[MITgcm-support] 回复: 转发: The obvious difference between ERA5 and NCEP-R1 forcing

Raphael Dussin raphael.dussin at gmail.com
Mon Mar 16 08:24:58 EDT 2020


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 à 04:49, Stanislav Martyanov <martyanov.sd at gmail.com>
a écrit :

> 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
>
>
> пн, 16 мар. 2020 г. в 09:27, Leming Van <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
>>
>> 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.,
>>  &
>>
>> ------------------------------
>> *发件人:* MITgcm-support <mitgcm-support-bounces at mitgcm.org> 代表 Matthew
>> Mazloff <mmazloff at ucsd.edu>
>> *发送时间:* 2020年3月16日 0:44
>> *收件人:* mitgcm-support at mitgcm.org <mitgcm-support at mitgcm.org>
>> *主题:* Re: [MITgcm-support] 转发: 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> 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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