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

Stanislav Martyanov martyanov.sd at gmail.com
Mon Mar 16 04:48:30 EDT 2020


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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