Dust storm north of Dyngjujökull 20 October 2016

Wind gusts over 20 m/s on 20 October 2016 north of Dyngjujökull gave rise to re-suspension of dust from the glacier river, Jökulsá á Fjöllum.

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Landsat8 image from 12:34 on 20 October 2016 (image from NASA/USGS).

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Wind speed measured at Kárahnjúkar (vedur.is). At Upptyppingar on Thursday 20 October at 12:00 the wind speed was Suð-vestan 16 m/s with gusts of 21 m/s, 7,3 °C and RH 51 %.

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Dust storm 7 August 2016

Good weather for dust storms these days here in Iceland, dry and sunny and windy every once in a while.

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The MODIS image above (Image courtesy of NASA MODIS/Rapidfire), taken 14:50 on 7 August 2016, show that pretty well.

Quite windy in the SE-Iceland, as one can see from the wind velocity at Kirkjubæjarklaustur.

kirkjubklaustur_20160802_08_wind

There was an activity south of Langjökull, slightly visible white/grey plume in the figure, caught by an aerial photographer leikfok við Langjökul (RÙV)

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Dust storm 3 May 2016

Sunny and windy in the south today, and dust blowing in the area near Eldhraun and also Meðallandssandur.

Fairly strong winds, 11 m/s average wind speed and gusts of 19 m/s at Kirkjubæjarklaustur (Figure 1).

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Figure 1. Weather observations at 13:00 on 3 May 2016.

Maybe need to look carefully, but possible to see stuff from the coast and further inland in the area between Kúðafljót and Skaftá, where Meðallandssandur and Eldhraun are (Figure 2).

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Figure 2. MODIS image from 3 May 2016 at 13:15 (image from MODIS/Rapidfire).

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Dust storm – lots of clouds–on 28 April 2016

Despite cloud cover, it is possible to detect some dust blowing out to sea from the area east of Mýrdalsjökull. It is likely that this is the Eldhraun area that was flooded in jökulhlaup in Skaftá in October 2015. In the local news yesterday there was a story about a lot of dust blowing there, but clouds completely obscured the view that day.

The wind pattern is quite complicated, but large scale fits with quite strong northerly winds.
20160428_IMO
Weather at 15 on 28 April 2016 (from the IMO web-site).

The satellite images show the dust.

20160428_modis_truecol_A20161191240 12:40 (image from NASA/Rapidfire)

20160428_modis_truecol_P20161191255 12:55 (image from NASA/Rapidfire)

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14:35 (image from NASA/Rapidfire)

The story from yesterday [Dust storm in the flooded area] Sand­byl­ur á flóðasvæðunum. Sand­ur­inn æðir yfir gróður í Eld­hrauni við Brest [Dust blowing over vegetation at Eldhraun near Brest]. [Photo] Ljós­mynd/​Gúst­av M. Ásbjörns­son

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Small, tiny, dust storm on 24 April 2016

A small dust storm (rather than thin cloud) from Markarfljót area, NE of Vestmannaeyjar.

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24 April 2016 at 13:05 (image from MODIS/Nasa Rapidfire).

The wind direction fits, and does the wind speed around this time.

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Wind speed (black numbers), direction (arrows) and temperature on 24 April 2016 (data from the IMO).

 

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Dust storms on 18 April 2016

Strong northerly winds made for prime conditions for dust storms on the south coast of Iceland on 18 April 2016.

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Weather conditions at noon on the 18 April 2016 (courtesy of IMO web page). Below are MODIS images from 12:05 and 12:20 that show the dust blowing off the SE-coast especially.

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12:05 (Image from NASA MODIS/Rapidfire)

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12:20 (Image from NASA MODIS/Rapidfire)

Today, 19 April 2016, cloudy and slower winds.

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Air quality index, loftvís

To estimate air quality, or figure out the current conditions, one needs to know the different units of measure, µg/m3, or mg/m3, and the different health limits for the different pollutants. Also, short term pollution limits are not the same as 24-hour health limits.

Examples of available data are measurements of PM10:

NO2:

and H2S:

It is possible to show these in a simpler way, using an index that accounts for the health limits. Thus, a value of 1 for the index, I, means that one of the pollutants has reached it’s limit. Higher values than 1 mean that they have been exceeded, and lower values than 1 mean that the air quality is better. Below is an example for the past week:

I_recent_7days

It is clear that the air quality has been rather good lately. If we look at the whole year, we see that on 10-11 January the 24-hour health limit was exceeded (here using a running 24-hour mean), and that it was due to PM10.

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We can also show more current conditions this way. Several pollutants do though not have public health limits for shorter periods than 24-hours. Also, using hourly values would lead to very rapidly fluctuating values, since short peaks (real and in the data) complicate things. Therefore I show 4-hour averages, which give good indication about the current conditions (using 50 µg/m3 for PM10 and H2S, but 110 µg/m3 for NO2, is 75 for 24-hours).

i4hour_recent_7days

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