caa a22 4500 445800933 CHVBK 20180317145140.0 cr unu---uuuuu 170323e20110801xx s 000 0 eng 10.1007/s00704-010-0393-5 doi (NATIONALLICENCE)springer-10.1007/s00704-010-0393-5 The study of near-ground free convection conditions at Nam Co station on the Tibetan Plateau [Elektronische Daten] [Degang Zhou, Rafael Eigenmann, Wolfgang Babel, Thomas Foken, Yaoming Ma] This study investigates the near-ground free convection conditions (FCCs) based on eddy covariance (EC) measurements at Nam Co station near the Nam Co Lake on the Tibetan Plateau (TP). The spatial and temporal structure of EC measurements at this station is evaluated by using the comprehensive software package TK2 together with a footprint model. The obtained high-quality turbulent flux data are used to study the occurrence of FCCs, which can be detected with the EC system by calculating the stability parameter. Two types of generation of FCCs can be identified. (1) During the wind direction change of a diurnal thermally forced land-lake circulation system in the morning, strongly reduced wind speeds and simultaneously high buoyancy fluxes lead to a period of dominance of buoyancy over shear, and hence, to the occurrence of FCCs. (2) On days with the appearance of clouds, the land-lake circulation is weakened or reversed, dependent on the temperature gradients between the land and the Nam Co Lake. During the period of adaptation of the land-lake breeze to the alternating situation of heating differences, wind speeds decrease and buoyancy again dominates over shear near the ground. These are the situations where FCCs are also detected during the entire day at Nam Co station. The investigation of FCCs regarding the whole measurement period shows that FCCs can be mainly attributed to case (1) during the non-monsoon period, while FCCs are generated by both mechanisms (1 and 2) during the monsoon season. An impact of the FCCs on the near-ground profiles of air temperature and humidity is demonstrated. The FCCs are assumed to play an important role for the land surface-atmosphere exchange processes and the atmospheric boundary layer (ABL) conditions on the TP by providing an effective transport mechanism of near-ground air mass characteristics into upper parts of the ABL. Springer-Verlag, 2010 Zhou Degang Centre for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, No. 6, Bei'ertiao, Haidian district, P.O. Box2718, 100190, Beijing, China aut Eigenmann Rafael Department of Micrometeorology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany aut Babel Wolfgang Department of Micrometeorology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany aut Foken Thomas Department of Micrometeorology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany aut Ma Yaoming Institute of Tibetan Plateau Research, Chinese Academy of Sciences, P.O. Box2871, 100085, Beijing, China aut Theoretical and Applied Climatology Springer Vienna 105/1-2(2011-08-01), 217-228 0177-798X 105:1-2<217 2011 105 704 https://doi.org/10.1007/s00704-010-0393-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00704-010-0393-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhou Degang Centre for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, No. 6, Bei'ertiao, Haidian district, P.O. Box2718, 100190, Beijing, China aut NATIONALLICENCE 700 1- Eigenmann Rafael Department of Micrometeorology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany aut NATIONALLICENCE 700 1- Babel Wolfgang Department of Micrometeorology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany aut NATIONALLICENCE 700 1- Foken Thomas Department of Micrometeorology, University of Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany aut NATIONALLICENCE 700 1- Ma Yaoming Institute of Tibetan Plateau Research, Chinese Academy of Sciences, P.O. Box2871, 100085, Beijing, China aut NATIONALLICENCE 773 0- Theoretical and Applied Climatology Springer Vienna 105/1-2(2011-08-01), 217-228 0177-798X 105:1-2<217 2011 105 704 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer