7 JRA55 -Japanese Reanalysis Data

Hausfather

The Japanese Meteorological Agency’s JRA-55. This is one of the two next-generation reanalysis products (the other being ECMWF’s ERA5) that uses data from satellites, weather balloons, airplanes, surface stations, buoys, and ships to feed into state of the art weather models that calculate global temperatures back in time.

These reanalysis products differ from surface-only datasets like NASA’s GISTEMP or Berkeley Earth, but produce broadly similar estimates of global temperature over time. Unlike surface datasets, their ingestion of massive real-time data allows for much more rapid updates of global temperature estimates. We can get estimates of daily global average temperatures from JRA-55 or ERA5 from a few days ago, while we will have to wait until early October to get monthly September temperatures from traditional surface records.

Summer 2023 Extremes

Figure: Daily global temperature anomalies from the JRA-55 dataset for each day of the year between 1958 (when the reanalysis dataset starts) through a few days ago (Sep 21st 2023) at time of publication). The black line shows 2023 to-date, the red line shows the prior warmest year on record (2016), and the light grey lines show all other years in the dataset. The month of September is highlighted.

Hausfather (2023) Visualizing a summer of extremes in 7 charts