Boreal Ecosystem Productivity Simulator in Julia

Dongdong Kong

BEPS.jl is alive in Julia now. All functions have been ported to Julia, and the performance is about 2.5 times faster than C version.

• Julia: 0.286327 seconds (822.38 k allocations: 22.998 MiB, 0.85% gc time)
• C : 0.787059 seconds (629.95 k allocations: 13.915 MiB)

• For developers

  git clone https://github.com/jl-pkgs/BEPS.jl
  cd BEPS.jl/deps
  git clone https://github.com/jl-pkgs/BEPS.c

• For users

  # In Julia
  ] add https://github.com/jl-pkgs/BEPS.jl

using BEPS
d = deserialize("data/p1_meteo")
lai = readdlm("examples/input/p1_lai.txt")[:]

par = (lon=120.5, lat=30.5, landcover=25, clumping=0.85,
  soil_type=8, Tsoil=2.2,
  soilwater=0.4115, snowdepth=0.0)

@time df_jl, df_ET_jl, Tg = besp_main(d, lai, par; version="julia");

Figure1: The bias of Julia version compared with C, bias = (Julia - C)/ C.

The bias of SH is the largest due to double number accuracy, about 1.48%, which is acceptable.

Figure2: The variation of soil temperature at different depths.

See examples/example_01.qmd for details.

• 通量站上测试模型表现 (top1 task)
• 热浪期间，土壤温度的表现
• 土壤类型参数
• clumping index数据处理

• LAMBDA function in the photosynthesis module, the unit of lambda_ice is error, 333 J/kg should be 333000 J/kg.

• snowpack_stage1:

  • snowrate_o未被初始化，导致snowrate_o > 0为true.
  • 雪深最大设置为10m，防止不合理的不断累积：*depth_snow=min(*mass_snow_g/(*density_snow), 10.0);

• snowpack_stage3: max(mass_water_frozen,*depth_water*density_water), max should be min

• snowpack: 积雪夏季不融化，z_snow不断增加，一直到无穷

  • snowpack_stage3_jl融雪和结冻条件的改正：

  # con_melt = Tsnow > 0 && Tsnow_last <= 0 && ms_sup > 0
  # con_frozen = Tsnow <= 0 && Tsnow_last > 0 && z_water > 0
  con_melt = Tsnow > 0 && ms_sup > 0
  con_frozen = Tsnow <= 0 && z_water > 0

  • ρ_snow: 初始值设置为250 [kg m-3]，避免在0处跳动。
  • z_snow: 积雪深度，最大限制在10m
  • ρ_snow: 传入状态变量state，前后沿用

  修复前的结果

  修复后的结果

  详细代码见：Figure3_snowpack_diagnose.jl

• 植被光合中的叶片温度 传入参数有误，待修正

• surface_temperature_jl中T_weighted求解公式错误，分子第二项漏写了z_snow，推导过程见：<docs/modules/TS_Case02.md>。
• surface_temperature_jl中case02 G_soil

  G_soil = G_snow * (T_soil_surf - T_soil1_last) / z_soil1   # wrong
  G_soil = κ_soil1 * (T_soil_surf - T_soil1_last) / Δz_soil1 # correct

1. Hourly BEPS model. https://github.com/JChen-UToronto/BEPS_hourly_site

2. Daily BEPS model developed by Jane Liu. https://github.com/JChen-UToronto/BEPS_D

3. 统一C与Julia接口，https://github.com/CUG-hydro/BEPS.c