Lamp mapping technique for independent determination of the water vapor mixing ratio calibration factor for a Raman lidar system

Abstract. We have investigated calibration variations in the Rameau water vapor Raman lidar. This lidar system was developed by the Institut National de l'Information Géographique et Forestière (IGN) together with the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). It aims at calibrating Global Navigation Satellite System (GNSS) measurements for tropospheric wet delays and sounding the water vapor variability in the lower troposphere. The Rameau system demonstrated good capacity in retrieving water vapor mixing ratio (WVMR) profiles accurately in several campaigns. However, systematic short-term and long-term variations in the lidar calibration factor pointed to persistent instabilities. A careful testing of each subsystem independently revealed that these instabilities are mainly induced by mode fluctuations in the optic fiber used to couple the telescope to the detection subsystem and by the spatial nonuniformity of the photomultiplier photocathodes. Laboratory tests that replicate and quantify these instability sources are presented. A redesign of the detection subsystem is presented, which, combined with careful alignment procedures, is shown to significantly reduce the instabilities. Outdoor measurements were performed over a period of 5 months to check the stability of the modified lidar system. The calibration changes in the detection subsystem were monitored with lidar profile measurements using a common nitrogen filter in both Raman channels. A short-term stability of 2–3 % and a long-term drift of 2–3 % per month are demonstrated. Compared to the earlier Development of Methodologies for Water Vapour Measurement (DEMEVAP) campaign, this is a 3-fold improvement in the long-term stability of the detection subsystem. The overall water vapor calibration factors were determined and monitored with capacitive humidity sensor measurements and with GPS zenith wet delay (ZWD) data. The changes in the water vapor calibration factors are shown to be fairly consistent with the changes in the nitrogen calibration factors. The nitrogen calibration results can be used to correct the overall calibration factors without the need for additional water vapor measurements to within 1 % per month.

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Diffuse sunlight based calibration of the water vapor channel in the upc raman lidar

EPJ Web of Conferences ◽

10.1051/epjconf/201817605035 ◽

2018 ◽

Vol 176 ◽

pp. 05035

Author(s):

Constantino Muñoz-Porcar ◽

Adolfo Comeron ◽

Michaël Sicard ◽

Ruben Barragan ◽

David Garcia-Vizcaino ◽

...

Keyword(s):

Water Vapor ◽

Raman Scattering ◽

Calibration Factor ◽

Raman Lidar ◽

Lidar System ◽

System Parameters ◽

Vapor Channel ◽

Technical University

A method for determining the calibration factor of the water vapor channel of a Raman lidar, based on zenith measurements of diffuse sunlight and on assumptions regarding some system parameters and Raman scattering models, has been applied to the lidar system of Universitat Politècnica de Catalunya (UPC; Technical University of Catalonia, Spain). Results will be analyzed in terms of stability and comparison with typical methods relying on simultaneous radiosonde measurements.

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Temperature profiling of the atmospheric boundary layer with rotational Raman lidar during the HD(CP)<sup>2</sup> Observational Prototype Experiment

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-2867-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 2867-2881 ◽

Cited By ~ 44

Author(s):

E. Hammann ◽

A. Behrendt ◽

F. Le Mounier ◽

V. Wulfmeyer

Keyword(s):

Boundary Layer ◽

Water Vapor ◽

Temperature Gradient ◽

Atmospheric Boundary Layer ◽

Average Power ◽

Mixing Ratio ◽

Raman Lidar ◽

Backscatter Signal ◽

Low Background ◽

Water Vapor Mixing Ratio

Abstract. The temperature measurements of the rotational Raman lidar of the University of Hohenheim (UHOH RRL) during the High Definition of Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observation Prototype Experiment (HOPE) in April and May 2013 are discussed. The lidar consists of a frequency-tripled Nd:YAG laser at 355 nm with 10 W average power at 50 Hz, a two-mirror scanner, a 40 cm receiving telescope, and a highly efficient polychromator with cascading interference filters for separating four signals: the elastic backscatter signal, two rotational Raman signals with different temperature dependence, and the vibrational Raman signal of water vapor. The main measurement variable of the UHOH RRL is temperature. For the HOPE campaign, the lidar receiver was optimized for high and low background levels, with a novel switch for the passband of the second rotational Raman channel. The instrument delivers atmospheric profiles of water vapor mixing ratio as well as particle backscatter coefficient and particle extinction coefficient as further products. As examples for the measurement performance, measurements of the temperature gradient and water vapor mixing ratio revealing the development of the atmospheric boundary layer within 25 h are presented. As expected from simulations, a reduction of the measurement uncertainty of 70% during nighttime was achieved with the new low-background setting. A two-mirror scanner allows for measurements in different directions. When pointing the scanner to low elevation, measurements close to the ground become possible which are otherwise impossible due to the non-total overlap of laser beam and receiving telescope field of view in the near range. An example of a low-level temperature measurement is presented which resolves the temperature gradient at the top of the stable nighttime boundary layer 100 m above the ground.

