[MITgcm-support] 回复: MITgcm-support Digest, Vol 201, Issue 13
Leming Van
ifanliming at outlook.com
Tue Mar 17 03:14:17 EDT 2020
Hi, Estanislao
I got it, I selected Mean surface downward long-wave radiation flux instead of Surface thermal radiation downwards, so their units are different. Are there significant differences in the spatial distribution of these two variables?
-Mike
________________________________
发件人: MITgcm-support <mitgcm-support-bounces at mitgcm.org> 代表 ESTANISLAO GAVILAN PASCUAL-AHU <e.gavilan at hhu.edu.cn>
发送时间: 2020年3月17日 14:35
收件人: mitgcm-support at mitgcm.org <mitgcm-support at mitgcm.org>
主题: Re: [MITgcm-support] MITgcm-support Digest, Vol 201, Issue 13
Hi Mike,
I have just double checked the units in the documentation. Unless I am looking to the wrong parameter, the downward radiation is given in J m-2 see page.
https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels
Surface solar radiation downward:
This parameter is the amount of solar radiation (also known as shortwave radiation)....The units are joules per square metre (J m-2 ). To convert to watts per square metre (W m-2 ), the accumulated values should be divided by the accumulation period expressed in seconds. ....
Surface thermal radiation downwards:
Idem...
Kind regards,
Estanislao
> Content-Type: text/plain; charset="gb2312"
>
> Hi,
>
> I am grateful to everyone for your reply, and here I will respond to your suggestions.
>
> 1.for Dr. Stanislav Martyanov =========================================
>
> Thank you for sharing the meteorological forcing variables used in the ERA5 dataset, which has benefited me a lot.
>
> But I am a bit puzzled. The GLOBAL_REANALYSIS_PHY_001_030 you mentioned should be a product of the NEMO model. Is this the open boundary forcing data you use?
>
>
> 2.for Estanislao ===================================================
>
> Thank you for your reminding. Before using the data, it is very important to know the unit of the variable, just like the unit of precipitation in ERA5 is kg ? m-2 s-1, and the unit of the corresponding variable in MITgcm-EXF is m ? s-1. In this case, you need to divide by the density of fresh water for conversion.
>
> About the unit of long and short wave radiation flux in ERA5, I'm sure that it is W ? m-2, and there should be no problem in the unit of other variables.
>
>
> 3.for Raf =======================================================
>
> Thank you for your experience. The package I use is EXF. I simply looked at the code of EXF and found that it is calling exf_bulkformulae.F for related calculations.
>
> C us - mean wind speed (m/s) at height hu (m)
> C th - mean air temperature (K) at height ht (m)
> C qh - mean air humidity (kg/kg) at height hq (m)
>
> As for the definition of various variables in height, exf_readparms. F has made relevant definitions, and I have checked that it is correct.
>
> zref = 10.000 _d 0
> hu = 10.000 _d 0
> ht = 2.000 _d 0
>
>
> 4.for Hong =======================================================
>
> Thank you for your checking. I'm sorry I didn't make it clear. I put net short-wave radiation flux (nswrs) in swfluxfile, since swdown will be ignored when using swdown and swflux at the same time, so I removed swdownfile.
>
> (PID.TID 0000.0001) ** WARNING ** EXF_CHECK: "swdown" field is loaded from file but not used within pkg/exf
>
>
> Next ============================================================
> It seems that you don't have the same problem as me. Next, I plan to use ERA5 and NCEP data at the same time to find the reason for the difference between the results of model by the method of exclusion.
>
>
>
> Best,
> -Mike
> ________________________________
> ???: MITgcm-support <mitgcm-support-bounces at mitgcm.org> ?? Raphael Dussin <raphael.dussin at gmail.com>
> ????: 2020?3?16? 20:24
> ???: mitgcm-support at mitgcm.org <mitgcm-support at mitgcm.org>
> ??: Re: [MITgcm-support] ??: ??: The obvious difference between ERA5 and NCEP-R1 forcing
>
> Have you checked the heights for the atmospheric variables are correctly set?
> you should have something like this in data.blk
>
> zref = 10.0
> zwd = 10.0
> zth = 2.0
>
> I've seen a lot of runs going off the rails because of this kind of problem:
> If the height is not set right, the fluxes are not either and you end up with large biases.
