Abstract:
On the basis of scattering and attenuation theory of raindrop, the coupling relation between vertical and horizontal polarimetric wave is analyzed with numerical simulation methods in the same transmission and receiving waves (STSR) and alternate transmission and receiving horizontal and vertical waves (ATAR) model. While radar beam passes through uniform rain area, the variety of horizontal reflectivity
ZH and its error Δ
ZH, differential reflectivity
ZDR and its error Δ
ZDR, the differential propagation phase shift Φ
DP and specific differential propagation phase shift
KDP and its difference Δ
KDP brought by raindrop slant are compared respectively along with distance between the two polarimetric models. The results indicate that the
ZH of STSR are bigger and
ZDR are smaller than ATAR model while raindrop is slant, so the errors of
ZH and
ZDR in STSR model are bigger when attenuation are not considered. While attenuation is considered, the errors of
ZH in STSR are small, the errors of
ZDR of 3.2 cm are small too, and that of 5.7, 10.7 cm are big. However, the difference of
ZH and
ZDR between models is little because the raindrop slant is small in real air. Influenced by raindrop slant
KDP is bigger in ATAR model than in STSR, it decreases less than in STSR model, so the difference of Δ
KDP between models is more while the slant angle increases. The shorter the wave length, the bigger the
KDP, and the larger the Δ
KDP are impacted by slant. In addition, two real value definitions of
ZH and
ZDR are addressed, by which the scattering effect of raindrop slant is considered or not. The actual microphysical structure of raindrop can be better represented by the value of not considering slant, the influence of propagation effect is eliminated, and the full size is reflected accurately, which are better representatives on the application of radar data such as quantitative estimation precipitation. It is more reasonable that the none-slant-consideration
ZH,
ZDR values are regarded as the real definitions.