Modelling Key Parameters Characterising Land Surface in 1D Space using the SimSphere SVAT model: Findings from its use at European Ecosystems

The present study investigates the ability of SimSphere, a Soil Vegetation Atmosphere Transfer (SVAT) model, to predict key parameters in characterising land Surface interactions. In particular, the model’s performance in predicting Net Radiation (Rnet), Latent Heat (LE), and Sensible Heat (H) was examined. For this purpose, concurrent in-situ measurements of the corresponding parameters for a total of 70 days of the year 2011 from 7 CarboEurope network sites were acquired, incorporating a variety of environmental biomes and climatic conditions in the model evaluation.

Download Full-text

Validating a 1-D SVAT model in a range of USA and Australian ecosystems: evidence towards its use as a tool to study Earth's system interactions

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-2437-2015 ◽

2015 ◽

Vol 8 (3) ◽

pp. 2437-2495 ◽

Cited By ~ 2

Author(s):

G. P. Petropoulos ◽

M. R. North ◽

G. Ireland ◽

P. K. Srivastava ◽

D. V. Rendall

Keyword(s):

Air Temperature ◽

Climatic Conditions ◽

In Situ Measurements ◽

Observation Data ◽

Monitoring Networks ◽

Ongoing Research ◽

Model Predictions ◽

Earth’S System ◽

Svat Model

Abstract. This paper describes the validation of the SimSphere SVAT model conducted at different ecosystem types in the USA and Australia. Specific focus was given to examining the models' ability in predicting Shortwave Incoming Solar Radiation (Rg), Net Radiation (Rnet), Latent Heat (LE), Sensible Heat (H), Air Temperature at 1.3 m (Tair 1.3 m) and Air Temperature at 50 m (Tair 50 m). Model predictions were compared against corresponding in situ measurements acquired for a total of 72 selected days of the year 2011 obtained from 8 sites belonging to the AmeriFlux (USA) and OzFlux (Australia) monitoring networks. Selected sites were representative of a variety of environmental, biome and climatic conditions, to allow for the inclusion of contrasting conditions in the model evaluation. The application of the model confirmed its high capability in representing the multifarious and complex interactions of the Earth system. Comparisons showed a good agreement between modelled and measured fluxes, especially for the days with smoothed daily flux trends. A good to excellent agreement between the model predictions and the in situ measurements was reported, particularly so for the LE, H, T1.3 m and T 50 m parameters (RMSD = 39.47, 55.06 W m−2, 3.23, 3.77 °C respectively). A systematic underestimation of Rg and Rnet (RMSD = 67.83, 58.69 W m−2, MBE = 67.83, 58.69 W m−2 respectively) was also found. Highest simulation accuracies were obtained for the open woodland savannah and mulga woodland sites for most of the compared parameters. Very high values of the Nash–Sutcliffe efficiency index were also reported for all parameters ranging from 0.720 to 0.998, suggesting a very good model representation of the observations. To our knowledge, this study presents the first comprehensive validation of SimSphere, particularly so in USA and Australian ecosystem types. Findings are important and timely, given the rapidly expanding use of this model worldwide both as an educational and research tool. This includes ongoing research by different Space Agencies examining its synergistic use with Earth Observation data towards the development of global operational products.

Download Full-text

Appraising the capability of a land biosphere model as a tool in modelling land surface interactions: results from its validation at selected European ecosystems

Earth System Dynamics Discussions ◽

10.5194/esdd-6-217-2015 ◽

2015 ◽

Vol 6 (1) ◽

pp. 217-265 ◽

Cited By ~ 10

Author(s):

M. R. North ◽

G. P. Petropoulos ◽

G. Ireland ◽

J. P. McCalmont

Keyword(s):

