IMERG

Typhoon Hagibis, a once powerful super typhoon, struck the main Japanese island of Honshu over the weekend, bringing very heavy rains and widespread flooding. Hagibis formed into a tropical storm on the 5th of October from a tropical depression that originated from a westward moving tropical wave north of the Marshall Islands. At first, Hagibis strengthened steadily becoming a typhoon about 24 hours after becoming a tropical storm. But, then on the 7th, Hagibis underwent a remarkable rapid intensification cycle and quickly intensified into a super typhoon with sustained winds estimated at 160 mph by the Joint Typhoon Warning Center (JTWC) less than 24 hours after becoming a minimal typhoon.

NASA’s Precipitation Measurement Missions (PMM) have collected rain and snowfall from space for nearly 20 years, and for the first time in 2019, scientists can access PMM’s entire record as one data set. PMM includes two missions – the Tropical Rainfall Measuring Mission (TRMM), which orbited Earth from 1997 to 2015, and its successor, the joint NASA-JAXA Global Precipitation Measurement mission (GPM), which has been collecting data since 2014. This year, however, the GPM project upgraded its data algorithms to calibrate and incorporate TRMM data into its release, giving researchers, modelers...

In addition to the powerful winds that have raked the northern Bahamas over the past few days, Hurricane Dorian’s slow motion has brought very heavy rainfall to the islands as well. Dorian first formed into a tropical depression on the 24th of August about 800 miles east southeast of Barbados in the Lesser Antilles from an area of low pressure; the depression was quickly upgraded to a minimal tropical storm and named Dorian by the National Hurricane Center (NHC) later in the day. As Dorian made its way westward under the influence of a high pressure ridge to the north, it was held in check...

UPDATE 9/9/19: On Monday morning, September 9, Hurricane Dorian was a post-tropical storm after a mid-latitude weather front and cold seas had altered its tropical characteristics over the weekend. On Saturday and Sunday, Hurricane Dorian struck eastern Canada, causing wind damage and bringing heavy rainfall. According to the Associated Press, a peak of 400,000 people were without power in Nova Scotia, Canada, because of Dorian. This graphic shows precipitation that fell during the almost two-week period from August 27 to the early hours of September 9. The near-realtime rain estimates come...

The intertropical convergence zone or “ITCZ” roughly forms a band that circumnavigates the Earth near the Equator where the northeast trade winds in the Northern Hemisphere converge with the southeast trade winds in the Southern Hemisphere. Sailors have often referred to it as the “doldrums” due to its generally light winds. Yet, the ITCZ is an important part of the global circulation as it forms the ascending branch of the Hadley circulation. This is ultimately driven by incoming solar radiation, which peaks near the Equator. This warms the air and the ocean, causing warm buoyant air to rise...