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Diana,<br>
<br>
I'm not exactly sure what you are trying to do. But maybe this example
will help you figure a solution.<br>
Ex:<br>
Say you have a lat-lon grid, temp, which has 20*365 (=7300) days of
data, and you just want to sum up the number of days over that period
at each grid point when the temperature was > 300. You could do
something like:<br>
<br>
'define ndays = sum( maskout(temp/temp,temp-300.), t=1,t=7300)'<br>
<br>
"sum" is a grads function which sums over the dimensions specified. In
this case, we sum over time. (Please see the grads documentation for
full explanation.)<br>
ndays is a new lat-lon field created by adding the value of one
(="temp/temp") for each grid point and day over the period from t =1 to
t = 7300 whenever "temp-300" > 0.. (At whichever grid point and
time temp < 300, maskout will set "temp/temp" = missing for that
grid point and time and not included it in the sum). <br>
<br>
Does this help?<br>
MJ<br>
<br>
na na wrote:
<blockquote cite="mid110149.52039.qm@web58908.mail.re1.yahoo.com"
type="cite">
<div>Dear all, </div>
<div>I am trying to find the frequency of extreme events ( higher
than normal temperatures and precipitation) from 20 years of daily .nc
data. I don't know how to calculate the frequency so I thouhgt that if
I construct a loop through time it would work. So, I tried to construct
a loop to pull from these 20 years only values of temperature higher
than a certain value (for example tmax > 300K) but it didn't work
and I don't know what else to do. Can anyone please please help me with
an advice? </div>
<div>Thank you,</div>
<div> </div>
<div>Diana Pop</div>
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