[Bldg-sim] *****SPAM***** Re: The effect of the Novel Coronavirus epidemic on weather observations

Joe Huang yjhuang at whiteboxtechnologies.com
Wed Feb 24 10:58:50 PST 2021


Tim, 
NASA POWER is now providing hourly long-wave as well as short-wave radiation downwards on a 1/2 degree grid, currently on a Beta test basis to those interested. I’ve been receiving such data on a limited basis from their staff over the past year for locations not covered currently by other sources of satellite-derived solar. I’ve promised the last TC 4.2 virtual meeting I would compare the NASA’s long-wave data I have to the Berdahl Model as soon as I can convert that data to an effective sky  temperature as well as code up the Berdahl Model provided me by Chip. So far I’ve only got such NASA data for locations in Japan, China, and Myanmar, but I’m intending to get NASA POWER in bulk now that it can be downloaded directly by users. I don’t want to overpromise anything as I haven’t personally used the NASA POWER portal for their solar “products” yet. 

Joe

Sent from my iPhone 
Joe Huang
White Box Technologies
346 Rheem Blvd Suite 108D
Moraga CA 94556
(o) 1(925)388-0265
(c) 1(510)928-2683
yjhuang at whiteboxtechnologies.com

> On Feb 24, 2021, at 7:44 AM, Tim McDowell via Bldg-sim <bldg-sim at lists.onebuilding.org> wrote:
> 
> Joe -
> 
> The cloud cover data is also used in the algorithms for estimating the sky temperature.  Hopefully something can be figured out to either get the cloud cover data or determine the radiation and sky temperature values without it.
> 
> Tim
> 
> ---
> Timothy P. McDowell
> Executive Vice President
> Thermal Energy System Specialists, LLC
> 3 N Pinckney St, Suite 202
> Madison, WI 53703
> office: 608-274-2577
> cell: 608-225-5250
> 
>> On 2021-02-23 19:14, Joe Huang via Bldg-sim wrote:
>> Please note that I wrote "weather observations", not "weather" per se :-)
>> I'm just finishing up processing all the 2020 weather data from NCEI's
>> ISD (National Center for Environmental Information Integrated Surface
>> Database), which has become a ritual for me every January for the past
>> decade.  When I got to processing the data for East Asia, I was
>> puzzled initially to get only 64 usable weather files for China,
>> instead of the usual 400, and  even fewer for Japan.  When I looked in
>> the metadata, I found  this was due to the absence of Cloud Cover
>> information I need to calculate the solar radiation.  Attached is a
>> table showing the number of cloud cover reports by month, followed by
>> the annual average, for all ISD stations in China and Japan for 2020.
>> I was startled when I first looked at this table.  In China, 80% of
>> the weather stations all stopped reporting cloud cover in April.  In
>> Japan,  the dropoff was even greater, although not as uniform as in
>> China, with many stations not reporting Cloud Cover throughout the
>> year,  many others stopping in February or March, leaving only 21
>> stations (8%)  that had Cloud Cover data  for the entire year.
>> I can't find any reasonable explanation for this change except for the
>> lockdowns due to the pandemic.  Although weather stations have become
>> automated everywhere, Cloud Cover reports are still based on human
>> observation, excepting those ASOS (Automated Surface Observing System)
>> stations equipped with  upward-looking lasers and ceilometers. I've
>> noted two years ago that Cloud Cover data have been dropping steadily
>> in recent years (see attached e-mail "Decline of cloud cover report in
>> the ISD"), but what's happened  this time in China and Japan clearly
>> has a very different cause.  All the more reason to move to
>> satellite-derived solar radiation !
>> Joe
>> Me, again.
>> This plot is related to the topic that Neal and I will be discussing
>> later in the Research SC meeting.
>> ,,,Another benefit to the satellite-derived solar is to increases the
>> number of available weather stations, which in many places has been
>> limited by the lack of cloud cover data needed to model the solar
>> radiation.  For reasons that are not immediately identifiable,
>> several English-speaking Commonwealth countries has seen a marked drop
>> in the number of available stations due to the decreases in the
>> reporting of cloud cover (see plot, ZAF = South Africa). For example,
>> the number of stations in the UK has dropped by almost 2/3s between
>> 2001 and 2017 (174 to 64), but with satellite-derived solar, it will
>> go back up to over 180, while in Australia and South Africa the
>> comparable numbers are from 175 to well over 500, and from 37 to over
>> 100, respectively.
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