Release of EarthCARE-GPM Coincidence Dataset

The Japan Aerospace Exploration Agency (JAXA) began distribution of a dataset related to clouds and precipitation that combines simultaneous observation data from the Global Precipitation Measurement (GPM) Core Observatory and the Earth Cloud Aerosol and Radiation Explorer “EarthCARE” satellite on November 27, 2025.

EarthCARE-GPM Coincidence Dataset

Data Provision Period	From August 2024
Contents of Provided Data	GPM/DPR, GPM/GMI, EarthCARE/CPR, and ECMWF environmental field data are stored while maintaining the resolution and other properties of each original dataset.
Format of Provided Data	netCDF4 format *Quick-look PNG images are provided for the vertical distribution of radar reflectivity (GPM/DPR and EarthCARE/CPR) and Doppler velocity (EarthCARE/CPR), and the brightness temperature data of GPM/GMI.
Extraction conditions for simultaneous observations	+/-15-min time difference between the cross-over time of the two spacecraft
How to obtain	Please check the terms of use, etc., on the dataset’s webpage and register as a user. After registration, information necessary to obtain the data will be sent by email.
DOI	10.57746/EO.01ka7xakvwj6pcthxkvgt0vr0y

👉 Please check the documents on the dataset’s webpage for details about the data.

The GPM Core Observatory, a joint mission between JAXA and NASA, was launched in February 2014. It is equipped with the Dual-frequency Precipitation Radar (DPR) developed jointly by JAXA and the National Institute of Information and Communications Technology (NICT) in Japan, as well as the GPM Microwave Imager (GMI) developed by NASA, to observe global precipitation from space. The DPR consists of a Ku-band precipitation radar (KuPR) and a Ka-band precipitation radar (KaPR), with its greatest feature being the ability to observe precipitation in three dimensions from space.

The EarthCARE satellite, a joint JAXA- European Space Agency (ESA) cloud aerosol radiation mission, is equipped with the Cloud Profiling Radar (CPR) developed collaboratively by JAXA and the NICT to observe global clouds from space, and atmospheric instruments developed by the ESA including the Atmospheric Lidar (ATLID), the Multi-Spectral Imager (MSI), and the Broad-Band Radiometer (BBR); it was launched in May 2024. The CPR is the world’s first W-band cloud radar with Doppler velocity measurement, and its greatest feature is the ability to observe the vertical distribution of clouds and the vertical motion of cloud particles from space.

Both the GPM Core Observatory and the EarthCARE satellite are low Earth orbit satellites flying at altitudes of 400 to 450 km, but the GPM Core Observatory follows a non-sun-synchronous orbit while the EarthCARE satellite follows a sun-synchronous sub-recurrent orbit. Due to the difference in these orbits, when the orbits of both satellites intersect at the same timing, such combined observational data can be utilized. JAXA has developed this dataset through a joint research with Dr. F. Joseph Turk of the Joint Institute for Regional Earth System Science and Engineering (JIFRESSE) at the University of California, Los Angeles (UCLA).

👉 For those who want to know more about the orbits:
“Satellites Watching Over the Earth” — The positions of the satellites are displayed in real time.

From the developed EarthCARE-GPM coincidence dataset, we introduce a case of simultaneous observation by the EarthCARE satellite and the GPM Core Observatory over the southern United States around 7:30 (UTC) on October 19, 2025 (Figure 2). From Figure 2(a), the area where precipitation was detected by GPM/DPR (in color) can be seen, and as indicated by the red lines, EarthCARE/CPR observed the same rain cloud with a 144-second difference. Figure 2(b) shows the precipitation types measured by DPR, indicating that the precipitation system includes various types of rain such as convective and stratiform.

Figure 3 presents the vertical cross-sectional observation results along the red line in Figure 2. The radar reflectivity observed by EarthCARE/CPR in Figure 3(a) shows that areas with high values (red) indicate either large cloud or rain particles or a large number of these particles. The Doppler velocity measured by EarthCARE/CPR in Figure 3(b) represents the speed of upward and downward motions of cloud particles and raindrops based on the Doppler effect. In the horizontal distribution shown in Figure 2, within the heavy-rain area indicated with black circle near latitude 32.8 degrees where convective precipitation was observed, the clouds have developed to great heights, and the Doppler velocity values are large (yellow to red), indicating that the cloud particles are rising significantly. As observations corresponding to this by GPM/DPR, looking at the radar reflectivity of KaPR in Figure 3(c) and KuPR in Figure 3(d), it is confirmed that precipitation particles exist up to an altitude of 10 km. Especially, the KuPR in Figure 3(d) has the characteristic of being able to observe strong precipitation near the ground that cannot be captured by CPR or KaPR, and this result can also be confirmed from the vertical cross-sectional diagram.

In the region around latitude 33.5 to 35 degrees where stratiform precipitation is falling, the Doppler velocity of the CPR shown in Figure 3(b) is overall negative (blue) below the altitude where the temperature indicated by the dotted line is around 0 degrees Celsius, indicating that particles are falling, that is, it is raining in the lower levels of the rain cloud. Correspondingly, precipitation can also be observed by the DPR in Figures 3(c) and (d). Also, looking south of latitude 32 degrees, Figure 2 shows that no precipitation is observed on the ground by DPR, but above it, as can be seen in Figure 3(a), there is a spread of thin clouds.

In this way, the “EarthCARE-GPM Coincidence Dataset,” released on November 27, 2025, combines data from dates and times when the EarthCARE satellite and the GPM core satellite observed simultaneously (within ±15 minutes time difference), and this synergy between the two satellites is effective for comprehensively analyzing various information related to clouds and precipitation. Recent research has succeeded in developing a method to estimate vertical motions within precipitation systems by combining CPR and DPR, allowing for a quantitative confirmation of the differences in vertical motion characteristics between stratiform and convective precipitation (*1). Such research and development is expected to contribute to the evaluation and improvement of weather and climate models regarding cloud and wind movement within precipitation systems.

*1: This research has been submitted as a paper to the journal Atmospheric Measurement Techniques (AMT) (Aoki et al. 2025). The preprint was published in August 2025 (https://doi.org/10.5194/egusphere-2025-3596).

Furthermore, it stores data from the GPM Microwave Imager (GMI) onboard the GPM core satellite, cloud-related products from EarthCARE/CPR, and environmental field data. In addition, a website to visualize this data set is currently under development. We will announce once the visualization website goes live, so please look forward to it. It is expected that the use of the EarthCARE-GPM coincidence dataset will lead to further progress in scientific research that enables a comprehensive understanding of clouds and precipitation.