Radiofax: JMH/JMH2/JMH4 (Japan Meteorological Agency)

The radiofax station JMH, JMH2 and JMH4 is one of the nearby “powerhouses”, sending charts almost continually around the clock on three frequencies (3622.5kHz, 7795kHz and 13988.5kHz). It’s often heard in Australia, albeit I often receive it very “noisily” and is a station I am fairly fond of because of the multitude of different chart types and the transmission of satellite imagery.

As a result, on my 2017 trip to Japan, I decided that it would be a good opportunity to receive JMH “locally”, which should result in better quality copy. As it turns out, this was not always the case both due to skip-zone propagation as well as the QRM that exists in built-up city centres, especially in hotels filled with elevators that have variable-speed drives. Regardless, a majority of the charts presented were received in late 2017 on my holiday, predominantly in my room in Osaka where the radio noise seemed most quiet, but only recently processed to a presentable state.

The remainder of the charts were received in January 2019 through the use of JP7FSO’s KiwiSDR in Fukushima, Japan, JH1PGF’s KiwiSDR in Tokyo, Japan and the Northeast Asian Broadcasting Institute (NEABI)’s KiwiSDR in Seoul, South Korea.

As usual, the charts presented represent a snapshot in time and are not kept up to date or current. Charts should not be used for navigation purposes. Copyright of the chart material resides with the transmitting agency, Japan Meterological Agency, Tokyo. Provision of the chart images is made for documentary purposes, to illustrate the variety and format of the charts on offer, specific transmission characteristics of the charts and as proof of the activity status of the station at the dates the charts were issued.

Faxes

Compared with other stations, JMH seems to have a slightly longer start tone, a standard phasing interval and black margins. While there are some similarities to the NOAA/Canadian faxes, are no scale bars or coded dots.

One of the most interesting charts they send is a very short chart, labelled “Test Chart” and transmitted at 0103/1303UTC. This chart does feature a number of gradations, scale bars and pushes the resolution of the fax to its limit. Unfortunately, on the day I didn’t dial-in the slant settings (the latter day), the propagation was favourable resulting in the clearest test chart I have received from JMH. However, the next day (18th September 2017) once I dialled in the slant … well … the propagation changed its mind. The test chart does, however, illustrate the greyscale nature of radiofacsimile.

No other chart illustrates the use of greyscale in practice more clearly than the infrared satellite image from Japanese Himawari weather satellite dated 20th September 2017. Note the presence of the greyscale level bar at the end of the chart which has a total of 17 segments which have black at both ends for a 16-level greyscale image. Also note the image not filling the entire width of the paper, which seems to be characteristic of JMH transmissions.

The next most important fax when it comes to identifying a station is the broadcast schedule. This is broadcast just once a day at 0340UTC, received via JP7FSO’s KiwiSDR on 15th January 2019 and combines the tabular schedule with a section for manual amendments (MANAM). Unfortunately, the propagation was poor on that day with noticeable multipath causing the image to “skitter” left and right. Unfortunately, with such fine text, it can be difficult to get a copy.

As a result, due to the “value” of this chart, I reattempted reception today (27th January 2019), on 7795kHz via JH1PGF which had a much more solid copy. Very satisfied with that. Notice how, unlike some other stations, JMH does issue charts which are seasonal and or dependent on the day of the week. This is also common to the way JJC operates.

As can be seen from the schedule, most products are identified with a four or five letter code followed by an optional set of numerals (often indicating hours). It is very systematic, allowing for clear identification of the charts. I suspect the lettering identifies the type and area of coverage.

Assorted Charts

The FWJP chart is one that I most commonly receive and depicts the 24hr wave forecast for the Japan area. It is oriented to be read in portrait orientation with a tabular letter coding. This example received 22nd September 2017.

The FWPN chart represents the 24 hr wave forecast with illustrated typhoons. The above example dated 27th August 2017.

FWPN07 differs from most of the other products by combining four “tiled” charts into one, with T12, T24, T48 and T72 forecasts of wave height, period and direction.

The analog to FWJP is AWJP, which is the wave analysis chart. I suspect A standing for “actual” or “analysis”, whereas F would stand for forecast. Thea bove from 26th August 2017.

Likewise, FWPN has an AWPN counterpart, received 15th January 2019.

The ASAS chart is also fairly commonly received, representing the surface analysis. The above example from 17th September 2017.

AUAS50 appears to illustrate height and temperatures, sent 16th September 2017 occupying the full page.

There is also an AUAS85 which seems to illustrate the same type of data but probably for a different height (?) or validity time, received 20th September 2017.

WTAS07 was not particularly easy to receive, as the typhoon forecast is likely only issued when an active system is in the area. This was received 26th August 2017.

COPQ is an odd, nearly square-shaped chart, illustrating the coverage of sea ice and daily mean sea surface temperature. The above is from 14th January 2019.

SOPQ is another chart which follows the nearly square shape, illustrating sea ice coverage, speed, sea surface and 100m temperatures. The above example was received on the same day.

STPN is the sea ice concentration chart, also rarely received as it is seasonal. Also received on the same day, it contains a significant amount of Japanese and English text.

FSAS-series

The FSAS series of charts appear to be concerned with surface pressure and precipitation.

In the series, FSAS04 and FSAS07 are sent with both charts combined to a single portrait page. The above example is dated 19th September 2017. For the other FSAS charts, they are sent as portrait orientation but with content formatted for landscape reading, maximising clarity.

This includes FSAS09, which fully occupies the chart area and is also dated 19th September 2017.

FSAS12 follows the same format.

However, FSAS24 and the following FSAS48 differ, with a chart that is skinnier with white margins either side and a slightly different coverage area. There is also a nautical mile scale on the chart and shaded warning areas.

FSAS48 follows the conventions of FSAS24.

F*FE-series

The F*FE series of charts seem to be a collection of miscellaneous charts which follow the convention of being sent as “short” charts with two to a page.

The above chart is an example of FUFE502 (Height, Vort, Height) and FSFE02 (Surface Pressure, Precipitation, Wind Arrow at Surface), from 15th January 2019.

The above chart is an example of FUFE503 and FSFE03 from 22nd September 2017, which illustrate the same types of information but with a different validity time.

The chart above is coded FXFE572 (Temp at 500/700hPa) and FXFE782 (Temp, Wind Arrow at 850hPa, P-Vel at 700hPa), transmitted 21st September 2017.

Likewise, the above chart FXFE573 and FXFE783 was transmitted on the same day and presents the same data at a different validity time.

Conclusion

Amongst all radiofax stations, JMH is one of the favourites. JMH issues charts with a variety of formats – tall, wide, multiple-side-by-side in a tiled fashion, as well as satellite images. Even the test chart is rather interesting. The signals are rather powerful and are on the air around-the-clock with white tone to aid tuning. While it is active on fewer frequencies than in the past, it is still very much providing valuable service to the Asia-Pacific region.

While I did not collect every type of chart available as some are seasonal, I did manage to show the majority of them that could be clearly received. I would expect the unseen charts to follow very similar conventions.

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