scholarly journals Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

2012 ◽  
Vol 16 (7) ◽  
pp. 1817-1831 ◽  
Author(s):  
F. Alkhaier ◽  
G. N. Flerchinger ◽  
Z. Su
Keyword(s):  
Energy Balance ◽  
Surface Temperature ◽  
Land Surface ◽  
Shallow Groundwater ◽  
Bare Soil ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Soil Conditions ◽  
Potential Evaporation ◽  
Available Energy

Abstract. Understanding when and how groundwater affects surface temperature and energy fluxes is significant for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To investigate the shallow groundwater effect under bare soil conditions, we numerically exposed two soil profiles to identical metrological forcing. One of the profiles had shallow groundwater. The different responses that the two profiles manifested were inspected regarding soil moisture, temperature and energy balance at the land surface. The findings showed that the two profiles differed in three aspects: the absorbed and emitted amounts of energy, the portioning out of the available energy and the heat fluency in the soil. We concluded that due to their lower albedo, shallow groundwater areas reflect less shortwave radiation and consequently get a higher magnitude of net radiation. When potential evaporation demand is sufficiently high, a large portion of the energy received by these areas is consumed for evaporation. This increases the latent heat flux and reduces the energy that could have heated the soil. Consequently, lower magnitudes of both sensible and ground heat fluxes are caused to occur. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. For the reliability of remote sensors in detecting shallow groundwater effect, it was concluded that this effect can be sufficiently clear to be detected if at least one of the following conditions occurs: high potential evaporation and high contrast between day and night temperatures. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

scholarly journals Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

2011 ◽  
Vol 8 (5) ◽  
pp. 8639-8670 ◽  
Author(s):  
F. Alkhaier ◽  
G. N. Flerchinger ◽  
Z. Su
Keyword(s):  
Energy Balance ◽  
Surface Temperature ◽  
Land Surface ◽  
Shallow Groundwater ◽  
Bare Soil ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Soil Conditions ◽  
Potential Evaporation ◽  
Meteorological Forcing

Abstract. Appreciating when and how groundwater affects surface temperature and energy fluxes is important for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To explore the shallow groundwater effect, we numerically exposed two soil profiles – one having shallow groundwater – to the same meteorological forcing, and inspected their different responses regarding surface soil moisture, temperature and energy balance. We found that the two profiles differed in the absorbed and emitted amounts of energy, in portioning out the available energy and in heat fluency within the soil. We conclude that shallow groundwater areas reflect less shortwave radiation due to their lower albedo and therefore they get higher magnitude of net radiation. When potential evaporation demand is high enough, a large portion of the energy received by these areas is spent on evaporation. This makes the latent heat flux predominant, and leaves less energy to heat the soil. Consequently, this induces lower magnitudes of both sensible and ground heat fluxes. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. In view of remote sensors' capability of detecting shallow groundwater effect, we conclude that this effect can be sufficiently clear to be sensed if at least one of two conditions is met: high potential evaporation and big contrast in air temperature between day and night. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

scholarly journals Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS

2012 ◽  
Vol 16 (7) ◽  
pp. 1833-1844 ◽  
Author(s):  
F. Alkhaier ◽  
Z. Su ◽  
G. N. Flerchinger
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Temperature ◽  
Water Table ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Surface Energy Balance ◽  
Shallow Groundwater ◽  
Companion Paper ◽  
Daily Evaporation

Abstract. The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Moreover, these measurements can help to include the effect of shallow groundwater on surface energy balance within land surface models and climate studies, which broadens the methods that yield more reliable and informative results. To examine the capacity of MODIS in detecting the effect of shallow groundwater on land surface temperature and the surface energy balance in an area within Al-Balikh River basin in northern Syria, we studied the interrelationship between in-situ measured water table depths and land surface temperatures measured by MODIS. We, also, used the Surface Energy Balance System (SEBS) to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. We found out that the daytime temperature increased while the nighttime temperature decreased when the depth of the water table increased. And, when the water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. This concords with the findings of a companion paper (Alkhaier et al., 2012). The observed clear relationships were the result of meeting both conditions that were concluded in the companion paper, i.e. high potential evaporation and big contrast in day-night temperature. Moreover, the prevailing conditions in this study area helped SEBS to yield accurate estimates. Under bare soil conditions and under the prevailing weather conditions, we conclude that MODIS is suitable for detecting the effect of shallow groundwater because it has proper imaging times and adequate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.

