Surface Energy Fluxes on the Great Lakes Based on Satellite-Observed Surface Temperatures 1992 to 1995 (original) (raw)
Related papers
Journal of Hydrometeorology, 2003
This paper addresses interannual and seasonal variability in the thermal regime and surface energy fluxes in central Great Slave Lake during three contiguous open-water periods, two of which overlap the Canadian Global Energy and Water Cycle Experiment (GEWEX) Enhanced Study (CAGES) water year. The specific objectives are to compare the air temperature regime in the midlake to coastal zones, detail patterns of air and water temperatures and atmospheric stability in the central lake, assess the role of the radiation balance in driving the sensible and latent heat fluxes on a daily and seasonal basis, quantify magnitudes and rates of the sensible and latent heat fluxes and evaporation, and present a comprehensive picture of the seasonal and interannual thermal and energy regimes, their variability, and their most important controls. Atmospheric and lake thermal regimes are closely linked. Temperature differences between midlake and the northern shore follow a seasonal linear change from 6ЊC colder midlake in June, to 6ЊC warmer in November-December. These differences are a response to the surface energy budget of the lake. The surface radiation balance, and sensible and latent heat fluxes are not related on a day-to-day basis. Rather, from final lake ice melt in mid-June through to mid-to late August, the surface waters strongly absorb solar radiation. A stable atmosphere dominates this period, the latent heat flux is small and directed upward, and the sensible heat flux is small and directed downward into the lake. During this period, the net solar radiation is largely used in heating the lake. From mid-to late August to freeze up in December to early January, the absorbed solar radiation is small, the atmosphere over the lake becomes increasingly unstable, and the sensible and latent heat fluxes are directed into the atmosphere and grow in magnitude into the winter season. Comparing the period of stable atmospheric conditions with the period of unstable conditions, net radiation is 6 times larger during the period of stable atmosphere and the combined latent and sensible heat fluxes are 9 times larger during the unstable period. From 85% to 90% of total evaporation occurs after mid-August, and evaporation rates increase continuously as the season progresses. This rate of increase varies from year to year. The time of final ice melt exerts the largest single control on the seasonal thermal and energy regimes of this large northern lake.
Changing thermal dynamics of lakes in the Great Lakes region: Role of ice cover feedbacks
Global and Planetary Change, 2011
Keywords: lakes VIC model climate variability climate change heat storage ice cover feedback The impacts of climate variability and lake ice cover feedbacks on the seasonal thermal dynamics of inland lakes were evaluated for the period of 1916-2007. Analysis of regional scale impacts for the small inland lakes remains a major challenge in the Great Lakes region due to lack of observations at regional scale. Regional lakes were included into a land surface modeling perspective to understand the roles of climate variability on their open water season dynamics. The Variable Infiltration Capacity (VIC) model was applied with a physically based lake algorithm to simulate thermal conditions of lakes at regional scale during the open water period. Prior to its implementation, the VIC model was evaluated for lake surface water temperature in the selected lakes within the study domain. Results suggested that the cold (October-May) and spring (March-May) season air temperatures have increased by 1.38 and 1.54°C, respectively during the period of 1916-2007. Increase in air temperature was statistically significant at the regional scale. Onset of the stratified season has occurred earlier by more than five days during the period of 1916-2007. Earlier onset of the stratified season was significantly related to the length of the stratified season, thermal storage in the lakes, and mean lake surface water temperatures. The combined impacts of increased air temperature and earlier onset of the stratified season led to increased heat storage in lakes by 82.5 × 10 16 J. Degree-days above 15 and 20°C also increased by 97.5 and 33.0 degree-days during the period of 1916-2007. The lake ice cover was significantly related with the annual lake evaporation, timing of ice formation and break-up in lakes, and heat storage during the spring and summer. Results suggested the climate warming may lead to increased rate of evaporation that is driven by feedbacks of ice cover and snow storage.
Evaluating and improving modeled turbulent heat fluxes across the North American Great Lakes
Hydrology and Earth System Sciences, 2018
Turbulent fluxes of latent and sensible heat are important physical processes that influence the energy and water budgets of the North American Great Lakes. These fluxes can be measured in situ using eddy covariance techniques and are regularly included as a component of lakeatmosphere models. To help ensure accurate projections of lake temperature, circulation, and regional meteorology, we validated the output of five algorithms used in three popular models to calculate surface heat fluxes: the Finite Volume Community Ocean Model (FVCOM, with three different options for heat flux algorithm), the Weather Research and Forecasting (WRF) model, and the Large Lake Thermodynamic Model. These models are used in research and operational environments and concentrate on different aspects of the Great Lakes' physical system. We isolated only the code for the heat flux algorithms from each model and drove them using meteorological data from four over-lake stations within the Great Lakes Evaporation Network (GLEN), where eddy covariance measurements were also made, enabling colocated comparison. All algorithms reasonably reproduced the seasonal cycle of the turbulent heat fluxes, but all of the algorithms except for the Coupled Ocean-Atmosphere Response Experiment (COARE) algorithm showed notable overestimation of the fluxes in fall and winter. Overall, COARE had the best agreement with eddy covariance measurements. The four algorithms other than COARE were altered by updating the parameterization of roughness length scales for air temperature and humidity to match those used in COARE, yielding improved agreement between modeled and observed sensible and latent heat fluxes.