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Profiling water vapor mixing ratios in Finland by means of a Raman lidar, a satellite and a model

Atmospheric Measurement Techniques ◽

10.5194/amt-10-4303-2017 ◽

2017 ◽

Vol 10 (11) ◽

pp. 4303-4316 ◽

Cited By ~ 7

Author(s):

Maria Filioglou ◽

Anna Nikandrova ◽

Sami Niemelä ◽

Holger Baars ◽

Tero Mielonen ◽

...

Keyword(s):

Water Vapor ◽

Weather Prediction ◽

Limited Area ◽

Mixing Ratio ◽

Atmospheric Conditions ◽

Raman Lidar ◽

Mixing Ratios ◽

Seasonal Analysis ◽

Relative Errors ◽

Water Vapor Mixing Ratio

Abstract. We present tropospheric water vapor profiles measured with a Raman lidar during three field campaigns held in Finland. Co-located radio soundings are available throughout the period for the calibration of the lidar signals. We investigate the possibility of calibrating the lidar water vapor profiles in the absence of co-existing on-site soundings using water vapor profiles from the combined Advanced InfraRed Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU) satellite product; the Aire Limitée Adaptation dynamique Développement INternational and High Resolution Limited Area Model (ALADIN/HIRLAM) numerical weather prediction (NWP) system, and the nearest radio sounding station located 100 km away from the lidar site (only for the permanent location of the lidar). The uncertainties of the calibration factor derived from the soundings, the satellite and the model data are  < 2.8, 7.4 and 3.9 %, respectively. We also include water vapor mixing ratio intercomparisons between the radio soundings and the various instruments/model for the period of the campaigns. A good agreement is observed for all comparisons with relative errors that do not exceed 50 % up to 8 km altitude in most cases. A 4-year seasonal analysis of vertical water vapor is also presented for the Kuopio site in Finland. During winter months, the air in Kuopio is dry (1.15±0.40 g kg−1); during summer it is wet (5.54±1.02 g kg−1); and at other times, the air is in an intermediate state. These are averaged values over the lowest 2 km in the atmosphere. Above that height a quick decrease in water vapor mixing ratios is observed, except during summer months where favorable atmospheric conditions enable higher mixing ratio values at higher altitudes. Lastly, the seasonal change in disagreement between the lidar and the model has been studied. The analysis showed that, on average, the model underestimates water vapor mixing ratios at high altitudes during spring and summer.

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Water Vapor Calibration: Using a Raman Lidar and Radiosoundings to Obtain Highly Resolved Water Vapor Profiles

Remote Sensing ◽

10.3390/rs11060616 ◽

2019 ◽

Vol 11 (6) ◽

pp. 616 ◽

Cited By ~ 3

Author(s):

Birte Kulla ◽

Christoph Ritter

Keyword(s):

Water Vapor ◽

Correlation Coefficients ◽

Small Scale ◽

Mixing Ratio ◽

Raman Lidar ◽

Independent Information ◽

European Arctic ◽

Water Vapor Mixing Ratio ◽

A Site ◽

Individual Profiles

We revised the calibration of a water vapor Raman lidar by co-located radiosoundings for a site in the high European Arctic. For this purpose, we defined robust criteria for a valid calibration. One of these criteria is the logarithm of the water vapor mixing ratio between the sonde and the lidar. With an error analysis, we showed that for our site correlations smaller than 0.95 could be explained neither by noise in the lidar nor by wrong assumptions concerning the aerosol or Rayleigh extinction. However, highly variable correlation coefficients between sonde and consecutive lidar profiles were found, suggesting that small scale variability of the humidity was our largest source of error. Therefore, not all co-located radiosoundings are useful for lidar calibration. As we assumed these changes to be non-systematic, averaging over several independent measurements increased the calibration’s quality. The calibration of the water vapor measurements from the lidar for individual profiles varied by less than ±5%. The seasonal median, used for calibration in this study, was stable and reliable (confidence ±1% for the season with most calibration profiles). Thus, the water vapor mixing ratio profiles from the Koldewey Aerosol Raman Lidar (KARL) are very accurate. They show high temporal variability up to 4 km altitude and, therefore, provide additional, independent information to the radiosonde.

