scholarly journals Direct and indirect effects of atmospheric conditions and soil moisture on surface energy partitioning revealed by a prolonged drought at a temperate forest site

2006 ◽  
Vol 111 (D16) ◽  
Author(s):  
Lianhong Gu ◽  
Tilden Meyers ◽  
Stephen G. Pallardy ◽  
Paul J. Hanson ◽  
Bai Yang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Surface Energy ◽  
Indirect Effects ◽  
Temperate Forest ◽  
Energy Partitioning ◽  
Forest Site ◽  
Direct And Indirect Effects ◽  
Atmospheric Conditions ◽  
Prolonged Drought

scholarly journals Satellite‐Based Assessment of Land Surface Energy Partitioning–Soil Moisture Relationships and Effects of Confounding Variables

2019 ◽  
Vol 55 (12) ◽  
pp. 10657-10677 ◽  
Author(s):  
Andrew F. Feldman ◽  
Daniel J. Short Gianotti ◽  
Isabel F. Trigo ◽  
Guido D. Salvucci ◽  
Dara Entekhabi
Keyword(s):  
Soil Moisture ◽  
Surface Energy ◽  
Land Surface ◽  
Energy Partitioning ◽  
Confounding Variables

scholarly journals Intercomparison of the Surface Energy Partitioning in CMIP5 Simulations

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 602 ◽  
Author(s):  
Yang ◽  
Wang ◽  
Huang
Keyword(s):  
Soil Moisture ◽  
Surface Energy ◽  
Land Surface ◽  
Radiative Forcing ◽  
Climate Models ◽  
Water Cycle ◽  
Potential Evapotranspiration ◽  
Sensible Heat Flux ◽  
Coupled Model ◽  
Energy Partitioning

The warming climate significantly modifies the global water cycle. Global evapotranspiration has increased over the past decades, yet climate models agree on the drying trend of land surface. In this study, we conducted an intercomparison analysis of the surface energy partitioning across Coupled Model Intercomparison Phase 5 (CMIP5) simulations and evaluated its behaviour with surface temperature and soil moisture anomalies, against the theoretically derived thermodynamic formula. Different responses over land and sea surfaces to elevated greenhouse gas emissions were found. Under the Representative Concentration Pathway of +8.5 W m−2 (RCP8.5) warming scenario, the multi-model mean relative efficiency anomaly from CMIP5 simulations is 3.83 and −0.12 over global sea and land, respectively. The significant anomaly over sea was captured by the thermodynamic solution based on the principle of maximum entropy production, with a mean relative error of 14.6%. The declining trend over land was also reproduced, but an accurate prediction of its small anomaly will require the inclusions of complex physical processes in future work. Despite increased potential evapotranspiration under rising temperatures, both CMIP5 simulations and thermodynamic principles suggest that the soil moisture-temperature feedback cannot support long-term enhanced evapotranspiration at the global scale. The dissipation of radiative forcing eventually shifts towards sensible heat flux and accelerates the warming over land, especially over South America and Europe.

scholarly journals Reviews and syntheses: Changing ecosystem influences on soil thermal regimes in northern high-latitude permafrost regions

2018 ◽  
Author(s):  
Michael M. Loranty ◽  
Benjamin W. Abbott ◽  
Daan Blok ◽  
Thomas A. Douglas ◽  
Howard E. Epstein ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Thermal Properties ◽  
Surface Energy ◽  
Terrestrial Ecosystem ◽  
Energy Partitioning ◽  
Climate Feedback ◽  
Permafrost Soil ◽  
Thermal Dynamics ◽  
Soil Thermal Properties ◽  
Permafrost Soils

Abstract. Permafrost soils in arctic and boreal ecosystems store twice the amount of current atmospheric carbon that may be mobilized and released to the atmosphere as greenhouse gases when soils thaw under a warming climate. This permafrost carbon climate feedback is among the most globally important terrestrial biosphere feedbacks to climate warming, yet its magnitude remains highly uncertain. This uncertainty lies in predicting the rates and spatial extent of permafrost thaw and subsequent carbon cycle processes. Terrestrial ecosystem influences on surface energy partitioning exert strong control on permafrost soil thermal dynamics and are critical for understanding permafrost soil responses to climate change and disturbance. Here we review how arctic and boreal ecosystem processes influence permafrost soils and characterize key ecosystem changes that regulate permafrost responses to climate. While many of the ecosystem characteristics and processes affecting soil thermal dynamics have been examined in isolation, interactions between processes are less well understood. In particular connections between vegetation, soil moisture, and soil thermal properties affecting permafrost conditions could benefit from additional research. In particular, connections between vegetation, soil moisture, and soil thermal properties affecting permafrost could benefit from additional research. Changes in ecosystem distribution and vegetation characteristics will alter spatial patterns of interactions between climate and permafrost. In addition to shrub expansion, other vegetation responses to changes in climate and disturbance regimes will all affect ecosystem surface energy partitioning in ways that are important for permafrost. Lastly, changes in vegetation and ecosystem distribution will lead to regional and global biophysical and biogeochemical climate feedbacks that may compound or offset local impacts on permafrost soils. Consequently, accurate prediction of the permafrost carbon climate feedback will require detailed understanding of changes in terrestrial ecosystem distribution and function and the net effects of multiple feedback processes operating across scales in space and time.

