Mar. 7, 2022 Updated
JAXA Himawari Monitor
Sep. 2015 JAXA/EORC

Frequently Asked Questions (FAQs)

1. Himawari Monitor Website

Q1-1. I would like to see past images on the Himawari Monitor Website, but only the ones that were observed during 00-09 minutes per hour are displayed.

Due to the system constraints, only those observed during 00 to 09 minutes per hour are shown for images that has passed over 3 months from the observations, and others are removed from the web server. Note that all the physical products can be obtained from the ftp site (including those data taken during 10-59 minutes). Note that geophysical products of all past periods are available via FTP in NetCDF format.

Q1-2. How can I obtain Himawari data?

We provide you the geostationary satellite Himawari Standard Data provided by the Japan Meteorological Agency (JMA) as well as the geophysical parameter data produced by JAXA using the Himawari Standard Data via our FTP site. Request your account from here.

Q1-3. I cannot access to P-Tree’s FTP site with my Web browser.

No major web browser accept you to access FTP sites. Use FTP client software, such as FileZilla or WinSCP.

Q1-4. How can I change my registered affiliation information?

May we ask you to register again?

Q1-5. I can't download data fron the FTP site.

Our FTP server limits the number of simultaneous connections. You can simultaneously download data up to 30 connections from a host or 100 hosts.

Q1-6. It takes long time to download data from the FTP site.

When a server trouble occurs, we will announce in What's New. Network traffic might be temporarily very busy. Try to access later. If data down load delays to long time, contact us.

2. Himawari Standard Data (HSD)

Q2-1. What kind of data is the Himawari Standard Data (HSD)?

The Himawari Standard Data(HSD) is the most closest data to raw data and is the data with the largest amount of information among the Himawari observation data provided from the Japan Meterology Agency (JMA). JAXA disseminates the HSD data to users for non-profit purposes such as research and education based on cooperative agreement with JMA. For details on the HSD data, please refer to the following URLs.
- Himawari Standard Data (Meteorological Satellite Center of JMA)
- Himawari Standard Data User's Guide

Q2-2. Can I obtain previous Himawari Standard Data observed before 30 days from observation?

Due to system constraints, those data that has passed over 30 days has been deleted from the P-Tree FTP server. The other services distributing the Himawari Original Data are listed below. Please contact the administrator of each sites for further details.
- World Science Data Bank by NICT
Data Integration and Analysis System (DIAS) by the University of Tokyo

3. L1 Gridded Data and Geophysical Products

Q3-1. What kind of format is the NetCDF, which is provided from JAXA Himawari Monitor?

NetCDF is a self-describing, machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data. The detail of the NetCDF can be found in the following URL:

Q3-2. How can I read the data in NetCDF format provided from the JAXA Himawari Monitor?

Use the programming languages (C, FORTRAN, C++, Java, etc.) with including the NetCDF libraries, which are freely distributed from the NetCDF official website. As a GUI-based software, the 'hdfview' is also useful to access There are also some other commercial software that support the NetCDF.

Q3-3. Are there any references describing the aerosol property (ARP) algorithm?

Please refer the following websites and references.
- JAXA Himawari Monitor Aerosol Products
- References
(L2 Aerosol Algorithm)
Yoshida, M, M. Kikuchi, T. M. Nagao, H. Murakami, T. Nomaki, and A. Higurashi, 2018: Common retrieval of aerosol properties for imaging satellite sensors, J. Meteor. Soc. Japan, doi:10.2151/jmsj.2018-039.
(L3 Hourly Aerosol Algorithm)
Kikuchi, M., H. Murakami, K. Suzuki, T. M. Nagao, and A. Higurashi, Improved Hourly Estimates of Aerosol Optical Thickness using Spatiotemporal Variability Derived from Himawari-8 Geostationary Satellite, IEEE Transactions on Geoscience and Remote Sensing, accepted.

Q3-4. Where can I get Algorithm Theoretical Basis Document (ATBD) for Himawari products?

ATBD has not been published for Himawari products. See our User’s guide as well as documents and references.

Q3-5. Why does the format of the Sea Surface Temperature (SST) product differ from the other products?

The format of SST product conforms to Group for High Resolution Sea Surface Temperature (GHRSST) format instead of other Himawari products.

Q3-6. Does the the Himawari L1 Gridded data provide surface reflectance?

No. We distribute top of atmosphere (TOA) reflectance without atmospheric correction. We define albedo as reflectance*cos(SOZ), where SOZ is solar zenith angle, for Himawari product.

Q3-7. Is the Himawari8 L1 data corrected for parallax effect?

