modify diurnal

JessicaYang

grads书上介绍有限，想向大家请教下modify diurnal这个自定义变量声明如何使用，能有详例更好，谢谢大家！

river

看一下GrADS官方文档
modify

modify varname type
This command defines a climatological variable, which is year-independent. varname is a defined grid. There are two options for type:

seasonal    - For creating monthly or multi-monthly climatologies
diurnal     - For creating climatologies over a time period less than a day
Usage Notes

Example

Say you have a 50-year timeseries of monthly mean sea surface temperatures (a variable named sst with 600 time steps) and you want to create a climatology and then look at the monthly anomalies. First, set the time range for 1 to 12, to span a complete year. Second, define the variable "sstclim" which will contain the January mean in the first time step, the February mean in the second time set, etc. Then use 'modify' to turn 'sstclim' into a climatological variable. This means that the calendar year associated with 'sstclim' (the first year in the original sst data set) becomes a wild card. Then you can define the anomaly by subtracting the climatology from the original time series. The commands are as follows:

'set t 1 12'
'define sstclim = ave(sst, t+0, t=600, 12)'
'modify sstclim seasonal'
'set t 1 last'
'define anom = sst - sstclim'

JessicaYang

river 发表于 2015-9-9 21:48
看一下GrADS官方文档
modify

谢谢哈，我在论坛上也看到您给别人解释的这个函数，但seasonal使用的挺多的，diurnal不敢贸然使用，感谢您的留言，您不妨把这个官网的链接发我一下，再次对您的回答表示感谢！

river

JessicaYang 发表于 2015-9-10 10:36
谢谢哈，我在论坛上也看到您给别人解释的这个函数，但seasonal使用的挺多的，diurnal不敢贸然使用，感谢 ...

就是GrADS的官网啊http://grads.iges.org/grads/gadoc/gadocindex.html