Temperature 2m ​​above the ground too cold

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Gippox
Posts: 65
Joined: Sat Mar 02, 2013 1:16 am

Temperature 2m ​​above the ground too cold

Post by Gippox » Tue Dec 24, 2013 4:53 pm

Hello all,
i continue to have problems with the temperatures at 2m above the ground, especially at night, that is too cold to 3-4 degrees. Temperatures above the sea seem correct.
I use arw core initialized by wrfda.
This is my namelist:

Code: Select all

&time_control
 start_year                 = 2013, 2013
 start_month                = 12, 12
 start_day                  = 24, 24
 start_hour                 = 06, 06
 start_minute               = 00, 00
 start_second               = 00, 00
 end_year                   = 2013, 2013
 end_month                  = 12, 12
 end_day                    = 28, 26
 end_hour                   = 06, 06
 end_minute                 = 00, 00
 end_second                 = 00, 00
 interval_seconds           = 10800
 input_from_file            = T, T
 history_interval           = 180, 60
 history_outname            = "wrfout_d<domain>_<date>"
 frames_per_outfile         = 1, 1
 io_form_history            = 2
 io_form_input              = 2
 io_form_restart            = 2
 io_form_boundary           = 2
 io_form_auxinput2          = 2
 restart                    = F
 restart_interval           = 11520
 auxhist1_outname           = "auxhist1_d<domain>_<date>"
 auxhist1_interval          = 0, 0
 frames_per_auxhist1        = 1, 1
 io_form_auxhist1           = 2
 auxhist2_outname           = "auxhist2_d<domain>_<date>"
 auxhist2_interval          = 0, 0
 output_diagnostics         = 0
 auxhist3_outname           = "wrfxtrm_d<domain>_<date>"
 auxhist3_interval          = 0, 0
 frames_per_auxhist2        = 1, 1
 io_form_auxhist2           = 2
 auxinput4_inname           = "wrflowinp_d<domain>"
 auxinput4_interval         = 360, 360
 io_form_auxinput4          = 2
 fine_input_stream          = 0, 2
 adjust_output_times        = T
 reset_simulation_start     = F
 cycling                    = F
 diag_print                 = 0
 debug_level                = 0
 write_input                = .true.
 inputout_interval          = 360, 360
 inputout_begin_h           = 6, 6
 inputout_end_h             = 6, 6
 input_outname              = "wrfout_d<domain>_3dvar"
/

&domains
 time_step                  = 30
 time_step_fract_num        = 0
 time_step_fract_den        = 10
 time_step_dfi              = 60
 max_dom                    = 2
 s_we                       = 1, 1
 e_we                       = 170, 190
 s_sn                       = 1, 1
 e_sn                       = 170, 184
 s_vert                     = 1, 1
 e_vert                     = 50, 50
 dx                         = 12000.0000, 4000.0000
 dy                         = 12000.0000, 4000.0000
 grid_id                    = 1, 2
 parent_id                  = 1, 1
 i_parent_start             = 1, 54
 j_parent_start             = 1, 53
 parent_grid_ratio          = 1, 3
 parent_time_step_ratio     = 1, 3
 feedback                   = 0
 smooth_option              = 0
 grid_allowed               = T, T
 max_dz                     = 1000.
 numtiles                   = 4
 nproc_x                    = 1
 nproc_y                    = 4
 num_metgrid_soil_levels    = 4
 num_metgrid_levels         = 48
 interp_type                = 2
 extrap_type                = 2
 t_extrap_type              = 2
 use_levels_below_ground    = T
 use_surface                = T
 lagrange_order             = 1
 zap_close_levels           = 500
 lowest_lev_from_sfc        = F
 force_sfc_in_vinterp       = 1
 sfcp_to_sfcp               = F
 smooth_cg_topo             = F
 use_tavg_for_tsk           = F
 aggregate_lu               = F
 rh2qv_wrt_liquid           = T
 rh2qv_method               = 1
 p_top_requested            = 5000
 vert_refine_fact           = 1
 use_adaptive_time_step     = T
 adaptation_domain          = 1
 step_to_output_time        = T
 target_cfl                 = 1.2, 1.2
 target_hcfl                = 0.84, 0.84
 max_step_increase_pct      = 5, 51
 starting_time_step         = 60, 20
 max_time_step              = 180, 60
 min_time_step              = 36, 12
/

