Help decoding the Met Office Data re:2012 extreme rain
Discussion
Can someone who undertands these things, please explain what the graph in the Met Office press release is showing:
http://www.metoffice.gov.uk/news/releases/archive/...
Defra says:
"changes in climate extremes are based on the 99th percentile. Assuming each season is 100 days long, the 99th percentile roughly corresponds to 1 day per season. Hence, this variable can be thought of as the change in the precipitation of the wettest day of each season"
The Met Office article states that the extreme event - originaly expected every 100 days, is now expected every 70 days.
Yet that event is - "the change in the precipitation of the wettest day of each season".
How can 'the wettest day of the season' happen more often than it used to ????
What is the vertical axis actually measuring ?
My brain hurts....
http://www.metoffice.gov.uk/news/releases/archive/...
Defra says:
"changes in climate extremes are based on the 99th percentile. Assuming each season is 100 days long, the 99th percentile roughly corresponds to 1 day per season. Hence, this variable can be thought of as the change in the precipitation of the wettest day of each season"
The Met Office article states that the extreme event - originaly expected every 100 days, is now expected every 70 days.
Yet that event is - "the change in the precipitation of the wettest day of each season".
How can 'the wettest day of the season' happen more often than it used to ????
What is the vertical axis actually measuring ?
My brain hurts....
Forget about the Defra bit, as it means you're trying to conflate two definitions.
The Met site says, under the graph, "frequency of what climate averages tell us should be roughly 1 in 100 day heavy rainfall events in each year". I imagine this means that their '1 in 100 day level' is historically based, and not about the current 100 days.
They're saying that reality shows those events happening more than the model.
The Met site says, under the graph, "frequency of what climate averages tell us should be roughly 1 in 100 day heavy rainfall events in each year". I imagine this means that their '1 in 100 day level' is historically based, and not about the current 100 days.
They're saying that reality shows those events happening more than the model.
trashbat said:
Forget about the Defra bit, as it means you're trying to conflate two definitions.
The Met site says, under the graph, "frequency of what climate averages tell us should be roughly 1 in 100 day heavy rainfall events in each year". I imagine this means that their '1 in 100 day level' is historically based, and not about the current 100 days.
They're saying that reality shows those events happening more than the model.
But the vertical axis isnt frequency - it looks like percentile. Someone else said it was probability...The Met site says, under the graph, "frequency of what climate averages tell us should be roughly 1 in 100 day heavy rainfall events in each year". I imagine this means that their '1 in 100 day level' is historically based, and not about the current 100 days.
They're saying that reality shows those events happening more than the model.
Chimune said:
But the vertical axis isnt frequency - it looks like percentile. Someone else said it was probability...
It is frequency, expressed unusually. The basis is their '1 every 100 days historically' extreme rain event. If a mark was plotted against '1 in 50' on the scale, it means that at that point there were two of these events in the actual 100 day period.Chimune said:
Can someone who undertands these things, please explain what the graph in the Met Office press release is showing:
http://www.metoffice.gov.uk/news/releases/archive/...
Defra says:
"changes in climate extremes are based on the 99th percentile. Assuming each season is 100 days long, the 99th percentile roughly corresponds to 1 day per season. Hence, this variable can be thought of as the change in the precipitation of the wettest day of each season"
The Met Office article states that the extreme event - originaly expected every 100 days, is now expected every 70 days.
Yet that event is - "the change in the precipitation of the wettest day of each season".
How can 'the wettest day of the season' happen more often than it used to ????
What is the vertical axis actually measuring ?
My brain hurts....
Here's my reading of it - 'The more we make it look like things are really bad, the more funding we are likely to get.' http://www.metoffice.gov.uk/news/releases/archive/...
Defra says:
"changes in climate extremes are based on the 99th percentile. Assuming each season is 100 days long, the 99th percentile roughly corresponds to 1 day per season. Hence, this variable can be thought of as the change in the precipitation of the wettest day of each season"
The Met Office article states that the extreme event - originaly expected every 100 days, is now expected every 70 days.
Yet that event is - "the change in the precipitation of the wettest day of each season".
How can 'the wettest day of the season' happen more often than it used to ????
What is the vertical axis actually measuring ?
My brain hurts....
Caulkhead said:
Here's my reading of it - 'The more we make it look like things are really bad, the more funding we are likely to get.'
Truth in that...Metoffice Websh!te said:
Professor Julia Slingo, Chief Scientist at the Met Office, said: "The trend towards more extreme rainfall events is one we are seeing around the world, in countries such as India and China, and now potentially here in the UK. Much more research is needed to understand more about the causes and potential implications.
