Variation In Precipitation At Washington Reagan National Airport (DCA) 1945-2018

Recently the weather, at least precipitation wise, in the DCA area has been variable. It was very wet and rainy, then we had dry conditions for several weeks with essentially no rain. Now, it is very wet again. Are we seeing extreme (some may say historic) changes in the weather? Or are these just the usual variations?

Are rainfall events are becoming less common, but more extreme? That is, it rains less often, but we get more rain when it does rain, rather than getting rainfall spread out evenly over time as it used to be. And maybe we’re getting more rain overall. Or possibly less rain, those two claims seems to depend on recent weather memory.

To check this claim, data for Washington Reagan National Airport (DCA) was downloaded from the NOAA NCDC site and analyzed in several ways. You can download this data yourself, if you wish: https://www.ncdc.noaa.gov/cdo-web/

The dataset runs from July 1, 1945 to July 18, 2018. There appear to be a few days with missing data, as for some years there is only data for 364 days. The actual number of days per year of data was taken into account when computing means. Also, some data is not plotted for 1945 or 2018, namely the number of days with/without rain for those years, as a full year of data is not available.

Each of the graphs can be clicked to be viewed full size.

First, is there a significant long term trend in the amount of precipitation at DCA? No, there does not seem to be (if you squint you may see a very small decline over time, the sign of this slope likely changes from year to year with normal variability in rainfall):
Mean daily precipitation

Second, are rain events becoming less common, but with higher rainfall totals from those events? That would mean we are seeing fewer days with rain, but more rain on those days. The following two graphs show the number of days without any rain, and the number of days with rain, defined as 0.01″ or more. First the number of days without rain. Which is not increasing, but actually decreasing:
Days per year without precipitation

And the number of days per year with rain, which of course is just the inverse of the previous graph. It’s raining 5 or 6 more days per year (sorry, Walter):
Days per year with precipitation

Third, what about the rainfall totals on days when it actually rains. Is that increasing, leading to more extreme rain events? No, it isn’t. It is actually decreasing, which makes sense considering the mean rainfall per year is essentially steady, and it is raining a few more days out of the year:
Mean precipitation for days with precipitation

OK, maybe it is mostly the same, but we’re getting a few more extreme rainfall events per year? Let’s look at the standard deviation of the rainfall amounts, again only for days when it actually rains.

Standard deviation is amount of variation of a set of data values around the mean (average), there is an explanation here: https://en.wikipedia.org/wiki/Standard_deviation If you get this joke, you understand standard deviation: “Yo mama is so mean she has no standard deviation”

Hmm, no, that is also steady:
Standard deviation of daily precipitation

One more thing, look at the number of days with very extreme rainfall. How about the number of days where the rainfall exceeded two standard deviations? That also seems to be flat:
Days above two standard deviations

Anything else we can check to see if precipitation is indeed getting more extreme in Washington DC? So far, it doesn’t seem to be.

Note, the purpose of this analysis was not to try and discredit man made climate change aka AGW, which is certainly real. Only to see if claims of a noticeable effect on the precipitation patterns in the DC area can be confirmed, which does not seem to be the case.

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Listening To Pirate Radio Stations from South America

Looking for a new DX challenge? In addition to shortwave pirate stations in the USA, and Europe (Europirates as we call them), there’s a relatively new group of pirate radio stations being heard in North America, those from South America.

It’s really only been the previous year that we’ve confirmed that there’s a significant number of pirate radio stations in South America that can be received here. Radio Pirana has been known for some time, and I believe thee were a few reports of it, and at least one other station that I cannot remember the name of, but that’s about it. For years there have been logs of very weak UNID stations heard on the 43 meter band (6800-7000 kHz), presumed to be pirates of some sort, and it is possible some of these were South American pirates.

