Comments on: Visualizing Drought http://joewheatley.net/visualizing-drought/ Earth Vegetation Wed, 28 Dec 2011 13:05:49 +0000 hourly 1 http://wordpress.org/?v=3.1 By: joe http://joewheatley.net/visualizing-drought/comment-page-1/#comment-444 joe Tue, 11 Oct 2011 23:00:14 +0000 http://joewheatley.net/?p=1877#comment-444 Hi Peter, I uploaded a better version of the SPI script. It takes a vector of precipitation value e.g. from an individual weather station. You might find it more useful. Hi Peter,

I uploaded a better version of the SPI script. It takes a vector of precipitation value e.g. from an individual weather station. You might find it more useful.

]]> By: Peter Maclean http://joewheatley.net/visualizing-drought/comment-page-1/#comment-443 Peter Maclean Tue, 11 Oct 2011 00:38:14 +0000 http://joewheatley.net/?p=1877#comment-443 As Claudia indicated I get the following message after replacing N_timescale by 12. How you got the # 756? Warning message: In matrix(unlist(spi.m), 756, 12) : data length [9216] is not a sub-multiple or multiple of the number of rows [756] As Claudia indicated I get the following message after replacing N_timescale by 12. How you got the # 756?
Warning message:
In matrix(unlist(spi.m), 756, 12) :
data length [9216] is not a sub-multiple or multiple of the number of rows [756]

]]> By: joe http://joewheatley.net/visualizing-drought/comment-page-1/#comment-195 joe Tue, 26 Oct 2010 14:24:02 +0000 http://joewheatley.net/?p=1877#comment-195 Claudia, my apologies. replace N_timescale with 12 to reproduce the plot in the post i.e 12 SPI indices SPI1, SPI2, SPI3 ... SPI12 are calculated for each month. This should deal with the warning message. Claudia,

my apologies. replace N_timescale with 12 to reproduce the plot in the post i.e 12 SPI indices SPI1, SPI2, SPI3 … SPI12 are calculated for each month. This should deal with the warning message.

]]> By: Claudia http://joewheatley.net/visualizing-drought/comment-page-1/#comment-194 Claudia Tue, 26 Oct 2010 12:11:04 +0000 http://joewheatley.net/?p=1877#comment-194 Hi I tried to run your R code. I used the same data as you did (but only till Dec 2009, so 744 months). First, I had to make a little correction, as you didn't define N_timescale. I defined N_timescale <- Nt (I hope so far, I understood it correctly). The point now: I get the same plot as result, but with the warning message "Warning message: In matrix(unlist(spi.m), Nt, 12) : data length [9804] is not a sub-multiple or multiple of the number of rows [744]". I guess the mistake lies within the calculation of the spi. Do you know this error message already? If yes, can you possibly help me? Thanks, Claudia Hi

I tried to run your R code. I used the same data as you did (but only till Dec 2009, so 744 months).
First, I had to make a little correction, as you didn’t define N_timescale. I defined N_timescale <- Nt (I hope so far, I understood it correctly).
The point now: I get the same plot as result, but with the warning message "Warning message: In matrix(unlist(spi.m), Nt, 12) : data length [9804] is not a sub-multiple or multiple of the number of rows [744]".
I guess the mistake lies within the calculation of the spi. Do you know this error message already? If yes, can you possibly help me?

Thanks, Claudia

]]> By: Response of African Vegetation to Drought | Biospherica http://joewheatley.net/visualizing-drought/comment-page-1/#comment-146 Response of African Vegetation to Drought | Biospherica Wed, 12 May 2010 16:36:07 +0000 http://joewheatley.net/?p=1877#comment-146 [...] graph below shows the correlation between VCI and 3-month Standardized Precipitation Index (SPI3) computed for Africa by calendar month. In this analysis GIMMS NDVI was upscaled to 200km to [...] [...] graph below shows the correlation between VCI and 3-month Standardized Precipitation Index (SPI3) computed for Africa by calendar month. In this analysis GIMMS NDVI was upscaled to 200km to [...]

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