vapor Raman Lidar through Noncollocated Operational Soundings: Optimization and Characterization of Accuracy and Variability

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2009jtecha1327.1 ◽

2010 ◽

Vol 27 (1) ◽

pp. 108-121 ◽

Cited By ~ 21

Author(s):

Davide Dionisi ◽

Fernando Congeduti ◽

Gian Luigi Liberti ◽

Francesco Cardillo

Keyword(s):

Water Vapor ◽

National Research Council ◽

Calibration Procedure ◽

System Stability ◽

Calibration Coefficient ◽

Spatial And Temporal Variability ◽

Raman Lidar ◽

Measurement Session ◽

Definition Of ◽

Water Vapor Mixing Ratio

Abstract This paper presents a parametric automatic procedure to calibrate the multichannel Rayleigh–Mie–Raman lidar at the Institute for Atmospheric Science and Climate of the Italian National Research Council (ISAC-CNR) in Tor Vergata, Rome, Italy, using as a reference the operational 0000 UTC soundings at the WMO station 16245 (Pratica di Mare) located about 25 km southwest of the lidar site. The procedure, which is applied to both channels of the system, first identifies portions of the lidar and radiosonde profiles that are assumed to sample the same features of the water vapor profile, taking into account the different time and space sampling. Then, it computes the calibration coefficient with a best-fit procedure, weighted by the instrumental errors of both radiosounding and lidar. The parameters to be set in the procedure are described, and values adopted are discussed. The procedure was applied to a set of 57 sessions of nighttime 1-min-sampling lidar profiles (roughly about 300 h of measurements) covering the whole annual cycle (February 2007–September 2008). A calibration coefficient is computed for each measurement session. The variability of the calibration coefficients (∼10%) over periods with the same instrumental setting is reduced compared to the values obtained with the previously adopted, operator-assisted, and time-consuming calibration procedure. Reduction of variability, as well as the absence of evident trends, gives confidence both on system stability as well as on the developed procedure. Because of the definition of the calibration coefficient and of the different sampling between lidar and radiosonde, a contribution to the variability resulting from aerosol extinction and to the spatial and temporal variability of the water vapor mixing ratio is expected. A preliminary analysis aimed at identifying the contribution to the variability from these factors is presented. The parametric nature of the procedure makes it suitable for application to similar Raman lidar systems.

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Ground-based water vapor raman lidar measurements up to the upper troposphere and lower stratosphere for long-term monitoring

Atmospheric Measurement Techniques ◽

10.5194/amt-5-17-2012 ◽

2012 ◽

Vol 5 (1) ◽

pp. 17-36 ◽

Cited By ~ 43

Author(s):

T. Leblanc ◽

I. S. McDermid ◽

T. D. Walsh

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Lower Troposphere ◽

Atmospheric Composition ◽

Raman Lidar ◽

Upper Troposphere ◽

Lidar Measurements ◽

Development Data ◽

Instrumental Development

Abstract. Recognizing the importance of water vapor in the upper troposphere and lower stratosphere (UTLS) and the scarcity of high-quality, long-term measurements, JPL began the development of a powerful Raman lidar in 2005 to try to meet these needs. This development was endorsed by the Network for the Detection of Atmospheric Composition Change (NDACC) and the validation program for the EOS-Aura satellite. In this paper we review the stages in the instrumental development, data acquisition and analysis, profile retrieval and calibration procedures of the lidar, as well as selected results from three validation campaigns: MOHAVE (Measurements of Humidity in the Atmosphere and Validation Experiments), MOHAVE-II, and MOHAVE 2009. In particular, one critical result from this latest campaign is the very good agreement (well below the reported uncertainties) observed between the lidar and the Cryogenic Frost-Point Hygrometer in the entire lidar range 3–20 km, with a mean bias not exceeding 2% (lidar dry) in the lower troposphere, and 3% (lidar moist) in the UTLS. Ultimately the lidar has demonstrated capability to measure water vapor profiles from ∼1 km above the ground to the lower stratosphere with a precision of 10% or better near 13 km and below, and an estimated accuracy of 5%. Since 2005, nearly 1000 profiles have been routinely measured, and since 2009, the profiles have typically reached 14 km for one-hour integration times and 1.5 km vertical resolution, and can reach 21 km for 6-h integration times using degraded vertical resolutions. These performance figures show that, with our present target of routinely running our lidar two hours per night, 4 nights per week, we can achieve measurements with a precision in the UTLS equivalent to that achieved if launching one CFH per month.

