Thermally-driven Mesoscale Flows and their Interaction with Atmospheric Boundary Layer Turbulence PDF
Preview Thermally-driven Mesoscale Flows and their Interaction with Atmospheric Boundary Layer Turbulence
Springer Theses Recognizing Outstanding Ph.D. Research Jon Ander Arrillaga Mitxelena Thermally-driven Mesoscale Flows and their Interaction with Atmospheric Boundary Layer Turbulence Springer Theses Recognizing Outstanding Ph.D. Research Aims and Scope The series “Springer Theses” brings together a selection of the very best Ph.D. theses from around the world and across the physical sciences. Nominated and endorsed by two recognized specialists, each published volume has been selected foritsscientificexcellenceandthehighimpactofitscontentsforthepertinentfield of research. For greater accessibility to non-specialists, the published versions includeanextendedintroduction,aswellasaforewordbythestudent’ssupervisor explainingthespecialrelevanceoftheworkforthefield.Asawhole,theserieswill provide a valuable resource both for newcomers to the research fields described, and for other scientists seeking detailed background information on special questions. Finally, it provides an accredited documentation of the valuable contributions made by today’s younger generation of scientists. Theses are accepted into the series by invited nomination only and must fulfill all of the following criteria (cid:129) They must be written in good English. (cid:129) ThetopicshouldfallwithintheconfinesofChemistry,Physics,EarthSciences, Engineeringandrelatedinterdisciplinary fields such asMaterials,Nanoscience, Chemical Engineering, Complex Systems and Biophysics. (cid:129) The work reported in the thesis must represent a significant scientific advance. (cid:129) Ifthethesisincludespreviouslypublishedmaterial,permissiontoreproducethis must be gained from the respective copyright holder. (cid:129) They must have been examined and passed during the 12 months prior to nomination. (cid:129) Each thesis should include a foreword by the supervisor outlining the signifi- cance of its content. (cid:129) The theses should have a clearly defined structure including an introduction accessible to scientists not expert in that particular field. More information about this series at http://www.springer.com/series/8790 Jon Ander Arrillaga Mitxelena Thermally-driven Mesoscale Flows and their Interaction with Atmospheric Boundary Layer Turbulence Doctoral Thesis accepted by Universidad Complutense de Madrid, Spain 123 Author Supervisors Dr. Jon AnderArrillaga Mitxelena Prof. JordiVilàGueraudeArellano Departamento deFísica delaTierra y Meteorology andAirQuality Group Astrofísica Wageningen University Universidad Complutense deMadrid Wageningen,The Netherlands Madrid,Spain Prof. Carlos Yagüe Departamento deFísica delaTierra y Astrofísica Universidad Complutense deMadrid Madrid,Spain ISSN 2190-5053 ISSN 2190-5061 (electronic) SpringerTheses ISBN978-3-030-48578-8 ISBN978-3-030-48579-5 (eBook) https://doi.org/10.1007/978-3-030-48579-5 ©TheEditor(s)(ifapplicable)andTheAuthor(s),underexclusivelicensetoSpringerNature SwitzerlandAG2020 Thisworkissubjecttocopyright.AllrightsaresolelyandexclusivelylicensedbythePublisher,whether thewholeorpartofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseof illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmissionorinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilar ordissimilarmethodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland ’ Supervisors Foreword The main objective of the thesis carried out by Jon A. Arrillaga and defended in January2019atthe Complutense University ofMadrid(Spain),was to advance in the knowledge of the physical processes that take place in the interaction of thermally-driven mesoscale flows (mainly sea breezes and mountain breezes) with boundary-layer turbulence. This is an important question as was highlighted in the lastinternationalSymposiumonBoundaryLayersandTurbulenceheldin2018and organised in Oklahoma (USA) by the American Meteorological Society, where Jon A., as a Ph.D. student participated and won the Outstanding Student Poster Presentation. The novelty of his research lies in the simultaneous analysis of mesoscale fluxes (with a characteristic spatial scale between 10 and 100 km) with atmospheric turbulence (with a maximum characteristic scale of 1 km). As a con- sequence of this combined analysis, different atmospheric regimes have been identified during his Ph.D. thesis in the transition of turbulence dominated by convection