Hourly Observations of Precipitable Water and Precipitation for Weather Forecasting

1. Hourly Observations of Precipitable Water and Precipitation for Weather Forecasting Stan Kidder CIRA/Colorado State University

2. Why Hourly? • Need to have observations on the time-scale of the phenomena to be studied • Hourly observations are a forecasting standard of many years. Water Cycle Missions for the Next Decade

3. Microwave Observations • Need to sense water vapor through the clouds • Need to sense precipitation inside the clouds • Need low frequency microwaves (~23 & ~31 GHz) (still lower if you want to do winds and soil moisture) Water Cycle Missions for the Next Decade

4. Current Water-Cycle Satellites Gaps Traffic Jam at 1330 Aqua NOAA 19 Suomi NPP GCOM-W1 Water Cycle Missions for the Next Decade

5. Non-Sunsynchronous Satellites TRMM Megha-Tropiques Inclination = 35 Inclination = 20 Important, but still only two observations per day Water Cycle Missions for the Next Decade

6. Regularly Spaced Constellation 7 orbital planes 2 satellites per plane ––––––– 1 observation everywhere each 50 minutes Note: If regularly spaced planes are used, the satellites do not have to be in sunsynchronous orbits, just ones that sense the polar regions. Water Cycle Missions for the Next Decade

7. Or GEO Microwave 1 Full-Disk image per hour ––––––––––– Must have water vapor and precipitation-sensing channels, including 23 and 31 GHz. TPW (mm) 0 25 50 75 Water Cycle Missions for the Next Decade