NOAA weather Data

[Michael Hurd]

We can purchase additional NOAA weather data through the NCDC website here in the USA but before our company spends the money to do so I want to make sure we have the data that WUFI requires.

I have read the posts on the forum and noted the comments about the data matching what WUFI is expecting. Unfortunately, from the NCDC website and NOAA information I cannot tell if radiation is measured on a horizontal surface or not. Will not knowing this be an important issue? Will the data below meet WUFI’s requirements? I know some of the NOAA fields are probably not required. Sorry for the length of this post by the way.

The data provided by NOAA is as follows:

1 Station ID Station Number (WBAN)

2 Time
Year - Year of observation

(2) Month Month of observation
(2) Day Day of month
(2) Hour Hour of day in local standard
time

3 GRAD Global radiation. Hourly values
are one-minute samples summed
over the hour and divided by 60
to obtain the mean hourly value
ending on the hour indicated in
Local Standard Time (LST).
(Nearest
tenth watt per meter squared).

4 DRAD Direct radiation. Hourly values
are one-minute samples summed
over the hour and divided by 60
to obtain the mean hourly value
ending on the hour indicated in
Local Standard Time (LST).
(Nearest
tenth watt per meter squared).

5 Total Sky Cover Amount of sky dome (in tenths)
covered by clouds.
6 Opaque Sky Cover Amount of sky dome (in tenths)
covered by clouds that prevent
observing the sky or higher cloud
layers. .
7 Dry Bulb Dry bulb temperature in degrees
Temperature Celsius.

Dry Bulb Temperature An "I" in this field indicates
Interpolation Flag that the dry bulb temperature
was linearly interpolated.
8 Dew Point Dew point temperature in degrees
Temperature Celsius.
9 Relative Humidity Relative humidity in percent.
999 = missing data.
10 Station Station atmospheric pressure in
Pressure millibars.

Station Pressure An "I" in this field indicates
Interpolation Flag that the station pressure was
linearly interpolated.
11 Wind Direction Wind direction in degrees.
(N = 360, E = 90, S = 180,
W = 270) 999 = missing data.
12 Wind Speed Wind speed in meters per second.

13 Visibility Horizontal visibility in
kilometers. 777.7 = unlimited
visibility.
14 Ceiling Height Ceiling height in meters.
77777 = unlimited ceiling height.
88888 = cirroform.

15 Present Weather Present weather conditions
denoted by left justified pairs
of digits. See present weather
table below.
16 ASOS CLOUD LAYER 1 Sky condition and height
for first layer. Data-value =
XXYYY. XX = code for sky
condition. YYY = The layer
height (hundreds of meters).
99999 = missing data.
See Sky Condition table below.



17 ASOS CLOUD LAYER 2 Sky condition and height for
second layer. Data-value = XXYYY.
XX = code for sky condition.
YYY = The layer height (hundreds
of meters).
See Sky Condition table below.
18 ASOS CLOUD LAYER 3 Sky condition and height for
third layer. Data-value = XXYYY.
XX = code for sky condition.
YYY = The layer height (hundreds
of meters). .
See Sky Condition table below.
19 Hourly Precipitation Rainfall in millimeters
for the past hour.

Hourly Precipitation blank, A, See 'Data Format--Hourly
Flag D, or M Precipitation' section below.
20 Snow Depth Snow depth in centimeters on the
day indicated.

[Thomas]

Unfortunately, from the NCDC website and NOAA information I cannot tell if radiation is measured on a horizontal surface or not. Will not knowing this be an important issue?

Dear Mr. Hurd,
radiation data provided by official meteorological stations are usually measured on a horizontal surface; I have never seen radiation on inclined surfaces reported in general-purpose data sets. If there is any doubt, inspection of the global radiation values for a clear day will show whether the values before and after noon are symmetrical. For a more stringent test, the measured values could be compared with a simple model for hourly global radiation. If needed, I could do such a test for you.

Will the data below meet WUFI’s requirements? I know some of the NOAA fields are probably not required.

The list appears to contain everything that is needed for a WUFI calculation. If you want to convert the data to the *.TRY format, you additionally need values for the atmospheric counterradiation. It should not simply be set to zero; see the on-line help topic discussing the *.TRY file format.

Regards,
Thomas

[Michael Hurd]

Thomas, our company purchased a CD of additional NOAA weather data for cities here and I have started to create my first weather file. I am using the spreadsheet that is in the WUFI tools folder and I happened to notice that the NOAA data for the city I was inputing is missing the data for Direct and Global radiation. I checked several other cities on the CD and haven't found one yet where this data was actually gathered by NOAA. NOAA lists the radiation as data they provide but so far I haven't found a city on the CD that actually has it. If I have the other data required by WUFI will I get reasonable results?

[Thomas]

I happened to notice that the NOAA data for the city I was inputing is missing the data for Direct and Global radiation. [...] If I have the other data required by WUFI will I get reasonable results?

Dear Mr. Hurd,

whether solar radiation data are necessary for a given investigation depends on whether the heating caused by the radiation affects the moisture balance of the building component or not. I'm afraid that in most cases it does.

Under special circumstances you may get away with ignoring solar radiation, for example if you investigate cellar walls below ground level, strongly shaded facades, walls inside a building etc. Or you may deliberately do a simulation without solar radiation in order to expose a newly-designed construction to more severe conditions (weaker drying potential) than is actually expected so as to check its robustness against unusually severe conditions. However, these are very specific questions, and unless you specialize in these, I'm afraid the usefulness of weather data without solar radiation will be very limited.

Are you sure that the data is really not there? Maybe it has some obscure name or unfamiliar units? If there were only global radiation, direct or diffuse radiation could be estimated with appropriate statistical methods. Unfortunately, I am not familiar with the various kinds of data provided by NOAA, so I cannot tell what usually to expect in their files and what not...

Regards,
Thomas

[Michael Hurd]

Thomas, thanks for the quick reply. The NOAA information that comes with the data explains that when the information for a field is not available they place 99999 in the field - for all the cities I've looked at so far the radiation fields have the 99999 indication in them. I have sent an email to NOAA/NCDC asking them if they have some other data we can purchase or download that actually has the data for radiation. They advertised this particular CD as having the data but it seems as if it just isn't there at least for most of the cities. At this point I'm waiting for their reply. Thanks again for all your help!