"It's essential we look at how this may impact our rainfall patterns going forward over the next decade and beyond, so we can advise on the frequency of extreme weather in the future and the potential for more surface and river flooding. This will help inform decision-making about the need for future resilience both here in the UK and globally."
"It's essential we look at how this may impact our rainfall patterns going forward over the next decade and beyond, so we can advise on the frequency of extreme weather in the future and the potential for more surface and river flooding. This will help inform decision-making about the need for future resilience both here in the UK and globally."
For me you need to look at their starting point which ignores the wet season in the 1940s I understand.
It could simply be the met office making sure the message fits the cause of course, look what they were saying a little over a year ago.....
http://www.guardian.co.uk/news/datablog/2011/jun/1...
Has there ever been a drier time in the last 100 years? Of course that suited the climate change message then, now there has been so much rain they want a "it's getting wetter" message because that is what people see out Of their windows.
The once in a hundred days / years/ weeks meme doesn't mean it will happen every 100 (measure of time) , I'm not an expert and am happy to learn from a PH expert but I doubt it has any mathematical or statistical meaning other than to use in headlines.
It could simply be the met office making sure the message fits the cause of course, look what they were saying a little over a year ago.....
http://www.guardian.co.uk/news/datablog/2011/jun/1...
Has there ever been a drier time in the last 100 years? Of course that suited the climate change message then, now there has been so much rain they want a "it's getting wetter" message because that is what people see out Of their windows.
The once in a hundred days / years/ weeks meme doesn't mean it will happen every 100 (measure of time) , I'm not an expert and am happy to learn from a PH expert but I doubt it has any mathematical or statistical meaning other than to use in headlines.
My view of the article linked in the original post? A spinning top, dressed up in bits of high-falutin' language but saying very little except toeing the "we're all doomed, here's the facts" line 
with a graph incorporating a red line of doom... Spinnier than a spinny thing in etc etc
Yeah, we've had some very wet days last year - but to base the "we're all doomed" line on them? Wow...
And an assumption of "seasons of 100 days" (as in the article - which makes daily data over 100 days easily divisible into percentiles
& 
) )? DON'T MAKE ME LARF!!! We have 365 days per year (91ish days per season) the last time I looked; as much as Prof Julia Slingo would like to think she can shape the Earth's climate ...
Note the mention of:
"preliminary evidence suggests we are getting slightly more rain in total and it may be falling in more intense bursts"
"Changes in sea surface temperatures due to natural cycles and reducing amounts of Arctic sea-ice could..."
"Increasing global temperatures may..."
and
"From basic physics... would... means..."
Also the "2012 provisional stats" table is interesting - compared to the 1981-2010 average the mean temp was around 0.1C lower than the long term average, the average sunshine hours 2% lower and the average rainfall around 20mm higher overall on average ("regions" & "districts" info - eh?
apart from incorporating doomworthy changes ). What can we draw from this? A bit cooler and with less sun - but wetter...
This cynical enough??
PS We're all doomed, pay more taxes!
...
with a graph incorporating a red line of doom... Spinnier than a spinny thing in etc etcYeah, we've had some very wet days last year - but to base the "we're all doomed" line on them? Wow...
And an assumption of "seasons of 100 days" (as in the article - which makes daily data over 100 days easily divisible into percentiles
& ) )? DON'T MAKE ME LARF!!! We have 365 days per year (91ish days per season) the last time I looked; as much as Prof Julia Slingo would like to think she can shape the Earth's climate ...Note the mention of:
"preliminary evidence suggests we are getting slightly more rain in total and it may be falling in more intense bursts"
"Changes in sea surface temperatures due to natural cycles and reducing amounts of Arctic sea-ice could..."
"Increasing global temperatures may..."
and
"From basic physics... would... means..."
Also the "2012 provisional stats" table is interesting - compared to the 1981-2010 average the mean temp was around 0.1C lower than the long term average, the average sunshine hours 2% lower and the average rainfall around 20mm higher overall on average ("regions" & "districts" info - eh?
apart from incorporating doomworthy changes ). What can we draw from this? A bit cooler and with less sun - but wetter...This cynical enough??
PS We're all doomed, pay more taxes!
...A longer term graph can be seen at
http://bishophill.squarespace.com/blog/2013/1/5/uk...
Paints a different picture, pity our MSM can't do this type of thing rather than just report what they are told.
http://bishophill.squarespace.com/blog/2013/1/5/uk...
Paints a different picture, pity our MSM can't do this type of thing rather than just report what they are told.
nelly1 said:
Quoted from the comments:'The Met office needs a new dart board. The one they have now is obviously faulty.'
Sums it up for me.
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