Near 40 Years MERRA-2 Data at NASA GES DISC – Opportunity and Challenge to Support Extremes Study

To the end of 2019, 40 years NASA climate reanalysis datasets from the Modern Era Retrospective-analysis for Research and Applications, Version 2 (MERRA-2) will be available at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). MERRA-2 consists atmosphere, land, and ocean data, which may be used for the studies ranging from the short scale weather events to the large scale decadal variabilities. The hourly products, such as precipitation, soil moisture, temperature, and aerosols etc., have been used widely to study extreme events.

In supporting users from broad user communities, GES DISC have developed various data access services, including subsetter – for downloading only data of interest with preferred format; OPeNDAP - for machine-to-machine data access; and Giovanni- for online visualization and analysis, etc. A big challenge for extreme study is to downloading and processing long-term hourly or daily data. The data downloading performance is not very satisfied by many users with current services and the native archived data structure.

Late June 2019, many people in Europe had experienced extreme heat waves. The temperatures in several countries exceeded 40^oC (104^oF). For example, MERRA-2 shows that the near surface daily maximum temperature of June 28 2019 over Marseille, a city in southern France, reached 41.1 ^oC (106^oF), which is the record breaking temperature in the last 40 years. Figure 1 shows a) the image of daily maximum 2-meter temperature (T2MMAX) over Europe for June 21-30 2019, generated from Giovanni (https://giovanni.gsfc.nasa.gov/); b) time series of T2MMAX over Marseille for June 15-30, and c) histogram of T2MMAX over Marseille for June 28, and 7-days before and after Jun 28 from 1980 to 2018.

GES DISC is working together with domain science experts to improve the performance of long time series access, making analysis ready datasets in supporting application researches, such as extreme study. In this presentation, using Europe heat wave as an example, we will show prototype of the in-developing service for finding extremes from near 40 years MERRA-2 data at a given location. MERRA-2 data can be accessed from NASA GES DISC (https://disc.gsfc.nasa.gov/ ) by search keyword “MERRA-2” .