scholarly journals Lidar Observations of the Vertical Aerosol Flux in the Planetary Boundary Layer

2008 ◽  
Vol 25 (8) ◽  
pp. 1296-1306 ◽  
Author(s):  
Ronny Engelmann ◽  
Ulla Wandinger ◽  
Albert Ansmann ◽  
Detlef Müller ◽  
Egidijus Žeromskis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Vertical Wind ◽  
Particle Mass ◽  
Eddy Correlation ◽  
Correlation Technique ◽  
Atmospheric Conditions ◽  
Raman Lidar ◽  
Mass Fluxes ◽  
Lidar Observations

Abstract The vertical aerosol transport in the planetary boundary layer (PBL) is investigated with lidars. Profiles of the vertical wind velocity are measured with a 2-μm Doppler wind lidar. Aerosol parameters are derived from observations with an aerosol Raman lidar. Both instruments were operated next to each other at the Institute for Tropospheric Research (IfT) in Leipzig, Germany. The eddy correlation technique is applied to calculate turbulent particle mass fluxes on the basis of aerosol backscatter and vertical wind data obtained with a resolution of 75 m and 5 s throughout the PBL. A conversion of particle backscatter to particle mass is performed by applying the IfT inversion scheme to three-wavelength Raman lidar observations. The method, so far, is restricted to stationary and dry atmospheric conditions under which hygroscopic particle growth can be neglected. In a case study, particle mass fluxes of 0.5–2.5 μg m−2 s−1 were found in the upper part of a convective PBL on 12 September 2006.

Characterization of the time evolution of the PBL structure and dry-layers based on the us of Raman Lidar measurements collected during HYMEX-SOP1

2021 ◽  
Author(s):  
Donato Summa ◽  
Paolo Di Girolamo ◽  
Noemi Franco ◽  
Benedetto De Rosa ◽  
Fabio Madonna ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Water Vapour ◽  
Planetary Boundary Layer ◽  
Grid Point ◽  
Laser Source ◽  
Raman Lidar ◽  
Water Vapour Concentration ◽  
Vapour Concentration

<p>The exchange processes between the Earth and the atmosphere play a crucial role in the development of the Planetary Boundary Layer (PBL). Different remote sensing techniques can provide PBL measurement with different spatial and temporal resolutions. Vertical profiles of atmospheric thermodynamic variables, i.e.  temperature and humidity, or wind speed, clouds and aerosols can be used as proxy to retrieve PBL height from active and passive remote sensing instruments. The University of BASILicata ground-based Raman Lidar system (BASIL) was deployed in the North-Western Mediterranean basin in the Cévennes-Vivarais site (Candillargues, Southern France, Lat: 43°37' N, Long: 4° 4' E, Elev: 1 m) and operated between 5 September and 5 November 2012, collecting more than 600 hours of measurements, distributed over 51 days and 19 intensive observation periods (IOPs). BASIL is capable to provide high-resolution and accurate measurements of atmospheric temperature and water vapour, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. This measurement capability makes BASIL a key instrument for the characterization of the water vapour concentration. BASIL makes use of a Nd:YAG laser source capable of emitting pulses at 355, 532 and 1064 nm, with a single pulse energy at 355nm of 500 mJ [1] .In the presented research effort, water vapour concentration was  computed and used to determine the PBL height. [2]. A dynamic index  included in the European Centre for Medium-range Weather Forecasts (ECMWF) ERA5 atmospheric reanalysis (CAPE, Friction velocity, etc.) is also considered and compared with BASIL resutls. ERA5 provides hourly data on regular latitude-longitude grids at 0.25° x 0.25° resolution at 37 pressure levels [3]. ERA5 is publicly available through the Copernicus Climate Data Store (CDS, https://cds.climate.copernicus.eu).  In order to properly carry out the comparison, the nearest ERA5 grid point to the lidar site has been considered assuming the representativeness uncertainty due to the use of the nearest grid-point comparable with other methods (e.g. kriging, bilinear interpolation, etc.). More results from this  measurement  effort will  be reported and discussed at the Conference.</p><p><strong>Reference</strong></p><p>[1] Di Girolamo, Paolo, De Rosa, Benedetto, Flamant, Cyrille, Summa, Donato, Bousquet, Olivier, Chazette, Patrick, Totems, Julien, Cacciani, Marco. Water vapor mixing ratio and temperature inter-comparison results in the framework of the Hydrological Cycle in the Mediterranean Experiment—Special Observation Period 1. BULLETIN OF ATMOSPHERIC SCIENCE AND TECHNOLOGY, ISSN: 2662-1495, doi: 10.1007/s42865-020-00008-3</p><p>[2] D. Summa, P. Di Girolamo, D. Stelitano, and M. Cacciani. Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches  Atmos. Meas. Tech., 6, 3515–3525, 2013 www.atmos-meas-tech.net/6/3515/2013/doi:10.5194/amt-6-3515-2013</p><p>[3] Hersbach et al. The ERA5 global reanalysis Hans  https://doi.org/10.1002/qj.3803[3]</p>