scholarly journals Effects of soil temperature and moisture on methane uptakes and nitrous oxide emissions across three different ecosystem types

2013 ◽  
Vol 10 (1) ◽  
pp. 927-965 ◽  
Author(s):  
G. J. Luo ◽  
R. Kiese ◽  
B. Wolf ◽  
K. Butterbach-Bahl
Keyword(s):  
Nitrous Oxide ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Tropical Forest ◽  
Environmental Conditions ◽  
Temperate Forest ◽  
Explanatory Power ◽  
Nitrous Oxide Emissions ◽  
Forest Site ◽  
Methane Uptake

Abstract. In this paper, we investigate similarities of effects of soil environmental drivers on year-round daily soil fluxes of nitrous oxide and methane for three distinct semi-natural or natural ecosystems: temperate spruce forest, Germany; tropical rain forest, Queensland, Australia; and ungrazed semi-arid steppe, Inner Mongolia, China. Annual cumulative fluxes of nitrous oxide and methane varied markedly among ecosystems, with nitrous oxide fluxes being highest for the tropical forest site (tropical forest: 0.96 kg N ha−1yr−1; temperate forest: 0.67 kg N ha−1yr−1; steppe: 0.22 kg N ha−1yr−1), while rates of soil methane uptake were approximately equal for the temperate forest (3.45 kg C ha−1yr−1) and the steppe (3.39 kg C ha−1yr−1), but lower for the tropical forest site (2.38 kg C ha−1yr−1). In order to allow for cross-site comparison of effects of changes in soil moisture and soil temperature on fluxes of methane and nitrous oxide, we used a normalization approach. Data analysis with normalized data revealed that across sites, optimum rates of methane uptake are found at environmental conditions representing approximately average site environmental conditions. This might have rather important implications for understanding effects of climate change on soil methane uptake potential, since any shift in environmental conditions is likely to result in a reduction of soil methane uptake ability. For nitrous oxide, our analysis revealed expected patterns: highest nitrous oxide emissions under moist and warm conditions and large nitrous oxide fluxes if soils are exposed to freeze-thawing effects at sufficient high soil moisture contents. However, the explanatory power of relationships of soil moisture or soil temperature to nitrous oxide fluxes remained rather poor (≤ 0.36). When combined effects of changes in soil moisture and soil temperature were considered, the explanatory power of our empirical relationships with regard to temporal variations in nitrous oxide fluxes were at maximum about 50%. This indicates that other controlling factors such as N and C availability or microbial community dynamics might exert a significant control on the temporal dynamic of nitrous oxide fluxes. Though underlying microbial processes such as nitrification and denitrification are sensitive to changes in the environmental regulating factors, important regulating factors like moisture and temperature seem to have both synergistic and antagonistic effects on the status of other regulating factors. Thus we cannot expect a~simple relationship between them and the pattern in the rate of emissions, associated with denitrification or nitrification in the soils. In conclusion, we hypothesize that our approach of data generalization may prove beneficial for the development of environmental response models which can be used across sites, and which are needed to help better understanding climate change feedbacks on biospheric sinks or sources of nitrous oxide and methane.

scholarly journals Reducing soil moisture measurement scale mismatch to improve surface energy flux estimation

2016 ◽  
Author(s):  
Joost Iwema ◽  
Rafael Rosolem ◽  
Mostaquimur Rahman ◽  
Eleanor Blyth ◽  
Thorsten Wagener
Keyword(s):  
Soil Moisture ◽  
Surface Energy ◽  
Energy Flux ◽  
Spatial Scales ◽  
Cosmic Ray ◽  
Energy Partitioning ◽  
Surface Model ◽  
Surface Energy Flux ◽  
Soil Moisture Data ◽  
Scale Mismatch