&dfi_control
 dfi_opt                    = 0
/

&physics
 mp_physics                 = 14, 16
 cu_physics                 = 1, 0
 cudt                       = 5, 5
 cugd_avedx                 = 1
 shcu_physics               = 0, 0
 sf_sfclay_physics          = 1, 1
 sf_surface_physics         = 2, 2
 num_soil_layers            = 4
 sf_urban_physics           = 0, 0
 num_land_cat               = 24
 num_soil_cat               = 16
 bl_pbl_physics             = 1, 1
 bldt                       = 0, 0
 ra_lw_physics              = 1, 1
 ra_sw_physics              = 2, 2
 radt                       = 12, 12
 mp_zero_out                = 0
 mp_zero_out_thresh         = 1.e-8
 no_mp_heating              = 0
 isfflx                     = 1
 surface_input_source       = 1
 ishallow                   = 0
 kfeta_trigger              = 2
 icloud                     = 0
 slope_rad                  = 0, 0
 topo_shading               = 0, 0
 cu_rad_feedback            = F, F
 gsmdt                      = 0, 0
 omlcall                    = 0
 isftcflx                   = 0
 seaice_threshold           = 271
 fractional_seaice          = 0
 mfshconv                   = 0
 iz0tlnd                    = 0
 ra_call_offset             = -1
 rdmaxalb                   = T
 rdlai2d                    = F
 bucket_mm                  = -1
 bucket_j                   = -1
 tmn_update                 = 0
 sst_skin                   = 1
 mp_tend_lim                = 10.
 prec_acc_dt                = 180, 60
 topo_wind                  = 1, 1
 imomentum                  = 0
 sst_update                 = 0
 do_radar_ref               = 1
 chem_opt                   = 0, 0
 windturbines_spec          = "none"
 td_turbgridid              = -1
/

&noah_mp
/

&dynamics
 non_hydrostatic            = T, T
 gwd_opt                    = 1
 rk_ord                     = 3
 h_mom_adv_order            = 5, 5
 h_sca_adv_order            = 5, 5
 v_mom_adv_order            = 3, 3
 v_sca_adv_order            = 3, 3
 moist_adv_opt              = 1, 1
 moist_adv_dfi_opt          = 0
 scalar_adv_opt             = 1, 1
 momentum_adv_opt           = 1, 1
 chem_adv_opt               = 1, 1
 tke_adv_opt                = 1, 1
 diff_opt                   = 1
 km_opt                     = 4
 km_opt_dfi                 = 1
 w_damping                  = 1
 diff_6th_opt               = 2, 2
 diff_6th_factor            = 0.10, 0.10
 damp_opt                   = 0
 zdamp                      = 5000., 5000.
 dampcoef                   = 0.2, 0.2
 khdif                      = 0, 0
 kvdif                      = 0, 0
 time_step_sound            = 8, 8
 do_avgflx_em               = 0, 0
 do_avgflx_cugd             = 0, 0
 smdiv                      = 0.1, 0.1
 emdiv                      = 0.01, 0.01
 epssm                      = 0.1, 0.1
 top_lid                    = F, F
 mix_isotropic              = 0, 0
 mix_upper_bound            = 0.1, 0.1
 rotated_pole               = F
 tke_upper_bound            = 1000., 1000.
 sfs_opt                    = 0, 0
 m_opt                      = 0, 0
 iso_temp                   = 0.
 tracer_opt                 = 0, 0
 tracer_adv_opt             = 0, 0
/

&scm
 scm_force                  = 0
 scm_force_dx               = 4000.
 num_force_layers           = 8
 scm_lu_index               = 2
 scm_isltyp                 = 4
 scm_vegfra                 = 0.5
 scm_canwat                 = 0.0
 scm_lat                    = 37.600
 scm_lon                    = -96.700
 scm_th_adv                 = .true.
 scm_wind_adv               = .true.
 scm_qv_adv                 = .true.
 scm_vert_adv               = .true.
/

