scholarly journals A new methodology for PBL height estimations based on lidar depolarization measurements: analysis and comparison against MWR and WRF model-based results

2017 ◽  
Vol 17 (11) ◽  
pp. 6839-6851 ◽  
Author(s):  
Juan Antonio Bravo-Aranda ◽  
Gregori de Arruda Moreira ◽  
Francisco Navas-Guzmán ◽  
María José Granados-Muñoz ◽  
Juan Luis Guerrero-Rascado ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Prediction ◽  
Microwave Radiometer ◽  
Wrf Model ◽  
Saharan Dust ◽  
Aerosol Layer ◽  
Night Time ◽  
Signal Ratio ◽  
Lidar Measurements

Abstract. The automatic and non-supervised detection of the planetary boundary layer height (zPBL) by means of lidar measurements was widely investigated during the last several years. Despite considerable advances, the experimental detection still presents difficulties such as advected aerosol layers coupled to the planetary boundary layer (PBL) which usually produces an overestimation of the zPBL. To improve the detection of the zPBL in these complex atmospheric situations, we present a new algorithm, called POLARIS (PBL height estimation based on lidar depolarisation). POLARIS applies the wavelet covariance transform (WCT) to the range-corrected signal (RCS) and to the perpendicular-to-parallel signal ratio (δ) profiles. Different candidates for zPBL are chosen and the selection is done based on the WCT applied to the RCS and δ. We use two ChArMEx (Chemistry-Aerosol Mediterranean Experiment) campaigns with lidar and microwave radiometer (MWR) measurements, conducted in 2012 and 2013, for the POLARIS' adjustment and validation. POLARIS improves the zPBL detection compared to previous methods based on lidar measurements, especially when an aerosol layer is coupled to the PBL. We also compare the zPBL provided by the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model with respect to the zPBL determined with POLARIS and the MWR under Saharan dust events. WRF underestimates the zPBL during daytime but agrees with the MWR during night-time. The zPBL provided by WRF shows a better temporal evolution compared to the MWR during daytime than during night-time.

scholarly journals PBL height estimation based on lidar depolarisation measurements (POLARIS)

2016 ◽  
Author(s):  
Juan Antonio Bravo-Aranda ◽  
Gregori de-Arruda-Moreira ◽  
Francisco Navas-Guzmán ◽  
María José Granados-Muñoz ◽  
Juan Luís Guerrero-Rascado ◽  
...  
Keyword(s):  
Weather Prediction ◽  
Microwave Radiometer ◽  
Numerical Weather Prediction Model ◽  
Saharan Dust ◽  
Night Time ◽  
Signal Ratio ◽  
Height Estimation ◽  
Boundary Layer Height ◽  
Lidar Measurements ◽  
Dust Events

Abstract. The automatic and non-supervised detection of the planetary boundary layer height (zPBL) by means of lidar measurements was widely investigated during the last years. Despite the considerable advances achieved the experimental detection still present difficulties either because the PBL is stratified (typically, during night-time) either because advected aerosol layers are coupled to the PBL. The coupling uses to produce an overestimation of the zPBL. To improve the detection even in these complex atmospheric situations, we present a new algorithm, called POLARIS (PBL height estimatiOn based on Lidar depolARISation). POLARIS applies the wavelet covariance transform (WCT) to the range corrected signal and to the perpendicular-to-parallel signal ratio (δ) profiles. Different candidates for zPBL are chosen and the attribution is done, based on the WCT applied to the RCS and the δ. We use two ChArMEx campaigns with lidar and microwave radiometer (MWR), conducted on 2012 and 2013, for the POLARIS' adjustment and validation. POLARIS improves the zPBL detection thanks to the consideration of the relative changes in the depolarization capabilities of the aerosol particles in the lower part of the atmospheric column. Taking the advantage of a proper determination of the zPBL determined by POLARIS and by MWR under Saharan dust events, we compare the POLARIS and MWR zPBL with the zPBL provided by the Weather Research and Forecasting (WRF) numerical weather prediction model. WRF underestimates the zPBL during daytime but agrees with the MWR during night-time. The zPBL provided by WRF showed a better temporal evolution during daytime than during night-time.