Land Surface ◽

Model Performance ◽

Global Scale ◽

Surface Interactions ◽

Climatic Conditions ◽

Model Parameters ◽

Observation Data ◽

Ongoing Research ◽

In Situ Data

Abstract. In this present study the ability of the SimSphere Soil Vegetation Atmosphere Transfer (SVAT) model in estimating key parameters characterising land surface interactions was evaluated. Specifically, SimSphere's performance in predicting Net Radiation (Rnet), Latent Heat (LE), Sensible Heat (H) and Air Temperature (Tair) at 1.3 and 50 m was examined. Model simulations were validated by ground-based measurements of the corresponding parameters for a total of 70 days of the year 2011 from 7 CarboEurope network sites. These included a variety of biomes, environmental and climatic conditions in the models evaluation. Overall, model performance can largely be described as satisfactory for most of the experimental sites and evaluated parameters. For all model parameters compared, predicted H fluxes consistently obtained the highest agreement to the in-situ data in all ecosystems, with an average RMSD of 55.36 W m−2. LE fluxes and Rnet also agreed well with the in-situ data with RSMDs of 62.75 and 64.65 W m−2 respectively. A good agreement between modelled and measured LE and H fluxes was found, especially for smoothed daily flux trends. For both Tair 1.3 m and Tair 50 m a mean RMSD of 4.14 and 3.54 °C was reported respectively. This work presents the first all-inclusive evaluation of SimSphere, particularly so in a European setting. Results of this study contribute decisively towards obtaining a better understanding of the model's structure and its correspondence to the real world system. Findings also further establish the model's capability as a useful teaching and research tool in modelling Earth's land surface interactions. This is of considerable importance in the light of the rapidly expanding use of the model worldwide, including ongoing research by various Space Agencies examining its synergistic use with Earth Observation data towards the development of operational products at a global scale.

Download Full-text

Discrepancies in the Simulated Global Terrestrial Latent Heat Flux from GLASS and MERRA-2 Surface Net Radiation Products

Remote Sensing ◽

10.3390/rs12172763 ◽

2020 ◽

Vol 12 (17) ◽

pp. 2763

Author(s):

Xiaozheng Guo ◽

Yunjun Yao ◽

Yuhu Zhang ◽

Yi Lin ◽

Bo Jiang ◽

...

Keyword(s):

Land Cover ◽

Latent Heat ◽

Land Surface ◽

Net Radiation ◽

Land Cover Types ◽

Daily Scale ◽

Modern Era ◽

Globally Distributed ◽

Beta Version

Surface all-wave net radiation (Rn) is a crucial variable driving many terrestrial latent heat (LE) models that estimate global LE. However, the differences between different Rn products and their impact on global LE estimates still remain unclear. In this study, we evaluated two Rn products, Global LAnd Surface Satellite (GLASS) beta version Rn and Modern-Era Retrospective Analysis for Research and Applications-version 2 (MERRA-2) Rn, from 2007–2017 using ground-measured data from 240 globally distributed in-situ radiation measurements provided by FLUXNET projects. The GLASS Rn product had higher accuracy (R2 increased by 0.04–0.26, and RMSE decreased by 2–13.3 W/m2) than the MERRA-2 Rn product for all land cover types on a daily scale, and the two Rn products differed greatly in spatial distribution and variations. We then determined the resulting discrepancies in simulated annual global LE using a simple averaging model by merging five diagnostic LE models: RS-PM model, SW model, PT-JPL model, MS-PT model, and SIM model. The validation results showed that the estimated LE from the GLASS Rn had higher accuracy (R2 increased by 0.04–0.14, and RMSE decreased by 3–8.4 W/m2) than that from the MERRA-2 Rn for different land cover types at daily scale. Importantly, the mean annual global terrestrial LE from GLASS Rn was 2.1% lower than that from the MERRA-2 Rn. Our study showed that large differences in satellite and reanalysis Rn products could lead to substantial uncertainties in estimating global terrestrial LE.

