How to calculate drought index SPI? | Jalal | Research Society
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- Опубліковано 20 вер 2024
- In this video, we'll walk you through the process of calculating the Standardized Precipitation Index (SPI), a widely used measure to monitor drought conditions. We'll cover each step, from data collection and distribution fitting to cumulative probability and interpretation. By the end of this tutorial, you'll have a solid understanding of how to calculate SPI and what the values mean for assessing wet and dry periods in a given region.
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Steps to Calculate the SPI:
Data Collection:
Gather historical precipitation data for the location and time period of interest.
Ensure the data is continuous, with no missing values, to get an accurate calculation.
Precipitation Distribution Fitting:
Fit the historical precipitation data to a probability distribution. The Gamma distribution is commonly used due to its flexibility in modeling precipitation data.
Estimate the parameters (α and β) of the Gamma distribution using the Maximum Likelihood Estimation (MLE) method.
Cumulative Probability:
Convert the observed precipitation data to cumulative probabilities using the fitted distribution.
Normalization:
Transform the cumulative probabilities into a standard normal distribution (mean of 0 and standard deviation of 1).
The result is the SPI value, which indicates the number of standard deviations the observed precipitation deviates from the mean.
Interpretation:
Positive SPI values indicate above-average precipitation (wetter conditions).
Negative SPI values indicate below-average precipitation (drier conditions).
The severity of the drought or wet condition is determined by how far the SPI value deviates from zero.
Example Interpretation:
SPI = -2.0 or less: Extremely dry (severe drought)
SPI = -1.5 to -1.99: Severely dry
SPI = -1.0 to -1.49: Moderately dry
SPI = -0.99 to 0: Near normal
SPI = 0 to 0.99: Near normal
SPI = 1.0 to 1.49: Moderately wet
SPI = 1.5 to 1.99: Severely wet
SPI = 2.0 or more: Extremely wet
SPI Calculation
Standardized Precipitation Index
Drought Index
Climate Monitoring
Precipitation Analysis
Drought Assessment
Weather Data Analysis
Climate Science
Meteorology Tutorial
Environmental Monitoring
#SPI #Jalal #Research_Society #SPICalculation #StandardizedPrecipitationIndex #DroughtIndex #ClimateMonitoring #PrecipitationAnalysis #DroughtAssessment #WeatherDataAnalysis #ClimateScience #MeteorologyTutorial #EnvironmentalMonitoring #drjalal #mdjalaluddin #researchsociety #bangladesh
Calculate SPI, SPEI and PET in Python:
www.drought.gov/data-maps-tools/climate-and-drought-indices-python-spi-spei-pet
Alternative link: github.com/monocongo/climate_indices
Thank u sir for this link. I will try....
VERY INFORMATIVE AND HELPFUL VIDEO. I've read your publications and it saved me a lot of stress while writing my thesis. Thank you sir
Thank you very much.
Very informative video clips sir! I really appreciate your time and efforts. May you br blessed
Thank you so much.
Hello Dr. Jalal. Why Spi_sl_6 application that you add to Dropbox give me the output with size 0 kB? I want to calculate SPI for 3 Years. my PRCP data unit are mm. and I multiplied the units by 1000(e.g. 11.3 mm --> 11300 micrometer) "because you said in video our units shouldn't be fractional". I want SPI for time scales: 1, 3, 6, 9, 12, 18, 24, 36). but it gives me an empty folder. Would you mind advice me how to calculate SPI ?
You may send me your input data.
dmjalal90@gmail.com
@@DrJalal90 I sent an email, Thank you Dr. Jalal for the help
@@DrJalal90 Hello Dr. Jalal. I sent you an email about my problem with my SPI output. Would you mind checking your mail inbox, I don't know why my output contains 9999
Hello Sir, . I am working on drought. Sir I calculated the SPEI value using 30 year data. Sir is there any way to get one value of SPEI for a grid for last 30 years.Can we get a one value for a grid by using trend analysis and Sen's slope analysis. Also sir I want to know how to make drought susptibility map by using SPEI value.
I will be great full for your help sir.