scholarly journals Analyzing the turbulence in the Planetary Boundary Layer by the synergic use of remote sensing systems: Doppler wind lidar and aerosol elastic lidar

2018 ◽  
Author(s):  
Gregori de Arruda Moreira ◽  
Juan Luís Guerrero-Rascado ◽  
Jose Antonio Benavent-Oltra ◽  
Pablo Ortiz-Amezcua ◽  
Roberto Román ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Forecasting ◽  
Saharan Dust ◽  
Aerosol Layer ◽  
Frequency Distributions ◽  
Sensing Systems ◽  
Turbulent Characteristics ◽  
Remote Sensing Systems

Abstract. The Planetary Boundary Layer (PBL) is the lowermost region of troposphere and endowed with turbulent characteristics, which can have mechanical or thermodynamic origins. Such behavior gives to this layer great importance, mainly in studies about pollutant dispersion and weather forecasting. However, the instruments usually applied in studies about turbulence in the PBL have limitations in spatial resolution (anemometer towers) or temporal resolution (aircrafts). In this study we propose the synergetic use of remote sensing systems (microwave radiometer [MWR], Doppler lidar [DL] and elastic lidar [EL]) to analyze the PBL behavior. Furthermore, we show how some meteorological variables such as air temperature, aerosol number density, vertical wind, relative humidity and net radiation might influence the PBL dynamic. The statistical moments of the high frequency distributions of the vertical velocity, derived from DL and of the backscattered coefficient derived from EL, are corrected by two methodologies, namely first lag and −2/3 correction. The corrected profiles present small differences when compare against the uncorrected profiles, showing low influence of noise and the viability of the proposed methodology. Two case studies were analyzed in detail, one corresponding to a well-defined PBL and another one corresponding to a situation with presence of a Saharan dust lofted aerosol layer and clouds. In both cases the results provided by the different instruments are complementary, thus the synergistic use of the different systems allow us performing a detailed monitoring of the PBL.

scholarly journals Supercooled Liquid Water Clouds observed and analysed at the Top of the Planetary Boundary Layer above Dome C, Antarctica

2019 ◽  
Author(s):  
Philippe Ricaud ◽  
Massimo Del Guasta ◽  
Eric Bazile ◽  
Niramson Azouz ◽  
Angelo Lupi ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Liquid Water ◽  
Weather Prediction ◽  
Microwave Radiometer ◽  
Mixing Layer ◽  
Austral Summer ◽  
Supercooled Liquid ◽  
Surface Radiation ◽  
Capping Inversion

Abstract. A comprehensive analysis of the water budget over the Dome C (Concordia, Antarctica) station has been performed during the austral summer 2018–2019 as part of the Year of Polar Prediction (YOPP) international campaign. Thin (~ 100-m) supercooled liquid water (SLW) clouds have been detected and analysed using remotely sensed observations at the station (tropospheric depolarization LIDAR, microwave radiometer HAMSTRAD, net surface radiation from Baseline Surface Radiation Network, BSRN), radiosondes and using satellite observations (CALIOP/CALIPSO) combined with a specific configuration of the Numerical Weather Prediction model: ARPEGE-SH. Two case studies are used to illustrate this phenomenon. On 24 December 2018, the atmospheric planetary boundary layer (PBL) evolved following a typical diurnal variation, that is to say with a warm and dry mixing layer at local noon thicker than the cold and dry stable layer at local midnight. Our study showed that the SLW clouds were observed at Dome C within the entrainment and the capping inversion zones at the top of the PBL. ARPEGE-SH was not able to correctly estimate the ratio between liquid and solid water inside the clouds. The SLW content was always strongly underestimated in the studied cases. The lack of simulated SLW in the model impacted the net surface radiation that was 20–30 W m−2 higher in the BSRN observations than in the ARPEGE-SH calculations, mainly attributable to longwave downward surface radiation from BSRN being 50 W m−2 greater than that of ARPEGE-SH. On 20 December 2018, a warm and wet episode impacted the PBL with no clear diurnal cycle of the PBL top height. SLW cloud appearance coincided with the warm and wet event within the entrainment and capping inversion zones. The amount of liquid water measured by HAMSTRAD was ~ 20 times greater in this perturbed PBL than in the typical PBL. Since ARPEGE-SH was not able to accurately reproduce these SLW clouds, the discrepancy between the observed and calculated net surface radiation was even greater than in the typical PBL period, reaching + 50 W m−2, mainly attributable to longwave downward surface radiation from BSRN being 100 W m−2 greater than that of ARPEGE-SH. The absence of SLW clouds in NWPs over Antarctica may indicate an incorrect simulation of the radiative budget of the polar atmosphere.