Download Full-text

Ablation and Heat Balance of the Yukikabe Snow Patch in the Daisetsu Mountains, Hokkaido, Japan

Annals of Glaciology ◽

10.3189/1984aog5-1-122-126 ◽

1984 ◽

Vol 5 ◽

pp. 122-126 ◽

Cited By ~ 1

Author(s):

A. Sato ◽

S. Takahashi ◽

R. Naruse ◽

G. Wakahama

Keyword(s):

Latent Heat ◽

Air Temperature ◽

Heat Balance ◽

Meteorological Parameters ◽

Heat Sources ◽

Sensible Heat ◽

Net Radiation ◽

Ice Caps ◽

Air Temperatures ◽

The Heat Balance

A good correlation was found between the ablation of snow and degree day index (cumulative values of positive daily mean air temperature) during the summer of 1978 on the Yukikabe snow patch in the Daisetsu mountains, central Hokkaido. The volume change of the snow patch in the ablation season of any year can hence be estimated from air temperature using this relationship. Each of the heat-balance terms controlling the ablation is evaluated separately by using empirical equations and assumed values for meteorological parameters at the snow patch. Triangular diagrams are constructed in order to illustrate the relative contributions of sensible heat, latent heat, and net radiation, the main three heat sources. A higher contribution from sensible and latent heat is found for the snow patches of Japan than for many glaciers and ice caps elsewhere. This may be due to higher mid-summer air temperatures than in other glaciated parts of the world.

Download Full-text

Numerical simulation of extreme snow melt observed at the SIGMA-A site, northwest Greenland, during summer 2012

The Cryosphere Discussions ◽

10.5194/tcd-9-495-2015 ◽

2015 ◽

Vol 9 (1) ◽

pp. 495-539

Author(s):

M. Niwano ◽

T. Aoki ◽

S. Matoba ◽

S. Yamaguchi ◽

T. Tanikawa ◽

...

Keyword(s):

Heat Flux ◽

Grain Size ◽

Latent Heat ◽

Latent Heat Flux ◽

In Situ Measurements ◽

The Arctic ◽

Snow Surface ◽

Near Surface ◽

Surface Snow

Abstract. The surface energy balance (SEB) from 30 June to 14 July 2012 at site SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic)-A, (78°03' N, 67°38' W; 1490 m a.s.l.) on the northwest Greenland Ice Sheet (GrIS) was investigated by using in situ atmospheric and snow measurements, as well as numerical modeling with a one-dimensional, multi-layered, physical snowpack model called SMAP (Snow Metamorphism and Albedo Process). At SIGMA-A, remarkable near-surface snowmelt and continuous heavy rainfall (accumulated precipitation between 10 and 14 July was estimated to be 100 mm) were observed after 10 July 2012. Application of the SMAP model to the GrIS snowpack was evaluated based on the snow temperature profile, snow surface temperature, surface snow grain size, and shortwave albedo, all of which the model simulated reasonably well. However, comparison of the SMAP-calculated surface snow grain size with in situ measurements during the period when surface hoar with small grain size was observed on-site revealed that it was necessary to input air temperature, relative humidity, and wind speed data from two heights to simulate the latent heat flux into the snow surface and subsequent surface hoar formation. The calculated latent heat flux was always directed away from the surface if data from only one height were input to the SMAP model, even if the value for roughness length of momentum was perturbed between the possible maximum and minimum values in numerical sensitivity tests. This result highlights the need to use two-level atmospheric profiles to obtain realistic latent heat flux. Using such profiles, we calculated the SEB at SIGMA-A from 30 June to 14 July 2012. Radiation-related fluxes were obtained from in situ measurements, whereas other fluxes were calculated with the SMAP model. By examining the components of the SEB, we determined that low-level clouds accompanied by a significant temperature increase played an important role in the melt event observed at SIGMA-A. These conditions induced a remarkable surface heating via cloud radiative forcing in the polar region.

