Comparisons of Raman Lidar Measurements of Tropospheric Water Vapor Profiles with Radiosondes, Hygrometers on the Meteorological Observation Tower, and GPS at Tsukuba, Japan

Sakai, Tetsu; Nagai, Tomohiro; Nakazato, Masahisa; Matsumura, Takatsugu; Orikasa, Narihiro; Shoji, Yasuhiro

doi:10.1175/jtech2056.1

Cited by 28 publications

(21 citation statements)

References 38 publications

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“…The means and standard deviations amount to 15.2 ± 0.4 and 12.4 ± 0.6 g kg −1 before and after the major rearrangement in the optical setup on 15 April 2013, 10:06 UTC, respectively. These values correspond to relative errors of 3 and 5 % and are comparable to studies of Mona et al (2007) and Sakai et al (2007). Without any strong rearrangements in the optical setup, the calibration factor is very stable, enabling an operational applicability.…”

Section: Stability Of the Calibration Factorsupporting

confidence: 75%

Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

et al. 2015

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Abstract. In this paper, we present a method to derive water vapour profiles from Raman lidar measurements calibrated by the integrated water vapour (IWV) from a collocated microwave radiometer during the intense observation campaign HOPE in the frame of the HD(CP) 2 initiative. The simultaneous observation of a microwave radiometer and a Raman lidar allowed an operational and continuous measurement of water vapour profiles also during cloudy conditions. The calibration method provides results which are in a good agreement with conventional methods based on radiosondes. The calibration factor derived from the proposed IWV method is very stable with a relative uncertainty of 5 %. This stability allows for the calibration of the lidar even in the presence of clouds using the calibration factor determined during the most recent clear sky interval. Based on the application of this approach, it is possible to retrieve water vapour profiles during all non-precipitating conditions. A statistical analysis shows a good agreement between the lidar measurements and collocated radiosondes. The relative biases amount to less than 6.7 % below 2 km.

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Section: Stability Of the Calibration Factorsupporting

confidence: 75%

Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

et al. 2015

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“…The vertical distribution of water vapor is also monitored using a water vapor Raman lidar technique (e.g., Sakai et al 2003). The receiver system to measure the water vapor Raman backscatter signal at 660 nm is added to an HSRL onboard the R/V Mirai (Nishizawa et al 2012).…”

Section: A Cindy/dynamo Observationsmentioning

confidence: 99%

“…Figure 1c shows the mean and standard deviation of the relative difference between the HSRL and sonde water vapor mixing ratios. Following Sakai et al (2007), this relative difference is defined as (HSRL 2 sonde)/[(HSRL 1 sonde)/2] and is expressed as a percentage. The mean relative difference is less than 15% up to approximately 3.5 km.…”

Section: A Cindy/dynamo Observationsmentioning

confidence: 99%

Observation of Moisture Tendencies Related to Shallow Convection

Yoneyama

Katsumata

Nishizawa

et al. 2015

Journal of the Atmospheric Sciences

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Tropospheric moisture is a key factor controlling the global climate and its variability. For instance, moistening of the lower troposphere is necessary to trigger the convective phase of a Madden-Julian oscillation (MJO). However, the relative importance of the processes controlling this moistening has yet to be quantified. Among these processes, the importance of the moistening by shallow convection is still debated. The authors use high-frequency observations of humidity and convection from the Research Vessel (R/V) Mirai that was located in the Indian Ocean ITCZ during the Cooperative Indian Ocean Experiment on Intraseasonal Variability/ Dynamics of the MJO (CINDY/DYNAMO) campaign. This study is an initial attempt to directly link shallow convection to moisture variations within the lowest 4 km of the atmosphere from the convective scale to the mesoscale. Within a few tens of minutes and near shallow convection occurrences, moisture anomalies of 0.25-0.5 g kg 21 that correspond to tendencies on the order of 10-20 g kg 21 day 21 between 1 and 4 km are observed and are attributed to shallow convective clouds. On the scale of a few hours, shallow convection is associated with anomalies of 0.5-1 g kg 21 that correspond to tendencies on the order of 1-4 g kg 21 day 21 according to two independent datasets: lidar and soundings. This can be interpreted as the resultant mesoscale effect of the population of shallow convective clouds. Large-scale advective tendencies can be stronger than the moistening by shallow convection; however, the latter is a steady moisture supply whose importance can increase with the time scale. This evaluation of the moistening tendency related to shallow convection is ultimately important to develop and constrain numerical models.

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“…Over the past decades, Raman lidar capabilities have been successively upgraded with larger commercial laser power availability and improvements on the configuration of the systems (Sakai et al, 2007;Leblanc et al, 2008;Whiteman et al, 2010;Dinoev et al, 2013). The acceptance of the Raman lidar approach within the NDACC attests that the technique has achieved a comfortable level of maturity.…”

Section: Introductionmentioning

confidence: 99%

Water vapor observations up to the lower stratosphere through the Raman lidar during the Maïdo Lidar Calibration Campaign

et al. 2015

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Abstract.A new lidar system devoted to tropospheric and lower stratospheric water vapor measurements has been installed at the Maïdo altitude station facility of Réunion island, in the southern subtropics.To evaluate the performances and the capabilities of the new system with a particular focus on UTLS (Upper Troposphere Lower Stratosphere) measurements, the Maïdo Lidar Calibration Campaign (MALICCA) was performed in April 2013.Varying the characteristics of the transmitter and the receiver components, different system configuration scenarios were tested and possible parasite signals (fluorescent contamination, rejection) were investigated. A hybrid calibration methodology has been set up and validated to insure optimal lidar calibration stability with time. In particular, the receiver transmittance is monitored through the calibration lamp method that, at the moment, can detect transmittance variations greater than 10-15 %. Calibration coefficients are then calculated through the hourly values of IWV (Integrated Water Vapor) provided by the co-located GPS. The comparison between the constants derived by GPS and Vaisala RS92 radiosondes launched at Maïdo during MALICCA, points out an acceptable agreement in terms of accuracy of the mean calibration value (with a difference of approximately 2-3 %), but a significant difference in terms of variability (14 % vs. 7-9 %, for GPS and RS92 calibration procedures, respectively).We obtained a relatively good agreement between the lidar measurements and 15 co-located and simultaneous RS92 radiosondes. A relative difference below 10 % is measured in the low and middle troposphere (2-10 km). The upper troposphere (up to 15 km) is characterized by a larger spread (approximately 20 %), because of the increasing distance between the two sensors.To measure water vapor in the UTLS region, nighttime and monthly water vapor profiles are presented and compared. The good agreement between the lidar monthly profile and the mean WVMR profile measured by satellite MLS (Microwave Limb Sounder) has been used as a quality control procedure of the lidar product, attesting the absence of significant wet biases and validating the calibration procedure.Due to its performance and location, the MAIDO H 2 O lidar will become a reference instrument in the southern subtropics, insuring the long-term survey of the vertical distribution of water vapor. Furthermore, this system allows the investigation of several scientific themes, such as stratospheretroposphere exchange, tropospheric dynamics in the subtropics, and links between cirrus clouds and water vapor.

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Comparisons of Raman Lidar Measurements of Tropospheric Water Vapor Profiles with Radiosondes, Hygrometers on the Meteorological Observation Tower, and GPS at Tsukuba, Japan

Cited by 28 publications

References 38 publications

Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

Observation of Moisture Tendencies Related to Shallow Convection

Water vapor observations up to the lower stratosphere through the Raman lidar during the Maïdo Lidar Calibration Campaign

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