and turbulence dominated by shear. This result isvery relevant since it allows already a better understanding of the interaction between mesoscale flows, explicitly resolved in numerical models, with the parameterization of turbulence under the different mechanical and convective regimes. As such, this research provides observational and numerical evidence on phenomena that occurs in the gray zone (the scales ranging from hectometres to 5 km). To carry out his work, Jon A. Arrillaga designs a methodology that combines observations with systemic numerical experiments. Jon A. has been actively involved in collecting these observations, and in performing high-resolution numerical simulations carried out with the WRF mesoscale prediction model. The work covers three study locations of different complexities: The Cantabrian Coast in the Basque Country (Spain), the relative topographically flat region around the 213-mmeteorologicaltowerofCabauw(TheNetherlands),andthesurroundingsof La Herrería Forest, nearby Guadarrama Mountains (Madrid, Spain). These three locations,characterisedbydifferentlandusesandtopography,provideawiderange ofpossibilitiesregardingthetypeofinteractionbetweenthestudiedbreezesandthe turbulence in the atmospheric boundary layer. A key new finding of the Ph.D. has been the development of an algorithm that allows to discern and isolate the sea v vi Supervisors’Foreword breeze and the nocturnal katabatic flow from the synoptic scales (>100 km), mesoscales and boundary-layer scales. The algorithm has been developed satis- factorilyinthethreesitesreferenced aboveanditwillbeusedinfuturestudiesfor the discrimination of scales in atmospheric phenomena, for both observations and numerical results. TheThesisiscomposedoffourchaptersofresults.Chapter3studiessea-breeze events in a complex area such as the Cantabrian Coast. Analyses of observations gathered in two stations during one summer are used for this purpose. The observational analysis showsthefrequencyoftheseeventsatthistime ofyear and the consequences of the arrival of the sea-breeze front on the temperature and humidity.Thedetailedtreatmentoftheobservationsisusedtostudywhichaspects of the numerical simulations are still not able to reproduce the main sea-breeze features. Chapter 4 analyses 10 years of data from the 213-m meteorological observatory (as part of the Ruisdael Observatory https://ruisdael-observatory.nl/) and combines surface observations with upper-atmospheric measurements, including boundary-layer depth. One of the main findings is that the arrival of the sea breeze accelerates the afternoon transition, i.e., the transition from the con- vectivetostableboundary-layerconditions.Insomecasestheconvectiveboundary layercollapsesduetothefrontalpassage,producingasaconsequenceasignificant variability of gases such as the CO and radon-222. Chapter 5 connects this 2 observational study with high-resolution numerical simulations to determine the abilityofnumericalweathermodelstoreproducetheseabreeze.Onlyaround30% of the observed sea-breeze events are reproduced by the model, and the use of the selectionalgorithmreflectstheroleofthedifferentatmosphericscalesinexplaining the biases. The final chapter (Chap. 6), investigates a new observational network (Guadarrama Monitoring Network, GuMNet: www.ucm.es/gumnet) in Spain, developedbytheMoncloaCampusofInternationalExcellenceinthesurroundings of La Herrería Forest. Here, Jon A. Arrillaga studied how thermally-induced downslope winds influence turbulence and the transport of CO . Jon A. Arrillaga 2 concluded that depending on the onset of weaker or stronger downslope winds, there is a respective transition to a strongly or weakly stable nocturnal boundary layer, influencing at the same time the evolution of CO . The originality of the 2 study relies on its interdisciplinarity. It is shown that to understand and model greenhouse gases like CO , it is key to reproduce satisfactorily the interaction 2 between mesoscale flows and local turbulence. In conclusion, the quality of this Thesis is supported by the associated 4 publi- cations in high-impact journals, as well as the numerous presentations at interna- tionalconferencesheldduringthe4yearsofhisPh.D.,whereJonA.obtainedsome prestigiousprizes:OutstandingStudentPosterAward(EGU2015,Vienna,Austria), Supervisors’Foreword vii StudentHonourableMention(BLTSymposium2016,SaltLakeCity,USA),Young ScientistTravelAward(EMS2017,Dublin,Ireland),GraduateStudentAward(UC Davis Air Quality Research Center MAC-MAQ 2017, USA), Outstanding