Download Full-text

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

10.5194/egusphere-egu21-6903 ◽

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

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.&#160;

Download Full-text

Towards an operationally capable satellite-based 0-100 cm soil moisture dataset from C3S

10.5194/egusphere-egu21-12268 ◽

2021 ◽

Author(s):

Adam Pasik ◽

Wolfgang Preimesberger ◽

Bernhard Bauer-Marschallinger ◽

Wouter Dorigo

Keyword(s):

Soil Moisture ◽

Soil Profile ◽

Land Surface ◽

Root Zone ◽

Soil Layer ◽

Land Surface Model ◽

In Situ Measurements ◽

Surface Model ◽

T Values

Multiple satellite-based global surface soil moisture (SSM) datasets are presently available, these however, address exclusively the top layer of the soil (0-5cm). Meanwhile, root-zone soil moisture cannot be directly quantified with remote sensing but can be estimated from SSM using a land surface model. Alternatively, soil water index (SWI; calculated from SSM as a function of time needed for infiltration) can be used as a simple approximation of root-zone conditions. SWI is a proxy for deeper layers of the soil profile which control evapotranspiration, and is hence especially important for studying hydrological processes over vegetation-covered areas and meteorological modelling.Here we introduce the advances in our work on the first operationally capable SWI-based root-zone soil moisture dataset from C3S Soil Moisture v201912 COMBINED product, spanning the period 2002-2020. The uniqueness of this dataset lies in the fact that T-values (temporal lengths ruling the infiltration) characteristic of SWI were translated into particular soil depths making it much more intuitive, user-friendly and easily applicable. Available are volumetric soil moisture values for the top 1 m of the soil profile at 10 cm intervals, where the optimal T-value (T-best) for each soil layer is selected based on a range of correlation metrics with in situ measurements from the International Soil Moisture Network (ISMN) and the relevant soil and climatic parameters. Additionally we present the results of an extensive global validation against in situ measurements (ISMN) as well as the results of investigations into the relationship between a range of soil and climate characteristics and the optimal T-values for particular soil depths.

Download Full-text

Validation of Collection 6 MODIS land surface temperature product using in situ measurements

Remote Sensing of Environment ◽

10.1016/j.rse.2019.02.020 ◽

2019 ◽

Vol 225 ◽

pp. 16-29 ◽

Cited By ~ 52

Author(s):

Si-Bo Duan ◽

Zhao-Liang Li ◽

Hua Li ◽

Frank-M. Göttsche ◽

Hua Wu ◽

...

Keyword(s):

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

In Situ Measurements ◽

Modis Land Surface Temperature

Download Full-text

Diurnal Energy Balance in a Mango Orchard in the Northeast of Pará, Brazil

Revista Brasileira de Meteorologia ◽

10.1590/0102-7786333012 ◽

2018 ◽

Vol 33 (3) ◽

pp. 537-546 ◽

Cited By ~ 1

Author(s):

Paulo Jorge de Oliveira Ponte de Souza ◽

Juliana Chagas Rodrigues ◽

Adriano Marlisom Leão de Sousa ◽

Everaldo Barreiros de Souza

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Latent Heat ◽

Latent Heat Flux ◽

Soil Cover ◽

Sensible Heat Flux ◽

Sensible Heat ◽

Net Radiation ◽

Growing Seasons ◽

Available Energy

Abstract This study aimed to evaluate the diurnal energy balance during the reproductive stage of two growing seasons of a mango orchard in the northeast of Pará, Brazil. Therefore, a micrometeorological tower was installed and instrumented, in the center of the experimental area, to monitor meteorological variables, besides the phenological evaluation of the mango orchard, which was carried out during growing seasons of 2010-2011 (October 2010 to January 2011) and of 2011-2012 (September 2011 to January 2012). The energy balance was obtained by the bowen ration technique, and the available energy partitioned into heat flux to the ground, sensible heat and latent heat. The amount of rainfall was crucial to the partition of the net radiation in the energy balance components. It provided the variation in the consumption of available energy between 69% and 78% as latent heat flux, and between 23% and 32% as sensible heat flux. The heat flux to the ground was small, representing less than 1% of the net radiation, showing that the mango orchard exhibits good soil cover preventing large variations in soil heating.

Download Full-text