Thank You Sir
The following links are for SPEI calculation for a grided data.
www.drought.gov/data-maps-tools/climate-and-drought-indices-python-spi-spei-pet
github.com/monocongo/climate_indices
Sorry, I have no idea how to draw a drought susptibility map.
The video is very important but unable to download the software you say
Here it is. www.dropbox.com/s/zodso9oors4quns/SPI_paper_data.zip?dl=0
sir please make a video how to claculate spi and sri in matlab
I will try. Thank you.
@@DrJalal90 ok sir thank you
sir i tried using same technique but I received same result for all the time scales. kindly help I mailed u the document output and input please help me
Please check your email.
Excellent work, thanks
Welcome!
Excuse me one question again, I have daily data , is it possible to calculate spi for 15 day ? if it is yes ,is it the same method in your video?
No, you will get monthly values.
Thank you. But if we say SPI-3, after calculate SPI, shall we sum the SPI of three consecutive months?
I didn’t get you.
Superb sir,
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Sir it was really helpful, kindly make a video describing about the different timescales.
The following video might help you to understand timescale. Sorry, the language is in Bengali. I might make a English video in future. Please share my channel with your friends. I would be happy to know your academic background.
ua-cam.com/video/o2mGQW8ECVU/v-deo.html
Python free online training for international participants
The training will start on 20 September 2021.
Deadline for registration: 15 September 2021
Registration link: researchsociety20.org/registration/
Download link for training outline: www.dropbox.com/s/aybmuw0rrxu7zjb/Outline_python_International.png?dl=0
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Please share the event with your friends or colleagues.
Hi sir , I wanna know for any area in the world the SPI calculation is the same method, as you did in the video?
Yes, it is.
Thank you for replying, God bless you
Great video👌🏾. How do you then create the maps for SPI and SPEI?. I need it for my research project.
You can use IDW technique in GIS. You can also use gridded dataset in Python if you wish. You can watch my video ua-cam.com/video/WMF45KQiQAM/v-deo.html.
Thanks. Could you please recommend a step-by-step video where you create the final SPI maps using the SPI you calculated.
@@nandebija6763 Sorry, I did not make such video.
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The training will start on 20 September 2021.
Deadline for registration: 15 September 2021
Registration link: researchsociety20.org/registration/
Download link for training outline: www.dropbox.com/s/aybmuw0rrxu7zjb/Outline_python_International.png?dl=0
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Awesome
Thank you.
i have no word
where is the output file for 3 and 6 month time scale ?? you get only one file of .txt
Everything is there.
Very helpful. If we have a time series with daily rainfall, we need to aggregate in order to have a the monthly value? or we take the mean??
For rainfall, we do sum.
@@DrJalal90 so in order to use the packages that you show in your about how to calculate SPI, SPEI we should give as input the sum of the rainfall for every month?
@@kritidaki Please download the sample data from video description.
@@DrJalal90 Yes, thank you. Actually my question was about your video proposing some packages to work on python. I try to use these packages, Aand I inserted the summation of rainfall for every month. It was so clear if this code needs the sum or the average
Python free online training for international participants
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Can i get the software?thanks doc
drought.unl.edu/Monitoring/SPI/SPIProgram.aspx
Thank for your video! really nice. please I am trying to use a grided dataset to calculate SPEI drought for Ethiopia. do you have any suggestion on how i can best do this?
Thank you. You can watch my video. ua-cam.com/video/WMF45KQiQAM/v-deo.html
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It’s an amazing
Thank you.
Assalamu alaikum bhai ,how can i create .cor extension file?
Walikum salam wa rahmatullah. Using notepad, you can save the input file as .cor extension [File name: name.cor Save as type: All]. See more: noobie.com/save-document-notepad/
Good day sir , how to convert my files to cor file before to use in the software. thank you
You can save your file as .cor (SaveAs).
@@DrJalal90 Thanks it works
any calculation on drought duration intensity frequency?
I did not make such a video.
Please provide the software link... And can you suggest, how to do the calculations in MATLAB, it will be helpful for my project.
drought.unl.edu/droughtmonitoring/MonitoringHome.aspx
www.mediafire.com/file/rlcayoaiaqxz77k/file
Python free online training for international participants
The training will start on 20 September 2021.