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Tropospheric ozone profiles by DIAL at Maïdo Observatory (Reunion Island): system description, instrumental performance and result comparison with ozone external data set

Atmospheric Measurement Techniques ◽

10.5194/amt-10-3359-2017 ◽

2017 ◽

Vol 10 (9) ◽

pp. 3359-3373 ◽

Cited By ~ 1

Author(s):

Valentin Duflot ◽

Jean-Luc Baray ◽

Guillaume Payen ◽

Nicolas Marquestaut ◽

Francoise Posny ◽

...

Keyword(s):

Current System ◽

Atmospheric Composition ◽

Integration Time ◽

Data Sets ◽

Buffer Gas ◽

Reunion Island ◽

Data Set ◽

Upper Troposphere ◽

Réunion Island ◽

Good Agreement

Abstract. In order to recognize the importance of ozone (O3) in the troposphere and lower stratosphere in the tropics, a DIAL (differential absorption lidar) tropospheric O3 lidar system (LIO3TUR) was developed and installed at the Université de la Réunion campus site (close to the sea) on Reunion Island (southern tropics) in 1998. From 1998 to 2010, it acquired 427 O3 profiles from the low to the upper troposphere and has been central to several studies. In 2012, the system was moved up to the new Maïdo Observatory facility (2160 m a.m.s.l. – metres above mean sea level) where it started operation in February 2013. The current system (LIO3T) configuration generates a 266 nm beam obtained with the fourth harmonic of a Nd:YAG laser sent into a Raman cell filled up with deuterium (using helium as buffer gas), generating the 289 and 316 nm beams to enable the use of the DIAL method for O3 profile measurements. The optimal range for the actual system is 6–19 km a.m.s.l., depending on the instrumental and atmospheric conditions. For a 1 h integration time, vertical resolution varies from 0.7 km at 6 km a.m.s.l. to 1.3 km at 19 km a.m.s.l., and mean uncertainty within the 6–19 km range is between 6 and 13 %. Comparisons with eight electrochemical concentration cell (ECC) sondes simultaneously launched from the Maïdo Observatory show good agreement between data sets with a 6.8 % mean absolute relative difference (D) between 6 and 17 km a.m.s.l. (LIO3T lower than ECC). Comparisons with 37 ECC sondes launched from the nearby Gillot site during the daytime in a ±24 h window around lidar shooting result in a 9.4 % D between 6 and 19 km a.m.s.l. (LIO3T lower than ECC). Comparisons with 11 ground-based Network for Detection of Atmospheric Composition Change (NDACC) Fourier transform infrared (FTIR) spectrometer measurements acquired during the daytime in a ±24 h window around lidar shooting show good agreement between data sets with a D of 11.8 % for the 8.5–16 km partial column (LIO3T higher than FTIR), and comparisons with 39 simultaneous Infrared Atmospheric Sounding Interferometer (IASI) observations over Reunion Island show good agreement between data sets with a D of 11.3 % for the 6–16 km partial column (LIO3T higher than IASI). ECC, LIO3TUR and LIO3T O3 monthly climatologies all exhibit the same range of values and patterns. In particular, the Southern Hemisphere biomass burning seasonal enhancement and the ozonopause altitude decrease in late austral winter–spring, as well as the sign of deep convection bringing boundary layer O3-poor air masses up to the middle–upper troposphere in late austral summer, are clearly visible in all data sets.

