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Also, most maps of any data that NOAA/NWS uses, has some degree of extrapolation to smooth out the data. This is also done because it gives a professional (a meteorologist, or more likely a climatologist) the ability to consider environmental/geographic irregularities; Meaning a group of several stations might report similar numbers of some data point – but one station for some reason (wind flow, topography, origination to what’s being measured…etc) shows something different. Any map NOAA creates is smoothed out data from many points.
But the issue with the NWS sunshine records are:
1) Some stations had known recording issues [mentioned several times in threads, including the link I provided from a real NWS meterologist]
2) The recording method is different from the rest of the world uses, making it difficult to make international comparisons. Note the discrepancies between American and Canadian sunshine data — nearly 400 sunshine hours between adjacant Detroit and Windsor. The American sunshine number may be consistent compared to themselves, but it's unclear whether it is to be trusted.
On the other hand, the data itself from Blue Hill would be risky to use. I would never use it.
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Blue Hill is great for folks with an interest in weather....but true science/academic folks would never use their data, trust me.
The Blue Hill sunshine recorder is likely automated (it's a C-S recorder), making human error less of an issue.
Either way, whenever we mention about what scientific folks would do, a source should provided showing what they actually do. This academic site does use Blue Hill sunshine data:
For the last time, would you mind explaining how Blue Hill Observatory, following WMO standards for years measures 2250 hours of sunshine using CS vs Logan Airport 10 miles away averaging 2600 hours using the US method. .
I know nothing about Blue Hill, but what you state it uses a CS right? I addressed this too
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Originally Posted by chicagogeorge
I did. I stated that most other countries used the Campbell Stokes which provides different results. That doesn't mean that the US data is invalid, or that the instruments used are less reliable.
Btw how many years of record are there for that Blue Hill CS recorder?
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The US method overestimates sunshine hours no matter how you slice it. And it is by 350 hours in a place like Boston. Explain the discrepancy
You mean the Foster right overestimates sunshine right? I addressed that to. Do I have to re post the email I received from the Chicago Weather Center? Our sunshine monitor at Midway airport stated in EXTREME CASES the 87watts compared to 120watts can vary up to an hour. So OUR site 1000 miles away from Boston on the Atlantic Ocean according to the only NWS observer at a MAJOR international airport to still record sunshine in the US stated in EXTREME CASES up to an hour.
How would you define extreme?
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Most remote in any direction; outermost or farthest: the extreme edge of the field. 2. Being in or attaining the greatest or highest degree; very intense: extreme ...
Pretty coincidental that the Marvin recorded similar sunshine hours from 1894-1913 for Chicago
Of course LIKE the CS the Marvin has it's flaws. But, irregardless, above is 20 years worth of observations.... And you can't argue that wattage is the issue with the Marvin as it might be with the Foster.
And from the journal I posted before that no one seemed to want to address.... What was the effective change when the National Weather Service switched from the Marvin over to the Foster
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. Data from many more sites were available to assess the effect of the second change of instruments, from thermometric to photoelectric recorders. Based on the mean annual sunshine duration measured for 11 yr before and after the year of change (which occurred between 1953 and 1964) at 34 sites, each from a different continental U.S. state, the average value of SS increased from 2740 to 2806 h yr1, a rise of 2.4%.
The value to be added to convert CS to US (corrected) is greatest in summer and least in winter. The annual conversion value is a percentage of sunshine duration increasing from 11 per cent in the northern United States to 14 per cent in the south.
The value to be added to convert CS to US (corrected) is greatest in summer and least in winter. The annual conversion value is a percentage of sunshine duration increasing from 11 per cent in the northern United States to 14 per cent in the south.
If the inaccuracies are random errors (not biased to a type of weather), over a month or longer, the 20% inaccuracies might become much less. It's hard to tell without more information. As to the red underline, that's not such a Campbell-Stokes disadvantage, as just as a disadvantage with two types of recording systems.
If one is interested in making sunshine comparisons of US stations with international stations, even if the US instruments are accurate, they all give different than the Campbell-Stokes, which seems to be the norm outside the US. Judging by how much lower the Canadian stations are than the American ones (consistently), I'm rather convinced US sunshine numbers (not by Campbell-Stokes) need to adjusted downwards to be comparable.
Winters are a very different story. My guess is coastal cities get more hazy humidity?
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You're right, leeward locations like London ON receive less hours than parts of the UK
Don't underestimate the cloudy winters though
I don't think anyone who's lived that region can underestimate them. Do you have a monthly breakdown for Ontario cities? Do you think London, ON is similar to western NY State cities?
Midway airport not only continues to use the Foster at 87 watts for purposes of continuity, they also record sunshine with the newest equipment manufactured by Kipp and Zonen
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A new instrument being used today (and recommended by the World Meteorological Organization) is made by Kipp and Zonen Leaders in Radiation Equipment. It consists of three sensors--one that detects all direct and diffuse sunlight, and two others that look only at portions of the sky. Sunshine times are determined by differential measurements between the three sensors. Sunshine data from both systems are being collected by Midway Airport weather observer Frank Wachowski, and the results are being compared.
Midway airport not only continues to use the Foster at 87 watts for purposes of continuity, they also record sunshine with the newest equipment manufactured by Kipp and Zonen
Why is it so hard to get sunshine observations for the US if some weather stations are recording. Does Midway Airport post its data. Even if those instruments are better than Campbell-Stokes, the fact that the rest of the world uses Campbell-Stokes is a big drawback. It'd be nice it were used just so we could make comparisons. None of your posts address that problem, maybe because of different interests.
Could diurnal ranges be a indicator of sunshine between different locations?
NYC has the same sunshine hours as here during winter, yet has a diurnal range 4-5C lower. It could just be my Oceanic perspective, but a higher diurnal range would typically indicate clearer skies. Although NYC is so cold in winter, that different rules may apply . Do colder, less humid, Continental winters have a lower diurnal range, than warmer, more humid, Oceanic winters? - I wouldn't think so, unless the data is incorrect.
It lists the years of data and sunshine percentage for the year. Blue Hill is down around 52% with 112 years of data. Not saying I disagree with your statement, am just wondering why NOAA would list data from that site. They don't list anything from the Franklin Institute climate center here in Philly.
Last edited by tom77falcons; 07-03-2013 at 01:17 PM..
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