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Nanjing University of Information Science and Technology (2020)

Observation and Fine-resolution Simulation of Dust Devil in the Southwest Edge of Tengger Desert

王康宏

Titre : Observation and Fine-resolution Simulation of Dust Devil in the Southwest Edge of Tengger Desert

Auteur : 王康宏

Grade : Doctoral Dissertation 2020

Université : Nanjing University of Information Science and Technology

Résumé partiel
Atmospheric aerosols have a significant impact on climate change.Dust aerosols,accounting for nearly half of the total atmospheric aerosols,can affect climate and ecosystem through their direct and indirect effects,and their total amount is the most important link affecting the global material cycle and climate change.Dust storm process has been considered as the most important source of dust aerosols.but another important source of dust aerosols-dust devil should not be ignored.Compared with the dust storm process,although the amount of dust aerosols in the atmosphere lifted by the dust devil is limited every day,the frequency of this small and medium-sized dust devil is very high,and its contribution may account for 30~65%of the total annual dust aerosol,and it is a very important source of dust aerosols.At present,there are few observations on this kind of small and medium-sized dust devil,and the research on its formation mechanism and spatial and temporal distribution characteristics is still very weak.Therefore,it is of great scientific significance and value to carry out the dust devil observation and fine-resolution simulation research.Based on many years’ first-hand observation data in the southern margin of Tengger Desert near in northwest China’s Gansu province,we analyzed features and their relationship with the related meteorological factors of dust devil.Surface temperature by means of satellite remote sensing data of downscale and the temperature interpolation processing,reduction of relations with the observed data in the desert area,A resolution of 1km ground-air temperature difference field in the study area was established to solve the problem of underestimation of ground-air temperature difference,which is the most important judgment condition for dust devil and simulation by model.The spatial distribution of sediment in the study area from June to August 2019 was carefully simulated by using the latest sediment parameterization scheme of dust devil and WRF/ Chem model coupling.The spatial-temporal variation characteristics were analyzed,and the relationship between wind-induced sediment intensity and related factors such as desert surface type in this area was discussed.Based on the observation of the early stage of the formation mechanism and the dust devil "heat convection bubble" theory,we developed "heat convection bubble-power" concept model and theory that can reasonably explain the characteristics of sediment by dust devil.The main conclusions of this study are as follows :(1)Through 2014 ~ 2017 in southwest margin of Tengger desert dust devil observation of summary data analysis found that : the dust devil of diameter of less than 2m in the area of probability is larger than 2m diameter of more than 8 times,dust devil is Often appear in the daily 9:00-16:00,the peak is in commonly between 14:00 to 15:00,More than 70% of dust devils occured in June and August of each year.The meteorological conditions and thresholds of dust devil are as follows : when the air temperature is between 19℃~35℃ and the wind speed is between 1~5m/s,the frequency of clear sky or little cloud is much greater than that of cloudy or cloudy weather.In the case of precipitation,dust storm does not occurred.It is found by practical observation that the local small terrain in desert area has an important effect on the surface temperature

Mots clés : Dust devil ;Fine simulation ;Conceptual model ;

Présentation (CNKI)

Page publiée le 21 octobre 2021