scholarly journals Functional convergence of biosphere–atmosphere interactions in response to meteorological conditions

2021 ◽  
Vol 18 (7) ◽  
pp. 2379-2404
Author(s):  
Christopher Krich ◽  
Mirco Migliavacca ◽  
Diego G. Miralles ◽  
Guido Kraemer ◽  
Tarek S. El-Madany ◽  
...  
Keyword(s):  
Land Surface ◽  
Water Cycle ◽  
Causal Structure ◽  
Spatial Scales ◽  
Terrestrial Ecosystems ◽  
Mediterranean Ecosystems ◽  
Meteorological Conditions ◽  
Surface Fluxes ◽  
Time Lags ◽  
Vegetation Types

Abstract. Understanding the dependencies of the terrestrial carbon and water cycle with meteorological conditions is a prerequisite to anticipate their behaviour under climate change conditions. However, terrestrial ecosystems and the atmosphere interact via a multitude of variables across temporal and spatial scales. Additionally these interactions might differ among vegetation types or climatic regions. Today, novel algorithms aim to disentangle the causal structure behind such interactions from empirical data. The estimated causal structures can be interpreted as networks, where nodes represent relevant meteorological variables or land-surface fluxes and the links represent the dependencies among them (possibly including time lags and link strength). Here we derived causal networks for different seasons at 119 eddy covariance flux tower observations in the FLUXNET network. We show that the networks of biosphere–atmosphere interactions are strongly shaped by meteorological conditions. For example, we find that temperate and high-latitude ecosystems during peak productivity exhibit biosphere–atmosphere interaction networks very similar to tropical forests. In times of anomalous conditions like droughts though, both ecosystems behave more like typical Mediterranean ecosystems during their dry season. Our results demonstrate that ecosystems from different climate zones or vegetation types have similar biosphere–atmosphere interactions if their meteorological conditions are similar. We anticipate our analysis to foster the use of network approaches, as they allow for a more comprehensive understanding of the state of ecosystem functioning. Long-term or even irreversible changes in network structure are rare and thus can be indicators of fundamental functional ecosystem shifts.

scholarly journals Functional convergence of biosphere–atmosphere interactions in response to meteorology

2020 ◽  
Author(s):  
Christopher Krich ◽  
Mirco Migliavacca ◽  
Diego G. Miralles ◽  
Guido Kraemer ◽  
Tarek S. El-Madany ◽  
...  
Keyword(s):  
Land Surface ◽  
Water Cycle ◽  
Causal Structure ◽  
Terrestrial Ecosystems ◽  
Mediterranean Ecosystems ◽  
Meteorological Conditions ◽  
Surface Fluxes ◽  
Vegetation Types ◽  
Climatic Regions ◽  
Novel Algorithms

Abstract. Understanding the dependencies of the terrestrial carbon and water cycle is a prerequisite to anticipate their behaviour under climate change conditions. However, terrestrial ecosystems and the atmosphere interact via a multitude of variables, time- and space scales. Additionally the interactions might differ among vegetation types or climatic regions. Today, novel algorithms aim to disentangle the causal structure behind such interaction from empirical data. Visualising the estimated structure in networks, the nodes represent relevant meteorological determinants and land-surface fluxes, and the links dependencies among them possibly including their lag and strength. Here we show that biosphere–atmosphere interactions are strongly shaped by meteorological conditions. For example, we find that temperate and high latitude ecosystems during peak productivity exhibit very similar biosphere–atmosphere interaction networks as tropical forests. In times of anomalous conditions like drought though, both ecosystems behave more like Mediterranean ecosystems during their dry season. Our results demonstrate that ecosystems from different climate or vegetation types have similar biosphere–atmosphere interactions if their meteorological conditions are similar. We anticipate our analysis to foster the use of network approaches as they allow a more comprehensive understanding of the state of ecosystem functioning. Long term or even irreversible changes in network structure are rare and thus can be indicators of fundamental functional ecosystem shifts.

scholarly journals Vegetation dynamics and soil water balance in a water-limited Mediterranean ecosystem on Sardinia, Italy