An improved representation of the land surface temperature including the effects of vegetation in the COSMO model

2020 ◽  
Author(s):  
Jan-Peter Schulz ◽  
Gerd Vogel
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Temperature ◽  
Land Surface ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Surface Processes ◽  
Atmospheric Models ◽  
Land Surface Processes ◽  
Near Surface

<p>Land surface processes have a significant impact on near-surface atmospheric phenomena. They determine, among others, near-surface sensible and latent heat fluxes and the radiation budget, and thus influence atmosphere and land characteristics, such as temperature and humidity, the structure of the planetary boundary layer, and even cloud formation processes. It is therefore important to simulate the land surface processes in atmospheric models as realistically as possible.</p><p>Verifications have shown that the amplitude of the diurnal cycle of the surface temperature simulated by the land surface scheme TERRA of the COSMO atmospheric model is systematically underestimated. In contrast, the diurnal cycles of the temperatures in the soil are overestimated, instead. This means that the other components of the surface energy balance are biased as well, for instance, the surface turbulent heat fluxes or the ground heat flux.</p><p>Data from the Meteorological Observatory Lindenberg of the German Meteorological Service (DWD) were used to analyse this model behaviour. In the standard model configuration of TERRA, there is no representation of the vegetation in the surface energy balance. This means, there is no energy budget including a temperature for the vegetation layer. Furthermore, the insulating effects by the vegetation at the sub-canopy level are missing as well. In this work, a scheme providing both of these missing model characteristics was implemented in TERRA. As a result, the simulated diurnal amplitude of the surface temperature is increased and the one of the soil temperature is reduced, both leading to better agreements with the measurements. These improvements are found in TERRA in offline mode, using Lindenberg observations, as well as in coupled mode in the atmospheric models of DWD, i.e. the limited-area COSMO model and the global ICON model.</p>

scholarly journals Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS

2011 ◽  
Vol 8 (5) ◽  
pp. 8671-8700 ◽  
Author(s):  
F. Alkhaier ◽  
Z. Su ◽  
G. N. Flerchinger
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Temperature ◽  
Water Table ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Surface Energy Balance ◽  
Shallow Groundwater ◽  
Companion Paper ◽  
Daily Evaporation

Abstract. The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Besides, these measurements help bringing groundwater effect on surface energy balance within land surface models and climate studies. To inspect the MODIS capacity of detecting shallow groundwater effect on land surface temperature and surface energy balance in an area within Al-Balikh River basin in northern Syria, we investigated the interrelationship between in-situ measured water table depths and land surface temperatures of MODIS. Further, we used the Surface Energy Balance System (SEBS) to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. In agreement with the findings of a companion paper (Alkhaier et al., 2011), we found that daytime temperature increased and nighttime temperature decreased with increasing water table depth. Where water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. The clear observed relationships resulted from meeting both conditions concluded in the companion paper, i.e. high potential evaporation and big contrast in air temperature. Moreover, the prevailing conditions in this study area helped SEBS producing accurate estimates. We conclude that MODIS is suitable for shallow groundwater effect detection since it has proper imaging times and appropriate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.

scholarly journals Intercomparison of Three Two-Source Energy Balance Models for Partitioning Evaporation and Transpiration in Semiarid Climates

2018 ◽  
Vol 10 (7) ◽  
pp. 1149 ◽  
Author(s):  
Yongmin Yang ◽  
Jianxiu Qiu ◽  
Renhua Zhang ◽  
Shifeng Huang ◽  
Sheng Chen ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Large Scale ◽  
Heat Fluxes ◽  
Temperature Decomposition ◽  
Component Temperature ◽  
The Impact ◽  
Mean Square Errors

Evaporation (E) and transpiration (T) information is crucial for precise water resources planning and management in arid and semiarid areas. Two-source energy balance (TSEB) methods based on remotely-sensed land surface temperature provide an important modeling approach for estimating evapotranspiration (ET) and its components of E and T. Approaches for accurate decomposition of the component temperature and E/T partitioning from ET based on TSEB requires careful investigation. In this study, three TSEB models are used: (i) the TSEB model with the Priestley-Taylor equation, i.e., TSEB-PT; (ii) the TSEB model using the Penman-Monteith equation, i.e., TSEB-PM, and (iii) the TSEB using component temperatures derived from vegetation fractional cover and land surface temperature (VFC/LST) space, i.e., TSEB-TC-TS. These models are employed to investigate the impact of component temperature decomposition on E/T partitioning accuracy. Validation was conducted in the large-scale campaign of Heihe Watershed Allied Telemetry Experimental Research-Multi-Scale Observation Experiment on Evapotranspiration (HiWATER-MUSOEXE) in the northwest of China, and results showed that root mean square errors (RMSEs) of latent and sensible heat fluxes were respectively lower than 76 W/m2 and 50 W/m2 for all three approaches. Based on the measurements from the stable oxygen and hydrogen isotopes system at the Daman superstation, it was found that all three models slightly overestimated the ratio of E/ET. In addition, discrepancies in E/T partitioning among the three models were observed in the kernel experimental area of MUSOEXE. Further intercomparison indicated that different temperature decomposition methods were responsible for the observed discrepancies in E/T partitioning. The iterative procedure adopted by TSEB-PT and TSEB-PM produced higher LEC and lower TC when compared to TSEB-TC-TS. Overall, this work provides valuable insights into understanding the performances of TSEB models with different temperature decomposition mechanisms over semiarid regions.

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