&fdda
 grid_fdda                  = 0
/

&tc
 insert_bogus_storm         = F
 remove_storm               = F
 num_storm                  = 1
 latc_loc                   = -999.
 lonc_loc                   = -999.
 vmax_meters_per_second     = -999.
 rmax                       = -999.
 vmax_ratio                 = -999.
/

&fire
/

&bdy_control
 spec_bdy_width             = 5
 spec_zone                  = 1
 relax_zone                 = 4
 spec_exp                   = 0
 specified                  = T, F
 nested                     = F, T
/

&grib2
/

&namelist_quilt
 nio_tasks_per_group        = 0
 nio_groups                 = 1
/

For example, for this meteogram for Treviso Italy the night temperature is underestimated plenty of four degrees than the real.
Image
Image

If you have any suggestions on what to change I'd be very grateful :)

Thanks


Gippox

meteoadriatic
Posts: 1602
Joined: Wed Aug 19, 2009 10:05 am

Re: Temperature 2m ​​above the ground too cold

Post by meteoadriatic » Tue Dec 24, 2013 6:37 pm

Hello, first try to change long wave radiation scheme. Try (4):
ra_lw_physics = 4, 4

It can be better but also can be even worse.

You can also try recreating domains with modis landuse. And, if you're brave enough you can try to modify emissivity parameters in VEGPARM.TBL file...

Gippox
Posts: 65
Joined: Sat Mar 02, 2013 1:16 am

Re: Temperature 2m ​​above the ground too cold

Post by Gippox » Wed Dec 25, 2013 9:15 am

Hello Meteo thank you :) , i will try for now to change long wave radiation scheme (RRTMG), if with this solution improves the problem.
From what i can understand the problem appears to be due to an excessive nocturnal radiation from the terrain, while the sea does not happen.
I use new data set greenfrac_fpar_modis.
This its my modified GEOGRID.TBL.ARW for GREENFRAC, but i dont think the problem its due to this setting.

