Sensitivity and Uncertainty of a Long-Term, High-Resolution, Global, Terrestrial Sensible Heat Flux Data Set

2018 ◽  
Vol 123 (10) ◽  
pp. 4988-5000 ◽  
Author(s):  
Amanda L. Siemann ◽  
Nathaniel Chaney ◽  
Eric F. Wood
Keyword(s):  
Heat Flux ◽  
High Resolution ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Data Set ◽  
Flux Data

Characteristics of Long-term Surface Heat Source and Its Climate Influence Factors in Central Tibetan Plateau

2021 ◽  
Author(s):  
Zeyong Hu ◽  
Xiaoqiang Yan
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Sensible Heat Flux ◽  
Surface Heat ◽  
Sensible Heat ◽  
Net Radiation ◽  
Maximum Value

<p>Based on multi-level AWS data during 2001 to 2015 and eddy covariance data during 2011 to 2014 at Nagqu Station of Plateau Climate and Environment, the turbulent fluxes were calculated by a surface energy balance combination (CM) and eddy covariance ( EC) method. A long-term heat fluxes and surface heat source were obtained with comparison and correction of EC and CM fluxes. The surface energy closure ratio is close to 1 in spring, summer and autumn. But it reaches to 1.34 in winter due to low net radiation observation value on snow surface. The sensible heat flux shows a ascend trend while latent heat flux shows a descend trend during 2002 to 2015. The surface heat source shows a descend trend. The analysis of the surface heat source indicates that it has a significant relationship with net radiation flux, surface temperature, soil moisture and wind speed. Particularly, the surface heat source has a significant response to net radiation flux throughout the year. There are obvious influences of surface temperature and soil moisture on the surface heat source in spring, autumn and winter. And the influence of wind speeds on surface heat source is strong only in spring. The annual variation of sensible heat flux and latent heat flux are obvious. Sensible heat flux reaches the maximum value of the year in April and the minimum value in July. however, latent heat flux shows the maximum value in July and the minimum value in January. </p>

A long-term Climatology of Planetary Boundary Layer Height over the Tibetan Plateau revealed by ERA5

2020 ◽  
Author(s):  
Nils Slättberg ◽  
Deliang Chen
Keyword(s):  
Heat Flux ◽  
Monsoon Season ◽  
Sensible Heat Flux ◽  
Dry Season ◽  
The Tibetan Plateau ◽  
Climate Variables ◽  
Sensible Heat ◽  
Boundary Layer Height ◽  
Surface Sensible Heat Flux

<p>The Planetary Boundary Layer Height (PBLH) is important for the exchange of energy, water, and momentum between the surface and the free atmosphere, making it a significant factor in studies of surface climate and atmospheric circulation. Over the Tibetan Plateau (TP) - a vast elevated heat source exerting significant influence on the Asian monsoon systems - the climate is changing rapidly. Among the many climate variables expected to change as global temperatures rise is the PBLH which, in addition to temperature profile, mechanical turbulence production, vertical velocity, and horizontal advection, is highly dependent on the surface sensible heat  fluxes. Our understanding of PBLH over the TP is very limited, although scattered estimates has indicated that it sometimes reach unusual heights – up to the vicinity of the tropopause. Long-term assessment of PBLH covering the whole TP is hampered by the fact that observations are scarce in time and space. This study takes advantage of a recently available high-resolution reanalysis (ERA5) for 1979-2018 to create a multi-decadal climatology of PBLH over the TP, and assess the seasonality, interannual variation and long-term trend of PBLH in relation to other climate variables such as tropopause height and surface sensible heat flux as well as large-scale atmospheric circulation. </p><p>The results show that the most prominent feature of the PBLH trend is a large region of decline in the central TP during the monsoon season. Notably, this is a region where the temperature increase is smaller than in the rest of the region, and the precipitation shows a statistically significant increasing trend. Increased cloudiness may therefore have decreased the surface heating and thus the sensible heat flux and PBLH. Assessing the spatially averaged trends for the first and second halves of the period separately reveals that the monsoon season PBLH does in fact increase during the first half of the period. In the dry season in contrast, the spatially averaged PBLH decreases by almost 30 meter per decade during the first half of the period and increases slightly in the second. Although none of the spatially averaged PBLH trends are statistically significant at the 95% level, it can be noted that the shift from decreasing to increasing PBLH for the dry season is in accordance with a recent study of spring sensible heat flux over the TP. The aforementioned study found that although the sensible heat flux has been declining because of wind speed decreases, it has recently started to recover in response to an increased difference between the ground surface temperature and the air temperature. Given that the PBLH is highly dependent on the surface sensible heat flux, this decline and recovery may very well have produced the PBLH trends for the dry season. In the monsoon season, with cloudy conditions and less solar radiation reaching the ground, other factors are likely of greater importance for the PBLH.</p>

scholarly journals A ‘hurricane-like’ polar low fuelled by sensible heat flux: high-resolution numerical simulations