scholarly journals Determination and climatology of the planetary boundary layer height by in-situ and remote sensing methods as well as the COSMO model above the Swiss plateau

2014 ◽  
Vol 14 (10) ◽  
pp. 15419-15462 ◽  
Author(s):  
M. Collaud Coen ◽  
C. Praz ◽  
A. Haefele ◽  
D. Ruffieux ◽  
P. Kaufmann ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Prediction ◽  
Microwave Radiometer ◽  
Atmospheric Composition ◽  
Detection Methods ◽  
Raman Lidar ◽  
Radio Sounding ◽  
Swiss Plateau

Abstract. The planetary boundary layer (PBL) height is a key parameter in air quality control and pollutant dispersion. The PBL height can however not be directly measured and its estimation relies on the analysis of the vertical profiles of the temperature, the turbulences or the atmospheric composition. An operational PBL height detection including several remote sensing instruments (windprofiler, Raman lidar, microwave radiometer) and several algorithms (Parcel and bulk Richardson number methods, surface-based temperature inversion, aerosol or humidity gradient analysis) were developed and the first year of application allowed validating these various detection methods against radio sounding measurements. The microwave radiometer provides convective boundary layer heights in good agreement with the radio sounding (median bias < 25 m, R2 > 0.70) and allows to fully analyzing the PBL height diurnal cycle due to its smaller time granularity. The Raman lidar also leads to good results whereas the windprofiler yields some more dispersed results. Comparisons with the numerical weather prediction model COSMO-2 were also established and point out a general overestimation by the model. Finally the seasonal cycles of the daytime and nighttime PBL heights are discussed for each instrument and each detection algorithm for two stations on the Swiss plateau.

scholarly journals Determination and climatology of the planetary boundary layer height above the Swiss plateau by in situ and remote sensing measurements as well as by the COSMO-2 model

2014 ◽  
Vol 14 (23) ◽  
pp. 13205-13221 ◽  
Author(s):  
M. Collaud Coen ◽  
C. Praz ◽  
A. Haefele ◽  
D. Ruffieux ◽  
P. Kaufmann ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Prediction ◽  
Microwave Radiometer ◽  
Wind Profiler ◽  
Raman Lidar ◽  
Radio Sounding ◽  
Swiss Plateau ◽  
Good Agreement

Abstract. The planetary boundary layer (PBL) height is a key parameter in air quality control and pollutant dispersion. The PBL height cannot, however, be directly measured, and its estimation relies on the analysis of the vertical profiles of the temperature, turbulence or the atmospheric composition. An operational PBL height detection method including several remote sensing instruments (wind profiler, Raman lidar, microwave radiometer) and several algorithms (Parcel and bulk Richardson number methods, surface-based temperature inversion, aerosol or humidity gradient analysis) was developed and tested with 1 year of measurements, which allows the methods to be validated against radio sounding measurements. The microwave radiometer provides convective boundary layer heights in good agreement with the radio sounding (RS) (median bias < 25 m, R2 > 0.70) and allows the analysis of the diurnal variation of the PBL height due to its high temporal resolution. The Raman lidar also leads to a good agreement with RS, whereas the wind profiler yields some more dispersed results mostly due to false attribution problems. A comparison with the numerical weather prediction model COSMO-2 has shown a general overestimation of the model PBL height by some hundreds to thousand meters. Finally the seasonal cycles of the daytime and nighttime PBL heights are discussed for each instrument and each detection algorithm for two stations on the Swiss plateau.

