Study of the statistics of water vapor mixing ratio determined from Raman lidar measurements

2007 ◽  
Vol 46 (33) ◽  
pp. 8170 ◽  
Author(s):  
Pierre Bosser ◽  
Olivier Bock ◽  
Christian Thom ◽  
Jacques Pelon
Keyword(s):  
Water Vapor ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Lidar Measurements ◽  
Water Vapor Mixing Ratio

scholarly journals Aircraft Evaluation of Ground-Based Raman Lidar Water Vapor Turbulence Profiles in Convective Mixed Layers

2014 ◽  
Vol 31 (5) ◽  
pp. 1078-1088 ◽  
Author(s):  
D. D. Turner ◽  
R. A. Ferrare ◽  
V. Wulfmeyer ◽  
A. J. Scarino
Keyword(s):  
Water Vapor ◽  
Great Plains ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Southern Great Plains ◽  
Lidar Measurements ◽  
Atmospheric Radiation Measurement ◽  
Convective Mixed Layer ◽  
Water Vapor Mixing Ratio ◽  
Mixed Layers

AbstractHigh temporal and vertical resolution water vapor measurements by Raman and differential absorption lidar systems have been used to characterize the turbulent fluctuations in the water vapor mixing ratio field in convective mixed layers. Since daytime Raman lidar measurements are inherently noisy (due to solar background and weak signal strengths), the analysis approach needs to quantify and remove the contribution of the instrument noise in order to derive the desired atmospheric water vapor mixing ratio variance and skewness profiles. This is done using the approach outlined by Lenschow et al.; however, an intercomparison with in situ observations was not performed.Water vapor measurements were made by a diode laser hygrometer flown on a Twin Otter aircraft during the Routine Atmospheric Radiation Measurement (ARM) Program Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign over the ARM Southern Great Plains (SGP) site in 2009. Two days with Twin Otter flights were identified where the convective mixed layer was quasi stationary, and hence the 10-s, 75-m data from the SGP Raman lidar could be analyzed to provide profiles of water vapor mixing ratio variance and skewness. Airborne water vapor observations measured during level flight legs were compared to the Raman lidar data, demonstrating good agreement in both variance and skewness. The results also illustrate the challenges of comparing a point sensor making measurements over time to a moving platform making similar measurements horizontally.

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

2015 ◽  
Vol 15 (5) ◽  
pp. 2867-2881 ◽  
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.

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

2017 ◽  
Vol 10 (11) ◽  
pp. 4303-4316 ◽  
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.

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

2019 ◽  
Vol 11 (6) ◽  
pp. 616 ◽  
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.

scholarly journals Water Vapor Mixing Ratio Distribution Inversion by Raman Lidar in Beijing

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.

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

2014 ◽  
Vol 14 (18) ◽  
pp. 9583-9596 ◽  
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.

scholarly journals The mobile Water vapor Aerosol Raman LIdar and its implication in the framework of the HyMeX and ChArMEx programs: application to a dust transport process

2014 ◽  
Vol 7 (6) ◽  
pp. 1629-1647 ◽  
Author(s):  
P. Chazette ◽  
F. Marnas ◽  
J. Totems
Keyword(s):  
Water Vapor ◽  
Raman Lidar ◽  
Scientific Application ◽  
Dust Transport ◽  
New Device ◽  
Dust Aerosols ◽  
Lidar Measurements ◽  
Lidar Ratio ◽  
Observation Tools ◽  
Water Vapor Mixing Ratio

Abstract. The increasing importance of the coupling of water and aerosol cycles in environmental applications requires observation tools that allow simultaneous measurements of these two fundamental processes for climatological and meteorological studies. For this purpose, a new mobile Raman lidar, WALI (Water vapor and Aerosol LIdar), has been developed and implemented within the framework of the international HyMeX and ChArMEx programs. This paper presents the key properties of this new device and its first applications to scientific studies. The lidar uses an eye-safe emission in the ultraviolet range at 354.7 nm and a set of compact refractive receiving telescopes. Cross-comparisons between rawinsoundings performed from balloon or aircraft and lidar measurements have shown a good agreement in the derived water vapor mixing ratio (WVMR). The discrepancies are generally less than 0.5 g kg−1 and therefore within the error bars of the respective instruments. A detailed study of the uncertainty of the WVMR retrieval was conducted and shows values between 7 and 11%, which is largely constrained by the quality of the lidar calibration. It also proves that the lidar is able to measure the WVMR during daytime over a range of about 1 km. In addition the WALI system provides measurements of aerosol optical properties such as the lidar ratio (LR) or the particulate depolarization ratio (PDR). An important example of scientific application addressing the main objectives of the HyMeX and ChArMEx programs is then presented, following an event of desert dust aerosols over the Balearic Islands in October 2012. This dust intrusion may have had a significant impact on the intense precipitations that occurred over southwestern France and the Spanish Mediterranean coasts. During this event, the LR and PDR values obtained are in the ranges of ~45–63 ± 6 and 0.10–0.19 ± 0.01 sr, respectively, which is representative of dust aerosols. The dust layers are also shown to be associated with significant WVMR, i.e., between 4 and 6.7 g kg−1.