scholarly journals An empirical method to correct for temperature-dependent variations in the overlap function of CHM15k ceilometers

2016 ◽  
Vol 9 (7) ◽  
pp. 2947-2959 ◽  
Author(s):  
Maxime Hervo ◽  
Yann Poltera ◽  
Alexander Haefele
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Correction Method ◽  
Empirical Method ◽  
Cloud Base ◽  
Atmospheric Conditions ◽  
Cloud Detection ◽  
Temperature Dependent ◽  
Night Time ◽  
Gradient Based

Abstract. Imperfections in a lidar's overlap function lead to artefacts in the background, range and overlap-corrected lidar signals. These artefacts can erroneously be interpreted as an aerosol gradient or, in extreme cases, as a cloud base leading to false cloud detection. A correct specification of the overlap function is hence crucial in the use of automatic elastic lidars (ceilometers) for the detection of the planetary boundary layer or of low cloud. In this study, an algorithm is presented to correct such artefacts. It is based on the assumption of a homogeneous boundary layer and a correct specification of the overlap function down to a minimum range, which must be situated within the boundary layer. The strength of the algorithm lies in a sophisticated quality-check scheme which allows the reliable identification of favourable atmospheric conditions. The algorithm was applied to 2 years of data from a CHM15k ceilometer from the company Lufft. Backscatter signals corrected for background, range and overlap were compared using the overlap function provided by the manufacturer and the one corrected with the presented algorithm. Differences between corrected and uncorrected signals reached up to 45 % in the first 300 m above ground. The amplitude of the correction turned out to be temperature dependent and was larger for higher temperatures. A linear model of the correction as a function of the instrument's internal temperature was derived from the experimental data. Case studies and a statistical analysis of the strongest gradient derived from corrected signals reveal that the temperature model is capable of a high-quality correction of overlap artefacts, in particular those due to diurnal variations. The presented correction method has the potential to significantly improve the detection of the boundary layer with gradient-based methods because it removes false candidates and hence simplifies the attribution of the detected gradients to the planetary boundary layer. A particularly significant benefit can be expected for the detection of shallow stable layers typical of night-time situations. The algorithm is completely automatic and does not require any on-site intervention but requires the definition of an adequate instrument-specific configuration. It is therefore suited for use in large ceilometer networks.

Efficient Ultraviolet Rotational Raman Lidar for Temperature Profiling of the Planetary Boundary Layer

2012 ◽  
Vol 51 (5R) ◽  
pp. 052401 ◽  
Author(s):  
Masaharu Imaki ◽  
Hisaji Kawai ◽  
Tadashi Kato ◽  
Toshikazu Hasegawa ◽  
Takao Kobayashi
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Raman Lidar

The Pulsed Coherent Doppler Lidar: Observations of Frontal Structure and the Planetary Boundary Layer

1988 ◽  
Vol 116 (8) ◽  
pp. 1671-1681
Author(s):  
Paul J. Neiman ◽  
M. A. Shapiro ◽  
R. Michael Hardesty ◽  
B. Boba Stankov ◽  
Rhidian T. Lawrence ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Doppler Lidar ◽  
Coherent Doppler Lidar ◽  
Frontal Structure ◽  
Lidar Observations

scholarly journals An empirical method to correct for temperature dependent variations in the overlap function of CHM15k ceilometers

