Observing Atmospheric Dynamics from Satellite Sounding Pairs

The NPP and the Aqua satellites share the same sun synchronous orbital plane with an equator crossing Local Solar Time (LST) of ~0130 am and pm in ascending and descending nodes, respectively. However, since the two satellites are at slightly different altitudes (i.e., 825 km for NPP and 705 km for Aqua), the same regions of the Earth are observed with time differences varying between zero and fifty minutes during a period of ~2.7 days. Also, the Metop-A and Metop-B satellites fly in a sun-synchronous orbit, at an altitude of about 820km and an equator crossing Local Solar Time (LST) of ~9:30 am and pm in descending and ascending nodes, respectively. They have a constant time separation time of about 50 minutes. Since the AIRS on Aqua, CrIS on NPP, and IASI on Metop-A and Metop-B are ultraspectral sounding instruments, atmospheric profile time tendency and water vapor flux measurements are achieved from the Aqua/NPP and Metop-A/Metop-B pairs of satellites. Thus, new atmospheric dynamics measurements are available globally four times per day. Vertically resolved water vapor convergence and divergence and atmospheric stability change are important predictors of convective tornadic weather initiation and tropical storm intensity change. Although the Joint Polar Satellite System (JPSS) does not provide continuous time tendency measurements with the high spatial resolution achievable from geostationary orbit, it does provide a stepping-stone for the use of such data from future operational geostationary satellites (i.e., the Chinese FY-4 and the European MTG). Furthermore, since the US does not plan to fly a geostationary advanced sounder before the next decade, the polar orbiting time tendency data provide a unique opportunity for improving storm prediction for the North American region. Results from the determination of dynamic weather forecast variables from the Aqua/NPP and Metop-A/Metop-B pairs of satellites and some example applications of these new data are presented