Current status and plans of JMA operational wind product Kazuki Shimoji Japan Meteorological Agency / Meteorological Satellite Center 3-235, Nakakiyoto, Kiyose, Tokyo, Japan Abstract The Meteorological Satellite Centre of the Japan Meteorological Agency (JMA/MSC) is currently operating two geostationary meteorological satellites, MTSAT-1R and MTSAT-2. Atmospheric Motion Vector (AMV) from MTSAT is derived by tracking cloud feature from animated satellite images, and the AMV data is utilized by NWP users for computing analysis field. The agency is going to launch follow-on meteorological satellite Himawari-8 on October 2014, and will start dissemination of operational Himawari-8 AMV from June 2015. MTSAT AMV will be disseminated in parallel with Himawari-8 AMV until end of 2015 as a transition period for NWP users. 1. INTRODUCTION This paper reports on the Atmospheric Motion Vectors produced by the Meteorological Satellite Center of the Japan Meteorological Agency using images from MTSAT-1R and MTSAT-2. The status of the AMV production and dissemination plan is covered in Section 2, MTSAT AMV status is described in Section 3 and Plan for switching over from MTSAT to Himawari-8 is outlined in Section 4. For details of algorithm and statistical result for Himawari-8, please refer JMA/MSC s another proceeding Motion tracking and cloud height assignment methods for Himawari-8 AMV for IWW12. 2. CURRENT STATUS OF MTSAT AMV Table 1 lists the details of current MTSAT-2 AMV dissemination. JMA currently generates four types of AMVs: MTSAT-2 Infrared (IR: 10.8 micrometers), Water Vapor (WV: 6.8 micrometers), Visible (VIS: 0.63 micrometers) and Short-wave Infrared (IR4: 3.8 micrometers) images (referred to here as IR, WV, VIS and IR4 AMVs, respectively). These are disseminated via the Global Telecommunication System (GTS) in Binary Universal Form for data Representation (BUFR) format. Short-wave Infrared AMVs are operationally assimilated into JMA s NWP system. Table 1 MTSAT-2 Atmospheric Motion Vector products generated by JMA * Upper: above 400 hpa; Middle: 400 700 hpa; Low: below 700 hpa
3. STATUS OF AMV QUALITY IR upper-level and low-level AMVs This section reports on the monthly quality of six-hourly IR and WV AMVs produced from July 2005 to November 2013 based on standard CGMS AMV statistics. AMVs are compared with radiosonde observations for quality evaluation. Figures 1 and 2 show time-series representations of monthly statistics (number, root mean square vector difference (RMSVD) and wind speed bias (BIAS)) for upper- (above 400 hpa) and lower- (below 700 hpa) level IR AMVs. For these statistics, AMVs with quality indicator (QI) values above 0.85 were used. To match radiosonde observation times, AMVs from 00 and 12 UTC were used. Figure 1 shows that upper-level IR AMVs have slow biases that still remain in the winter hemisphere. Figure 2 shows that lower-level IR AMVs have relatively small RMSVDs and BIAS (about 4 5 m/s and 0 1 m/s, respectively). This is because lower-level wind speeds are lower than upper-level ones (not shown). Figure 1 : Long-term time-series representation of the number (upper part), RMSVDs and BIAS (lower part) for upper-level IR AMVs (QI > 0.85) over the Northern Hemisphere (between 20 N and 60 N; blue lines), the tropics (between 20 S and 20 N; red lines) and the Southern Hemisphere (between 60 S and 20 S; green lines). RMSVDs (solid lines) and BIAS (dashed lines) are shown. Figure 2 : As per Figure 1, but for lower-level IR AMVs.
WV AMVs over cloudy areas Figure 3 is similar to Figures 1 and 2, but for high-level WV AMVs over cloudy regions. Positive wind speed BIAS values can be seen over all regions. Figure 3 : As per Figure 1, but for cloudy-region WV AMVs O-B STATISTICS USING JMA FIRST GUESS WIND Figure 4 shows O-B statistic of operational MTSAT AMV against JMA first guess wind for January 2013. Negative wind speed BIAS can be seen in upper level (-400hpa) IR upper AMV (left) around Jet stream region. As for lower level AMV (middle), positive wind speed BIAS can be confirmed over tropical region. WV AMV (right) shows positive wind speed BIAS globally. Figure 4: Wind speed BIAS map with the operational MTSAT-AMV. IR upper level AMV (left) shows strong wind speed BIAS (blue) around jet region. IR lower level AMV (middle) derives positive wind speed BIAS (red) over tropical region. Wind speed of WV AMV (right) is globally faster than JMA first guess wind
4. PLAN FOR SWITCHING OVER FROM MTSAT TO HIMAWARI-8 JMA/MSC is going to launch Himawari-8 on October 2014 and operation of Himawari-8 will start from July 2015. Parallel dissemination of Himawari-8 AMV will be started from April 2015 for NWP users via JMA ftp server. Dissemination of Himawari-8 AMV via GTS is planned from July 2015 and MTSAT-AMV will be sent via the JMA ftp server. Parallel dissemination of Himawari-8 and MTSAT is planned to be continued by end of October 2015. Schedule diagram is shown in following figure 5. 5. SUMMARY Figure 5: schedule for switching over from MTSAT to Himawari-8 JMA/MSC is generating and disseminating AMV derived from geostationally meteorological satellite MTSAT. MTSAT AMVs for IR upper, IR lower, WV and VIS are hourly disseminated via GTS. Quality of MTSAT AMV is as shown in figure 1 4. As a result of radiosonde and O-B statistic, IR upper level AMV has 7m/s RMSVD and negative BIAS about 1 m/s but significant strong wind speed BIAS is seen around jet stream especially in norhtern winter season. IR lower level AMV has about 4 m/s RMSVD and wind speed BIAS between -1 and 1 m/s in sonde statistic. But positive wind speed BIAS over tropical region can be seen in O-B statistic. WV AMV has positive wind speed BIAS about 1-2m/s in both of sonde and O-B analysis. JMA/MSC plans to start operation of Himawari-8 from July 2015, parallel dissemination for Himawari-8 will be started from April 2015. Parallel dissemination of Himawari-8 and MTSAT AMV is planned to be continued by end of October 2015. Details of algorithm change for Himawari-8 AMV is outlined in another proceeding Motion tracking and cloud height assignment methods for Himawari-8 AMV for IWW12.
6. REFERENCES Oyama, R., 2010: Upgrade of Atmospheric Motion Vector derivation algorithms at JMA/MSC, MSC technical note, 54, in printing. James Cotton, 2013: NWP SAF AMV monitoring: the 6th Analysis Report (AR6)