Annual report on GFS GCM performance

January 30, 2015 Leave a comment

A mailing list I receive from UCAR brought news of an addition to the GFS forecast archive “New Dataset: NCEP GFS 0.25 Degree Global Forecast Grids Historical Archive” and links to a web page.

On browsing an excellent general interest snippet appeared

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Page 16/17, performance over time for a few parameters of various GCM and with the observation on the GFS useful horizon “Increase is about one day per decade”.

Review of GFS Forecast Skills in 2013
Fanglin Yang
IMSG – Environmental Modeling Center
National Centers for Environmental Prediction

Link is on the performance review page, 2013 rev. is PDF (2.7MB)

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Categories: analysis, Modelling, weather

Fast tidal data facility, UNESCO / IOC

January 3, 2015 Leave a comment

A couple of days I spotted a data event worth following up but I needed high resolution tidal data, difficult to find.

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UNESCO / IOC have created a facility directly linked to many (768 listed) tidal gauges provided true high resolution data, such as 15 minute and with a record of up to 30 days.

The intent seems to be providing public data for safety and research, such as Tsunami monitoring.

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Categories: Datasets, sea level

Katesbridge exponential cooling

December 29, 2014 2 comments

The night of 28th to 29th December 2014 was calm under high pressure across much of the UK after a clear sunny winter’s day. It was going to be cold.

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[UPDATE: Met Office, -8.8C ]

This is a partial weather station in Northern Ireland, red trace is temperature, pink is dewpoint and green is wind. No other data.

This blog article is an addition to this one at Tallbloke’s, and providing the data.

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Categories: weather

History of early polar ice cores

December 12, 2014 Leave a comment

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From time to time the US military produce historical works.

Chester Langway[1] in retirement wrote this work to commemorate a 50th anniversary. Published by the US Army Corps of Engineers.

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Categories: History, Ice core

A real world demonstration of cloud controlling radiation

December 7, 2014 Leave a comment

The original text struck me as inappropriate so I’ve edited it. I put it down to being overtired. The original is archived if anyone wants to see it, just ask (there is a contact form), no questions asked on why.

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This is a huge plot including hourly data from WMO3768 Farnborough, England, a synoptic Met Office station where I estimate the site meets WMO 2010 recommendation Class 1, although the presence of a triangular airfield runway layout surrounding the station will have some side effects.

A details view of the plot is only practical via PDF (201kB)  Very likely the PDF will open looking as above so you need to set magnification and scroll around the plot, 100% is the intended view. Some details of interest are reproduced below at a normal scale.

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Categories: analysis, temperature, weather

Czech-Canadian tree ring study

September 26, 2014 1 comment

This post is in honour of a great mind where I have more to say sometime.

The late Vít Klemeš who died 2010 gave a talk on July 12, 2007, in the HW2003 Workshop on Analysis of Variability in Hydrological Data Series, at the IAHS General Assembly in Perugia, Italy.

He concluded with a truism I believe in

The moral of my talk is this: The most fun and perhaps the greatest value of doing something is in doing it. The results may well go up in smoke, be wrong, become obsolete and forgotten, but some new ideas may have emerged in pursuing them, and some of them may somewhere, sometime, bear fruit. …”

They have, right now.

And that is Vít Klemeš. He had a sense of fun, sense of humour, yet enough is revealed in past writing showing he comes across as quietly subtle, a real technician, the lack of ego which comes with confidence.

This presentation is as a PDF at a moderate technical level which might seem somewhat wooden in places. It needs a degree of background knowledge, without this maybe there is enough.

 

 

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Categories: humour, Minder

Met Office, HadSST3, CRUTEM3, HadCRUT3, questions over gridded coverage

September 18, 2014 3 comments

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[update: I used an incorrect mix of datasets, see Talkshop thread here. Corrected PDF and now expanded to include HadCRUT4.

corrected PDF bundled in .zip (9.5MB) linked here HadCRUT3 and here  HadCRUT4]

The UK Met Office / Hadley Centre (Met Office) / Climatic Research Unit (UEA) construct and publish global time series for temperature based on published 5 degree gridded. How this is derived from land meteorological station readings and ship board for sea surface temperature is unclear. The gridded to eg. global is a simple (cosine) weighted average which takes into account the variable area of a linear grid representing a sphere.

I have put together maps showing the data counts for decades over a world shore outline. These are provided as vector plots (master work), PDF, or for casual looks, PNG. The results are disturbing and particularly in the light of the Met Office producing 100 different versions of HadSST3. “Each of the following files is a zip archive containing ten realisations of the HadSST3 data set. There are 100 realisations in total.”

Do I detect obfuscation, flapping for distraction?

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Categories: analysis, Datasets, temperature

The poor state of HadSST

September 11, 2014 Leave a comment

What follows is first art. I have yet to work out a better pictorial method. For now a tortured spreadsheet will do well enough.

You can just make out continental land masses…

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Met Office HadSST3 (Hadley centre Sea Surface Temperature version 3) total cell data counts for monthly 2005..2014 on published linear 5 degree latitude/longitude grid. Should be 115 counts in all sea grid cells. Click image for full size version.

Data: Met Office HadSST3

I’ve known for a number of years of the dreadful state of climatic datasets, HadSST being one of those but did not have the pictorial evidence. Period from 2005 is an arbitary choice arising during software development.

When I first looked at the gridded SST data, some time before 2010 I noticed what seemed to be a mix of monthly and annual in cells, with many missing data. It also looked very dubious on coastline handling. This was noted but nothing further done.

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August 2014 radiative cooling East Anglia, Northern Ireland, South Midlands

August 30, 2014 1 comment

August 2014 there was a meteorological gift of both exceptional conditions and good data. What can be learnt?

Three Met Office sites showed a signature of exponential cooling. This requires clear sky and a calm. Given somewhat limited parameter hourly data the following shows the commonality. The computed terminal conditions are shown later in this article.

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Benson and Santon Downham data has been normalised to Katesbridge[3], which has the least noisy data or the three.

Achieving a close overlay requires taking earth rotation into account, dusk and dawn move relatively both by geographic location and the peculiar movement throughout the year as night length changes, these do not move together [1]. Fractional delay (less that the sample period) was used to equalize diurnal time. (see the two blog articles here)

Dusk appears to be the important factor, a surprising finding, I assume cooling is time from dusk, dawn terminates cooling.

General information, under essentially calm conditions wind drops for a period during the night then reappears just after dawn. (not shown here)

Temperature normalisation defined is for the cold period, not as accurate for Benson where the better site exposure (more open) led to more wind at times.

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Categories: analysis, temperature, weather

UK outline map and Met Office Datapoint

August 24, 2014 1 comment

I’ve been busy pottering on code as a mindless intermission during house repairs, can only do so much at a time. Argue with a piece of wood or with a computer screen? :-)

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This is a bitmap copy of a map of the UK with markers showing the location of Met Office weather sites with hourly data published via their Datapoint service. Data is under OGL (Open Government Licence) which allows usage. Unfinished work, references are not yet included.

The real file is part of a large PDF (vector format) containing plots for all those stations during a 24 hour period.

Example PDF https://daedalearth.files.wordpress.com/2014/08/uk-2014-08-24-0045.pdf  (1.2MB, work in progress, more to be done)

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Categories: software, weather
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