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Water Vapor Mixing Ratio Distribution Inversion by Raman Lidar in Beijing

EPJ Web of Conferences ◽

10.1051/epjconf/202023706020 ◽

2020 ◽

Vol 237 ◽

pp. 06020

Author(s):

SiQi Yu ◽

Dong Liu ◽

JiWei Xu ◽

ZhenZhu Wang ◽

DeCheng Wu ◽

...

Keyword(s):

Water Vapor ◽

Radiosonde Data ◽

Mixing Ratio ◽

Raman Lidar ◽

Ratio Distribution ◽

Water Vapor Mixing Ratio ◽

Detection Instrument ◽

Active Detection ◽

The Vertical Distribution ◽

Good Agreement

Water Aerosol Raman Lidar-II is an active detection instrument with high temporal and spatial resolution at Nanjiao observation station, and that could continuous water vapor mixing ratio (WVMR) measurements. WVMR profiles inversion from lidar data and water ratio retrieved from radiosonde data are in good agreement. The statistical results of the vertical distribution of WVMR indicate that WVMR seasonal mean distribution is consistent with precipitation. In addition, WVMR in Nanjiao station is related to total cloud cover.

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Comparison of IASI water vapor retrieval with H<sub>2</sub>O-Raman lidar in the framework of the Mediterranean HyMeX and ChArMEx programs

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-9583-2014 ◽

2014 ◽

Vol 14 (18) ◽

pp. 9583-9596 ◽

Cited By ~ 14

Author(s):

P. Chazette ◽

F. Marnas ◽

J. Totems ◽

X. Shang

Keyword(s):

Water Vapor ◽

Root Mean Square ◽

Vertical Profiles ◽

Mean Square ◽

Mixing Ratio ◽

Raman Lidar ◽

Operational Level ◽

The Mediterranean ◽

Water Vapor Mixing Ratio ◽

Level 2

Abstract. The Infrared Atmospheric Sounding Interferometer (IASI) is a new generation spaceborne passive sensor mainly dedicated to meteorological applications. Operational Level-2 products have been available via the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) for several years. In particular, vertical profiles of water vapor measurements are retrieved from infrared radiances at the global scale. Nevertheless, the robustness of such products has to be checked because only a few validations have been reported. For this purpose, the field experiments that were held during the HyMeX and ChArMEx international programs are a very good opportunity. A H2O-Raman lidar was deployed on the Balearic island of Menorca and operated continuously for ~ 6 and ~ 3 weeks during fall 2012 (Hydrological cycle in the Mediterranean eXperiment – HyMeX) and summer 2013 (Chemistry–Aerosol Mediterranean Experiment – ChArMEx), respectively. It measured simultaneously the water vapor mixing ratio and aerosol optical properties. This article does not aim to describe the IASI operational H2O inversion algorithm, but to compare the vertical profiles derived from IASI onboard (meteorological operational) MetOp-A and the ground-based lidar measurements to assess the reliability of the IASI operational product for the water vapor retrieval in both the lower and middle troposphere. The links between water vapor contents and both the aerosol vertical profiles and the air mass origins are also studied. About 30 simultaneous observations, performed during nighttime in cloud free conditions, have been considered. For altitudes ranging from 2 to 7 km, root mean square errors (correlation) of ~ 0.5 g kg−1 (~ 0.77) and ~ 1.1 g kg−1 (~ 0.72) are derived between the operational IASI product and the available lidar profiles during HyMeX and ChArMEx, respectively. The values of both root mean square error and correlation are meaningful and show that the operational Level-2 product of the IASI-derived vertical water vapor mixing ratio can be considered for meteorological and climatic applications, at least in the framework of field campaigns.

