Retrieval and applications of atmospheric motion vectors derived from Indian geostationary satellites INSAT-3D/INSAT-3DR

摘要

The atmospheric motion vectors (AMVs) from Indian geostationary meteorological satellites are derived operationally at Space Applications Centre (SAC), Ahmedabad. Over the years, many improvements in the operational retrieval algorithm have taken place with the advancement in the retrieval techniques as well as in the sensors. Two Indian geostationary meteorological satellites INSAT-3D and INSAT-3DR launched on 26 July 2013 (placed at 82 degrees E) and 08 September 2016 (placed at 74 degrees E), respectively, are providing continuous coverage at every 15 min. The data from these satellites have enhanced the scope for better understanding of atmospheric processes over the Indian Ocean region. The retrieval techniques and accuracy of AMVs have improved significantly with improved spatial resolution data along with more number of spectral channels available in both satellites. In this work, quality assessment of operational AMVs retrieved using four different spectral channels (visible, mid-infrared, infrared and water vapour) of both the satellites at 4-km spatial resolution is discussed. It also discusses the retrieval of staggering AMVs with simultaneous usage of INSAT-3D and INSAT-3DR data. The derivation of different atmospheric parameters (viz. convergence, divergence, vorticity, wind shear etc.) using AMVs of both the satellites and their possible applications during tropical cyclogenesis are also discussed. Recently, the algorithm for the retrieval of high-resolution (HR) visible AMVs and rapid-scan (RS) AMV using INSAT-3DR data has been developed and tested; however, these new algorithms are yet to be implemented operationally. To demonstrate the initial applications, AMVs are assimilated into numerical model to assess their impact for forecast improvement. The quality and impact assessment from this study will provide useful guidance to the operational meteorological agencies for applications of existing and new INSAT-3D and INSAT-3DR AMV data for future applications in the numerical weather prediction (NWP) model over the South Asian region.