2012 ◽  
Vol 138 (666) ◽  
pp. 1308-1324 ◽  
Author(s):  
Ivan Føre ◽  
Jón Egill Kristjánsson ◽  
Erik W. Kolstad ◽  
Thomas J. Bracegirdle ◽  
Øyvind Saetra ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Resolution ◽  
Numerical Simulations ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Polar Low

Long-term Trend of Planetary Boundary Layer Height in Climate Models and Observations over East Asia

2020 ◽  
Author(s):  
Man Yue ◽  
Minghuai Wang
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
East Asia ◽  
Planetary Boundary Layer ◽  
Climate Models ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Term Trend ◽  
Long Term Trend

<p>Abstract: Planetary boundary layer (PBL) plays an important role in climate and air quality simulations. Large uncertainties remain in understanding the long-term trend of PBL height (PBLH). In this study, radiosonde data and ERA-Interim reanalysis data are applied to reveal the critical climate factors and mechanisms dominating the long-term trend of PBLH over East Asia. Our results show that, observed long-term shift in PBLH trend is found to be consistent with changes in sensible heat flux (SHFLX), net downward surface shortwave flux (SWFLX) and low cloud cover (LCC). Increases in soil moisture and LCC in recent years can modulate the energy partition through the SHFLX and modifying the surface radiation budget, and further lead to the long-term shift trend of PBLH. Long-term trend of PBLH over East Asia is further examined in climate models (including NCAR CESM2) and data from the Coupled Model Inter-comparison Project Phase 6 (CMIP6) experiments. The global climate models are not able to reproduce the long-term trend of PBLH over East Asia. CESM2 is shown to not catch the long-term variability of sensible heat flux and surface shortwave flux. Further analysis is performed to examine how the trend of mean PBLH and extreme low PBLH may be different.</p>

Progress in Preliminary Processing of Eddy Covariance Flux Data

2013 ◽  
Vol 807-809 ◽  
pp. 1909-1914
Author(s):  
Xin Ying Tang ◽  
Lin Han ◽  
Ge Wang
Keyword(s):  
Heat Flux ◽  
Eddy Covariance ◽  
Sensible Heat Flux ◽  
Observation Data ◽  
Sensible Heat ◽  
Data Quality Control ◽  
Flux Data ◽  
Preliminary Processing ◽  
Processing Software ◽  
The Difference

The eddy covariance (EC) technique of observation is a standard method for direct measurement of CO2, H2O and energy flux between vegetation and the atmosphere, the calculation formula of which is based on a series of assumptions. In reality, the assumed conditions are usually not satisfied, and the flux data is subject to significant deviation, thus the measured result should be corrected. The difference in data processing may lead to obvious difference in the calculated results of sensible heat flux and latent heat flux, while the universality of existing flux processing software is not verified. On the basis of domestic and foreign literature, this paper systematically summarizes and evaluates the preliminary processing of EC observation data in the aspects of principle and method of flux observation, rejection and interpolation of flux data, quality control and evaluation of flux data.

Quantifying the influence of management strategies on surface radiation budgets and energy patterns in tea fields

2021 ◽  
Author(s):  
Siang-Heng Wang ◽  
Jehn-Yih Juang
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Management Strategies ◽  
Sensible Heat Flux ◽  
Radiation Budget ◽  
Sensible Heat ◽  
Crop Fields ◽  
Conventional Field ◽  
Energy Components

Abstract The surface energy balance from canopy to landscape scales in crop fields plays an essential role in surface-atmosphere interactions, and it is strongly influenced by the management strategies and field practices of farmers. To characterize how different agricultural practices of farmers affect the microenvironment in perennial crop fields, long-term observation of the radiation budget and energy components under different field practices was undertaken in two neighboring tea fields with different management strategies (a conventional operation and an organic-certified field managed by different farmers) in northern Taiwan. The results showed that the difference in the radiation budget in these two tea fields was minor (only 1% for net radiation), but the differences in the energy components were more significant (sensible heat was 10% lower and latent heat was 25% higher in the organic-certified field than in the conventional field) due to highly distinct practices in these two fields. This finding implies that the organic-certified application could lower the partitioning of sensible heat flux and increase the latent heat flux, thereby reducing the temperature variation and decreasing the vapor pressure deficit. The organic-certified field reduced the surface heating in terms of the long-term energy patterns. This study’s findings also indicate that field practices in conventional field can increase the sensible heat flux (51.5% at noon time) on short-term time scales, compared with only 9.6% in organic-certified field. Furthermore, this study offers a comprehensive understanding of tea field practices, a scientific basis for in-field water conservation, and a quantitative analysis for modeling from micro to regional scales.

scholarly journals Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

1990 ◽  
Vol 36 (123) ◽  
pp. 217-221 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole B. Olesen
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Temperature Response ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

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