Code: Select all

# See options.txt for a (somewhat up to date) list of the 
# options that may be specified here.
===============================
name = HGT_M
        priority = 1
        dest_type = continuous
        df_dx=SLPX
        df_dy=SLPY
        smooth_option = smth-desmth_special; smooth_passes=1
        fill_missing=0.
        interp_option =     30s:average_gcell(4.0)+four_pt+average_4pt
        interp_option =      2m:four_pt
        interp_option =      5m:four_pt
        interp_option =     10m:four_pt
        interp_option = default:four_pt
        rel_path=     30s:topo_30s/
        rel_path=      2m:topo_2m/
        rel_path=      5m:topo_5m/
        rel_path=     10m:topo_10m/
        rel_path= default:topo_2m/
===============================
name=LANDUSEF
        priority=1
        dest_type=categorical
        z_dim_name=land_cat
        landmask_water =   modis_30s:17            # Calculate a landmask from this field
        landmask_water = modis_lakes:17,21         # Calculate a landmask from this field
        landmask_water =  usgs_lakes:16,28         # Calculate a landmask from this field
        landmask_water =    nlcd2006:17            # Calculate a landmask from this field
        landmask_water =     default:16            # Calculate a landmask from this field
        dominant=LU_INDEX
        interp_option =    nlcd2006:nearest_neighbor
        interp_option =    ssib_10m:four_pt
        interp_option =     ssib_5m:four_pt
        interp_option =   modis_30s:nearest_neighbor
        interp_option =         30s:nearest_neighbor
        interp_option =  usgs_lakes:nearest_neighbor
        interp_option = modis_lakes:nearest_neighbor
        interp_option =          2m:four_pt
        interp_option =          5m:four_pt
        interp_option =         10m:four_pt
        interp_option =      default:four_pt
        rel_path=    nlcd2006:nlcd2006_ll_30s/
        rel_path=    ssib_10m:ssib_landuse_10m/
        rel_path=     ssib_5m:ssib_landuse_5m/
        rel_path=   modis_30s:modis_landuse_20class_30s/
        rel_path=         30s:landuse_30s/
        rel_path=  usgs_lakes:landuse_30s_with_lakes/
        rel_path= modis_lakes:modis_landuse_21class_30s/
        rel_path=          2m:landuse_2m/
        rel_path=          5m:landuse_5m/
        rel_path=         10m:landuse_10m/
        rel_path=     default:landuse_2m/
===============================
name=SOILTEMP
        priority=1
        dest_type=continuous
        interp_option=default:sixteen_pt+four_pt+average_4pt+average_16pt+search
        masked=water
        fill_missing=0.
        rel_path=default:soiltemp_1deg/
===============================
name=SOILCTOP
        priority=1
        dest_type=categorical
        z_dim_name=soil_cat
        dominant=SCT_DOM
        interp_option =     30s:nearest_neighbor
        interp_option =      2m:four_pt
        interp_option =      5m:four_pt
        interp_option =     10m:four_pt
        interp_option = default:four_pt
        rel_path=     30s:soiltype_top_30s/
        rel_path=      2m:soiltype_top_2m/
        rel_path=      5m:soiltype_top_5m/
        rel_path=     10m:soiltype_top_10m/
        rel_path= default:soiltype_top_2m/
===============================
name=SOILCBOT
        priority=1
        dest_type=categorical
        z_dim_name=soil_cat
        dominant=SCB_DOM
        interp_option =     30s:nearest_neighbor
        interp_option =      2m:four_pt
        interp_option =      5m:four_pt
        interp_option =     10m:four_pt
        interp_option = default:four_pt
        rel_path=     30s:soiltype_bot_30s/
        rel_path=      2m:soiltype_bot_2m/
        rel_path=      5m:soiltype_bot_5m/
        rel_path=     10m:soiltype_bot_10m/
        rel_path= default:soiltype_bot_2m/
===============================
name=ALBEDO12M
        priority=1
        dest_type=continuous
        z_dim_name=month
        masked = water
        fill_missing = 8.
        interp_option=default:four_pt+average_4pt+average_16pt+search
        rel_path=default:albedo_ncep/
===============================
name=GREENFRAC
        priority=1
        dest_type=continuous
        interp_option=default:four_pt+average_4pt+average_16pt+search
        z_dim_name=month
        masked = water
        fill_missing = 0.
        rel_path=default:greenfrac_fpar_modis/
===============================
name=SNOALB
        priority=1
        dest_type=continuous
        interp_option=default:four_pt+average_4pt+average_16pt+search
        masked = water
        fill_missing = 0.
        rel_path=default:maxsnowalb/
===============================
name=SLOPECAT
        priority=1
        dominant_only=SLOPECAT
        dest_type=categorical
        z_dim_name=slope_cat
        masked = water
        fill_missing = 0.
        interp_option=default:nearest_neighbor+average_16pt+search
        rel_path=default:islope/
===============================
name = CON
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/con/
        rel_path = 10m:orogwd_10m/con/
        rel_path = 20m:orogwd_20m/con/
        rel_path = 30m:orogwd_30m/con/
        rel_path = 1deg:orogwd_1deg/con/
        rel_path = 2deg:orogwd_2deg/con/
===============================
name = VAR
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/var/
        rel_path = 10m:orogwd_10m/var/
        rel_path = 20m:orogwd_20m/var/
        rel_path = 30m:orogwd_30m/var/
        rel_path = 1deg:orogwd_1deg/var/
        rel_path = 2deg:orogwd_2deg/var/
===============================
name = OA1
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/oa1/
        rel_path = 10m:orogwd_10m/oa1/
        rel_path = 20m:orogwd_20m/oa1/
        rel_path = 30m:orogwd_30m/oa1/
        rel_path = 1deg:orogwd_1deg/oa1/
        rel_path = 2deg:orogwd_2deg/oa1/
===============================
name = OA2
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/oa2/
        rel_path = 10m:orogwd_10m/oa2/
        rel_path = 20m:orogwd_20m/oa2/
        rel_path = 30m:orogwd_30m/oa2/
        rel_path = 1deg:orogwd_1deg/oa2/
        rel_path = 2deg:orogwd_2deg/oa2/
===============================
name = OA3
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/oa3/
        rel_path = 10m:orogwd_10m/oa3/
        rel_path = 20m:orogwd_20m/oa3/
        rel_path = 30m:orogwd_30m/oa3/
        rel_path = 1deg:orogwd_1deg/oa3/
        rel_path = 2deg:orogwd_2deg/oa3/
===============================
name = OA4
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/oa4/
        rel_path = 10m:orogwd_10m/oa4/
        rel_path = 20m:orogwd_20m/oa4/
        rel_path = 30m:orogwd_30m/oa4/
        rel_path = 1deg:orogwd_1deg/oa4/
        rel_path = 2deg:orogwd_2deg/oa4/
===============================
name = OL1
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/ol1/
        rel_path = 10m:orogwd_10m/ol1/
        rel_path = 20m:orogwd_20m/ol1/
        rel_path = 30m:orogwd_30m/ol1/
        rel_path = 1deg:orogwd_1deg/ol1/
        rel_path = 2deg:orogwd_2deg/ol1/
===============================
name = OL2
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/ol2/
        rel_path = 10m:orogwd_10m/ol2/
        rel_path = 20m:orogwd_20m/ol2/
        rel_path = 30m:orogwd_30m/ol2/
        rel_path = 1deg:orogwd_1deg/ol2/
        rel_path = 2deg:orogwd_2deg/ol2/
===============================
name = OL3
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/ol3/
        rel_path = 10m:orogwd_10m/ol3/
        rel_path = 20m:orogwd_20m/ol3/
        rel_path = 30m:orogwd_30m/ol3/
        rel_path = 1deg:orogwd_1deg/ol3/
        rel_path = 2deg:orogwd_2deg/ol3/
===============================
name = OL4
        priority = 1
        dest_type = continuous
        masked=water
        fill_missing=0.
        interp_option = default:average_4pt
        interp_option = 10m:average_4pt
        interp_option = 20m:average_4pt
        interp_option = 30m:average_4pt
        interp_option = 1deg:average_4pt
        interp_option = 2deg:average_4pt
        rel_path = default:orogwd_10m/ol4/
        rel_path = 10m:orogwd_10m/ol4/
        rel_path = 20m:orogwd_20m/ol4/
        rel_path = 30m:orogwd_30m/ol4/
        rel_path = 1deg:orogwd_1deg/ol4/
        rel_path = 2deg:orogwd_2deg/ol4/
===============================
name = VAR_SSO 
        priority = 1
        dest_type = continuous
        fill_missing=0.
        interp_option =   default:average_gcell(4.0)+four_pt+average_4pt
        rel_path =        default:varsso/
===============================
#name=URB_PARAM
#        priority=1
#        dest_type=continuous
#        fill_missing = 0.
#        z_dim_name=num_urb_params
#        interp_option=default:nearest_neighbor
#        rel_path=default:NUDAPT44_1km/
#===============================