2016 ◽  
Author(s):  
Maxime Hervo ◽  
Yann Poltera ◽  
Alexander Haefele
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Correction Method ◽  
Empirical Method ◽  
Cloud Base ◽  
Atmospheric Conditions ◽  
Cloud Detection ◽  
Temperature Dependent ◽  
Gradient Based ◽  
High Benefit

Abstract. Imperfections in a lidar's overlap function lead to artefacts in the background, range and overlap corrected lidar signals. These artefacts can erroneously be interpreted as an aerosol gradient or, in extreme cases, as a cloud base leading to false cloud detection. A correct specification of the overlap function is hence crucial to use automatic elastic lidars (ceilometers) for the detection of the planetary boundary layer or low clouds. In this study an algorithm is presented to correct such artefacts. It is based on the assumption of a homogeneous boundary layer and a correct specification of the overlap function down to a minimum range, which must be situated within the boundary layer. The strength of the algorithm lies in a sophisticated quality check scheme which allows to reliably identify favorable atmospheric conditions. The algorithm has been applied to 2 years of data from a CHM15k ceilometer from the company Lufft. Backscatter signals corrected for background, range and overlap have been compared using the overlap function provided by the manufacturer and the one corrected with the presented algorithm. Differences between corrected and uncorrected signals reach up to 45 % in the first 300 m above ground. The amplitude of the correction turned out to be temperature dependent being larger for higher temperatures. A linear model of the correction as a function of the instrument's internal temperature has been derived from the experimental data. Case studies and a statistical analysis of the strongest gradient derived from corrected signals reveal that the temperature model is capable to correct overlap artefacts with high quality, in particular such due to diurnal variations. The presented correction method has the potential to significantly improve the detection of the boundary layer with gradient based methods because it removes false candidates and hence simplifies the attribution of the detected gradients to the planetary boundary layer. A particularly high benefit can be expected for the detection of shallow stable layers typical for nighttime situations. The algorithm is completely automatic and does not require any intervention on site but requires the definition of an adequate instrument specific configuration. It is therefore suited for the use in large ceilometer networks.

scholarly journals Variation of Ozone and PBL from the Lidar Observations and WRF-Chem Model in NYC Area During the 2018 Summer LISTOS Campaign

2020 ◽  
Vol 237 ◽  
pp. 08027
Author(s):  
Kaihui Zhao ◽  
Yonghua Wu ◽  
Jianping Huang ◽  
Rongsheng Jiang ◽  
Guillaume Gronoff ◽  
...  
Keyword(s):  
Boundary Layer ◽  
New York ◽  
Planetary Boundary Layer ◽  
Coastal Area ◽  
Model Performance ◽  
Early Morning ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Lidar Observations

High ozone (O3) episodes frequently occur in New York metropolitan and the downwind coastal area in summer. In this study, lidar/ceilometer are combined with WRF/Chem model to investigate an O3 event on Aug. 27~30 2018. We examine the spatial-temporal variabilities of O3 and planetary-boundary-layer height (PBLH) and assess the model performance on simulating surface O3 during this episode. By comparing with the lidar observations, the WRF/Chem is able to capture high O3 distribution in the PBL at noon and indicates consistent diurnal evolution for the ground O3. Nevertheless, in the early morning and night, the model overestimates the ground O3 and underestimates the PBLH.

Study of the planetary boundary layer and its influence on cloud properties

2016 ◽  
Author(s):  
Αθηνά Αργυρούλη
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Doppler Lidar ◽  
Raman Lidar ◽  
Cloud Properties

