scholarly journals Effects of Cropland Expansion on the Regional Land Surface Radiative Energy Balance and Heat Fluxes in Northern China

2021 ◽  
Vol 11 (4) ◽  
pp. 1556
Author(s):  
Jia Ning
Keyword(s):  
Heat Flux ◽  
Land Surface ◽  
Surface Heat Flux ◽  
Northeast China ◽  
Northern China ◽  
Northwest China ◽  
Surface Heat ◽  
Surface Radiation ◽  
Climate Zones ◽  
Arid Northwest China

Land use change can impact the land surface radiation budget and energy balance by changing surface biophysical processes. Based on satellite remote sensing data and land use data from 2000 to 2015, we quantitatively estimated radiative forcing induced by cropland expansion during the early 21st century in northern China. The results showed that heat flux from the land surface to the atmosphere due to cropland expansion was quite variable in different climate zones. The heat flux increased in humid North China, whereas it decreased in arid Northwest China, semiarid Inner Mongolia, and humid Northeast China. Cropland expansion from woodland areas led to a general decline in the land surface heat flux to the atmosphere, which led to a cooling effect on the climate. The surface heat flux to the atmosphere due to cropland expansion in grassland areas displayed significant variations in different climate zones. The surface heat flux decreased only in humid Northeast China and arid Northwest China. The net surface radiation and latent heat flux both increased when grasslands were changed into cropland, but to different extents, which produced the differences in the surface heat flux to the atmosphere between different zones.

scholarly journals Improving Soil Moisture and Surface Turbulent Heat Flux Estimates by Assimilation of SMAP Brightness Temperatures or Soil Moisture Retrievals and GOES Land Surface Temperature Retrievals

2020 ◽  
Vol 21 (2) ◽  
pp. 183-203 ◽  
Author(s):  
Yang Lu ◽  
Susan C. Steele-Dunne ◽  
Gabriëlle J. M. De Lannoy
Keyword(s):  
Heat Flux ◽  
Soil Moisture ◽  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Heat Fluxes ◽  
Transfer Model ◽  
Turbulent Heat

AbstractSurface heat fluxes are vital to hydrological and environmental studies, but mapping them accurately over a large area remains a problem. In this study, brightness temperature (TB) observations or soil moisture retrievals from the NASA Soil Moisture Active Passive (SMAP) mission and land surface temperature (LST) product from the Geostationary Operational Environmental Satellite (GOES) are assimilated together into a coupled water and heat transfer model to improve surface heat flux estimates. A particle filter is used to assimilate SMAP data, while a particle smoothing method is adopted to assimilate GOES LST time series, correcting for both systematic biases via parameter updating and for short-term error via state updating. One experiment assimilates SMAP TB at horizontal polarization and GOES LST, a second experiment assimilates SMAP TB at vertical polarization and GOES LST, and a third experiment assimilates SMAP soil moisture retrievals along with GOES LST. The aim is to examine if the assimilation of physically consistent TB and LST observations could yield improved surface heat flux estimates. It is demonstrated that all three assimilation experiments improved flux estimates compared to a no-assimilation case. Assimilating TB data tends to produce smaller bias in soil moisture estimates compared to assimilating soil moisture retrievals, but the estimates are influenced by the respective bias correction approaches. Despite the differences in soil moisture estimates, the flux estimates from different assimilation experiments are in general very similar.

What balloon soundings can tell about surface heat flux partitioning

2020 ◽  
Author(s):  
Jasper Denissen ◽  
Hendrik Wouters ◽  
René Orth ◽  
Diego Miralles ◽  
Ryan Teuling
Keyword(s):  
Heat Flux ◽  
Soil Moisture ◽  
Land Surface ◽  
Surface Heat Flux ◽  
Sensible Heat Flux ◽  
Surface Heat ◽  
Atmospheric Measurements ◽  
Flux Partitioning ◽  
Temperature And Humidity ◽  
Soil Moisture Availability

<p>The land surface can influence near-surface weather. This happens, amongst others, through the impact of soil moisture availability on surface heat fluxes: when soil moisture is unavailable in soil moisture-limited conditions, most of the available energy will be used for heating the air above the land surface (sensible heat flux). But as soil moisture increases, evapotranspiration (latent heat flux) increases, affecting the surface heat flux partitioning. At the point that ample soil moisture is available in energy-limited conditions, the surface heat flux partitioning remains unaffected by soil moisture. The atmospheric boundary layer (ABL) responds to changes in surface heat flux partitioning in particular in terms of its temperature and humidity. Based on these mechanisms, observations of boundary layer dynamics should allow to infer the large-scale land surface state.</p><p>The goal of this study is to use atmospheric measurements of temperature and humidity to estimate the surface heat flux partitioning. This is achieved by constraining an ABL model (CLASS4GL) with the vertical temperature and humidity profiles as observed by thousands of soundings of hot air balloons across the globe. In CLASS4GL, the initial soil moisture is adjusted to yield matching modelled versus observed vertical temperature and humidity profiles. By doing so, the resulting surface fluxes are inferred exclusively from atmospheric measurements.</p><p>We find that ABL’s tend to higher, warmer and drier in water-limited conditions. This largely results from changes in soil moisture availability, which mainly affects the sensible heat flux and consequently, the surface heat flux partitioning. We determine the critical soil moisture, which distinguishes between soil moisture- and energy- limited conditions, using the ratio between the sensible- and latent heat flux and independent satellite surface soil moisture.</p><p>This is the first time that balloon soundings are used globally to assess the critical soil moisture. This research will help to further improve our understanding of land-atmosphere feedbacks and foster a correct representation of land surface characteristics in Land Models and subsequently, Climate Models.</p>

Global intercomparison of 12 land surface heat flux estimates

2011 ◽  
Vol 116 (D2) ◽  
Author(s):  
C. Jiménez ◽  
C. Prigent ◽  
B. Mueller ◽  
S. I. Seneviratne ◽  
M. F. McCabe ◽  
...  
Keyword(s):  
Heat Flux ◽  
Land Surface ◽  
Surface Heat Flux ◽  
Surface Heat

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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