Hi Mark, It looks good to me (that's one :->), thanks for the update.
The practice is for a request to go at least 3 weeks without open concerns, so if nothing else appears on the list I imagine it can be confirmed in a week or two. Subject to availability of the managers. John On Jul 2, 2014, at 07:35, Hedley, Mark <[email protected]> wrote: > please may I obtain confirmation that this change is now amenable and will be > included in the next release of the standard names vocabulary? > > Explicitly: > > I would like to formally propose that the description text for standard names: > low_type_cloud_area_fraction > medium_type_cloud_area_fraction > high_type_cloud_area_fraction > be altered such that > 'X_type_cloud_area_fraction is determined on the basis of cloud type and not > on the vertical location of the cloud.' > instead reads > 'X_type_cloud_area_fraction is generally determined on the basis of cloud > type, though numerical weather prediction models often calculate them based > on the vertical location of the cloud.' > > thank you > mark > ________________________________________ > From: Heiko Klein [[email protected]] > Sent: 27 June 2014 09:30 > To: John Graybeal; Hedley, Mark > Cc: CF Metadata List; Alison Pamment > Subject: Re: [CF-metadata] cloud amounts > > NWP = numerical weather prediction > > Heiko > > On 2014-06-19 17:50, John Graybeal wrote: >> I like the change, but please spell out NWP (and if a proper noun, make sure >> it is an unambiguous reference for anyone in the world). >> >> john >> >> On Jun 19, 2014, at 03:55, Hedley, Mark <[email protected]> wrote: >> >>> Hi Heiko, Alison, CF >>> >>> that all sounds good to me, many thanks for your input and advice Heiko >>> >>> I would like to formally propose that the description text for standard >>> names: >>> low_type_cloud_area_fraction >>> medium_type_cloud_area_fraction >>> high_type_cloud_area_fraction >>> >>> be altered such that >>> >>> 'X_type_cloud_area_fraction is determined on the basis of cloud type and >>> not on the vertical location of the cloud.' >>> >>> instead reads >>> >>> 'X_type_cloud_area_fraction is generally determined on the basis of cloud >>> type, though NWP models often calculate them based on the vertical location >>> of the cloud.' >>> >>> thank you >>> mark >>> ________________________________________ >>> From: Heiko Klein [[email protected]] >>> Sent: 18 June 2014 08:20 >>> To: Hedley, Mark; [email protected] >>> Subject: Re: [CF-metadata] cloud amounts >>> >>> Hi Mark, >>> >>> the first proposal for the *_cloud_area_fraction was in fact >>> high/medium/low, and not high_type etc. But then, we found out that we >>> do not manage to give a concise description where a 'high' cloud starts >>> and where it ends. The altitude of the clouds changes by latitude and >>> other factors. >>> >>> The 'high/medium/low_type' words are rather concepts than precise model >>> descriptions, and when doing inter-comparison from model to model or >>> from model to observations it will be possible to do so on that basis. >>> >>> >>> I just reread the description in the standard_name list, and I see that >>> only half of the proposal made it the the final list. The sentence: >>> >>> The cloud types can be used for models, too, e.g. by the definitions >>> like (taken from ECMWF): >>> Let sigma = pressure / surface pressure. >>> Low type cloud is for 1.0 > sigma > 0.8 >>> Medium cloud is for 0.8 >= sigma > 0.45 >>> High cloud is for 0.45 >= sigma >>> The definition depends usually on model and/or latitude. >>> >>> didn't make it. >>> >>> >>> >>> So, I agree, that the current description needs a slight modification >>> because it currently rules out a common usage. I suggest to change from >>> >>> X_type_cloud_area_fraction is determined on the basis of cloud type and >>> not on the vertical location of the cloud. >>> >>> to >>> >>> X_type_cloud_area_fraction is generally determined on the basis of cloud >>> type, though NWP models often calculate them based on the vertical >>> location of the cloud. >>> >>> >>> Otherwise, we might end up with two standard-names describing the same >>> concept, just because the