Most of these stations use homemade transmitters, often of the “Lulu” design, with a IRF510 or similar MOSET RF final stage. That means they are generally in the 15 or 20 watt carrier range, although some are higher power. That also means that unless otherwise noted, all of these stations use AM mode, and in general the frequency is highly variable, easily varying 100 Hz or more from night to night, or even during transmissions.

One important caveat: Since most of these stations use relatively low power, and due to the long distances involved, signal levels are generally weak, although occasionally when conditions are excellent (especially if there’s grayline propagation), they can put in stronger signals. I am fortunate to live in a rural area with relatively low noise/RFI levels, and have several high end receivers and large antennas. My primary setup for catching these stations is a netSDR receiver and a 670 foot Sky Loop antenna. You’re going to want to use the best receiver and antenna you can for catching these stations, you’re not likely to have good (or any) results with a portable SW radio, RTL dongle, or small/indoor antenna. Also, I record the entire 43 meter band nightly on my netSDR, and then go through the recordings each morning. This lets me catch stations that may only appear for a brief period of time. That said, you can still hear them with a reasonable HF setup, although it may take persistence, checking each night, until conditions permit reception.

It’s well worth checking the Latin American Pirate logging forum on the HF Underground website, to see what is presently being heard. The HF Underground is the best way to keep up to date with the hobbyist radio scene in general, with dedicated forums for North American Pirates, Europirates, and of course radio in general.

And for those of you into collecting QSLs – many of these stations are reliable QSLers!

In general, the easiest station to hear is Lupo Radio from Argentina. It is on the air most evenings on 6973 kHz in AM mode. At least at my location, it puts in the strongest and most reliable signal. Usually in the SIO 222 to 333 range, sometimes stronger. There are frequent IDs. I use Lupo Radio as a “beacon” to gauge how good conditions are to South America on 43 meters.


luporadio@hotmail.com

Another station that is often on the air is RCW – Radio Compañía Worldwide from Chile. They use 6925.13 kHz, and their carrier is more stable and usually on this offset frequency, which makes it easier to determine that it’s likely you’re hearing them vs a US pirate station.


rcwradio@gmail.com

New to the scene is Radio Marcopolo on 6991 kHz.


Marcopoloradio@hotmail.com

Also new to the scene is an as yet UNID pirate from South America on 6934.9 kHz. I have received them for several weeks now in the local evenings, usually starting around the 2300-0300 UTC window. They put in a respectable signal (relatively speaking), strong enough for Shazam to ID songs. They have frequent breaks in their transmission, with the carrier often going off and on many times during a broadcast. They also occasionally transmit audio test tones, and sometimes seem to relay audio from licensed stations in Argentina such as Radio El Mundo. This could be someone testing a new transmitter? A new mystery to solve!

Radio Dontri is somewhat unique in that they use USB mode, on 6955 kHz. They also send SSTV, which is sometimes easier to receive than music, and helps to verify that you’re actually hearing them, vs a US pirate on 6955. They tend to drift a lot, however, which can make decoding the SSTV transmissions challenging.


radiodontri@gmail.com

Outside the 43 meter band, there is Rádio Casa 8000 kHz. I have only received weak carriers from this station, although partly that may be because I do not frequently check for it, and it does not turn up on my overnight SDR recordings.

Radio Triunfal Evangélica is other station outside of the 43 meter band, they use the nominal frequency of 5825 kHz, often closer to 5824.9 kHz. Again I have only received a carrier from them. As the name implies, they are a religious station, affiliated with a church.

Now that we’ve talked about the pirate stations from South America, we should probably mention things you are likely to hear that are not pirates. Specifically, what we call Peskies (or Pesky as the singular), short for pescadores, the Spanish word for fishermen. Peskies generally use LSB mode, and can be heard on many frequencies in the 43 meter band, engaging in QSOs. Years ago, pirate listeners started to call these stations pescadores, since some of them were indeed fishermen, and could be heard discussing related matters. It might be better to think of most of them as freebanders/outbanders, much in the tradition of those transmitting on 11 meters. There’s a logging forum on the HFU dedicated to Peskies, if you’re interesting in learning more about them.