No. The HImawari-8 L1 data is projected onto the WGS84 ellipsoid without orthorectification. Therefor ground elevation and cloud height are not corrected.

Q3-8. Why does the solar azimuth angle of L1 product have negative value?

The solar azimuth angle ranges from -180 to 180 degree. When you want them ranging from 0 to 360 degree, follow as following. From 0 to 180 degree, you can use the azimuth angle without any correction. From -180 to 0 degree, just add 360 degree to convert them into the range of 180 to 360 degree.

Q3-9. There is obviius stripe noise on Chlorophyll a product.

The artifact on the Chlorophyll a product is attributed to the pixel to pixel sensitivity variation of the scan unit of the AHI sensor, which is calibrated within the sensor spec. The slight difference between the pixel sensitivity can be emphasized after the atmospheric correction. This stripe noise is noticeable over daily and monthly products because temporal averaging reduce the other noises but the difference between the pixel sensitivity remains.

Q3-10. What does "Failed" for Cloud Retrieval Algorithm mean?

The cloud property retrieval relies on a lookup table of cloud optical thickness and effective particle radius calculated by radiative transfer simulation. The cloud retrieval algorithm flag would be 011=Failed when the retrieval algorithm could not find optimal solution which occurs when cloud is extremely thin or thick, land surface was coverd by ice/snow, or the  pixel was corresponding to sunglint. When the flag was 011=Failed, check an additional flag, namely, (4,3) Cloud Mask Confidence Level Flag: 00=Clear, 01=Probably Clear, 10=Probably Cloudy, 11=Cloudy; If the ""011=Failed"" occurred over the pixels with very thick cloud (perhaps, the Cloud Mask Confidence Level Flag=11), you should treat the pixel as cloud. However, when the ""011=Failed"" occurred on the edge of cloud or thick aerosol, the Cloud Mask Confidence Level Flag is usually 10=Probably Cloudy. In such case, the pixel is ambiguous to be cloudy or not."

Q3-11. Why does the release time of Aerosl Property product have no regularity and delay more than 3 hours?

The release timing of the Level 3 aerosol product is generally 2 and half hours to 6 hours from the observation. The algorithm to generate the Level 2 aerosol product sacrificed processing time to improve the accuracy. Usually it takes 2 to 5 hours from the observation to process the Level 2 aerosol product. Then the  Level 3 aerosol products are generally created 2 and half hours to 6 hours from the observation because the Level 3 products are created based on the Level 2 products during one hour.

Q3-12. Why were a dytime data totally missing?

The observation time contained in the file names time is in UTC. Convert to your local time.

Q3-13. How shoud I interpret Uncertaties of AHI AOT products?

The parameter "AOT_Merged_uncertainty" is a unitless and you can write the uncertainty as the following: "AOT_Merged" ± "AOT_Merged_uncertainty"

Q3-14. How are the level 3 daily data created?

The level 3 daily data are created from the Level 2 product at 00:00 to 23:50 UTC.

Q3-15. Which depth does the Chlorophyll-a concentrations represent?

The Chlorophyll-a concentrations represents the depth of about 0 to few m depending on the transmittance of the water, which generally increases from coastal to open ocean. Subsurface chlorophyll-a is not detected over subtropical stratified ocean.

Q3-16. How can I get latitude and longitude coordinate for a specific pixel?

The full-disk Himawari L1 Gridded Data covers 60S-60N, 80E-160W in 0.02 degree
resolution. You can convert x, y in the image to longitude and latitude as
 longitude = 80 + x * 0.02
 latitude = 60 - y * 0.02
Or, you can retrieve latitude and longitude table from the netCDF file by using software to treat netCDF format.

Q3-17 Why are the refrectance and brightness temperature for Himawari L1 Gridded Data larger than 1000?

Use the scale factor and add offset stored in NetCDF file to obtain the physical quantity. For bands 1 to 6, the scale factor and add offset are 0.0001 and 0.0. For bands 7 to 16, the scale factor and add offset are 0.01 and 273.15.

Q3-18 How can I obtain solar irradiane to calculate radiance from Himawari L1 Gridded Data?

See the document of Meteorological Satellite Center.

Q3-19 Can I get CLP product in nighttime?

No. CLP cannot be calculated without solar radiance.

Q3-20 How are the level 3 hourly data created?

The level 3 hourly data are created from the Level 2 product on the hour to 50 minutes past the hour. The time in the file name indicates the beginning of the period.

4. Data Use

Q4-1. Can I use the data provided by the Himawari Monitor (P-Tree) system for commercial purposes?

Use of the data provided from the system is limited to non-profit purposes such as research and education based on the policy of the JMA. For profit or business purposes, please contact the Japan Meteorological Business Support Center.