2008 ◽  
Vol 12 (6) ◽  
pp. 1257-1271 ◽  
Author(s):  
N. Montaldo ◽  
J. D. Albertson ◽  
M. Mancini
Keyword(s):  
Soil Water ◽  
Land Surface ◽  
Vegetation Dynamics ◽  
Mediterranean Ecosystems ◽  
Surface Fluxes ◽  
Annual Rainfall ◽  
Woody Vegetation ◽  
Wide Range ◽  
Hydrometeorological Conditions

Abstract. Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFTs, e.g. grass and woody vegetation) competing for water. Mediterranean ecosystems are also commonly characterized by strong inter-annual rainfall variability, which influences the distributions of PFTs that vary spatially and temporally. An extensive field campaign in a Mediterranean setting was performed with the objective to investigate interactions between vegetation dynamics, soil water budget and land-surface fluxes in a water-limited ecosystem. Also a vegetation dynamic model (VDM) is coupled to a 3-component (bare soil, grass and woody vegetation) Land surface model (LSM). The case study is in Orroli, situated in the mid-west of Sardegna within the Flumendosa river basin. The landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. Land surface fluxes, soil moisture and vegetation growth were monitored during the May 2003–June 2006 period. Interestingly, hydrometeorological conditions of the monitored years strongly differ, with dry and wet years in turn, such that a wide range of hydrometeorological conditions can be analyzed. The coupled VDM-LSM model is successfully tested for the case study, demonstrating high model performance for the wide range of eco-hydrologic conditions. Results demonstrate also that vegetation dynamics are strongly influenced by the inter-annual variability of atmospheric forcing, with grass leaf area index changing significantly each spring season according to seasonal rainfall amount.

An Integrated Variational Framework for Mapping Evapotranspiration by Assimilating GOES LST and SMAP data

2020 ◽  
Author(s):  
Leila farhadi ◽  
Abedeh Abdolghafoorian
Keyword(s):  
Soil Moisture ◽  
Great Plains ◽  
Land Surface ◽  
Water Cycle ◽  
Spatial Scales ◽  
Coupled Model ◽  
Balance Model ◽  
Parameter Estimates ◽  
Dynamic Feedback ◽  
Unknown Parameters

<p>Evapotranspiration (ET) is a key component of terrestrial water cycle that plays an important role in the Earth system. Aaccurate estimation of ET is crucial in various hydrological, meteorological, and agricultural applications. In situ measurements of ET are costly and cannot be readily scaled to regional scales relevant to weather and climate studies. Therefore, there is a need for techniques to make quantitative estimates of ET using land surface state observations that are widely available from remote sensing across a range of spatial scales.</p><p>In this work, A variational data (VDA) assimilation framework is developed to estimate ET by assimilating Soil Moisture Active Passive (SMAP) soil moisture and Geostationary Operational Environmental Satellite (GOES) land surface temperature data into a coupled dual-source energy and water balance model.</p><p>The VDA framework estimates the key parameters of the coupled model, which regulate the partitioning of available energy (i.e., neutral bulk heat transfer coefficient (CH<sub>N</sub>) and evaporative fraction from soil (EF<sub>S</sub>) and canopy (EF<sub>C</sub>)). The uncertainties of the retrieved unknown parameters are estimated through the inverse of Hessian of cost function, obtained using the Lagrangian methodology. Analysis of the second-order information provides a tool to identify the optimum parameter estimates and guides towards a well-posed estimation problem.</p><p>The VDA framework is implemented over an area of 21780 km<sup>2</sup> in the U.S. Southern Great Plains (with computational grid size of 0.05 degree) during a nine-month period. The maps of retrieved evaporation and transpiration are used to study a number of dynamic feedback mechanisms between the land and atmosphere, such as the dependence of evapotranspiration on vegetation and soil moisture.</p>

scholarly journals Implementation and validation of a new irrigation scheme in the ISBA land surface model

2021 ◽  
Author(s):  
Arsène Druel ◽  
Simon Munier ◽  
Anthony Mucia ◽  
Clément Albergel ◽  
Jean-Christophe Calvet
Keyword(s):  
Land Surface ◽  
Vegetation Type ◽  
Spatial Scales ◽  
Terrestrial Ecosystems ◽  
Moisture Stress ◽  
Surface Model ◽  
Irrigation Scheme ◽  
Area Index ◽  
Natural Processes ◽  
The Impact

