HMI data

How to search for HMI data.

This example shows how to search for, download, and load HMI data, using the sunpy.net.Fido interface. HMI data is available via. the Joint Stanford Operations Center (JSOC).

The polar filled radial magnetic field synoptic maps are obtained using the ‘hmi.synoptic_mr_polfil_720s’ series keyword. Note that they are large (1440 x 720), so you will probably want to downsample them to a smaller resolution to use them to calculate PFSS solutions.

For more information on the maps, see the synoptic maps page on the JSOC site.

First import the required modules

import os

import sunpy.map
from sunpy.net import Fido
from sunpy.net import attrs as a

import pfsspy.utils

Set up the search.

Note that for SunPy versions earlier than 2.0, a time attribute is needed to do the search, even if (in this case) it isn’t used, as the synoptic maps are labelled by Carrington rotation number instead of time

time = a.Time('2010/01/01', '2010/01/01')
series = a.jsoc.Series('hmi.synoptic_mr_polfil_720s')

Do the search. This will return all the maps in the ‘hmi_mrsynop_small_720s series.’

result = Fido.search(time, series)
print(result)

Out:

Results from 1 Provider:

153 Results from the JSOCClient:
Source: http://jsoc.stanford.edu

TELESCOP  INSTRUME WAVELNTH CAR_ROT
-------- --------- -------- -------
 SDO/HMI HMI_SIDE1   6173.0    2097
 SDO/HMI HMI_SIDE1   6173.0    2098
 SDO/HMI HMI_SIDE1   6173.0    2099
 SDO/HMI HMI_SIDE1   6173.0    2100
 SDO/HMI HMI_SIDE1   6173.0    2101
 SDO/HMI HMI_SIDE1   6173.0    2102
 SDO/HMI HMI_SIDE1   6173.0    2103
 SDO/HMI HMI_SIDE1   6173.0    2104
 SDO/HMI HMI_SIDE1   6173.0    2105
 SDO/HMI HMI_SIDE1   6173.0    2106
     ...       ...      ...     ...
 SDO/HMI HMI_SIDE1   6173.0    2239
 SDO/HMI HMI_SIDE1   6173.0    2240
 SDO/HMI HMI_SIDE1   6173.0    2241
 SDO/HMI HMI_SIDE1   6173.0    2242
 SDO/HMI HMI_SIDE1   6173.0    2243
 SDO/HMI HMI_SIDE1   6173.0    2244
 SDO/HMI HMI_SIDE1   6173.0    2245
 SDO/HMI HMI_SIDE1   6173.0    2246
 SDO/HMI HMI_SIDE1   6173.0    2247
 SDO/HMI HMI_SIDE1   6173.0    2248
 SDO/HMI HMI_SIDE1   6173.0    2249
Length = 153 rows

If we just want to download a specific map, we can specify a Carrington rotation number. In addition, downloading files from JSOC requires a notification email. If you use this code, please replace this email address with your own one, registered here: http://jsoc.stanford.edu/ajax/register_email.html

crot = a.jsoc.PrimeKey('CAR_ROT', 2210)
result = Fido.search(time, series, crot,
                     a.jsoc.Notify(os.environ['JSOC_EMAIL']))
print(result)

Out:

Results from 1 Provider:

1 Results from the JSOCClient:
Source: http://jsoc.stanford.edu

TELESCOP  INSTRUME WAVELNTH CAR_ROT
-------- --------- -------- -------
 SDO/HMI HMI_SIDE1   6173.0    2210

Download the files. This downloads files to the default sunpy download directory.

files = Fido.fetch(result)
print(files)

Out:

Export request pending. [id=JSOC_20211110_1525_X_IN, status=2]
Waiting for 0 seconds...
1 URLs found for download. Full request totalling 6MB

Files Downloaded:   0%|          | 0/1 [00:00<?, ?file/s]
Files Downloaded: 100%|##########| 1/1 [00:00<00:00,  8.42file/s]
Files Downloaded: 100%|##########| 1/1 [00:00<00:00,  8.39file/s]
['/home/docs/sunpy/data/hmi.synoptic_mr_polfil_720s.2210.Mr_polfil.fits']

Read in a file. This will read in the first file downloaded to a sunpy Map object. Note that HMI maps have several bits of metadata that do not comply to the FITS standard, so we need to fix them first.

hmi_map = sunpy.map.Map(files[0])
pfsspy.utils.fix_hmi_meta(hmi_map)
hmi_map.peek()
HMI carrington 2018-11-09 12:30:52

Out:

INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]
INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]

Total running time of the script: ( 0 minutes 13.564 seconds)

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