Gippox

meteoadriatic
Posts: 1602
Joined: Wed Aug 19, 2009 10:05 am

Re: Temperature 2m ​​above the ground too cold

Post by meteoadriatic » Wed Dec 25, 2013 9:36 am

No, that's ok.

Go into VEGPARM.TBL file and lower down emissivity values. This will keep some more heat in noah surface scheme and ground temperatures will remain higher, which will also increase night temperatures near ground (t2 should also be affected). I found that in some combinations when I modified those, model simply crashes. No idea why.

Antonix
Posts: 260
Joined: Fri Oct 16, 2009 8:53 am

Re: Temperature 2m ​​above the ground too cold

Post by Antonix » Wed Dec 25, 2013 5:33 pm

Hi Gippox
You use 3dvar in EMS.
've seen great improvements?
you think it's helpful?
is very complex to run!?
what data do you use??

try changing the patterns of short-wave radiation. Often combine great gui in the Po valley.
fr example i work well with 05-05

Gippox
Posts: 65
Joined: Sat Mar 02, 2013 1:16 am

Re: Temperature 2m ​​above the ground too cold

Post by Gippox » Fri Dec 27, 2013 3:43 pm

Antonix wrote:Hi Gippox
You use 3dvar in EMS.
've seen great improvements?
you think it's helpful?
is very complex to run!?
what data do you use??