Abstract. With an increase in the number of natural processes represented, global land surface models (LSMs) have become more and more accurate in representing natural terrestrial ecosystems. However, they are still limited, especially in the representation of the impact of agriculture on land surface variables. This is particularly true for agro-hydrological processes related to a strong human control on freshwater. While most LSMs consider natural processes only, the development of human-related processes, e.g. crop phenology and irrigation in LSMs, is key. In this study we present the implementation of a new irrigation scheme in the ISBA (Interaction between Soil, Biosphere, and Atmosphere) LSM. This highly flexible scheme is designed to account for various configurations and can be applied at different spatial scales. For each vegetation type within a model grid cell, three irrigation systems can be used at the same time. A limited number of parameters are used to control (1) the amount of water used for irrigation, (2) irrigation triggering (based on the soil moisture stress) and (3) crop seasonality (emergence, harvesting). After a presentation of the simulations of the new scheme at a plot scale, an evaluation is proposed over Nebraska (USA). This region is chosen for its high irrigation density and because independent observations of irrigation practices can be used to verify the simulated irrigation amounts. The ISBA simulations with and without the irrigation scheme are compared to different satellite-based observations. The comparison shows that the irrigation scheme improves the simulated vegetation variables such as leaf area index and gross primary productivity and other variables largely impacted by irrigation such as evapotranspiration and land surface temperature. In addition to a better representation of land surface processes, the results point to potential applications of this new version of the ISBA model for water resource monitoring and climate change impact studies.

scholarly journals The new portfolio of global precipitation data products of the Global Precipitation Climatology Centre suitable to assess and quantify the global water cycle and resources

2016 ◽  
Vol 374 ◽  
pp. 29-34 ◽  
Author(s):  
Udo Schneider ◽  
Markus Ziese ◽  
Anja Meyer-Christoffer ◽  
Peter Finger ◽  
Elke Rustemeier ◽  
...  
Keyword(s):  
Land Surface ◽  
Water Cycle ◽  
Spatial Scales ◽  
Research Programme ◽  
Special Importance ◽  
Product Portfolio ◽  
Precipitation Climatology ◽  
Global Precipitation Climatology Centre ◽  
The World ◽  
Global Precipitation

Abstract. Precipitation plays an important role in the global energy and water cycle. Accurate knowledge of precipitation amounts reaching the land surface is of special importance for fresh water assessment and management related to land use, agriculture and hydrology, incl. risk reduction of flood and drought. High interest in long-term precipitation analyses arises from the needs to assess climate change and its impacts on all spatial scales. In this framework, the Global Precipitation Climatology Centre (GPCC) has been established in 1989 on request of the World Meteorological Organization (WMO). It is operated by Deutscher Wetterdienst (DWD, National Meteorological Service of Germany) as a German contribution to the World Climate Research Programme (WCRP). This paper provides information on the most recent update of GPCC's gridded data product portfolio including example use cases.

scholarly journals Hydroclimatology of the Nile: results from a regional climate model

2005 ◽  
Vol 2 (1) ◽  
pp. 319-364 ◽  
Author(s):  
Y. A. Mohamed ◽  
B. J. J. M. van den Hurk ◽  
H. H. G. Savenije ◽  
W. G. M. Bastiaanssen
Keyword(s):  
Land Surface ◽  
Climate Model ◽  
Water Cycle ◽  
Regional Climate ◽  
Hydrologic Model ◽  
Surface Fluxes ◽  
Monthly Precipitation ◽  
Moisture Recycling ◽  
White Nile ◽  
Regional Water

Abstract. This paper is the result of the first regional coupled climatic and hydrologic model of the Nile. For the first time the interaction between the climatic processes and the hydrological processes on the land surface have been fully coupled. The hydrological model is driven by the rainfall and the energy available for evaporation generated in the climate model, and the runoff generated in the catchment is again routed over the wetlands of the Nile to supply moisture for atmospheric feedback. The results obtained are surprisingly accurate given the extremely low runoff coefficients in the catchment. The paper presents model results over the sub-basins: Blue Nile, White Nile, Atbara river and the Main Nile for the period 1995 to 2000, but focuses on the Sudd swamp. Limitations in both the observational data and the model are discussed. It is concluded that the model provides a sound representation of the regional water cycle over the Nile. The model is used to describe the regional water cycle in the Nile basin in terms of atmospheric fluxes, land surface fluxes and land surface-climate feedbacks. The monthly moisture recycling ratio (i.e. locally generated/total precipitation) over the Nile varies between 8 and 14%, with an annual mean of 11%, which implies that 89% of the Nile water resources originates from outside the basin physical boundaries. The monthly precipitation efficiency varies between 12 and 53%, and the annual mean is 28%. The mean annual result of the Nile regional water cycle is compared to that of the Amazon and the Mississippi basins.

