Effect of GNSS Radio Occultation Data Assimilation in JMA’s Global NWP System
Presenter:
Mitsuhiro Shimada
Numerical Prediction Division, Japan Meteorological Agency, Tokyo, Japan
(1) Numerical Prediction Division, Japan Meteorological Agency, Tokyo, Japan, (2) Office of Meteorological Analysis and Application Development, Japan Meteorological Agency, Tokyo, Japan
Talk
Global Navigation Satellite System (GNSS) Radio Occultation (RO) observation has been proven to be one of the most important elements in the global observing system because the data provide information of vertical temperature profile by assimilating into the Numerical Weather Prediction (NWP) model. The Japan Meteorological Agency (JMA) operationally assimilates RO data using the Radio Occultation Processing Package (ROPP) in the global NWP system. It is considered to be significant to investigate how the GNSS RO data improve analysis fields.
To investigate the impact of RO data, RO data denial experiments were performed using the global NWP system. The experiments showed that RO data have significant positive impact on temperature of analysis and forecast fields in the upper troposphere and stratosphere. On the other hand, the assimilation of RO data decreased analyzed temperature in the lower troposphere and brought negative impacts on forecasted temperature fields.
To understand the effect of RO data in detail, single observation tests in the data assimilation were performed. It was confirmed that the RO assimilation raised analysis increments of temperature not only near the RO data height but also below the height such as 850 hPa in the JMA’s global NWP system.
Presentation in PDF:
