Date: 12/08/2018 14:43:04
From: buffy
ID: 1262200
Subject: 1809 mystery volcanic eruption

Before Tambora went up in 1815, there was another large equatorial eruption in 1809. The two together affected climate – badly for humans. Very cold for a decade or so. Famine in Europe. It seems no-one even knew about the 1809 one until signs in the ice cores from both ends of the planet showed up in 2009.

https://www.forbes.com/sites/robinandrews/2017/02/06/can-you-solve-the-mystery-of-the-eruption-without-a-volcano/#306a7c9b73a0

Apparently it is still a mystery.

These graphs are interesting:

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Date: 12/08/2018 14:50:09
From: roughbarked
ID: 1262204
Subject: re: 1809 mystery volcanic eruption

buffy said:


Before Tambora went up in 1815, there was another large equatorial eruption in 1809. The two together affected climate – badly for humans. Very cold for a decade or so. Famine in Europe. It seems no-one even knew about the 1809 one until signs in the ice cores from both ends of the planet showed up in 2009.

https://www.forbes.com/sites/robinandrews/2017/02/06/can-you-solve-the-mystery-of-the-eruption-without-a-volcano/#306a7c9b73a0

Apparently it is still a mystery.

These graphs are interesting:


https://en.wikipedia.org/wiki/1808/1809_mystery_eruption

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Date: 12/08/2018 15:12:12
From: sibeen
ID: 1262206
Subject: re: 1809 mystery volcanic eruption

That’s the Berkley Earth dataset in the black line. Tambora blew up in 1815. Thing is, it looks like the global temps were trending downwards well before 1809 or 1815. So perhaps the volcanic eruptions had little to do with the years without summers.

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Date: 12/08/2018 16:07:41
From: mollwollfumble
ID: 1262213
Subject: re: 1809 mystery volcanic eruption

It’s only in the past few years that Samalas on Lombok was identified as the source of the even bigger eruption in 1257.

Tracking down the mystery of 1809.

https://www.volcanocafe.org/1809-the-missing-volcano/

Only in 2014 did a team with Caroline Williams,Alvaro Guevara-Murua and Erica Hendy uncover a new clue to the mystery eruption, in the records of the Bogota Observatory. In the ‘Semanario del Nuevo Reyno de Granada’, a regular publication compiled by its director Francisco Caldas, a description was given of a peculiar haze, starting in late 1808.

The description is consistent with a volcanic haze.

There are some more cautious reports. Glass fragments from this eruption have been found in Antarctica (comprising andesite) and in Alaska. But the Alaskan ones have been shown to be different, and caused by a different eruption.

For a local volcano, a smaller eruption may have sufficed to create the haze. In this case, the volcano that caused the haze may be different from the one that caused the sulphate spike and the poor weather. There are plenty of volcanoes around the region where the haze was seen, including some that are not easy to observe. Reventador comes to mind: it is very active, but eruptions are easily missed. Huaynaputina is here: it had a catastrophic eruption in 1600. Further south, Putana (a volcano with an unfortunate name) at the deserted northern end of Chile may have had a large eruption around 1810, and it should be considered a realistic possibility.

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Date: 12/08/2018 16:17:21
From: sarahs mum
ID: 1262214
Subject: re: 1809 mystery volcanic eruption

mollwollfumble said:


It’s only in the past few years that Samalas on Lombok was identified as the source of the even bigger eruption in 1257.

Tracking down the mystery of 1809.

https://www.volcanocafe.org/1809-the-missing-volcano/

Only in 2014 did a team with Caroline Williams,Alvaro Guevara-Murua and Erica Hendy uncover a new clue to the mystery eruption, in the records of the Bogota Observatory. In the ‘Semanario del Nuevo Reyno de Granada’, a regular publication compiled by its director Francisco Caldas, a description was given of a peculiar haze, starting in late 1808.

The description is consistent with a volcanic haze.

There are some more cautious reports. Glass fragments from this eruption have been found in Antarctica (comprising andesite) and in Alaska. But the Alaskan ones have been shown to be different, and caused by a different eruption.

For a local volcano, a smaller eruption may have sufficed to create the haze. In this case, the volcano that caused the haze may be different from the one that caused the sulphate spike and the poor weather. There are plenty of volcanoes around the region where the haze was seen, including some that are not easy to observe. Reventador comes to mind: it is very active, but eruptions are easily missed. Huaynaputina is here: it had a catastrophic eruption in 1600. Further south, Putana (a volcano with an unfortunate name) at the deserted northern end of Chile may have had a large eruption around 1810, and it should be considered a realistic possibility.

wiki suggests..

Known significant eruptions in 1808

In 1808 there were major eruptions in Urzelina, Azores in May (1st to 4th), and in Taal Volcano, Philippines in March. Neither of these occurred within the correct time period for the visual observations.

It is known that the Chilean Putana volcano also had a major eruption around this time with an approximate date of 1810 (with a 10-year margin of error).
——

Putana is favourite.

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Date: 12/08/2018 16:25:46
From: mollwollfumble
ID: 1262215
Subject: re: 1809 mystery volcanic eruption

sibeen said:


That’s the Berkley Earth dataset in the black line. Tambora blew up in 1815. Thing is, it looks like the global temps were trending downwards well before 1809 or 1815. So perhaps the volcanic eruptions had little to do with the years without summers.

Agree. Mt Pinatubo erupted in 1991 and I don’t really see much sign of the black line dipping shortly after that. That was supposed to be a big eruption, half the size of Krakatoa, but it didn’t seem all that big to me at the time.

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Date: 12/08/2018 16:40:41
From: roughbarked
ID: 1262216
Subject: re: 1809 mystery volcanic eruption

mollwollfumble said:


It’s only in the past few years that Samalas on Lombok was identified as the source of the even bigger eruption in 1257.

Tracking down the mystery of 1809.

https://www.volcanocafe.org/1809-the-missing-volcano/

Only in 2014 did a team with Caroline Williams,Alvaro Guevara-Murua and Erica Hendy uncover a new clue to the mystery eruption, in the records of the Bogota Observatory. In the ‘Semanario del Nuevo Reyno de Granada’, a regular publication compiled by its director Francisco Caldas, a description was given of a peculiar haze, starting in late 1808.

The description is consistent with a volcanic haze.

There are some more cautious reports. Glass fragments from this eruption have been found in Antarctica (comprising andesite) and in Alaska. But the Alaskan ones have been shown to be different, and caused by a different eruption.

For a local volcano, a smaller eruption may have sufficed to create the haze. In this case, the volcano that caused the haze may be different from the one that caused the sulphate spike and the poor weather. There are plenty of volcanoes around the region where the haze was seen, including some that are not easy to observe. Reventador comes to mind: it is very active, but eruptions are easily missed. Huaynaputina is here: it had a catastrophic eruption in 1600. Further south, Putana (a volcano with an unfortunate name) at the deserted northern end of Chile may have had a large eruption around 1810, and it should be considered a realistic possibility.

Manaya la putana.

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Date: 12/08/2018 17:09:16
From: buffy
ID: 1262218
Subject: re: 1809 mystery volcanic eruption

mollwollfumble said:


sibeen said:

That’s the Berkley Earth dataset in the black line. Tambora blew up in 1815. Thing is, it looks like the global temps were trending downwards well before 1809 or 1815. So perhaps the volcanic eruptions had little to do with the years without summers.

Agree. Mt Pinatubo erupted in 1991 and I don’t really see much sign of the black line dipping shortly after that. That was supposed to be a big eruption, half the size of Krakatoa, but it didn’t seem all that big to me at the time.

When it says anomaly on that graph, what is it comparing to? It always confuses me terribly with the graphs. Are we comparing to average of the whole timescale? Or some other average?

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Date: 12/08/2018 17:16:06
From: Peak Warming Man
ID: 1262219
Subject: re: 1809 mystery volcanic eruption

buffy said:


mollwollfumble said:

sibeen said:

That’s the Berkley Earth dataset in the black line. Tambora blew up in 1815. Thing is, it looks like the global temps were trending downwards well before 1809 or 1815. So perhaps the volcanic eruptions had little to do with the years without summers.