scholarly journals Simulating of snow cover formation by the model of interaction between the land surface and the atmosphere (SWAP)

2019 ◽  
Vol 59 (2) ◽  
pp. 167-181
Author(s):  
E. M. Gusev ◽  
O. N. Nasonova
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
Spatial Scales ◽  
Hydrological Regime ◽  
Terrestrial Ecosystems ◽  
Swap Model ◽  
Necessary And Sufficient ◽  
Different Characteristics ◽  
Water Problems ◽  
Snow Cover Formation

In framework of the project «The Earth system Models – Snow Models Intercomparison Project» (ESMSnowMIP), calculations of snow storages were carried out on ten experimental sites organized for longterm monitoring of the snow cover variability in various regions of the globe. The calculation method is based on the physical and mathematical description of heat and moisture exchange processes occurring within the system «ground water – soil – vegetation cover/snow cover – surface layer of the atmosphere», and it is implemented in the form of the model of interaction between the land surface and the atmosphere (SWAP). The model was developed at the Institute of water problems (IWP) of Russian Academy of Sciences. The model makes possible to calculate components of water and heat balances and different characteristics of the hydrological regime of terrestrial ecosystems and river basins having different spatial scales and located in different natural conditions. Good quality of reproduction of the snow storages variability on all considered sites is reached that allows consideration of the SWAP model as one of the best models of the snow cover formation. Thus, the SWAP model has a sufficiently optimal degree of complexity of the algorithm for reproducing the dynamics of snow cover, which is necessary and sufficient in global and regional hydrological models describing formation of the water balance of the land in the cold regions of the planet, and can be used to create scenario forecasts of snow dynamics (as the important part of the cryosphere). This conclusion is verified by the results of using the SWAP model to reproduce long-term variability of snow storages in basins of the River Lena and the River Ob (with its tributary Irtysh) which are the two largest rivers of the Russian Federation. The calculated and measured characteristics of snow cover dynamics for these basins are shown to be in good agreement.

scholarly journals Vegetation dynamics and soil water balance in a water-limited Mediterranean ecosystem on Sardinia, Italy

2008 ◽  
Vol 5 (1) ◽  
pp. 219-255 ◽  
Author(s):  
N. Montaldo ◽  
J. D. Albertson ◽  
M. Mancini
Keyword(s):  
Soil Water ◽  
Land Surface ◽  
Vegetation Dynamics ◽  
Mediterranean Ecosystems ◽  
Surface Fluxes ◽  
Annual Rainfall ◽  
Woody Vegetation ◽  
Wide Range ◽  
Hydrometeorological Conditions

Abstract. Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFTs, e.g., grass and woody vegetation) competing for the water use. Mediterranean ecosystems are also commonly characterized by strong inter-annual rainfall variability, which influences the distributions of PFTs that vary spatially and temporally. With the objective to investigate interactions between vegetation dynamics, soil water budget and land-surface fluxes in a water-limited ecosystem, an extensive field campaign in a Mediterranean setting was performed. Also a vegetation dynamic model (VDM) is coupled to a 3-component (bare soil, grass and woody vegetation) Land surface model (LSM). The case study is in Orroli, situated in the mid-west of Sardegna within the Flumendosa river basin. The landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. Land surface fluxes, soil moisture and vegetation growth were monitored during the May 2003–June 2006 period. Interestingly, hydrometeorological conditions of the monitored years strongly differ, with dry and wet years in turn, such that a wide range of hydrometeorological conditions can be analyzed. The coupled VDM-LSM model is successfully tested for the case study, demonstrating high model performance for the wide range of eco-hydrologic conditions. The use of the VDM in the LSM is demonstrated to be essential when studying the climate-soil-vegetation interactions of these water-limited ecosystems. Results demonstrate also that vegetation dynamics are strongly influenced by the inter-annual variability of atmospheric forcing, with grass leaf area index changing significantly each spring season according to seasonal rainfall amount.