Occasionally they use AM mode. We’ve logged several on 6965 kHz (+/- of course), that at first were thought to be pirates. But they never transmitted music, and after some discussions with DXers in South America, it was determined that they were more properly considered peskies.

An UNID Pirate Station on 1710 kHz

Several pirate stations use 1710 kHz, but reception here is difficult, due to the Hudson County NJ TIS station, which puts in a strong signal. It’s an annoying pest, and seems to just play the same 3 or 4 pre-recorded messages over and over. I doubt anyone in Hudson County actually listens to it.

Last night, I started to hear some music on 1710 around 2350 UTC (6 February 2018), so I decided to stick around and listen. I also started the SDR recording. Glad I did!

The station was fading in and out, so my reception was alternating with the TIS.

Here’s what I heard. Some songs were ID’d with Shazam, so they could be iffy, plus there could be another station in there:

2352 Eagles “What Do I Do With My Heart”.
2356 “Green Hornet Theme”
0002 Neil Diamond “Stones”
0005 “You Only Live Twice”
0042 Oliva Newton John “Let Me Be There”
0044 Country song?
0047 Johnny Mathis “Wonderful! Wonderful!”
0052 The New Seekers “Look What They’ve Done To My Song Ma”
0055 Jose Feliciano “High Heel Sneakers”
0057 Jewel “Standing Still”
0106 Donna Summer “Macarthur Park”
0109 Elvis “Don’t Be Cruel”
0112 “Wiggle Wobble”
0114 Conway Twitty “Hello Darlin”
0117 Colbie Caillat “Realize”
0121 Howard Jones “No One Is To Blame”
0125 “Heart Of Gold”
0128 “Little Bit O’ Soul”
0130 “As Time Goes By”
0133 “Ahab The Arab”
0148 “How Do You Do It?”
0150 “Nobody But Me”
0203 “Bittersweet”
0210 “Cinnamon Girl”
0217 “It Might Be You”
0221 “Baby, I’m Yours”
0223 “Sara”
0227 “Freaky Behavior”
0234 QRT I think.

I ran the SDR recording files through my Carrier Sleuth app, and produced this high resolution waterfall of 1710 kHz. Click on the image to view it full sized.

The pirate is the carrier around 1710.009 kHz that goes QRT around 0234 UTC. The carrier around 1710.0025 kHz is the Hudson County TIS. I think one of the carriers is another TIS in PA, I heard a mention of an address in PA at one point. Probably KID-761, Bedford, PA, the Flight 93 Memorial.

Look at all the other carriers on 1710! One is probably the Springfield MA TIS, others may be pirates? I am not sure how many other TIS stations are authorized on 1710.

It’s very interesting how there is another carrier around 1709.995 kHz that went QRT the same time as the pirate. It is weaker, and does not have the same wiggles as the pirate carrier, so I do not think it is a locally produced image. I am not sure what it is, or if the sign off time is coincidental.

If the operator of the 1710 pirate sees this post, and would like to send me a QSL / eQSL, it would be greatly appreciated!

KitchenAid Mixer QRM

I discovered a new QRM / RFI source today, my wife’s new KitchenAid 7-Quart Pro Line Stand Mixer. Here’s a waterfall screenshot after it turned on, you can see the roughly 15 kHz spaced bands of interference. These use a DC motor, presumably that is the cause of the RFI, vs mixers with a regular AC motor.

Fortunately she doesn’t use it that often, and she’s testing out a new low carb dough recipe, so I can live with it. Speaking of low carb, here’s our low carb pizza recipe.

A Christmas card from… the Voice of the Islamic Republic of Iran

The other day a large envelope from the Voice of the Islamic Republic of Iran arrived in the mail, the kind of envelopes they put QSL cards in. I had sent a report a few months ago, but already received that QSL card.

I opened it, and instead of a QSL card… there was a Christmas card: