These are the news starting 01 Jan 2019
Click here for the news of the previous years.

The thunderstorm yesterday showed a problem with our lightning sensor: it did not display flashes inside the 25km zone. I just checked the outside antenna and thoroughly cleaned the RJ45 connector...let's wait for the next storm to see if this helped.
I replaced the Delta_T logger by a spare one (same model); the problem of the jitter could be a creeping malfunction of one of the input just to be sure the old logger was replaced by a spare having identical hardware configuration... First check give a hint that this is successful...
Confirmation at 18:00 UTC. The jitter problem seems to be solved...
Still searching for the cause of jitter...some servers (like CO2) have been shut off...please bear with me the disturbances...
Continuing the search for the cause of the pressure jitter the barometric sensor has been switched of at 16:00 UTC...this allows to check if the jitter (also visible in the radioactive measurement) is still present (and so not caused by the barometer). I also rerouted everything around the UPS, so that this possible cause is also eleminated...
I continue the investigation to find the cause of the barometer and radioactivity jitter. Installed separate 12VDC power-supply for barometer; signal - (signal GND must be connected to logger GND). Inspection later today or tomorrow will tell if this helps. Inspection of the raw input voltage into the logger suggests stability...(slow jitter only 0.1 mV).
1. Raoul Tholl and myself checked and cleaned the Vaisala CO2 sensor; actually both the mirror and optics were quite clean, after 2 years of flawless operation.
2. We searched for the cause of the jitter on the barometric sensor and the radioactive readings. One sure culprit is the Fritz powerline system I installed to drive the Airvisual Pro PM sensor (but it may not be the sole cause!). I removed the powerline system and mounted a Netgear AP directly into the waterproof box inside the Stevenson hut. It was not easy to pull a RJ45 cable from the computer room to this hut, and it is a bit kludgy, but works. Tests with a AP located in the computer room showed that the WLAN signal was very poor, as attenuation by the steel-reinforced ceiling and metal cladding is strong, so the AP had to be installed close to the Airvisual sensor who communicates only by WiFi. The new system started about at 16:00 UTC today.
3. Uploaded jun19.dat file into the data archive.
28 Jun 19 Replaced the peristaltic pump of the WBGT sensor by a new one. As the flow rate is higher, pumping time has been reduced to 1 minute per session, and 5 sessions defined.
Changed dessicant on CM21, UVA and UVB instruments. The O3 (ground ozone) readings of the CAIRSENS sensor seem a bit overblown; I changed the special inlet filter. The clock timing the distilled water pump for the wet bulb sensor seems to have a bad character: somehow during the night the power on sequence (which should time out after 2 minutes) was stuck in the ON position, and the water storage canister ran dry. I changed the clock, checked 5 times the correct programming, and we will see... The WBGT readings for today are all ok.

In these hot days, you may look at this table for the WBGT threshhold conditions, which depend on the % of work done:

Notice that today we exceed the conditions for light work from 10:30 local time on (WBGT > 30°C).

Click here and here for further information on heat-stress and WBGT measurement.

1. The 17th and 24th June 2019 two classes (about 25 students each) of the LTPS (Lycée Technique pour les Professions de la Santé) of Luxembourg visited meteoLCD, watched some demonstrations and listened to a presentation by F.Massen titled "Changement climatique...pas de panique!". Our member Raoull Tholl who teaches physics at the LTPS has organized these visits.
2. The wet bulb sensor of the WBGT heat-stress sensor ran dry this morning after 10:00; has been refilled and everything ok since 12:00. Look here to watch how wet bulb temperature goes up and down.
Upload may19.dat  into data archive.
24 May 19 There was an interruption due to a problem with our main computer; relaunched this morning: ok. No data will be lost, as everything is stored on the datalogger.
1. Reactivated the heat-stress sensor display (even if times they are chilly...but this surely will change in the upcoming weeks)
2. Backup work on the main Lubuntu replacement computer.
02 May 19 1. Following some email exchanges with a professor from the SIUE (Southern Illinois University Edwardsville) I installed today a PurpleAir fine particle sensor in offline mode. The sensor records PM 1.0, PM 2.5, PM 10 and also the raw particle counts (*) on a .csv file of the internal SD card (as well as temperature, pressure and relative humidity), data which will be used later for comparisons and calibration research.

As shown on the pictures, the PurpleAir has two Plantower sensors in parallel, and the measurements of both are recorded so to have some sort of confidence check.

(*) Did you know that there are about 20000 fine particles > 0.3 micrometer in one liter of rather clean air?

2. We ( F. Massen, C. Baumann, R.Tholl, M. Zimmer) posted a very short paper in the papers section which compares our first Airvisual PM measurements with those made by the official Beidweiler station. The Airvisual data (daily average) must be corrected for high humidity levels, and follow the official ones quite nicely.
3. Upload apr19.dat  into data archive

30Apr19 1. The new barometer has big swings in its output signal; I tried to smooth this out with different capacitors, but no great success for the moment. The oscilloscope shows that the signal is noisy by <10mV which corresponds to about 6 HPa. Tried now using a 100uF Elko.
2. Big catastrophe with the old ESR backup pyranometer (channel 23). There is a 4-20mA converter at the outlet of the pyranometer, and the box holding this module was filled with rainwater, which badly corroded all contacts and gave meaningless readings since the 05Apr2019. Luckily the electronic module survived, and after thoroughly cleaning the contacts the sensor is working correctly again (since 09:00 UTC today).
08Apr19 Raoul and I replaced the old BS4 barometer (in use since 1994!) by a new one (Fischer FI05). The BS04 had some age-related jittering since over a year, and it was time to put him at rest. We had to shutoff some sensors and change the logger configuration. So do not be afraid by unusual readings in the plots and data-file, they will disappear by magic during the coming days...
03Apr19 1. The PM2.5 seems not to have been updated on the Airvisual cloud for a day, but the equipment works correctly here at meteoLCD. Problem seems to have been cleared today morning.
2. Installed new CAIRSENS O3/NO2 sensor (serial 5409) as a replacement for the old one which has come (or even exceeded) its normal lifespan of 1 year. These sensors are built to work without calibration (except 3 filter changes) for one year. Our experience (> 12 months) of the first sensor was very satisfying: the readings are in excellent conformity to the official ones. Calibration certificate here.
02Apr19 Upload mar19.dat  into data archive
01Apr19 Backup station ok again.
29Mar19 The Thinclient comnputer driving the Davis Backup station is sick. Will be replaced asap.
25Mar19 Installed new AVM 1220E/1260E powerline/WLAN combo to drive the Airvisual PM2.5 sensor.
17Mar19 Again a problem with the Devolo Powerlink tying our Airvisual PM sensor into the Lan. The PLC looses contact with the AP installed in the Stevenson hut on the terrace, for no apparent reason. I will probably replace the Devolo system by a AVM PLC which uses all 3 wires (neutral, line and ground); an installation I made at home showed that this system works much better in dubious/complicated 220 VAC installations.
01Mar19 Upload feb19.dat  into data archive
27Feb19 The axis orientation of  our PM2.5 measurement at the website were a bit confusing (timing increased either from left to right or right to left). This seems now ok: click  for annotated pictures of the hourly and daily graphs.
14Feb19 Trends 1998 to 2018 analysis finished!
13Feb19 Look at the Dobson (Total ozone) page for two plots comparing the ozone measurements done at Uccle with the very expensive Brewer MkIII (serial 178) and our Microtops (serial 5375) instrument during 2018. There are 180 same day, direct sun comparable measurements.
The two series and the calibration curve. I think we can be very satisfied with these results!
01Feb19 Upload jan19.dat  into data archive.
18Jan19 I started with the update of the trends section. This is heavy work and will take some time to finish. Updated sections are clearly marked as such.
10Jan19 The Airvisual web site of meteoLCD is now complete, with all data missing during the first days (like Temp, Humidity, ...) and forecast now present.

Look also at the Airvisual quality map, which allows easy picking of stations, worldwide:
Be aware that this map gives all available stations, without specifying wether they are official ones or come from the Airvisual community (for Luxembourg, meteoLCD is a community station, the others are those of the Environmental Agency).

You might re-read my multi-part blog on air quality and AQI.

09Jan19 Big news: our Airvisual Pro station to measure air quality (essentially PM2.5 fine particles concentration) has been accepted into the world-wide Airvisual network of AQI stations. The reported AQI is the US AQI, as defined by EPA.

Click here:

This link will be added to the page of live data.

Attention: on the hourly graph, the most recent values are at the left! The time axis decreases from left to right (don't ask why...)  Monday 14 January: This unusual behavior has been changed: the time axis now shows the most recent hourly measurement at the right (time increases from left to right).

06Jan19 Added file 2018_only.xls to data archive. This file contains all the meteoLCD measurements of the year 2018, some statistics, daily and monthly values and comparisons with measurements done at the Meteolux station at Findel airport.
01Jan19 1. The usual dogs-dinner in the 7days plot due to Gnuplot problems with handling previous and new year (the logger files do not contain the year number). This will be self healing in the next 7 days.
2. Upload dec18.dat  into data archive.



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