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Meteorological implementation issues in chemistry and transport models

Atmospheric Chemistry and Physics ◽

10.5194/acp-6-2895-2006 ◽

2006 ◽

Vol 6 (10) ◽

pp. 2895-2910 ◽

Cited By ~ 30

Author(s):

S. E. Strahan ◽

B. C. Polansky

Keyword(s):

Climate Models ◽

Lower Stratosphere ◽

Model Performance ◽

Transport Processes ◽

The Arctic ◽

Integration Time ◽

Vertical Resolution ◽

Transport Models ◽

Sensitivity Experiments ◽

The Antarctic

Abstract. Offline chemistry and transport models (CTMs) are versatile tools for studying composition and climate issues requiring multi-decadal simulations. They are computationally fast compared to coupled chemistry climate models, making them well-suited for integrating sensitivity experiments necessary for understanding model performance and interpreting results. The archived meteorological fields used by CTMs can be implemented with lower horizontal or vertical resolution than the original meteorological fields in order to shorten integration time, but the effects of these shortcuts on transport processes must be understood if the CTM is to have credibility. In this paper we present a series of sensitivity experiments on a CTM using the Lin and Rood advection scheme, each differing from another by a single feature of the wind field implementation. Transport effects arising from changes in resolution and model lid height are evaluated using process-oriented diagnostics that intercompare CH4, O3, and age tracer carried in the simulations. Some of the diagnostics used are derived from observations and are shown as a reality check for the model. Processes evaluated include tropical ascent, tropical-midlatitude exchange, poleward circulation in the upper stratosphere, and the development of the Antarctic vortex. We find that faithful representation of stratospheric transport in this CTM is possible with a full mesosphere, ~1 km resolution in the lower stratosphere, and relatively low vertical resolution (>4 km spacing) in the middle stratosphere and above, but lowering the lid from the upper to lower mesosphere leads to less realistic constituent distributions in the upper stratosphere. Ultimately, this affects the polar lower stratosphere, but the effects are greater for the Antarctic than the Arctic. The fidelity of lower stratospheric transport requires realistic tropical and high latitude mixing barriers which are produced at 2°×2.5°, but not lower resolution. At 2°×2.5° resolution, the CTM produces a vortex capable of isolating perturbed chemistry (e.g. high Cly and low NOy) required for simulating polar ozone loss.

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Ground-based water vapor Raman lidar measurements up to the upper troposphere and lower stratosphere – Part 2: Data analysis and calibration for long-term monitoring

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-5111-2011 ◽

2011 ◽

Vol 4 (4) ◽

pp. 5111-5145 ◽

Cited By ~ 2

Author(s):

T. Leblanc ◽

I. S. McDermid ◽

T. D. Walsh

Keyword(s):

Water Vapor ◽

Data Analysis ◽

Lower Stratosphere ◽

Companion Paper ◽

Atmospheric Composition ◽

Raman Lidar ◽

Upper Troposphere ◽

Current Configuration ◽

Instrumental Development

Abstract. The well-recognized, key role of water vapor in the upper troposphere and lower stratosphere (UT/LS) and the scarcity of high-quality, long-term measurements triggered the development by JPL of a powerful Raman lidar to try to meet these needs. This development started in 2005 and was endorsed by the Network for the Detection of Atmospheric Composition Change (NDACC) and the validation program for the EOS-Aura satellite. In this paper we review all the stages of the instrument data acquisition, data analysis, profile retrieval and calibration procedures, as well as selected results from the recent validation campaign MOHAVE-2009 (Measurements of Humidity in the Atmosphere and Validation Experiments). The stages in the instrumental development and the conclusions from three validation campaigns (including MOHAVE-2009) are presented in details in a companion paper (McDermid et al., 2011). In its current configuration, the lidar demonstrated capability to measure water vapor profiles from ~1 km above the ground to the lower stratosphere with an estimated accuracy of 5 %. Since 2005, nearly 1000 profiles have been routinely measured with a precision of 10 % or better near 13 km. Since 2009, the profiles have typically reached 14 km for 1 h integration times and 1.5 km vertical resolution, and can reach 21 km for 6-h integration times using degraded vertical resolutions.