scholarly journals Analyzing the turbulent planetary boundary layer by remote sensing systems: the Doppler wind lidar, aerosol elastic lidar and microwave radiometer

2019 ◽  
Vol 19 (2) ◽  
pp. 1263-1280 ◽  
Author(s):  
Gregori de Arruda Moreira ◽  
Juan Luis Guerrero-Rascado ◽  
Jose A. Benavent-Oltra ◽  
Pablo Ortiz-Amezcua ◽  
Roberto Román ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Latin American ◽  
Microwave Radiometer ◽  
Aerosol Layer ◽  
Sensing Systems ◽  
Turbulent Characteristics ◽  
Remote Sensing Systems ◽  
Influence Of Noise

Abstract. The planetary boundary layer (PBL) is the lowermost region of troposphere and is endowed with turbulent characteristics, which can have mechanical and/or thermodynamic origins. This behavior gives this layer great importance, mainly in studies about pollutant dispersion and weather forecasting. However, the instruments usually applied in studies of turbulence in the PBL have limitations in spatial resolution (anemometer towers) or temporal resolution (instrumentation aboard an aircraft). Ground-based remote sensing, both active and passive, offers an alternative for studying the PBL. In this study we show the capabilities of combining different remote sensing systems (microwave radiometer – MWR, Doppler lidar – DL – and elastic lidar – EL) for retrieving a detailed picture on the PBL turbulent features. The statistical moments of the high frequency distributions of the vertical wind velocity, derived from DL, and of the backscattered coefficient, derived from EL, are corrected by two methodologies, namely first lag correction and -2/3 law correction. The corrected profiles, obtained from DL data, present small differences when compared with the uncorrected profiles, showing the low influence of noise and the viability of the proposed methodology. Concerning EL, in addition to analyzing the influence of noise, we explore the use of different wavelengths that usually include EL systems operated in extended networks, like the European Aerosol Research Lidar Network (EARLINET), Latin American Lidar Network (LALINET), NASA Micro-Pulse Lidar Network (MPLNET) or Skyradiometer Network (SKYNET). In this way we want to show the feasibility of extending the capability of existing monitoring networks without strong investments or changes in their measurements protocols. Two case studies were analyzed in detail, one corresponding to a well-defined PBL and another corresponding to a situation with presence of a Saharan dust lofted aerosol layer and clouds. In both cases we discuss results provided by the different instruments showing their complementarity and the precautions to be applied in the data interpretation. Our study shows that the use of EL at 532 nm requires a careful correction of the signal using the first lag time correction in order to get reliable turbulence information on the PBL.

scholarly journals Planetary Boundary Layer variability over New Delhi, India, during EUCAARI project

2018 ◽  
Author(s):  
Konstantina Nakoudi ◽  
Elina Giannakaki ◽  
Aggeliki Dandou ◽  
Maria Tombrou ◽  
Mika Komppula
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Feature Detection ◽  
Potential Temperature ◽  
Satellite Observations ◽  
Radiosonde Data ◽  
New Delhi ◽  
Aerosol Layer ◽  
Lidar Measurements ◽  
Good Agreement

Abstract. Ground-based lidar measurements were performed at Gual Pahari measurement station, approximately 20 km South of New Delhi, India, from March 2008 to March 2009. The height of the Planetary Boundary Layer (PBL) was retrieved with a portable Raman lidar system, utilizing the modified Wavelet Covariance Transform (WCT) method. The lidar derived PBL heights were compared to radiosonde data, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite observations and two atmospheric models. The results were also analyzed on a seasonal basis. To examine the difficulties of PBL lidar detection under different meteorological and aerosol load conditions we focused on three case studies of PBL diurnal evolution. In the presence of a multiple aerosol layer structure, the WCT method exhibited high efficiency in PBL height determination. Good agreement with the European Center for Medium-range Weather Forecasts (ECMWF) and the Weather Research and Forecasting (WRF) estimations was found (r=0.69 and r=0.74, respectively) for a cumulus convection case. In the aforementioned cases, temperature, relative humidity and potential temperature radiosonde profiles were well compared to the respective WRF profiles. The Bulk Richardson Number scheme, which was applied to radiosonde profile data, was in good agreement with lidar data, especially during daytime (r=0.68). The overall comparison with CALIPSO satellite observations; namely, CALIOP Level 2 Aerosol Layer Product, was very satisfying (r=0.84), with CALIPSO Feature Detection Algorithms slightly overestimating PBL height. Lidar measurements revealed that the maximum PBL height was reached approximately three hours after the solar noon, whilst the daily evolution of the PBL was completed, on average, one hour earlier. The PBL diurnal cycle was also analyzed using ECMWF estimations, which produced a stronger cycle during the winter and pre-monsoon period. The seasonal analysis of lidar PBL heights yielded a less pronounced PBL cycle than the one expected from long term climate records. The lowest mean daytime PBL height (695 m) appeared in winter, while the highest mean daytime PBL height (1326 m) was found in the monsoon season as expected. PBL daily growth rates exhibited also a weak seasonal variability.

