Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden

In this study, four and a half months of ceilometer data from Östergarnsholm are used to analyze cloud related to processes in the boundary layer. Measurements are divided into two categories, which are defined by wind direction: a continental and a marine sector. The results show that there are sig...

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Bibliographic Details
Main Author: Stenlid, Aron
Format: Others
Language:English
Published: Uppsala universitet, Luft-, vatten och landskapslära 2019
Subjects:
LCL
DLS
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-380863
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spelling ndltd-UPSALLA1-oai-DiVA.org-uu-3808632019-04-02T03:08:18ZCloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, SwedenengMolnobservationer vid en kustnära plats – en analys av ceilometermätningar från ÖstergarnsholmStenlid, AronUppsala universitet, Luft-, vatten och landskapslära2019CeilometerStratocumuluscloud base heightLCLDLSupwellingcloud coverMeteorology and Atmospheric SciencesMeteorologi och atmosfärforskningIn this study, four and a half months of ceilometer data from Östergarnsholm are used to analyze cloud related to processes in the boundary layer. Measurements are divided into two categories, which are defined by wind direction: a continental and a marine sector. The results show that there are significant differences in the height of the lowest cloud bases detected for the two sectors, where cloud base heights are lower for the marine wind sector during unstable and neutral conditions. The ceilometer’s ability to detect several cloud base heights simultaneously is utilized to test whether a double layer structure (DLS) can be detected. The results of this particular analysis are inconclusive as to whether a DLS has been observed or not. Detected cloud base heights differ greatly from heights suggested by the lifting condensation level (LCL). A new empirical formula for lowest cloud base height is then derived using the measurements. The Ceilometer’s estimations of sky cover are assessed to be of reasonable quality. This is suggested by computed high correlation with incoming shortwave radiation at noon for three months.  However, histograms of cloud cover measurements suggest that the ceilometer tends to probably either overestimate or underestimate cloud cover.  Large differences in cloud cover were observed for the two wind sectors during unstable conditions. For the months of July and August, a diurnal cycle in cloud cover for the continental wind sector was observed which suggest the presence of Stratocumulus. Measurements performed during upwelling conditions closely resemble those of the marine wind sector performed during stable conditions. Student thesisinfo:eu-repo/semantics/bachelorThesistexthttp://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-380863Examensarbete vid Institutionen för geovetenskaper, 1650-6553 ; 454application/pdfinfo:eu-repo/semantics/openAccess
collection NDLTD
language English
format Others
sources NDLTD
topic Ceilometer
Stratocumulus
cloud base height
LCL
DLS
upwelling
cloud cover
Meteorology and Atmospheric Sciences
Meteorologi och atmosfärforskning
spellingShingle Ceilometer
Stratocumulus
cloud base height
LCL
DLS
upwelling
cloud cover
Meteorology and Atmospheric Sciences
Meteorologi och atmosfärforskning
Stenlid, Aron
Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden
description In this study, four and a half months of ceilometer data from Östergarnsholm are used to analyze cloud related to processes in the boundary layer. Measurements are divided into two categories, which are defined by wind direction: a continental and a marine sector. The results show that there are significant differences in the height of the lowest cloud bases detected for the two sectors, where cloud base heights are lower for the marine wind sector during unstable and neutral conditions. The ceilometer’s ability to detect several cloud base heights simultaneously is utilized to test whether a double layer structure (DLS) can be detected. The results of this particular analysis are inconclusive as to whether a DLS has been observed or not. Detected cloud base heights differ greatly from heights suggested by the lifting condensation level (LCL). A new empirical formula for lowest cloud base height is then derived using the measurements. The Ceilometer’s estimations of sky cover are assessed to be of reasonable quality. This is suggested by computed high correlation with incoming shortwave radiation at noon for three months.  However, histograms of cloud cover measurements suggest that the ceilometer tends to probably either overestimate or underestimate cloud cover.  Large differences in cloud cover were observed for the two wind sectors during unstable conditions. For the months of July and August, a diurnal cycle in cloud cover for the continental wind sector was observed which suggest the presence of Stratocumulus. Measurements performed during upwelling conditions closely resemble those of the marine wind sector performed during stable conditions.
author Stenlid, Aron
author_facet Stenlid, Aron
author_sort Stenlid, Aron
title Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden
title_short Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden
title_full Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden
title_fullStr Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden
title_full_unstemmed Cloud Observations at a Coastal site – Analysis of Ceilometer Measurements from Östergarnsholm, Sweden
title_sort cloud observations at a coastal site – analysis of ceilometer measurements from östergarnsholm, sweden
publisher Uppsala universitet, Luft-, vatten och landskapslära
publishDate 2019
url http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-380863
work_keys_str_mv AT stenlidaron cloudobservationsatacoastalsiteanalysisofceilometermeasurementsfromostergarnsholmsweden
AT stenlidaron molnobservationervidenkustnaraplatsenanalysavceilometermatningarfranostergarnsholm
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