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Study and mitigation of calibration error sources in a water vapor Raman lidar

10.5194/amt-2016-187 ◽

2016 ◽

Author(s):

Leslie David ◽

Olivier Bock ◽

Christian Thom ◽

Pierre Bosser ◽

Jacques Pelon

Keyword(s):

Water Vapor ◽

Standard Deviation ◽

Detection System ◽

Temporal Integration ◽

Experimental Tests ◽

Calibration Coefficient ◽

Calibration Error ◽

Path Delay ◽

Raman Lidar ◽

Alignment Procedure

Abstract. A detailed investigation of calibration variation sources in the instrumental part of the detection-fibered, water vapor Raman lidar, Rameau, is presented. This lidar has been developed by the Institut National de l'Information Géographique et Forestière (IGN) together with the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) and aims at calibrating GNSS wet delay signals and thus at improving vertical positioning. Several measurements campaigns enabled to validate the capacity of the instrument to retrieve high accuracy water vapor measurements. However, in order to insure a good stability, regular calibrations were necessary and led us to seek for instability sources in each sub-system of the instrument. The calibration variations are shown to be induced by fiber mode fluctuations and spatial non-uniformity of the photomultiplier photocathodes, and are responsible for significant calibration coefficient drifts. Such drifts are incompatible with both the long term stability required for applications such as climatology and the absolute accuracy needed for wet path delay correction of GNSS signals. We show by means of experimental tests that variation sources can be mitigated by means of an optimization and re-design of the optical detection system, a careful alignment procedure, and the operational monitoring of the system with dedicated measurements. In order to validate the modifications of the system and the new procedure, measurements were repeated over a period of 5 months. The detection subsystem stability was monitored from lidar profiles measured with a unique nitrogen filter used for detecting the signal in the two measurement channels. Compared to the previous campaign (Development of Methodologies for Water Vapor Measurement, Demevap), we observe an improvement in the stability of the system based on the nitrogen measurements which showed a drift of less than 3 % per month and a standard deviation of about 3 % during the campaign. The water vapor calibration coefficients were determined from capacitive humidity sensor measurements and from GPS zenith wet delays measurements. They show a similar small drift of 3 % per month and a standard deviation of ~ 6 %. Thanks to the N2 measurements, the drift can be completely removed. Lower standard deviation can be achieved by increasing the Signal to Noise Ratio and/or spatial and temporal integration window.

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Ground-based water vapor Raman lidar measurements up to the upper troposphere and lower stratosphere – Part 1: Instrument development, optimization, and validation

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-5079-2011 ◽

2011 ◽

Vol 4 (4) ◽

pp. 5079-5109 ◽

Cited By ~ 4

Author(s):

I. S. McDermid ◽

T. Leblanc ◽

T. D. Walsh

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Companion Paper ◽

Atmospheric Composition ◽

Raman Lidar ◽

Upper Troposphere ◽

Lidar Measurements ◽

Instrumental Development ◽

Validation Experiments

Abstract. Recognizing the importance of water vapor in the upper troposphere and lower stratosphere (UT/LS) and the scarcity of high-quality, long-term measurements, JPL began the development of a powerful Raman lidar in 2005 to try to meet these needs. This development was endorsed by the Network for the Detection of Atmospheric Composition Change (NDACC) and the validation program for the EOS-Aura satellite. In this paper we review the stages in the instrumental development of the lidar and the conclusions from three validation campaigns: MOHAVE, MOHAVE-II, and MOHAVE 2009 (Measurements of Humidity in the Atmosphere and Validation Experiments). The data analysis, profile retrieval and calibration procedures, as well as additional results from MOHAVE-2009 are presented in detail in a companion paper (Leblanc et al., 2011a). Ultimately the lidar has demonstrated capability to measure water vapor profiles from ~1 km above the ground to the lower stratosphere, reaching 14 km for 1-h integrated profiles and 21 km for 6-h integrated profiles, with a precision of 10 % or better near 13 km and below, and an estimated accuracy of 5 %.

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