Agree. Mt Pinatubo erupted in 1991 and I don’t really see much sign of the black line dipping shortly after that. That was supposed to be a big eruption, half the size of Krakatoa, but it didn’t seem all that big to me at the time.

When it says anomaly on that graph, what is it comparing to? It always confuses me terribly with the graphs. Are we comparing to average of the whole timescale? Or some other average?

It’s a 10 year moving average, see top left of graph.
The anomaly would make more sense if it was set against a fixed average.

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Date: 12/08/2018 17:17:50
From: Michael V
ID: 1262220
Subject: re: 1809 mystery volcanic eruption

buffy said:


mollwollfumble said:

sibeen said:

That’s the Berkley Earth dataset in the black line. Tambora blew up in 1815. Thing is, it looks like the global temps were trending downwards well before 1809 or 1815. So perhaps the volcanic eruptions had little to do with the years without summers.

Agree. Mt Pinatubo erupted in 1991 and I don’t really see much sign of the black line dipping shortly after that. That was supposed to be a big eruption, half the size of Krakatoa, but it didn’t seem all that big to me at the time.

When it says anomaly on that graph, what is it comparing to? It always confuses me terribly with the graphs. Are we comparing to average of the whole timescale? Or some other average?

In this case, the anomaly is a comparison to an arbitrary zero, set as the 1970 data point.

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Date: 12/08/2018 17:28:45
From: buffy
ID: 1262224
Subject: re: 1809 mystery volcanic eruption

Damn. Now I am even more confused. Ten year – which ten years? Five each way of each year data point? Or the 1970 one, in which case why that one?

And I just realized I also have never found out how you derive a global temperature anyway.

I’d better do some more searching to find out.

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Date: 12/08/2018 17:37:40
From: buffy
ID: 1262225
Subject: re: 1809 mystery volcanic eruption

OK, here is NOAA

——————————————————————————————————————————————————-
About surface temperature

The concept of an average temperature for the entire globe may seem odd. After all, at this very moment, the highest and lowest temperatures on Earth are likely more than 100°F (55°C) apart. Temperatures vary from night to day and between seasonal extremes in the Northern and Southern Hemispheres. This means that some parts of Earth are quite cold while other parts are downright hot. To speak of the “average” temperature, then, may seem like nonsense. However, the concept of a global average temperature is convenient for detecting and tracking changes in Earth’s energy budget—how much sunlight Earth absorbs minus how much it radiates to space as heat—over time.

To calculate a global average temperature, scientists begin with temperature measurements taken at locations around the globe. Because their goal is to track changes in temperature, measurements are converted from absolute temperature readings to temperature anomalies—the difference between the observed temperature and the long-term average temperature for each location and date. Multiple independent research groups across the world perform their own analysis of the surface temperature data, and they all show a similar upward trend.

Across inaccessible areas that have few measurements, scientists use surrounding temperatures and other information to estimate the missing values. Each value is then used to calculate a global temperature average. This process provides a consistent, reliable method for monitoring changes in Earth’s surface temperature over time. Read more about how the global surface temperature record is built in our Climate Data Primer.

———————————————————————————————————

So, from that:

“measurements are converted from absolute temperature readings to temperature anomalies—the difference between the observed temperature and the long-term average temperature for each location and date”

Isn’t this going to mean the combined data is kind of a mix of stuff that has more accuracy and less accuracy depending on how long measurements have been taken at various different places? Or is there so much data that this doesn’t matter?

REF: https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

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Date: 12/08/2018 17:45:21
From: mollwollfumble
ID: 1262230
Subject: re: 1809 mystery volcanic eruption

buffy said:

Damn. Now I am even more confused. Ten year – which ten years? Five each way of each year data point? Or the 1970 one, in which case why that one?

And I just realized I also have never found out how you derive a global temperature anyway.

I’d better do some more searching to find out.

I hope it’s five each way of the data point. It would be a bit biased if it was ten years before the data point.