>
> hope it helps,
> Raf
>
>
>
>
> Raf
>
>
>
> Le lun. 16 mars 2020 ? 04:49, Stanislav Martyanov <martyanov.sd at gmail.com<mailto:martyanov.sd at gmail.com>> a ?crit :
> Hello, Mike!
>
> I have recently downloaded the ERA5 reanalysis data (daily fields, GLOBAL_REANALYSIS_PHY_001_030 as labeled in Copernicus network) in order to construct the meteorological forcing for a regional ocean model (Kara Sea) based on the MITgcm. I chose the following fields:
>
> % 10m u-component of wind
> % 10m v-component of wind
> % 2m dewpoint temperature
> % 2m temperature
> % Mean total precipitation rate
> % Mean sea level pressure
> % Mean surface downward long-wave radiation flux
> % Mean surface downward short-wave radiation flux
>
> In order to compute the specific humidity, as advised in the ERA5 documentation, I used formulas given in IFS Documentation CY46R1 - part-iv-physical-processes (2m dewpoint temperature and Mean sea level pressure are used there).
>
> Regards,
>
> Dr. Stanislav Martyanov,
> Shirshov Institute of Oceanology,
> Russia
>
>
> ??, 16 ???. 2020 ?. ? 09:27, Leming Van <ifanliming at outlook.com<mailto:ifanliming at outlook.com>>:
> Hi, Matt
>
> Thank you for your advice. I'm sorry that I didn't provide enough information.
>
> I downloaded the ERA5 dataset at https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form
> Copernicus Climate Data Store | Copernicus Climate Data Store<https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form>
> CDS Menu. Home; Search; Datasets; Applications; Toolbox; FAQ; Live; Copernicus Climate Data Store
> cds.climate.copernicus.eu<http://cds.climate.copernicus.eu>
>
> And I selected precip[mean_total_precipitation_rate. kg m-2 s-1], atemp[2m_temperature. K], swdown[mean_surface_downward_short_wave_radiation_flux. W m-2], lwdown[mean_surface_downward_long_wave_radiation_flux. W m-2], uwind[10m_u_component_of_wind. m s-1], vwind[10m_v_component_of_wind. m s-1], because ERA5 does not provide aqh directly, I used air pressure[surface_pressure Pa] and dewpoint temperature[2m_dewpoint_temperature K] to calculate aqh.
>
> Since the data is hourly, I only downloaded the area of interest(bigger than South China Sea), and besides, the data is zonally aligned from 35N to 5S, I flipped it to 5S-35N.
>
> I compared the ERA5 with NCEP, and I don't think there is much difference except for the short-wave radiation. Please check the attachment.
>
> I only have one question, do you choose the same ERA5 variables like me? If not, could you tell me which variables you choose?
>
> Please let me know if any other files are needed for diagnosis. Thanks in advance.
>
>
> -Mike
>
>
> Here is the setting of my data.exf
>
> # $Header: /u/gcmpack/MITgcm_contrib/eh3/llc/ecco-godae/input_50lev/data.exf,v 1.1 2007/03/06 19:13:51 heimbach Exp $
> #
> # *********************
> # External Forcing Data
> # *********************
> &EXF_NML_01
> useAtmWind = .TRUE.,
> # rotateStressOnAgrid = .TRUE.,
> exf_iprec = 32,
> exf_yftype = 'RL',
> useExfYearlyFields = .false.,
> twoDigitYear = .false.,
> useExfCheckRange =.false.,
> &
>
