Cloud cover and sun hours

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felixrohloff@gmx.de
MOHID Beginner
Posts: 6
Joined: Mon May 12, 2014 15:01

Cloud cover and sun hours

Postby felixrohloff@gmx.de » Tue Jul 29, 2014 08:43

Hello at all,

i have obtained an Dataset which contains hourly data of Sun hours which i wanne use to compute the cloud cover. The Data are in min/h so for example 30 minutes sun per Hour. I´v read the Wiki and just found that the CLOUD_COVER_METHOD should be : 1 and i looked in the code where i find, that if cloud cover should compute from sun hours it calls for Property sun hours.
So i set up these 2 Block´s in the Atmosphere Data:

<beginproperty>
NAME : sunshine hours
UNITS : min
DESCRIPTION : sun hours from file
DEFAULTVALUE : 0.0
FILE_IN_TIME : TIMESERIE
FILENAME : ..\General Data\Boundary Conditions\Dresden.dat
DATA_COLUMN : 2
TIME_SERIE : 0
OUTPUT_HDF : 1
<endproperty>

<beginproperty>
NAME : cloud cover
UNITS : fraction
DESCRIPTION : cloud cover from sun hours
CLOUD_COVER_METHOD : 1
FILE_IN_TIME : NONE
REMAIN_CONSTANT : 0
DEFAULTVALUE : 0.
TIME_SERIE : 0
OUTPUT_HDF : 1
<endproperty>

the model run but i struggle with the results. It shows that the sunshine hours are for example 58 (for 58 min) witch i think is okay but the value for the cloud cover is -6.53. I hope someone can tell me more about the Units Mohid required. Thanks a lot for help.

best regards
Felix Rohloff

felixrohloff@gmx.de
MOHID Beginner
Posts: 6
Joined: Mon May 12, 2014 15:01

Re: Cloud cover and sun hours

Postby felixrohloff@gmx.de » Fri Aug 15, 2014 09:24

Hello,

Luis give me a hint that Mohid use "number of hours per day" as units for sun hours. But that ist not the resolution i want, and at night there will be no clound with this set-up, so i make a work around which may help.

The problem was the night, because there is no light and therefore no clouds. In my case i have also found daily-average data for the cloud cover(observation). So the most precise way is to convert the hourly sunshine data in hourly cloud cover and then at night, put there the daily average, so there are clouds at night.

It´s very time consuming but it works and the Block sunshine hours isn´t needed.

best regards
Felix


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