Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake
In the case of lakes, evaporation is one of the most significant losses of water and energy. Based on high-frequency eddy-covariance (EC) measurements between May and September of 2019, the offshore heat and water vapor exchanges are evaluated for the large (~600 km<sup>2</sup>) but shal...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-02-01
|
| Series: | Atmosphere |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4433/13/2/352 |
| _version_ | 1797482772253638656 |
|---|---|
| author | Gabriella Lükő Péter Torma Tamás Weidinger |
| author_facet | Gabriella Lükő Péter Torma Tamás Weidinger |
| author_sort | Gabriella Lükő |
| collection | DOAJ |
| description | In the case of lakes, evaporation is one of the most significant losses of water and energy. Based on high-frequency eddy-covariance (EC) measurements between May and September of 2019, the offshore heat and water vapor exchanges are evaluated for the large (~600 km<sup>2</sup>) but shallow (~3.2 m deep) Lake Balaton (Transdanubian region, Hungary). The role of local driving forces of evaporation in different time scales (from 20 min to one month) is explored, such as water surface and air temperatures, humidity, atmospheric stability, net radiation, and energy budget components. EC-derived water vapor roughness lengths and transfer coefficients (<i>C<sub>q</sub></i>) show an apparent intra-seasonal variation. Different energy balance-based evaporation estimation methods (such as the Priestley-Taylor and the Penman-Monteith) confirm this observation. Furthermore, this has suggested the existence of an intra-annual variation in these parameters. This hypothesis is verified using ten years of water balance measurements, from which, as a first step, evaporation rates and, second, transfer coefficients are derived on a monthly scale. <i>C<sub>q</sub></i> is highly reduced in winter months (~1 × 10<sup>−3</sup>) compared to summer months (~2.5 × 10<sup>−3</sup>) and strongly correlated with net radiation. The application of time-varying <i>C<sub>q</sub></i> significantly increases the accuracy of evaporation estimation when the Monin-Obukhov similarity theory-based aerodynamic method is applied. The determination coefficient increases to 0.84 compared to 0.52 when a constant <i>C<sub>q</sub></i> is employed. |
| first_indexed | 2024-03-09T22:38:14Z |
| format | Article |
| id | doaj.art-f1bc20148f3b4ffe86cff2af9fa42ce4 |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-09T22:38:14Z |
| publishDate | 2022-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-f1bc20148f3b4ffe86cff2af9fa42ce42023-11-23T18:46:18ZengMDPI AGAtmosphere2073-44332022-02-0113235210.3390/atmos13020352Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater LakeGabriella Lükő0Péter Torma1Tamás Weidinger2Department of Hydraulic and Water Resources Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, HungaryDepartment of Hydraulic and Water Resources Engineering, Faculty of Civil Engineering, Budapest University of Technology and Economics, H-1111 Budapest, HungaryDepartment of Meteorology, Institute of Geography and Geosciences, Eötvös Loránd University, H-1117 Budapest, HungaryIn the case of lakes, evaporation is one of the most significant losses of water and energy. Based on high-frequency eddy-covariance (EC) measurements between May and September of 2019, the offshore heat and water vapor exchanges are evaluated for the large (~600 km<sup>2</sup>) but shallow (~3.2 m deep) Lake Balaton (Transdanubian region, Hungary). The role of local driving forces of evaporation in different time scales (from 20 min to one month) is explored, such as water surface and air temperatures, humidity, atmospheric stability, net radiation, and energy budget components. EC-derived water vapor roughness lengths and transfer coefficients (<i>C<sub>q</sub></i>) show an apparent intra-seasonal variation. Different energy balance-based evaporation estimation methods (such as the Priestley-Taylor and the Penman-Monteith) confirm this observation. Furthermore, this has suggested the existence of an intra-annual variation in these parameters. This hypothesis is verified using ten years of water balance measurements, from which, as a first step, evaporation rates and, second, transfer coefficients are derived on a monthly scale. <i>C<sub>q</sub></i> is highly reduced in winter months (~1 × 10<sup>−3</sup>) compared to summer months (~2.5 × 10<sup>−3</sup>) and strongly correlated with net radiation. The application of time-varying <i>C<sub>q</sub></i> significantly increases the accuracy of evaporation estimation when the Monin-Obukhov similarity theory-based aerodynamic method is applied. The determination coefficient increases to 0.84 compared to 0.52 when a constant <i>C<sub>q</sub></i> is employed.https://www.mdpi.com/2073-4433/13/2/352latent heat fluxtransfer coefficienteddy-covariancelake evaporationenergy balancewater balance |
| spellingShingle | Gabriella Lükő Péter Torma Tamás Weidinger Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake Atmosphere latent heat flux transfer coefficient eddy-covariance lake evaporation energy balance water balance |
| title | Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake |
| title_full | Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake |
| title_fullStr | Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake |
| title_full_unstemmed | Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake |
| title_short | Intra-Seasonal and Intra-Annual Variation of the Latent Heat Flux Transfer Coefficient for a Freshwater Lake |
| title_sort | intra seasonal and intra annual variation of the latent heat flux transfer coefficient for a freshwater lake |
| topic | latent heat flux transfer coefficient eddy-covariance lake evaporation energy balance water balance |
| url | https://www.mdpi.com/2073-4433/13/2/352 |
| work_keys_str_mv | AT gabriellaluko intraseasonalandintraannualvariationofthelatentheatfluxtransfercoefficientforafreshwaterlake AT petertorma intraseasonalandintraannualvariationofthelatentheatfluxtransfercoefficientforafreshwaterlake AT tamasweidinger intraseasonalandintraannualvariationofthelatentheatfluxtransfercoefficientforafreshwaterlake |