1 00:00:00,000 --> 00:00:03,940 Our lives are in sync with Earth's rotation. 2 00:00:03,940 --> 00:00:06,400 As our planet rotates on its axis, 3 00:00:06,400 --> 00:00:09,960 we shift from day to night and warm to cool.  4 00:00:09,960 --> 00:00:14,440 As a response, our weather follows a daily cycle. 5 00:00:14,440 --> 00:00:18,080 Now, the most detailed view of our daily weather has been created 6 00:00:18,080 --> 00:00:23,340 using a new NASA record that combines almost 20 years of rain and snow. 7 00:00:23,340 --> 00:00:26,440 By combining these two satellites, 8 00:00:26,440 --> 00:00:32,850 scientists calculated the changes in precipitation every 30 minutes for two decades. 9 00:00:32,850 --> 00:00:36,990 This is part of NASA's newest extended precipitation record 10 00:00:36,990 --> 00:00:43,410 known as the Integrated Multi-satellitE Retrievals for GPM, or IMERG analysis. 11 00:00:43,410 --> 00:00:44,860 From the vantage of space, 12 00:00:44,860 --> 00:00:50,080 IMERG shows the 24-hour pulse in weather known as the diurnal cycle. 13 00:00:50,080 --> 00:00:54,120 This cycle helps shape how and when our weather develops 14 00:00:54,120 --> 00:00:57,450 and is fundamental to regulating our climate. 15 00:00:57,450 --> 00:01:03,190 In the case of precipitation, one of the main questions is — the different main modes of variability. 16 00:01:03,190 --> 00:01:06,560 One main mode of variability is the seasonal variation. 17 00:01:06,560 --> 00:01:11,750 But on a much shorter time scale, the main mode of variability is the so-called diurnal cycle. 18 00:01:11,750 --> 00:01:14,830 That is the variation in precipitation over the day. 19 00:01:14,830 --> 00:01:18,690 IMERG not only shows us how much the rainfall shifts, 20 00:01:18,690 --> 00:01:21,640 it tells us what time it shifts and peaks. 21 00:01:21,640 --> 00:01:25,090 Over the U.S. we see a variety of patterns. 22 00:01:25,090 --> 00:01:33,130 This shows the average amount of rainfall every 30 minutes during the summer months of June, July, and August. 23 00:01:33,130 --> 00:01:37,300 In Florida, heat from the Sun builds up over the course of the day, 24 00:01:37,300 --> 00:01:39,410 driving rainfall over land. 25 00:01:39,410 --> 00:01:42,830 Sea breezes from the Gulf of Mexico and Atlantic Ocean 26 00:01:42,830 --> 00:01:47,300 feed the storms over land driving storms to peak in the afternoon. 27 00:01:47,300 --> 00:01:50,560 At night, rainfall moves over the ocean. 28 00:01:50,560 --> 00:01:55,430 Storms intensify offshore only to move inland during the day again. 29 00:01:55,430 --> 00:01:58,990 Over the midwest and the Great Plains, 30 00:01:58,990 --> 00:02:03,490 heating over the Rocky mountains forms storm systems during the day, 31 00:02:03,490 --> 00:02:05,770 which then roll eastward overnight. 32 00:02:05,770 --> 00:02:11,840 In the U.S. Northeast, heating over land causes rainfall during the day 33 00:02:11,840 --> 00:02:14,400 that moves over the ocean at night, 34 00:02:14,400 --> 00:02:17,590 because the water doesn’t cool down as quickly as over land. 35 00:02:17,590 --> 00:02:21,670 Due to this, you can clearly see the warm Gulf Stream water 36 00:02:21,670 --> 00:02:25,030 moving past the East Coast, on its way to the North Atlantic.  37 00:02:25,030 --> 00:02:29,690 During the winter months of December, January, and February along the West Coast, 38 00:02:29,690 --> 00:02:32,750 the daily patterns of rainfall every 30 minutes 39 00:02:32,750 --> 00:02:38,280 how how the coastal regions generally receive similar amounts of precipitation throughout the day. 40 00:02:38,280 --> 00:02:43,320 In the winter, precipitation is driven less from the daily heating of the Sun 41 00:02:43,320 --> 00:02:47,140 and more from the Pacific Ocean bringing in atmospheric rivers — 42 00:02:47,140 --> 00:02:51,040 corridors of intense water vapor in the atmosphere. 43 00:02:51,040 --> 00:02:54,210 By studying the diurnal variation, 44 00:02:54,210 --> 00:02:57,810 this gives us basic scientific understanding of what the atmosphere is doing,  45 00:02:57,810 --> 00:03:03,000 and it prepares us to look at models and understand what the relationship is 46 00:03:03,000 --> 00:03:06,790 between rainfall and these other variables, like air quality. 47 00:03:06,790 --> 00:03:11,180 Current climate models have difficulty accounting for the diurnal cycle, 48 00:03:11,180 --> 00:03:15,140 but the improved detail in IMERG could help fill in the gaps 49 00:03:15,140 --> 00:03:19,180 to create a more complete and accurate picture of daily precipitation, 50 00:03:19,180 --> 00:03:22,710 not just in the U.S. but around the world. 51 00:03:22,710 --> 00:03:33,099