Ο βασικός στόχος της διατριβής είναι η μελέτη των επιπτώσεων των αιωρούμενων σωματιδίων στις ιδιότητες των νεφών υπό την επίδραση της τύρβης στο Ατμοσφαιρικό Οριακό Στρώμα (ΑΟΣ). Η συγκεκριμένη μελέτη κρίθηκε σημαντική καθώς υπάρχουν μεγάλες αβεβαιότητες στις προσαρμογές των νεφών λόγω της αλληλεπίδρασής τους με τα αιωρούμενα σωματίδια μέσα στο ΑΟΣ. Η επίδραση της τύρβης και των φυσικο-χημικών ιδιοτήτων των σωματιδίων στην ανάπτυξη των νεφών μελετήθηκε στο αστικό περιβάλλον της Αθήνας με χρήση των μετρήσεων που συλλέχθηκαν στην Αθήνα την περίοδο Μαΐος-Ιούνιος 2014.Η διατριβή είναι δομημένη σε οκτώ κεφάλαια. Στο Κεφάλαιο 1 παρουσιάζονται τα χαρακτηριστικά του ΑΟΣ. Στο Κεφάλαιο 2, εισάγουμε στον αναγνώστη την έννοια της αλληλεπίδρασης σωματιδίων-νεφών και την επιδρασή τους στην κλιματική αλλαγή. Συγκεκριμένα, αναφερόμαστε στις οπτικές ιδιότητες των αιωρούμενων σηματιδίων και την ενεργοποίηση αυτών σε νεφοσταγονίδια καθώς επίσης παρουσιάζουμε τους μηχανισμούς ανάπτυξης των νεφοσταγονιδίων στα θερμά νέφη. Στο Κεφάλαιο 3 ασχολούμαστε με μεθόδους τηλεπισκόπησης της ατμόσφαιρας και ιδιαίτερα των αιωρούμενων σωματιδίων. Αναλυτικά περιγράφεται το σύστημα lidar του ΕΜΠ με τα διάφορα τεχνικά χαρακτηριστικά της διάταξής του. Επιπρόσθετα, περιγράφουμε τις μεθόδους (Klett και Raman) για την ανάκτηση των οπτικών ιδιοτήτων των αιωρούμενων σωματιδίων από σήματα lidar. Οι μέθοδοι βαθμονόμησης και επεξεργασίας σήματος lidar παρουσιάζονται, επίσης, σε αυτό το κεφάλαιο. Με στόχο την περιγραφή της αλληλεπίδρασης ακτινοβολίας--ύλης, στο Κεφάλαιο 4 εισάγουμε τον αναγνώστη στην κλασσική θεωρία σκέδασης και στον τρόπο ανάκτησης των οπτικών ιδιοτήτων των αιωρούμενων σωματιδίων από το πεδίο σκέδασης. Στο ίδιο κεφάλαιο παρουσιάζονται μαθηματικές μέθοδοι αντιστροφής των οπτικών ιδιοτήτων των σωματιδίων με σκοπό τον προσδιορισμό των μικροφυσικών τους ιδιοτήτων. Ένας από τους αλγορίθμους αντιστροφής που χρησιμοποιήθηκε σε αυτή τη διατριβή είναι ο αλγόριθμος LIRIC που παρουσιάζεται στο Κεφάλαιο 5. Συνδυάζει όργανα ενεργητικής και παθητικής τηλεπισκόπησης προκειμένου να εξάγει πληροφορία για την καθ' ύψος ογκομετρική συγκέντρωση λεπτόκοκκων και χονδρόκοκκων σωματιδίων. Ο αλγόριθμος LIRIC εφαρμόστηκε σε διάφορα επεισόδια σωματιδιακής ρύπανσης στην Αθήνα.Το αντικείμενο του Κεφαλαίου 6 είναι η περιγραφή των επιστημονικών στόχων του διεθνούς πειράματος HygrA-CD. Τα πιο σημαντικά ευρύματα από το πείραμα παρουσιάζονται σε αυτό το κεφάλαιο. Συγκεκριμένα, οι οπτικές ιδιότητες των αιωρούμενων σωματιδίων καθ' ύψος όπως ανακτήθηκαν από το σύστημα Raman lidar παρατίθενται σε αυτό το κεφάλαιο καθώς επίσης και ο χαρακτηρισμός του είδους των ανιχνευθέντων αιωρούμενων σωματιδίων. Η θερμοδυναμική κατάσταση της ατμόσφαιρας διερευνήθηκε με χρήση ραδιοβολίσεων. Τέλος, η δυναμική του ΑΟΣ μελετήθηκε με τη βοήθεια ενός συστήματος Doppler lidar, όργανο ενεργητικής τηλεπισκόπησης για την ανάκτηση των συνιστωσών της ταχύτητας του ανέμου.Στο Κεφάλαιο 7 παρουσιάζονται οι δύο μεθοδολογίες που αναπτύχθηκαν στο πλαίσιο της παρούσας διδακτορικής διατριβής. Η πρώτη μεθοδολογία έχει στόχο να συσχετίσει τις συγκεντρώσεις των αιωρούμενων σωματιδίων με τις συγκεντρώσεις νεφοσταγονιδίων. Ο αλγόριθμος που αναπτύχθηκε χρησιμοποιεί συνεργιστικές μετρήσεις από ένα πολυκαναλικό σύστημα Raman lidar και ένα Doppler lidar με στόχο να παρέχει εκτιμήσεις του φάσματος Πυρήνων Συμπύκνωσης Νέφωσης (ΠΣΝ) και του αριθμού των νεφοσταγονιδίων. Η δεύτερη μεθοδολογία έχει ως στόχο να παρέχει την ποσοτικοποίηση της καθ' ύψος μεταφοράς μάζας αιωρούμενων σωματιδίων μέσα στο ΑΟΣ με χρήση μεθόδων τηλεπισκόπησης. Οι ταυτόχρονες μετρήσεις από το σύστημα Doppler lidar και το ελαστικό lidar σωματιδίων είναι απαραίτητες για την εκτίμηση της κατακόρυφης μεταφοράς αερολύματων μέσω της τεχνικής συσχέτισης στροβιλισμών. Και οι δύο μεθοδολογίες εφαρμόσθηκαν σε πραγματικές ατμοσφαιρικές συνθήκες κάνοντας χρήση της βάσης δεδομένων από το πείραμα HygrA-CD και παρουσιάζονται στο Κεφάλαιο 7. Τέλος, στο Κεφάλαιο 8 συνοψίζονται τα συμπεράσματα της παρούσας διδακτορικής διατριβής και διερευνώνται οι προοπτικές για μελλοντικές εργασίες.