scholarly journals Standardisation of chamber technique for CO2, N2O and CH4 fluxes measurements from terrestrial ecosystems

2018 ◽  
Vol 32 (4) ◽  
pp. 569-587 ◽  
Author(s):  
Marian Pavelka ◽  
Manuel Acosta ◽  
Ralf Kiese ◽  
Núria Altimir ◽  
Christian Brümmer ◽  
...  
Keyword(s):  
Land Surface ◽  
Spatial Scales ◽  
Terrestrial Ecosystems ◽  
Observation System ◽  
Ecosystem Monitoring ◽  
Gas Fluxes ◽  
Trace Gas Fluxes ◽  
Quality Checks ◽  
Minimum Requirements ◽  
Chamber Measurements

Abstract Chamber measurements of trace gas fluxes between the land surface and the atmosphere have been conducted for almost a century. Different chamber techniques, including static and dynamic, have been used with varying degrees of success in estimating greenhouse gases (CO2, CH4, N2O) fluxes. However, all of these have certain disadvantages which have either prevented them from providing an adequate estimate of greenhouse gas exchange or restricted them to be used under limited conditions. Generally, chamber methods are relatively low in cost and simple to operate. In combination with the appropriate sample allocations, chamber methods are adaptable for a wide variety of studies from local to global spatial scales, and they are particularly well suited for in situ and laboratory-based studies. Consequently, chamber measurements will play an important role in the portfolio of the Pan-European long-term research infrastructure Integrated Carbon Observation System. The respective working group of the Integrated Carbon Observation System Ecosystem Monitoring Station Assembly has decided to ascertain standards and quality checks for automated and manual chamber systems instead of defining one or several standard systems provided by commercial manufacturers in order to define minimum requirements for chamber measurements. The defined requirements and recommendations related to chamber measurements are described here.

scholarly journals Hydroclimatology of the Nile: results from a regional climate model

2005 ◽  
Vol 9 (3) ◽  
pp. 263-278 ◽  
Author(s):  
Y. A. Mohamed ◽  
B. J. J. M. van den Hurk ◽  
H. H. G. Savenije ◽  
W. G. M. Bastiaanssen
Keyword(s):  
Land Surface ◽  
Climate Model ◽  
Water Cycle ◽  
Regional Climate ◽  
Hydrologic Model ◽  
Surface Fluxes ◽  
Monthly Precipitation ◽  
Nile Basin ◽  
Moisture Recycling ◽  
Regional Water

Abstract. This paper presents the result of the regional coupled climatic and hydrologic model of the Nile Basin. For the first time the interaction between the climatic processes and the hydrological processes on the land surface have been fully coupled. The hydrological model is driven by the rainfall and the energy available for evaporation generated in the climate model, and the runoff generated in the catchment is again routed over the wetlands of the Nile to supply moisture for atmospheric feedback. The results obtained are quite satisfactory given the extremely low runoff coefficients in the catchment. The paper presents the validation results over the sub-basins: Blue Nile, White Nile, Atbara river, the Sudd swamps, and the Main Nile for the period 1995 to 2000. Observational datasets were used to evaluate the model results including radiation, precipitation, runoff and evaporation data. The evaporation data were derived from satellite images over a major part of the Upper Nile. Limitations in both the observational data and the model are discussed. It is concluded that the model provides a sound representation of the regional water cycle over the Nile. The sources of atmospheric moisture to the basin, and location of convergence/divergence fields could be accurately illustrated. The model is used to describe the regional water cycle in the Nile basin in terms of atmospheric fluxes, land surface fluxes and land surface-climate feedbacks. The monthly moisture recycling ratio (i.e. locally generated/total precipitation) over the Nile varies between 8 and 14%, with an annual mean of 11%, which implies that 89% of the Nile water resources originates from outside the basin physical boundaries. The monthly precipitation efficiency varies between 12 and 53%, and the annual mean is 28%. The mean annual result of the Nile regional water cycle is compared to that of the Amazon and the Mississippi basins.

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