Abstract. At the so-called hyper-resolution scale (i.e. grid cells of 1 km2) Land Surface Model (LSM) parameters are sometimes calibrated with Eddy-Covariance (EC) data and Point Scale (PS) soil moisture data. However, measurement scales of EC and PS data differ substantially. In our study, we investigated the impact of reducing the scale mismatch between surface energy flux data and soil moisture data by replacing PS soil moisture data with observations derived from Cosmic-Ray Neutron Sensors (CRNS) made at larger spatial scales. Five soil-evapotranspiration parameters of the Joint UK Land Environment Simulator (JULES) were calibrated against PS and CRNS soil moisture data separately. We calibrated the model for twelve sites in the USA representing a range of climatic, soil, and vegetation conditions. The improvement in surface energy partitioning for the two calibration solutions was assessed by comparing to EC data and to a version of JULES runs with default parameter values. We found that simulated surface energy partitioning did not differ substantially between the PS and CRNS calibrations, despite their differences in actual soil moisture observations. We concluded that potential differences due to distinct spatial scales represented by the PS and CRNS soil moisture sensor techniques were substantially undermined by the weak coupling between soil moisture and evapotranspiration within JULES.

scholarly journals Effects of soil temperature and moisture on methane uptake and nitrous oxide emissions across three different ecosystem types

2013 ◽  
Vol 10 (5) ◽  
pp. 3205-3219 ◽  
Author(s):  
G. J. Luo ◽  
R. Kiese ◽  
B. Wolf ◽  
K. Butterbach-Bahl
Keyword(s):  
Nitrous Oxide ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Tropical Forest ◽  
Environmental Conditions ◽  
Temperate Forest ◽  
Explanatory Power ◽  
Nitrous Oxide Emissions ◽  
Forest Site ◽  
Methane Uptake

Abstract. In this paper, we investigate similarities of effects of soil environmental drivers on year-round daily soil fluxes of nitrous oxide and methane for three distinct semi-natural or natural ecosystems: temperate spruce forest, Germany; tropical rain forest, Queensland, Australia; and ungrazed semi-arid steppe, Inner Mongolia, China. Annual cumulative fluxes of nitrous oxide and methane varied markedly among ecosystems, with nitrous oxide fluxes being highest for the tropical forest site (tropical forest: 0.96 kg N ha−1 yr−1; temperate forest: 0.67 kg N ha−1 yr−1; steppe: 0.22 kg N ha−1 yr−1), while rates of soil methane uptake were approximately equal for the temperate forest (−3.45 kg C ha−1 yr−1) and the steppe (−3.39 kg C ha−1 yr−1), but lower for the tropical forest site (−2.38 kg C ha−1 yr−1). In order to allow for cross-site comparison of effects of changes in soil moisture and soil temperature on fluxes of methane and nitrous oxide, we used a normalization approach. Data analysis with normalized data revealed that, across sites, optimum rates of methane uptake are found at environmental conditions representing approximately average site environmental conditions. This might have rather important implications for understanding effects of climate change on soil methane uptake potential, since any shift in environmental conditions is likely to result in a reduction of soil methane uptake ability. For nitrous oxide, our analysis revealed expected patterns: highest nitrous oxide emissions under moist and warm conditions and large nitrous oxide fluxes if soils are exposed to freeze–thawing effects at sufficiently high soil moisture contents. However, the explanatory power of relationships of soil moisture or soil temperature to nitrous oxide fluxes remained rather poor (R2 ≤ 0.36). When combined effects of changes in soil moisture and soil temperature were considered, the explanatory power of our empirical relationships with regard to temporal variations in nitrous oxide fluxes were at maximum about 50%. This indicates that other controlling factors such as N and C availability or microbial community dynamics might exert a significant control on the temporal dynamic of nitrous oxide fluxes. Though underlying microbial processes such as nitrification and denitrification are sensitive to changes in the environmental regulating factors, important regulating factors like moisture and temperature seem to have both synergistic and antagonistic effects on the status of other regulating factors. Thus we cannot expect a simple relationship between them and the pattern in the rate of emissions, associated with denitrification or nitrification in the soils. In conclusion, we hypothesize that our approach of data generalization may prove beneficial for the development of environmental response models, which can be used across sites, and which are needed to help achieve a better understanding of climate change feedbacks on biospheric sinks or sources of nitrous oxide and methane.

Direct and indirect effects of dynamic social impact

2005 ◽  
Author(s):  
Dana M. Binder ◽  
Martin J. Bourgeois ◽  
Christine M. Shea Adams
Keyword(s):  
Indirect Effects ◽  
Social Impact ◽  
Direct And Indirect Effects
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