This paper focuses on the methodology for brightness temperature component selection and temporal variations of these component values by an in situ experiment dedicated to urban brightness temperature distribution.Results reveal that the number of typical objects of an urban area and their brightness temperature values vary with time of day due to the complex of urban thermal feature and structures.More thorough analysis is needed in the further research.A modelling study on the variations of directional brightness temperature（DBT） for row-structured building arrays was carried out with the help of the ground observations over urban areas.The model assumes that the DBT is a function of component brightness temperatures and their directional fractions.Their fractions in the scene depend on sun-view geometry and the geometry of buildings.In the simulation of urban areas DBT

the results reveal an evident row-direction-oriented stripe in DBT polar map

where no hot spot appears.As an initial attempt

the research only focus on the simplified conditions

more complicated structure may be considered in the further researches.At last

we compared the solution of model with the experiment solution.The research showed that the solution revealed the phenomenon in experiment to a certain extent.