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

2007 ◽  
Vol 24 (8) ◽  
pp. 1377-1388 ◽  
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.

scholarly journals Notes on Temperature-Dependent Lidar Equations

2009 ◽  
Vol 26 (6) ◽  
pp. 1021-1039 ◽  
Author(s):  
Mariana Adam
Keyword(s):  
Water Vapor ◽  
Cross Sections ◽  
Differential Cross ◽  
Interference Filter ◽  
Transmission Efficiency ◽  
Mixing Ratio ◽  
Temperature Dependent ◽  
Howard University ◽  
Lidar Measurements ◽  
Water Vapor Mixing Ratio

Abstract The temperature dependence of molecular backscatter coefficients must be taken into account when narrowband interference filters are used in lidar measurements. Thus, the spectral backscatter differential cross section of the molecules involved in the backscattering of the radiation has to be calculated or measured and the interference filter transmission efficiency must be known. The present paper is intended to describe in an easily reproducible manner the procedure involved in calculating the temperature-dependent functions introduced in the lidar equations, including the computation of the differential cross sections for air, nitrogen, and water vapor. The temperature-dependent functions are computed for the Howard University Raman lidar (HURL). The interference filter efficiencies are given by the manufacturer. Error estimates in water vapor mixing ratio and aerosol backscatter ratio involved when temperature-dependent functions are omitted are given for measurements taken with HURL. For the data analyzed, it is found that errors in estimating the water vapor mixing ratio are up to ∼6% while in estimating the aerosol backscattering ratio the errors are up to ∼1.3% in the planetary boundary layer and ∼2.2% in cirrus clouds. Theoretical computations are performed to determine temperature-dependent functions for nitrogen, water vapor, and their ratio, using simulated Gaussian-shaped filters. The goal is to find the optimum combination of different filters that will determine the ratio profiles of the temperature-dependent functions that are either the closest to unity or the least variable. The analyses reveal that quite constant profiles can be obtained for several combinations of the filters.

scholarly journals The mobile Water vapor Aerosol Raman LIdar and its implication in the frame of the HyMeX and ChArMEx programs: application to a dust transport process

2013 ◽  
Vol 6 (6) ◽  
pp. 10653-10698 ◽  
Author(s):  
P. Chazette ◽  
F. Marnas ◽  
J. Totems
Keyword(s):  
Water Vapor ◽  
Ultra Violet ◽  
Raman Lidar ◽  
Scientific Application ◽  
Dust Transport ◽  
New Device ◽  
Dust Aerosols ◽  
Lidar Measurements ◽  
Observation Tools ◽  
Water Vapor Mixing Ratio

Abstract. The increasing importance of the coupling of water and aerosol cycles in environmental applications requires observation tools which allow simultaneous measurements of these two fundamental processes for climatological and meteorological studies. In this purpose, a new mobile Raman lidar, WALI (Water vapor and Aerosol LIDAR), has been developed and implemented within the framework of the international HyMeX/IODA-MED and ChArMEx programs. This paper presents the key properties of this new device and its first applications to scientific studies. The lidar uses an eye-safe emission in the ultra-violet range at 354.7 nm and a set of compact refractive receptors. Cross-comparisons between rawindsoundings performed from balloon or aircraft and lidar measurements have shown a good agreement in the derived water vapor mixing ratio (WVMR). The discrepancies are generally less than 0.5 g kg−1 and therefore within the error bars of the instruments. A detailed study of the uncertainties was conducted and shows a 7 to 11% accuracy of the WVMR retrieval, which is largely constrained by the quality of the calibration. It also proves that the lidar is able to measure the WVMR during the day over a range of about 1 km. The WALI system otherwise provides measurements of aerosol optical properties such as the lidar ratio (LR) or the particulate depolarization ratio (PDR). An important example of scientific application addressing the main objectives of the HyMeX and ChArMEx programs is then presented, following an event of desert dust aerosols over the Balearic Islands. This dust intrusion may have had a significant impact on the intense precipitations that occurred over southwestern France and the Spanish Mediterranean coasts. During this event, the LR and PDR values obtained are in the ranges of ~ 45–63 ± 6 sr and 0.1–0.19 ± 0.01, respectively, which is representative of dust aerosols. The dust layers are also shown to be associated with significant WVMR, i.e. between 4 and 6.7 g kg−1.

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