There are many different opinions on what global temperature was, once you get back before reliable historical records.

For a single author it looks like this.

For ten authors, all with access to the same data, it looks like this. Also northern hemisphere.

The difference isn’t surprising, given that we’re talking about temperature differences of less that one degree where even daily variations are +- 10 degrees.

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Date: 12/08/2018 17:46:54
From: buffy
ID: 1262232
Subject: re: 1809 mystery volcanic eruption

See, that first graph is, to me, a lot easier to understand. The axis is properly labelled. You know what they are comparing to.

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Date: 12/08/2018 17:56:17
From: Michael V
ID: 1262238
Subject: re: 1809 mystery volcanic eruption

I hope it’s five each way of the data point. It would be a bit biased if it was ten years before the data point.
———————————————————-

If one used an average of five years either side of a given year, the last analysis could only be 2012.

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Date: 12/08/2018 19:09:52
From: mollwollfumble
ID: 1262254
Subject: re: 1809 mystery volcanic eruption

Michael V said:


I hope it’s five each way of the data point. It would be a bit biased if it was ten years before the data point.
———————————————————-

If one used an average of five years either side of a given year, the last analysis could only be 2012.

Yes. It’s even worse for some data-smoothing methods, such as some Fourier analysis methods. That’s why I use a cubic smoothing spline in the joint paper with Buffy.

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Date: 12/08/2018 19:11:21
From: buffy
ID: 1262256
Subject: re: 1809 mystery volcanic eruption

mollwollfumble said:


Michael V said:

I hope it’s five each way of the data point. It would be a bit biased if it was ten years before the data point.
———————————————————-

If one used an average of five years either side of a given year, the last analysis could only be 2012.

Yes. It’s even worse for some data-smoothing methods, such as some Fourier analysis methods. That’s why I use a cubic smoothing spline in the joint paper with Buffy.

Which I think may have confused our reviewers…

;)

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Date: 12/08/2018 20:06:29
From: PermeateFree
ID: 1262287
Subject: re: 1809 mystery volcanic eruption

buffy said:


mollwollfumble said:

Michael V said:

I hope it’s five each way of the data point. It would be a bit biased if it was ten years before the data point.
———————————————————-

If one used an average of five years either side of a given year, the last analysis could only be 2012.

Yes. It’s even worse for some data-smoothing methods, such as some Fourier analysis methods. That’s why I use a cubic smoothing spline in the joint paper with Buffy.

Which I think may have confused our reviewers…

;)

Don’t try to blind your readers with science. Simplicity is usually the best option.

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Date: 12/08/2018 21:04:35
From: mollwollfumble
ID: 1262304
Subject: re: 1809 mystery volcanic eruption

PermeateFree said:


buffy said:

mollwollfumble said:

Yes. It’s even worse for some data-smoothing methods, such as some Fourier analysis methods. That’s why I use a cubic smoothing spline in the joint paper with Buffy.

Which I think may have confused our reviewers…

;)

Don’t try to blind your readers with science. Simplicity is usually the best option.


The computer algorithm was developed in 1967… or was it 1964 … not what I’d call high tech.

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Date: 12/08/2018 21:14:32
From: PermeateFree
ID: 1262306
Subject: re: 1809 mystery volcanic eruption

mollwollfumble said:


PermeateFree said:

buffy said:

Which I think may have confused our reviewers…

;)

Don’t try to blind your readers with science. Simplicity is usually the best option.


The computer algorithm was developed in 1967… or was it 1964 … not what I’d call high tech.

The timing has nothing to do with presenting information, which should be in the most simple and easy to understand manner.

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Date: 12/08/2018 21:28:09
From: sibeen
ID: 1262308
Subject: re: 1809 mystery volcanic eruption

mollwollfumble said:


PermeateFree said:

buffy said:

Which I think may have confused our reviewers…

;)

Don’t try to blind your readers with science. Simplicity is usually the best option.


The computer algorithm was developed in 1967… or was it 1964 … not what I’d call high tech.

Nah, I’m pretty sure that computer algorithms were developed well before that. In fact you don’t need a computer at all.

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