Journal of Geophysical Research: Biogeosciences, 2015
To understand the carbon and energy exchange between the lake surface and the atmosphere, direct measurements of latent, sensible heat and CO 2 fluxes were taken using the eddy covariance (EC) technique in western Lake Erie during October 2011-September 2013. We found that the latent heat flux (LE) had a marked one-peak seasonal change in both years that differed from the diurnal course and lacked a sinusoidal dynamic common in terrestrial ecosystems. Daily mean LE was 4.8±0.1 and 4.3±0.2 MJ m -2 d -1 in Year 1 and Year 2, respectively. The sensible heat flux (H) remained much lower than the LE, with a daily mean of 0.9±0.1 and 1.1±0.1 MJ m -2 d -1 in Year 1 and Year 2, respectively. As a result, the Bowen ratio was <1 during most of the two-year period, with the lowest summer value at 0.14. The vapor pressure deficit explained 35% of the variation in half-hourly LE, while the temperature difference between the water surface and air explained 65% of the variation in half-hourly H. Western Lake Erie acted as a small carbon sink holding -19.0±5.4 and -40.2±13.3 g C m -2 in the first and second summers (May-September) but as an annual source of 77.7±18.6 and 49.5±17.9 g C m -2 yr -1 in Year 1 and Year 2, respectively. The CO 2 flux ( 2 CO F ) rate varied from -0.45 g C m -2 d -1 to 0.98 g C m -2 d -1 . Similar to LE, 2 CO F had noticeable diurnal changes during the months that had high chlorophyll a months, but not during other months. A significantly negative correlation (P<0.05) was found between 2 CO F and chlorophyll a on monthly fluxes. Three gapfilling methods, including marginal distribution sampling (MDS), mean diurnal variation (MDV) and monthly mean, were quantitatively assessed, yielding an uncertainty of 4%, 6% and 10% in LE, H and 2 CO F , respectively.
Cuadernos de Investigación Geográfica, 2020
According to model projections, increases in the frequency and intensity of heatwaves are expected all over the world. This study analyzed, for the first time, the effect of heatwaves events on long-term surface latent (LE) and sensible heat fluxes (H) from two shallow lakes: La Salada lake (LS - 39°27′ S, 62°42′ W) and Sauce Grande lake (SG - 38°57′ S, 61°24′ W). The main drivers of LE and H are wind speed and direction, relative humidity, and the difference between air and water temperature. We found that the daily values of both fluxes were highly fluctuating. Mean daily H values ranged between -309.4 to 200.5 W m-2 and -78.6 to 104.8 W m-2 in LS and SG, respectively. LE oscillated between -152 and 463.9 W m-2 and between -59.2 and 360.1 W m-2 in LS and SG, respectively. Both fluxes decreased with the passage of heatwaves events, presenting a high variation in its amplitude. Changes up to 96% in mean daily LE and 671% in mean daily H for LS and up to 25% in LE and 987% in H for S...
Surface energy balance calculations for small northern lakes
International Journal of Climatology, 2006
An energy balance model is used to determine diurnal surface energy balance components for three different sized high-latitude Canadian lakes in the Mackenzie River Basin (MRB) during the open water seasons of 2000, 2001, and 2002. Surface net radiation is derived from the component fluxes of the radiation balance. Turbulent heat fluxes are calculated using the aerodynamic method with input from local meteorological stations and experimentally derived drag coefficients. Lake heat storage, determined as a residual of the surface energy balance, is used together with measured water temperature profiles to calculate the daily mixing layer depth. The model uses readily available meteorological inputs for radiation calculations. Verification results for surface energy balance components show mean bias error (MBE) generally less than 5% of the mean measured daily fluxes and root mean square error (RMSE) less than 38%, which decreases to less than 16% for 10-day averaging periods. The model tends to overestimate net radiation by 7% and latent and sensible heat fluxes by about 4% and 1%, respectively, on average. Inferred slab layer depths indicate that the shallowest lake was isothermal while the deeper lakes showed temporal variations as expected.
Automated Mapping of Surface Water Temperature in the Great Lakes
Journal of Great Lakes Research, 1999
A procedure for producing daily cloud-free maps of surface water temperature in the Great Lakes has been developed. It is based on satellite-derived AVHRR (Advanced Very High Resolution Radiometer) imagery from NOAA's CoastWatch program. The maps have a nominal resolution of 2.6 km and provide as complete as possible coverage of the Great Lakes on a daily basis by using previous imagery to estimate temperatures in cloud covered areas. Surface water temperature estimates derived from this procedure compare well with water temperatures measured at the eight NOAA weather buoys in the lakes. The mean difference between the buoy temperature and the satellite-derived temperature estimates is less than 0.5°C for all buoys. The root mean square differences range from 1.10 to 1.76°C.
Latent Heat Flux from Small Sheltered Lakes
Boundary-layer Meteorology - BOUND-LAY METEOROL, 1998
The dependency of the latent heat flux on the over-water fetch on lakes surrounded by tall, dense forest was studied by making use of measurements made on two different-sized lakes. The measurements were made during the NOPEX (Northern Hemisphere Climate-Processes Land Surface Experiment) field campaign. It was found that, in the case of a typical Scandinavian lake with a size of less than 10 km2, the latent heat flux will increase as a function of over-water fetch due to the increase of wind speed and in spite of the increased air humidity. This also has implications on area-averaged fluxes: when two lakes having similar shorelines, lake water temperatures and solar radiation conditions are compared, then the evaporation per unit area is smaller from the smaller lake. When the lakes are large, with fetches of several kilometres, then the significance of sheltering is small. If point measurements are used for the estimation of area-averaged latent heat fluxes from lakes with short f...