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Demonstration Measurements of Water Vapor, Cirrus Clouds, and Carbon Dioxide Using a High-Performance Raman Lidar

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech2058.1 ◽

2007 ◽

Vol 24 (8) ◽

pp. 1377-1388 ◽

Cited By ~ 27

Author(s):

David N. Whiteman ◽

Kurt Rush ◽

Igor Veselovskii ◽

Martin Cadirola ◽

Joseph Comer ◽

...

Keyword(s):

Carbon Dioxide ◽

Boundary Layer ◽

Water Vapor ◽

High Performance ◽

Cirrus Clouds ◽

Mixing Ratio ◽

Raman Lidar ◽

Cloud Optical Depth ◽

Temporal And Spatial ◽

Water Vapor Mixing Ratio

Abstract Profile measurements of atmospheric water vapor, cirrus clouds, and carbon dioxide using the Raman Airborne Spectroscopic lidar (RASL) during ground-based, upward-looking tests are presented here. These measurements improve upon any previously demonstrated using Raman lidar. Daytime boundary layer profiling of water vapor mixing ratio up to an altitude of approximately 4 km under moist, midsummer conditions is performed with less than 5% random error using temporal and spatial resolution of 2 min and 60–210 m, respectively. Daytime cirrus cloud optical depth and extinction-to-backscatter ratio measurements are made using a 1-min average. The potential to simultaneously profile carbon dioxide and water vapor mixing ratio through the boundary layer and extending into the free troposphere during the nighttime is also demonstrated.

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Comparing Water Vapor Mixing Ratio Profiles and Cloud Vertical Structure from Multiwavelength Raman Lidar Retrievals and Radiosounding Measurements

EPJ Web of Conferences ◽

10.1051/epjconf/201611924005 ◽

2016 ◽

Vol 119 ◽

pp. 24005

Author(s):

Montserrat Costa-Surós ◽

Iwona S. Stachlewska ◽

Krzysztof Markowicz

Keyword(s):

Water Vapor ◽

Vertical Structure ◽

Mixing Ratio ◽

Raman Lidar ◽

Water Vapor Mixing Ratio

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Water Vapor Measurements by Howard University Raman Lidar during the WAVES 2006 Campaign

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2009jtecha1331.1 ◽

2010 ◽

Vol 27 (1) ◽

pp. 42-60 ◽

Cited By ~ 15

Author(s):

M. Adam ◽

B. B. Demoz ◽

D. D. Venable ◽

E. Joseph ◽

R. Connell ◽

...

Keyword(s):

Water Vapor ◽

Relative Humidity ◽

Relative Difference ◽

Mixing Ratio ◽

State Variables ◽

Raman Lidar ◽

Ensemble Averaging ◽

Howard University ◽

Validation Experiment ◽

Water Vapor Mixing Ratio

Abstract Water vapor mixing ratio retrieval using the Howard University Raman lidar is presented with emphasis on three aspects: (i) comparison of the lidar with collocated radiosondes and Raman lidar, (ii) investigation of the relationship between atmospheric state variables and the relative performance of the lidar and sonde (in particular, their poor agreement), and (iii) comparison with satellite-based measurements. The measurements were acquired during the Water Vapor Validation Experiment Sondes/Satellites 2006 campaign. Ensemble averaging of water vapor mixing ratio data from 10 nighttime comparisons with Vaisala RS92 radiosondes shows, on average, an agreement within ±10%, up to ∼8 km. A similar analysis of lidar-to-lidar data of over 700 profiles revealed an agreement to within 20% over the first 7 km (10% below 4 km). A grid analysis, defined in the temperature–relative humidity space, was developed to characterize the lidar–radiosonde agreement and quantitatively localizes regions of strong and weak correlations as a function of altitude, temperature, or relative humidity. Three main regions of weak correlation emerge: (i) regions of low relative humidity and low temperature, (ii) regions of moderate relative humidity at low temperatures, and (iii) regions of low relative humidity at moderate temperatures. Comparison of Atmospheric Infrared Sounder and Tropospheric Emission Sounder satellite retrievals of moisture with those of Howard University Raman lidar showed a general agreement in the trend, but the satellites miss details in atmospheric structure because of their low resolution. A relative difference of about ±20% is usually found between lidar and satellite measurements for the coincidences available.

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