scholarly journals Sensitivity of an Idealized Tropical Cyclone to the Configuration of the Global Forecast System–Eddy Diffusivity Mass Flux Planetary Boundary Layer Scheme

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 284
Author(s):  
Evan A. Kalina ◽  
Mrinal K. Biswas ◽  
Jun A. Zhang ◽  
Kathryn M. Newman
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Prediction ◽  
Intensity Change ◽  
Rapid Intensification ◽  
Forecast System ◽  
Stability Functions ◽  
Non Local ◽  
The Stability ◽  
Heat And Moisture

The intensity and structure of simulated tropical cyclones (TCs) are known to be sensitive to the planetary boundary layer (PBL) parameterization in numerical weather prediction models. In this paper, we use an idealized version of the Hurricane Weather Research and Forecast system (HWRF) with constant sea-surface temperature (SST) to examine how the configuration of the PBL scheme used in the operational HWRF affects TC intensity change (including rapid intensification) and structure. The configuration changes explored in this study include disabling non-local vertical mixing, changing the coefficients in the stability functions for momentum and heat, and directly modifying the Prandtl number (Pr), which controls the ratio of momentum to heat and moisture exchange in the PBL. Relative to the control simulation, disabling non-local mixing produced a ~15% larger storm that intensified more gradually, while changing the coefficient values used in the stability functions had little effect. Varying Pr within the PBL had the greatest impact, with the largest Pr (~1.6 versus ~0.8) associated with more rapid intensification (~38 versus 29 m s−1 per day) but a 5–10 m s−1 weaker intensity after the initial period of strengthening. This seemingly paradoxical result is likely due to a decrease in the radius of maximum wind (~15 versus 20 km), but smaller enthalpy fluxes, in simulated storms with larger Pr. These results underscore the importance of measuring the vertical eddy diffusivities of momentum, heat, and moisture under high-wind, open-ocean conditions to reduce uncertainty in Pr in the TC PBL.

scholarly journals Tropospheric water vapour and relative humidity profiles from lidar and microwave radiometry

2014 ◽  
Vol 7 (5) ◽  
pp. 1201-1211 ◽  
Author(s):  
F. Navas-Guzmán ◽  
J. Fernández-Gálvez ◽  
M. J. Granados-Muñoz ◽  
J. L. Guerrero-Rascado ◽  
J. A. Bravo-Aranda ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Microwave Radiometer ◽  
Radiosonde Data ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Night Time ◽  
New Approach ◽  
Lidar Measurements ◽  
Humidity Profiles

Abstract. In this paper, we outline an iterative method to calibrate the water vapour mixing ratio profiles retrieved from Raman lidar measurements. Simultaneous and co-located radiosonde data are used for this purpose and the calibration results obtained during a radiosonde campaign in summer and autumn 2011 are presented. The water vapour profiles measured during night-time by the Raman lidar and radiosondes are compared and the differences between the methodologies are discussed. Then, a new approach to obtain relative humidity profiles by combination of simultaneous profiles of temperature (retrieved from a microwave radiometer) and water vapour mixing ratio (from a Raman lidar) is addressed. In the last part of this work, a statistical analysis of water vapour mixing ratio and relative humidity profiles obtained during 1 year of simultaneous measurements is presented.

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