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Lanzhou University (2018)

The Impacts of Boundary Layer Height on Dry and Wet Changes in East Asian Arid and Semiarid Regions

赵艳茹;

Titre : The Impacts of Boundary Layer Height on Dry and Wet Changes in East Asian Arid and Semiarid Regions

Auteur : 赵艳茹;

Grade : Doctoral Dissertation 2018

Université : Lanzhou University

Résumé partiel
The atmospheric boundary layer serves as an important bridge for the exchange of matter and energy between the atmosphere and the surface,plays a key role in the atmospheric adjustment at the weather and climate scales,and also plays an important role in the extreme weather and climate events.Therefore,it is of great importance to understand dry and wet changes from the perspective of atmospheric boundary layer.Using the existing observation data,CRU grid data,ERA-Interim and ERA-20C reanalysis data,the paper analyzed the applicability of ERA-20C reanalysis data in arid and semiarid regions,synthesized the characteristics of the boundary layer height and dry-wet changes characteristics in the East Asian arid and semiarid regions and its subtype climate regions as well as its four seasons,investigated the main factors affecting the boundary layer height changes in East Asian arid and semiarid regions and its subtype climate regions as well as its four seasons,and revealed the impacts of the boundary layer height changes on the dry and wet changes in the arid and semiarid regions.Through the study,hope to gain a deep understanding of the dry and wet changes,provide more information for their predictions,and provide a scientific basis for better understanding of drought issues and improving the fragile ecological environment in arid and semiarid regions.The main results are as follows:The boundary layer height BLH,temperature T and precipitation P data of the ERA-20C and the BLH,T and P data of the actual observed data,ERA-Interim and CRU obtained in the same period,were compared,and found that their characteristics of the spatial distributions and temporal changes were consistent.The correlation coefficients of BLH of ERA-20C with ERA-Interim,the P of the ERA-20C and CRU,and the T of the ERA-20C and CRU were 0.9695,0.9972 and 0.9570,respectively.The mean absolute errors were 86.8142 m,0.8593℃and 3.5774mm,respectively.The root mean square errors were 122.3089 m,1.0622℃and 5.0457 mm,respectively.These showed small differences and indicated that ERA-20C reanalysis data have good applicability in arid and semiarid regions,and can be used for related research in arid and semiarid regions.The spatial distributions of the BLH in East Asian arid and semiarid regions took the west extreme arid area as the highest center and decreased to the surroundings,showing the longitude flat characteristics.In 19002010,the BLH showed an upward trend.From the perspective of the subtype climate regions,the increase of the BLH was the result of the joint effect of all the subtype climate regions.And the arid-semiarid transitional regions,semiarid regions and semiarid-semihumid transitional regions had the greatest contributions,which were 22.74%,23.74%and 22.05%,respectively.From the perspective of the seasons,the increase of the BLH and PET was the result of the joint effect of all the four seasons.And the main contribution was in summer with the contribution rate of 58.50%.The spatial distributions of the AI,P and PET in East Asian arid and semiarid regions took the west extreme arid area as the lowest,lowest,highest center and increased,increased,decreased to the surroundings,showing the longitude flat characteristics.In 19002010,the AI showed a decreasing trend,the P showed a decreasing trend and PET showed an increasing trend.From the perspective of the subtype climate regions,the decrease of the AI as the result of the joint effect of arid regions,arid-semiarid transitional regions,semiarid regions and semiarid-semihumid transitional regions.And semiarid regions and semiarid-semihumid transitional regions had the greatest contributions,which were 34.14%and39.15%,respectively.From the perspective of the seasons,the decrease of the P was caused by summer and autumn,and the increase of PET was the result of the joint effect of all the four seasons.

Mots clés : East Asia; Arid and semiarid regions; Boundary layer height; Dry and wet changes; Characteristics; Relationship research; Mechanism analysis;

Présentation (CNKI)

Page publiée le 5 avril 2019