Deadline for registration: 15 September 2021
Registration link: researchsociety20.org/registration/
Download link for training outline: www.dropbox.com/s/aybmuw0rrxu7zjb/Outline_python_International.png?dl=0
Event link: fb.me/e/XMyJYOwn
Please share the event with your friends or colleagues.
Sir, Thank you for sharing. But why it is getting started in 3rd month in results. And what is the meaning of -99.00.
You need to understand the timescale. The following video might help you.
ua-cam.com/video/o2mGQW8ECVU/v-deo.html
@@DrJalal90 it would be better if it is in English....Please
But thank u ....understood few more things...
@@chandrakantkadam1953 I will if I have time.
Good day sir. I need your help, I am using CLIMPACT software to calculate SPEI like in your article, Now I need climpact2.sample.batch.metadata.txt file. Thank
github.com/ARCCSS-extremes/climpact2/blob/master/climpact2.batch.stations.r
Please read carefully the section 5 of user guide (climpact-sci.org/assets/climpact2-user-guide.pdf).
Hello Sir, I have serious doubts about the raw rainfall data. Do we have to take monthly SUM or monthly AVERAGE to find SPI?
Pls, advise.
monthly total.
Please download my data template.
@@DrJalal90 monthly Total divided by number of days in the month ?
@@chandrakantkadam1953 No, please read the article.
Thank you for intersting video sir .Infact i downloaded the software using the link you gave. but, when I open the program on command line and then after I fill all needed file my output results indicate that prased error(error logging ) .so how can I solve the problem and is it mandatory to run the program in the presence of C++?
"so how can I solve the problem and is it mandatory to run the program in the presence of C++?"
I don't think so.
Python free online training for international participants
The training will start on 20 September 2021.
Deadline for registration: 15 September 2021
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SIr, how to find SPI if the study area has multiple stations. I have 113 stations and precipitation data for 40 years. How to prepare data in this case? Please.
This is a very good question. I did manually. However, in your case, too many stations will take long-time to calculate. You might use Python or NCL, see the playlist (ua-cam.com/play/PL4T8G4Q9_JQ-55DtbmK0iXydTB7spuKCY.html).
@@DrJalal90 Manually means one by one station ? ready to calculate but how to represent at the end for the whole area?
@@chandrakantkadam1953
You might average for the whole country or climatic regions. For example, Bangladesh has 34 stations and 7 climatic zones, by which I mean that every climatic zone has distinct climate pattern. Therefore, the result of drought variability will be different from each other. I hope you will understand my point.
@@DrJalal90 Thank u Sir for the kind message. I will try using the concept. In one of the papers interpolation method is mentioned. Need to study and apply. Thanks.
How can I calculate SPI for large number of stations at same time?
You can calculate station by station.
@@DrJalal90 haha that would be a nightmare.
How can we calculate SPI with raster time series?
Hello.Is a Gamma function done for values before SPI?
I did not understand your question.
@@DrJalal90Gamma function needs to be done before SPI method. Has this been done in the exe file in the video?
@@DrJalal90 I m from Turkey.I am sorry for my English
@@yowy23 Everything is inside the software.
@@DrJalal90 Okey.Thank you.
How to save data .cor ?
just use 'save as' option.
Sir software download link is not working ...........please provide the proper link ...it will help a lot
You need to use vpn.
drought.unl.edu/droughtmonitoring/MonitoringHome.aspx
www.mediafire.com/file/rlcayoaiaqxz77k/file
Hi. Sir, how I can contact you please?
Email or Facebook.
researchsociety20.org/founder-and-director/
where I can find this file SPI_SI_6 ?
Please check the video description.
drought.unl.edu/Monitoring/SPI/SPIProgram.aspx
Sir I also doing research on drought can u share ur number.
Number sajha karte parben.
You can visit my official website.
researchsociety20.org/founder-and-director/
Some word pronouns with british and russian accents which sounds very odd 😢
What does it mean? Where are you from?