> &EXF_NML_02
> climsstfile = 'woa13_sst_monthly_globe_relax.box',
> climsssfile = 'woa13_sss_monthly_globe_relax.box',
> precipfile = 'era5_prate_2002-2005_hourly.box',
> atempfile = 'era5_air_2002-2005_hourly.box',
> aqhfile = 'era5_shum_2002-2005_hourly.box',
> swdownfile = '',
> swfluxfile = 'era5_nswrs_2002-2005_hourly.box',
> lwfluxfile = '',
> lwdownfile = 'era5_dlwrf_2002-2005_hourly.box',
> uwindfile = 'era5_uwnd_2002-2005_hourly.box',
> vwindfile = 'era5_vwnd_2002-2005_hourly.box',
> runofffile = 'run-off.bin_1x1',
> #
> climsststartdate1 = 20020101,
> climsststartdate2 = 000000,
> climsstperiod = -12,
> climsssstartdate1 = 20020101,
> climsssstartdate2 = 000000,
> climsssperiod = -12,
> runoffstartdate1 = 20020101,
> runoffstartdate2 = 000000,
> runoffperiod = -12,
> #
> precipstartdate1=20020101,
> precipstartdate2=000000,
> precipperiod=3600.0,
> atempstartdate1=20020101,
> atempstartdate2=000000,
> atempperiod=3600.0,
> aqhstartdate1=20020101,
> aqhstartdate2=000000,
> aqhperiod=3600.0,
> swdownstartdate1=20020101,
> swdownstartdate2=000000,
> swdownperiod=3600.0,
> lwfluxstartdate1=20020101,
> lwfluxstartdate2=000000,
> lwfluxperiod=3600.0,
> swfluxstartdate1=20020101,
> swfluxstartdate2=000000,
> swfluxperiod=3600.0,
> lwdownstartdate1=20020101,
> lwdownstartdate2=000000,
> lwdownperiod=3600.0,
> uwindstartdate1=20020101,
> uwindstartdate2=000000,
> uwindperiod=3600.0,
> vwindstartdate1=20020101,
> vwindstartdate2=000000,
> vwindperiod=3600.0,
> hfluxstartdate1=20020101,
> hfluxstartdate2=000000,
> hfluxperiod=3600.0,
> sfluxstartdate1=20020101,
> sfluxstartdate2=000000,
> sfluxperiod=3600.0,
> ustressstartdate1=20020101,
> ustressstartdate2=000000,
> ustressperiod=3600.0,
> vstressstartdate1=20020101,
> vstressstartdate2=000000,
> vstressperiod=3600.0,
> &
>
> &EXF_NML_03
> exf_inscal_precip=1.,
> exf_offset_atemp=0.0,
> exf_inscal_runoff = 3.1710e-08,
> &
>
> &EXF_NML_04
> precip_lon0 = 95.0D0,
> precip_lon_inc = 0.25D0,
> precip_lat0 = -5.0D0,
> precip_lat_inc = 160*0.25D0,
> precip_nlon = 160,
> precip_nlat = 160,
> #
> atemp_lon0 = 95.0D0,
> atemp_lon_inc = 0.25D0,
> atemp_lat0 = -5.0D0,
> atemp_lat_inc = 160*0.25D0,
> atemp_nlon = 160,
> atemp_nlat = 160,
> #
> aqh_lon0 = 95.0D0,
> aqh_lon_inc = 0.25D0,
> aqh_lat0 = -5.0D0,
> aqh_lat_inc = 160*0.25D0,
> aqh_nlon = 160,
> aqh_nlat = 160,
> #
> swdown_lon0 = 95.0D0,
> swdown_lon_inc = 0.25D0,
> swdown_lat0 = -5.0D0,
> swdown_lat_inc = 160*0.25D0,
> swdown_nlon = 160,
> swdown_nlat = 160,
> #
> lwflux_lon0 = 95.0D0,
> lwflux_lon_inc = 0.25D0,
> lwflux_lat0 = -5.0D0,
> lwflux_lat_inc = 160*0.25D0,
> lwflux_nlon = 160,
> lwflux_nlat = 160,
> #
> swflux_lon0 = 95.0D0,
> swflux_lon_inc = 0.25D0,
> swflux_lat0 = -5.0D0,
> swflux_lat_inc = 160*0.25D0,
> swflux_nlon = 160,
> swflux_nlat = 160,
> #
> lwdown_lon0 = 95.0D0,
> lwdown_lon_inc = 0.25D0,
> lwdown_lat0 = -5.0D0,
> lwdown_lat_inc = 160*0.25D0,
> lwdown_nlon = 160,
> lwdown_nlat = 160,
> #
> uwind_lon0 = 95.0D0,
> uwind_lon_inc = 0.25D0,
> uwind_lat0 = -5.0D0,
> uwind_lat_inc = 160*0.25D0,
> uwind_nlon = 160,
> uwind_nlat = 160,