try changing the patterns of short-wave radiation. Often combine great gui in the Po valley.
fr example i work well with 05-05
Hi Antonix, yes i use WRFDA with 3DVar technique in cycle mode.
I use most of the available data, such as NCEP BUFR conventional data (SYNOP, METAR, BUOY, SOUND, SHIPS etc.) GPSRO (GPS Radar Occultation) and satellite radiance data (NOAA, METOP, EOS, Suomi NPP)
The assimilation of meteorological data is very interesting, for example, i am trying to assimilate the Suomi NPP satellite radiance data, that are not yet officially implemented in WRFDA, to improve forecast.
I'm already able to assimilate the data of private networks, but when i get a bit 'of time i would like to merge them with data from official stations (via NCEP BUFR) to have an initial situation as complete as possible.
And the step after that will implement the 4DVar :lol:

Make it all work is not difficult, but you have to write code to automate various functions. I used shell scripting for example, but you can also use the Perl if you like this language.
I have seen improvements between 6-12 hours (precipitation, wind), because the model has a very short time to spin up, but also at a distance of 24 - 48 hours the differences are sensitive respect to the model initialized only with GFS data.
The variables are many and from this point of view i would need to confront someone, to exchange their experiences , but yet there is not still very much around.

Thanks for your suggestion , i will try the changes you suggested , in fact, the Po Valley interests me because I live there :D
Already with the modification that advised me Meteoadriatic i saw some improvement, at least in the current weather conditions.
The problem seems occur more during periods of high pressure , with excessive nocturnal radiation , as in days gone, when in fact there was fog formation for most of the day and the temperature remained about 7-8 ° C.

meteoadriatic
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Re: Temperature 2m ​​above the ground too cold

Post by meteoadriatic » Fri Dec 27, 2013 4:31 pm

Gippox wrote:The problem seems occur more during periods of high pressure , with excessive nocturnal radiation , as in days gone, when in fact there was fog formation for most of the day and the temperature remained about 7-8 ° C.
This looks to me like problem with model not seeing enough low level water vapour, thus not creating fog early enough. In that case, latent heating in model will not take place and temperatures will drop much more than should. Do you think this could be the case? Can you also compare 2m dewpoints from model and measured values? If dews in model are significantly lower than measured, and there is fog formation, then this is clearly going on.

Gippox
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Re: Temperature 2m ​​above the ground too cold

Post by Gippox » Mon Dec 30, 2013 8:41 pm

meteoadriatic wrote:
Gippox wrote:The problem seems occur more during periods of high pressure , with excessive nocturnal radiation , as in days gone, when in fact there was fog formation for most of the day and the temperature remained about 7-8 ° C.
This looks to me like problem with model not seeing enough low level water vapour, thus not creating fog early enough. In that case, latent heating in model will not take place and temperatures will drop much more than should. Do you think this could be the case? Can you also compare 2m dewpoints from model and measured values? If dews in model are significantly lower than measured, and there is fog formation, then this is clearly going on.
Initially i also thought that the model do not see the fog formation, however, expected soil moisture was close to 100%, thus i think the formation of fog should be seen from the model.
Currently, the sky is clear enough and the 2m temperature is about 6 degrees, while the model gives 3.5 degrees, while real RH is 80%, predicted 70-80%.
After the daily maximum about 15.00 PM, temperature is lowered too quickly and does not really think we would reach 1-2 degrees tonight as predicted by the model...
There is often a difference of three degrees :!: , i would not be due to assimilation, but it seems strange.

meteoadriatic
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Re: Temperature 2m ​​above the ground too cold

Post by meteoadriatic » Mon Dec 30, 2013 9:07 pm

This is from my operational model on meteoadriatic.net, ARW 4km. Domain is larger than plotted on maps there, so it somewhat covers your area that you put map in first post.

Image

It is forecast for 06z, 31.12.2013. Are these temperatures look better than yours?

Gippox
Posts: 65
Joined: Sat Mar 02, 2013 1:16 am

Re: Temperature 2m ​​above the ground too cold

Post by Gippox » Mon Dec 30, 2013 9:51 pm

This is my plot at the same time.

Image

p.s. : This image is a dynamic link, and changes with the next forecast. It's possible to upload a picture on the forum ?

On central Veneto my predicted temperatures are on average colder 2 ° C than yours, south of the Po river even more 2-3°C. Sea temperatures on the other hand are identical.

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