GPS掩星观测误差和边界层高度的判别

Observation Error of GPS Radio Occultation and Discrimination of Planetary Boundary Layer Height

使用2007-2014年COSMIC全球海洋掩星资料,分别用弯角和折射率梯度的极值来判别全球海洋边界层高度(分别记为PBL^(BA)和PBL^(N)),探讨了边界层高度处的局地波谱宽度(local spectral width,LSW)、折射率的垂直梯度、以及弯角和折射率判别的边界层高度差(记为PBL^(diff),PBL^(diff)=PBL^(BA)-PBL^(N))之间的关系。结果表明:大气折射率的垂直梯度与LSW存在明显的线性关系,在第一、第二边界层高度处,其相关系数可达0.60和0.68。折射率垂直梯度主要由干项和湿项构成,在低纬度地区,湿项是折射率的主要贡献项。折射率垂直梯度湿项与LSW在第一、第二边界层相关系数可达0.68和0.69。第一边界层PBL^(diff)随着折射率垂直梯度增大而增大,当折射率梯度绝对值达到80 N-unit·km^(-1)和100 N-unit·km^(-1),PBL^(diff)可达100 m和160 m。

COSMIC(Constellation Observing System for Meteorology,Ionosphere and Climate)global ocean RO data from 2007 to 2014 were used,and the extreme values of bending angle and refractivity gradient were used to determine the global marine PBL heights(respectively referred to as PBLBA and PBLN),and the relationship between the LSW at the PBL height,the vertical gradient of the refractivity,and the PBL difference between the bending angle and the refractivity(referred as PBLdiff,PBLdiff=PBLBA-PBLN)were discussed.The results show that there is a clear linear relationship between the vertical gradient of refractivity and LSW.At the first and second PBL height,the correlation coefficients can reach 0.60 and 0.68.The refractivity is mainly composed of dry and wet terms.In low latitudes,the wet term is the main contribution of the refractivity.The correlation coefficient between the vertical gradient of the wet term and the LSW in the first and second PBL height can reach 0.68 and 0.69.The first boundary layer PBLdiff increases with the vertical refractivity gradient.When the absolute value of the refractivity gradient reaches 80 N-unit·km^(-1)and 100 N-unit·km^(-1),PBLdiff can reach 100 meters and 160 meters.