Student Poster Presentation(BLT2018, Oklahoma City, USA). Wageningen, The Netherlands Prof. Jordi Vilà Guerau de Arellano Madrid, Spain Prof. Carlos Yagüe April 2020 Abstract Introduction Atmospheric motions are classified according to their spatial and time scales from largesttosmallestintomacroscales,mesoscalesandmicroscales.Amongmesoscale motions,wefindthethermally-drivenflows,whicharedrivenbyhorizontalthermal contrasts in scales between around 1 and 100–200 km, and occur in the form of closed circulations. They have a critical role in transferring energy between the macroscales and microscales. In this thesis, we investigate sea breezes (SBs) and mountain breezes (MBs). Apart from being ubiquitous, they play a fundamental role in the complex turbulent decay during the afternoon and evening transition (AET) of the atmospheric boundary layer (ABL). Intimately linked with the interaction between mesoscale flows and ABL turbulence, relevant scalars such as CO canalsobesignificantlyaffectedbytheonsetofthermally-drivencirculations. 2 Mesoscale models such as Weather Research & Forecasting (WRF) have shown deficienciesinreproducingtheturbulentdecayduringtheAETandtheinfluenceof mesoscale flows on the CO budget. 2 Objectives The main objectives of this thesis can be outlined in the following bullet points: (cid:129) Analysing the large-scale and local forcings influencing the formation of thermally-driven flows, and developing an objective algorithm to select the mesoscale events. (cid:129) Toshedlightontheinterconnectionsbetweenthermally-drivenflowsandABL turbulence during the AET. (cid:129) QuantifyingtheimpactofmesoscaleflowsonthedynamicsoftheABLandthe associated variability in CO and 222Rn. 2 (cid:129) ToevaluatetheperformanceoftheWRFmodelinsimulatingthecharacteristics of SB phenomena and their interaction with ABL turbulence during the AET. ix x Abstract Data and Methodology Theresearchstrategyfollowedinthisthesiscombinesobservationalmeteorological databasesandnumericalsimulationsfromtheWRFmesoscalemodel.Wefocuson three observational sites, each of them representing a distinct scenario for the for- mationofthermally-drivencirculations:theBasqueCoast(Spain)toanalysetheSB overcomplexterrain;theCESARsite(Netherlands),whereweexploretheSBover flatterrain;andLaHerreríasite(Spain),toinvestigatekatabaticwindsnearbyasteep mountainous slope. The model adds a spatial insight not provided by the observa- tions and allows to evaluate its performance in reproducing the thermally-driven winds. Furthermore, one of the key aspects of this thesis is the development of a systematic algorithm based on objective criteria to select mesoscale events and produce robust statistics. Results First, we characterise SB phenomena at the Basque Coast by comparing observa- tions from two topographically contrasting sites. Numerical simulations from the WRF model provide a more precise insight, and allowus to evaluate the influence of the SB onset on atmospheric variables and the associated turbulence. The investigation of SB phenomena is continued with the analysis of a 10-year observational database from the CESAR site. After applying the mesoscale selec- tion algorithm, we analyse 102 SB days taking place at different times along the AET,andweclassifythemaccordingtothesurface-turbulenceconditions.Wefind that the impacts of SB flows on the ABL dynamics and its thermal structure are contrasting depending on the encountered turbulent characteristics. Our findings furthermorerevealthedeterminantroleoftheSBdirectioninthetransportofwater vapour,CO and222Rn.NumericalsimulationsfromtheWRFmodelspanningthe 2 same 10-year period are employed to analyse its performance in reproducing the main characteristics of the SB, their influencing factors and the impact on ABL turbulence during the AET. We find that the sensible-heat flux is greatly overes- timated, and probably as a consequence, the simulated SB intensity is magnified. Finally,theroleofkatabaticflowsinthedynamicsandturbulentfeaturesofthe SBL is explored by employing observations from La Herrería site. Forty katabatic events are selected from a summer database by using the mesoscale selection algorithm. We find a direct relationship between the maximum intensity of the katabatic flows and the turbulent characteristics of the SBL. By relating the dynamics of the SBL regimes with the CO budget, we estimate the contribution 2 of the different forcings in the variability of this greenhouse gas.
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