> #
> vwind_lon0 = 95.0D0,
> vwind_lon_inc = 0.25D0,
> vwind_lat0 = -5.0D0,
> vwind_lat_inc = 160*0.25D0,
> vwind_nlon = 160,
> vwind_nlat = 160,
> #
> ustress_lon0 = 95.0D0,
> ustress_lon_inc = 0.25D0,
> ustress_lat0 = -5.0D0,
> ustress_lat_inc = 160*0.25D0,
> ustress_nlon = 160,
> ustress_nlat = 160,
> #
> vstress_lon0 = 95.0D0,
> vstress_lon_inc = 0.25D0,
> vstress_lat0 = -5.0D0,
> vstress_lat_inc = 160*0.25D0,
> vstress_nlon = 160,
> vstress_nlat = 160,
> #
> hflux_lon0 = 95.0D0,
> hflux_lon_inc = 0.25D0,
> hflux_lat0 = -5.0D0,
> hflux_lat_inc = 160*0.25D0,
> hflux_nlon = 160,
> hflux_nlat = 160,
> #
> sflux_lon0 = 95.0D0,
> sflux_lon_inc = 0.25D0,
> sflux_lat0 = -5.0D0,
> sflux_lat_inc = 160*0.25D0,
> sflux_nlon = 160,
> sflux_nlat = 160,
> #
> runoff_lon0 = 0.50D0,
> runoff_lon_inc = 1.0D0,
> runoff_lat0 = -79.5D0,
> runoff_lat_inc = 159*1.0D0,
> runoff_nlon = 360,
> runoff_nlat = 160,
> #
> climsst_lon0 = -179.875D0,
> climsst_lon_inc = 0.25D0,
> climsst_lat0 = -89.875D0,
> climsst_lat_inc = 719*0.25D0,
> climsst_nlon = 1440,
> climsst_nlat = 720,
> #
> climsss_lon0 = -179.875D0,
> climsss_lon_inc = 0.25D0,
> climsss_lat0 = -89.875D0,
> climsss_lat_inc = 719*0.25D0,
> climsss_nlon = 1440,
> climsss_nlat = 720,
> #
> &
>
> &EXF_NML_OBCS
> obcsNstartdate1 = 20020101,
> obcsNstartdate2 = 000000,
> obcsNperiod = 2628000.0,
> obcsEstartdate1 = 20020101,
> obcsEstartdate2 = 000000,
> obcsEperiod = 2628000.0,
> obcsSstartdate1 = 20020101,
> obcsSstartdate2 = 000000,
> obcsSperiod = 2628000.,
> &
>
> ________________________________
> ???: MITgcm-support <mitgcm-support-bounces at mitgcm.org<mailto:mitgcm-support-bounces at mitgcm.org>> ?? Matthew Mazloff <mmazloff at ucsd.edu<mailto:mmazloff at ucsd.edu>>
> ????: 2020?3?16? 0:44
> ???: mitgcm-support at mitgcm.org<mailto:mitgcm-support at mitgcm.org> <mitgcm-support at mitgcm.org<mailto:mitgcm-support at mitgcm.org>>
> ??: Re: [MITgcm-support] ??: The obvious difference between ERA5 and NCEP-R1 forcing
>
> Hi Mike
>
> It is possible it could give worse results, but very unlikely. However its too hard for me to diagnose what is going on. There are many variables to your problem.
>
> For ERA5 I have this in my data.exf:
> &EXF_NML_03
> exf_offset_atemp = 273.15,
> exf_inscal_swdown = -1.0,
> exf_inscal_lwdown = -1.0,
>
> Not sure how to help you,
> Matt
>
>
>
> On Mar 15, 2020, at 5:41 AM, Leming Van <ifanliming at outlook.com<mailto:ifanliming at outlook.com>> wrote:
>
> Hi, everyone
>
> Recently I tried to change forcing dataset from NCEP-R1(6-hourly) to ERA5(hourly), but the results of them look so different. I compared the results of NCEP-R1 with the reanalysis data of HYCOM, and these two data look similar.
>
> Did I pick the wrong variables from ERA5? Or does this mean that higher temporal and spatial resolution atmospheric forcing ERA5 results in worse simulation results than lower resolution NCEP-R1?
>
> I put the results at here, https://1drv.ms/u/s!AoS5GLJhmvDtjB5Ovnz63FidKeMo?e=c2hS7z
> Suggestions are welcome.
>
>
> -Mike
>
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