# Difference on Monthly precipitation of SEAS 5 data when computed on CDS and directly on ECMWF portal

**URL:** <https://forum.ecmwf.int/t/difference-on-monthly-precipitation-of-seas-5-data-when-computed-on-cds-and-directly-on-ecmwf-portal/1208>\
**Category:** C3S - Datasets and Usage\
**Tags:** seasonal\_forecast, c3s\
**Created:** [21 January 2022 09:11 UTC](https://forum.ecmwf.int/t/difference-on-monthly-precipitation-of-seas-5-data-when-computed-on-cds-and-directly-on-ecmwf-portal/1208 "2022-01-21T09:11:33Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![UnknownUser](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/u/35a633/32.png) [@UnknownUser](https://forum.ecmwf.int/u/UnknownUser)\
**Post date:** [21 January 2022 09:11 UTC](https://forum.ecmwf.int/t/difference-on-monthly-precipitation-of-seas-5-data-when-computed-on-cds-and-directly-on-ecmwf-portal/1208/1 "2022-01-21T09:11:33Z")

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Dear forum,

we extracted monthly accumulated rainfall from SEAS5 provided by CDS by using:

'seasonal-monthly-single-levels',  
 &nbsp; &nbsp; {  
 &nbsp; &nbsp; &nbsp; &nbsp; 'originating\_centre': 'ecmwf',  
 &nbsp; &nbsp; &nbsp; &nbsp; 'system': '5',  
 &nbsp; &nbsp; &nbsp; &nbsp; 'variable': 'total\_precipitation',  
 &nbsp; &nbsp; &nbsp; &nbsp; 'product\_type': 'monthly\_mean',  
 &nbsp; &nbsp; &nbsp; &nbsp; 'year': '2016',  
 &nbsp; &nbsp; &nbsp; &nbsp; 'month': '10',  
 &nbsp; &nbsp; &nbsp; &nbsp; 'leadtime\_month': [  
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; '1',

&nbsp; &nbsp; &nbsp; &nbsp; ],  
 &nbsp; &nbsp; &nbsp; &nbsp; 'area': [  
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 45, -180, -45,  
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 180,  
 &nbsp; &nbsp; &nbsp; &nbsp; ],  
 &nbsp; &nbsp; &nbsp; &nbsp; 'format': 'netcdf',  
 &nbsp; &nbsp; },  
 &nbsp; &nbsp; 'download.netcdf')

And we compared to the monthly rainfall extracted directly from the ECMWF portal by using this api:

server = ECMWFService("mars")

def retrieve\_s5():  
 &nbsp; &nbsp; year = 2016  
 &nbsp; &nbsp; month = 10  
 &nbsp; &nbsp; day = 1  
 &nbsp;&nbsp; startDate = '%04d%02d%02d' % (year, month, day)  
 &nbsp;&nbsp; target = "ecmwf/s5\_forecast\_%04d%[02d.nc](http://02d.nc)" % (year, month)  
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; requestSteps = '745'  
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; print("Run for " + startDate)  
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; s5\_request(startDate, requestSteps, target)

def s5\_request(startDate, requestSteps, target):

&nbsp; &nbsp; server.execute({

&nbsp; &nbsp; &nbsp; &nbsp;"class": "od",

&nbsp; &nbsp; &nbsp; &nbsp;"date": startDate,

&nbsp; &nbsp; &nbsp; &nbsp;"expver": "1",

&nbsp; &nbsp; &nbsp; &nbsp;"levtype": "sfc",

&nbsp; &nbsp; &nbsp; &nbsp;"method": "1",

&nbsp; &nbsp; &nbsp; &nbsp;"number": "00/to/24",

&nbsp; &nbsp; &nbsp; &nbsp;"origin": "ecmf",

&nbsp; &nbsp; &nbsp; &nbsp;"param": "228.128",

&nbsp; &nbsp; &nbsp; &nbsp;"step": requestSteps,

&nbsp; &nbsp; &nbsp; &nbsp;"stream": "mmsf",

&nbsp; &nbsp; &nbsp; &nbsp;"system": "5",

&nbsp; &nbsp; &nbsp; &nbsp;"time": "00:00:00",

&nbsp; &nbsp; &nbsp; &nbsp;"type": "fc",

&nbsp; &nbsp; &nbsp; &nbsp;"grid": "1.0/1.0",

&nbsp; &nbsp; &nbsp; &nbsp;"format": "netcdf",

&nbsp; &nbsp; &nbsp; &nbsp;},target)

We then compare the two netcdf generated and we got differences ? Any explanations ?

Thank you very much

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**Author:** ![Kevin\_Marsh](https://forum.ecmwf.int/user_avatar/forum.ecmwf.int/kevin_marsh/32/368_2.png) [@Kevin\_Marsh](https://forum.ecmwf.int/u/Kevin_Marsh)\
**Post date:** [26 January 2022 12:25 UTC](https://forum.ecmwf.int/t/difference-on-monthly-precipitation-of-seas-5-data-when-computed-on-cds-and-directly-on-ecmwf-portal/1208/2 "2022-01-26T12:25:21Z")

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Hi Christophe,

What kind of differences are you seeing?

Thanks,

Kevin

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<div class="post-metadata">

**Author:** ![UnknownUser](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/u/35a633/32.png) [@UnknownUser](https://forum.ecmwf.int/u/UnknownUser)\
**Post date:** [27 January 2022 08:20 UTC](https://forum.ecmwf.int/t/difference-on-monthly-precipitation-of-seas-5-data-when-computed-on-cds-and-directly-on-ecmwf-portal/1208/3 "2022-01-27T08:20:11Z")

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Dear Kevin,  
 Thank you for your answer.  
 I'm re-downloading these datasets from scratch (to double check) and I'm preparing a complete comparison for a specific month. I'll keep in touch.  
 Christophe&nbsp;