This work is the case study based on the remote sensing data about squall line in Shanghai at July 12 2004, focus on the
analysis on Doppler radar echo products, satellite image, surface and sounding data, automatic weather station data. The
purpose is to reveal the special structure of the squall line, recognize the evolution of strong convection with multi-scale
information, and find the prediction mechanism for reducing disaster on mankind.
In the study of radar wind field retrieval with variational assimilation method, the simple adjoint models have merits of simplifying calculation, saving time and improving efficiency. This paper studies wind field retrieval on levels of different height using the reflectivity advection equation as the control equation, proposes the parameterization method of sub-grid scale term which is related to the vertical motion. The flow pattern comparison and precision analysis with dual-Doppler radar have been made. Experiment results show this model could fully use the evolution information of reflectivity and effectively approximate to the real wind field.
An attempt has been made to compare and analyze the ST (surface temperature) between MODIS (Moderate Resolution Imaging Spectroradiometer) on the Terra satellite and AWS (Automatic Weather Station) data for monitoring the establishment of UHI (urban heat island) in this study. Results show that they are in good agreement. From the distribution of ST from MODIS, the highest values of ST appear in the center of urban. The UHI is evident in the urban area and its suburb towns. Another focus of this study is to analyze the relationship between ST, land cover and NDVI (Normalized Difference Vegetation Index) over urban area in order to improve the understanding of UHI. A negative correlation is observed between NDVI and ST correlation coefficient of - 0.73. The ST over urban is the largest among all other land-covers. The mean differences of ST between urban and rural from MODIS are about 2.29K and 1.22K at about 10:30 and 22:30 in April of 2004, respectively. Through this study, it could be clarified the surface temperature characteristics of spatial distribution for urbanization in the rural area. In summary, the relationships between NDVI, land cover and surface temperature will be regarded as one of effective methodologies to make manifest urban heat island. The difference of NDVI between urban and rural region appears to be an indicator of the difference in surface properties between the two environments that are responsible for difference in urban and rural surface temperature.
Studies of albedo over urban/rural surface are important to better understand the land surface process in the ABL(atmospheric boundary layer). Urban landscape is the most heterogeneous surface that strongly influences the structure and development of the ABL. In this paper, the directional hemispherical reflectance (black-sky albedo, BSA), the bihemispherical reflectance (white-sky albedo, WSA) and the actual albedo (blue-sky albedo, A) are retrieved from the MODIS BRDF/albedo product (MOD43B1) for three broadbands (0.3- 0.7μm, 0.7-5.0μm, 0.3-5.0μm) in the Changjiang Delta of China. Particular attention is directed to examine the difference of surface albedos over urban and rural areas. The seasonal and spatial variations are investigated. Validation has also been done against field observation and showed that the albedo from MODIS is less than the observed. Albedo in visible broadband (0.3-0.7μm) over urban area is larger than that over rural area, but is less in near infrared broadband (0.7-5.0μm). For the total short broadbrand, it is difficult to reach qualitative conclusion because of urban complexity. The correlations of albedos and NDVI are strongly influenced by the spectral band and land cover. They are positive for the visible and the total broadbands, but negative for the near infrared in same season.
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