description sounds to strict. >>> >>> >>> Best regards, >>> >>> Heiko >>> >>> On 2014-06-17 14:57, Hedley, Mark wrote: >>>> Hello Heiko, CF >>>> >>>> Many thanks for your feedback, that is really useful. I think I >>>> appreciate the utility of these standard names, the feedback I have had is >>>> that diagnostics like this are widely used by forecasters and model >>>> analysts. >>>> >>>> The concerns raised with me relate to the descriptions of these >>>> diagnostics, and the focus on 'cloud type identification' for >>>> classification. >>>> >>>> There are similarly named diagnostics in our models, which explicitly do >>>> not categorise clouds; they take defined vertical ranges and return data >>>> based on the amount of any cloud in a grid box for that range of model >>>> levels. >>>> >>>> The concern is that whilst the standard name is likely to be recognised by >>>> model developers and forecasters alike, the description which is bound to >>>> this standard name does not describe how these diagnostics are calculated >>>> within our model. >>>> >>>> This has lead to the concern that whilst these seem very useful standard >>>> names, they should not be used for our models, as the textual description >>>> of the standard names do not reflect the modelled quantity in our case. >>>> The |low/medium/high| cloud amount is always determined on the basis of >>>> the vertical location of the cloud, not on the cloud type, which is not >>>> modelled. >>>> >>>> Do you think that the description text statement: >>>> ''X_type_cloud_area_fraction is determined on the basis of cloud type >>>> and not on the vertical location of the cloud.'' >>>> properly represents the standard name and its usage across the community? >>>> >>>> Might we be better served by using a different name for these model >>>> outputs, even if this hides the generally accepted interpretation of >>>> high/medium/low cloud? (if so, what?) >>>> >>>> many thanks >>>> mark >>>> >>>> ________________________________________ >>>> From: Heiko Klein [[email protected]] >>>> Sent: 11 June 2014 18:53 >>>> To: Hedley, Mark; [email protected] >>>> Subject: Re: [CF-metadata] cloud amounts >>>> >>>> Hi Mark, >>>> >>>> I've been the original requestor for the >>>> low/middle/high_type_cloud_area_fraction. >>>> >>>> WMO has introduced the low/middle/high clouds already before models >>>> became as famous as they are today, and they still seem to be a >>>> excellent simplification and forecasters still use these 3 types (+fog). >>>> >>>> Model output can come in many levels, currently in Europe between 60 and >>>> 200. This is definitely too much to transfer and to handle for a >>>> forecaster and a reduction to 3 (4) cloud-types is done at all known >>>> centres (Norway/ECMWF/SMHI). You are right that this reduction is often >>>> just a summation of certain levels, but it doesn't need to - I've seen >>>> at least one model which calculates fog different than just taking >>>> clouds in ground-level. >>>> >>>> Examples: >>>> >>>> >>>> # using correct standard_name >>>> http://thredds.met.no/thredds/dodsC/arome25/arome_norway_default2_5km_latest.nc.html >>>> >>>> >>>> # layer named e.g. High cloud cover >>>> http://wrep.ecmwf.int/wms/?token=MetOceanIE&request=GetCapabilities&version=1.1.1&service=WMS >>>> >>>> >>>> Concerning your questions: >>>> >>>> 1. Forecasts are never accurate, but the definitions are at least well >>>> established by WMO, and it is the models task to translate them as best >>>> as possible >>>> >>>> 2. No, the cloud types predate models and model levels and eventually >>>> accurate height measurements. If a model-level - cloud type assumption >>>> is used, this is just a guess. >>>> >>>> 3. Really good question, I'll ask our modellers how they calculate the >>>> different types. >>>> >>>> Heiko >>>> >>>> On 2014-06-11 15:41, Hedley, Mark wrote: >>>>> Hello CF >>>>> >>>>> I have been having an interesting conversation with some modelling >>>>> colleagues regarding the standard names and descriptions for cloud amount: >>>>> >>>>> cloud_area_fraction: >>>>> 'X_area_fraction' means the fraction of horizontal area occupied by