scholarly journals Lidar characterization of the Arctic atmosphere during ASTAR 2007: four cases studies of boundary layer, mixed-phase and multi-layer clouds

2010 ◽  
Vol 10 (6) ◽  
pp. 2847-2866 ◽  
Author(s):  
A. Lampert ◽  
C. Ritter ◽  
A. Hoffmann ◽  
J.-F. Gayet ◽  
G. Mioche ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Case Studies ◽  
Airborne Lidar ◽  
Mixed Phase ◽  
Spherical Particles ◽  
The Arctic ◽  
Free Troposphere ◽  
Atmospheric Conditions ◽  
Raman Lidar ◽  
Tropospheric Aerosol

Abstract. During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR), which was conducted in Svalbard in March and April 2007, tropospheric Arctic clouds were observed with two ground-based backscatter lidar systems (micro pulse lidar and Raman lidar) and with an airborne elastic lidar. In the time period of the ASTAR 2007 campaign, an increase in low-level cloud cover (cloud tops below 2.5 km) from 51% to 65% was observed above Ny-Ålesund. Four different case studies of lidar cloud observations are analyzed: With the ground-based Raman lidar, a layer of spherical particles was observed at an altitude of 2 km after the dissolution of a cloud. The layer probably consisted of small hydrated aerosol (radius of 280 nm) with a high number concentration (around 300 cm−3) at low temperatures (−30 °C). Observations of a boundary layer mixed-phase cloud by airborne lidar and concurrent airborne in situ and spectral solar radiation sensors revealed the localized process of total glaciation at the boundary of different air masses. In the free troposphere, a cloud composed of various ice layers with very different optical properties was detected by the Raman lidar, suggesting large differences of ice crystal size, shape and habit. Further, a mixed-phase double layer cloud was observed by airborne lidar in the free troposphere. Local orography influenced the evolution of this cloud. The four case studies revealed relations of cloud properties and specific atmospheric conditions, which we plan to use as the base for numerical simulations of these clouds.

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