X. >>>>> 'X_area' means the horizontal area occupied by X within the grid cell. >>>>> Cloud area fraction is also called 'cloud amount' and 'cloud cover'. The >>>>> cloud area fraction is for the whole atmosphere column, as seen from the >>>>> surface or the top of the atmosphere. The cloud area fraction in a layer >>>>> of the atmosphere has the standard name >>>>> cloud_area_fraction_in_atmosphere_layer. >>>>> >>>>> low_type_cloud_area_fraction: >>>>> Low type clouds are: Stratus, Stratocumulus, Cumulus, Cumulonimbus. >>>>> "X_area_fraction" means the fraction of horizontal area occupied by X. >>>>> Cloud area fraction is also called "cloud amount" and "cloud cover". >>>>> X_type_cloud_area_fraction is determined on the basis of cloud type and >>>>> not on the vertical location of the cloud. >>>>> >>>>> middle_type_cloud_area_fraction: >>>>> Middle type clouds are: Altostratus, Altocumulus, Nimbostratus. >>>>> "X_area_fraction" means the fraction of horizontal area occupied by X. >>>>> Cloud area fraction is also called "cloud amount" and "cloud cover". >>>>> X_type_cloud_area_fraction is determined on the basis of cloud type and >>>>> not on the vertical location of the cloud. >>>>> >>>>> high_type_cloud_area_fraction: >>>>> High type clouds are: Cirrus, Cirrostratus, Cirrocumulus. >>>>> "X_area_fraction" means the fraction of horizontal area occupied by X. >>>>> Cloud area fraction is also called "cloud amount" and "cloud cover". >>>>> X_type_cloud_area_fraction is determined on the basis of cloud type and >>>>> not on the vertical location of the cloud. >>>>> >>>>> In our local models, we have diagnostics labelled: >>>>> TOTAL CLOUD AMOUNT - RANDOM OVERLAP >>>>> LOW CLOUD AMOUNT >>>>> MEDIUM CLOUD AMOUNT >>>>> HIGH CLOUD AMOUNT >>>>> >>>>> The model calculates LOW CLOUD AMOUNT by finding the maximum amount of >>>>> cloud cover in a model level which exists within a range defined as >>>>> low. The model has no inclination about cloud types and makes no >>>>> evaluation of overlap for these diagnostics. >>>>> >>>>> The model calculates TOTAL CLOUD AMOUNT - RANDOM OVERLAP by evaluating >>>>> the cloud over all vertical levels and its spatial displacement. >>>>> >>>>> Base on this, it seems reasonable to use the CF standard name >>>>> cloud_area_fraction >>>>> for output fields but based on the descriptive text then I do not see >>>>> how we could ever be able to use >>>>> low_type_cloud_area_fraction >>>>> for data output from our model. >>>>> >>>>> I would be really interested to hear from people who use these standard >>>>> names regularly on the applicability to our case; specifically: >>>>> >>>>> 1. Are these definitions explicit, complete and accurate? >>>>> >>>>> 2. Should all uses of these standard names be sure that they are based >>>>> on typing the cloud correctly, not on the level of the cloud within the >>>>> model? >>>>> >>>>> 3. Do these high/medium/low cloud type standard names also assume that >>>>> spatially displaced levels are summed, or are they aiming to report the >>>>> maximum in any one level within the range? >>>>> >>>>> many thanks >>>>> mark >>>>> >>>>> >>>>> _______________________________________________ >>>>> CF-metadata mailing list >>>>> [email protected] >>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >>>>> >>>> >>>> -- >>>> Dr. Heiko Klein Tel. + 47 22 96 32 58 >>>> Development Section / IT Department Fax. + 47 22 69 63 55 >>>> Norwegian Meteorological Institute http://www.met.no >>>> P.O. Box 43 Blindern 0313 Oslo NORWAY >>>> >>> >>> -- >>> Dr. Heiko Klein Tel. + 47 22 96 32 58 >>> Development Section / IT Department Fax. + 47 22 69 63 55 >>> Norwegian Meteorological Institute http://www.met.no >>> P.O. Box 43 Blindern 0313 Oslo NORWAY >>> _______________________________________________ >>> CF-metadata mailing list >>> [email protected] >>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> > > -- > Dr. Heiko Klein Tel. + 47 22 96 32 58 > Development Section / IT Department Fax. + 47 22 69 63 55 > Norwegian Meteorological Institute http://www.met.no > P.O. Box 43 Blindern 0313 Oslo NORWAY > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
