Changes between Version 117 and Version 118 of DevelopmentActivities/ORCHIDEE-DOFOCO


Ignore:
Timestamp:
2017-06-20T13:06:54+02:00 (8 years ago)
Author:
luyssaert
Comment:

--

Legend:

Unmodified
Added
Removed
Modified

  • DevelopmentActivities/ORCHIDEE-DOFOCO

    v117 v118  
    2727=== Age classes === 
    2828=== Diameter classes === 
    29 Diameter classes were introduced to better simulate the canopy structure. Given that the canopy is the interface between the land and the atmosphere this feature has effects well beyond forest management. Stand structure affects albedo, transpiration, photosynthesis, soil temperature, roughness length, and recruitment. The computational cost of using diameter classes is negligible and when a reasonable low number of diameter classes is used, the memory cost is also very small. The number of diameter classes is the same for all PFTs and is set by the parameter NCIRC. ORCHIDEE-CN, ORCHIDEE-CNP, and ORCHIDEE-MICT are all coded and used for NCIRC = 1. ORCHIDEE-DOFOCO and ORCHIDEE-CN-CAN are coded and tested for NCIRC = 3. 
     29Diameter classes were introduced to better simulate the canopy structure. Given that the canopy is the interface between the land and the atmosphere this feature has effects well beyond forest management. Stand structure was observed to affect albedo, transpiration, photosynthesis, soil temperature, roughness length, and recruitment.  
    3030 
    31 Given earlier choices in ORCHIDEE, we either need to define the boundaries of each diameter class or the diameter distribution. While developing the code, we considered the second approach the most flexible. To allow maximal flexibility, each diameter class needs to be defined separately. From literature it is known that a truncated exponential distribution is a good first guess:  
    32 CIRC_CLASS_DIST__00001=9 
    33 CIRC_CLASS_DIST__00002=3 
    34 CIRC_CLASS_DIST__00003=1  
     31The computational cost of using diameter classes is negligible and when a reasonable low number of diameter classes is used, the memory cost remains very small as the dimensions of only two variables are increased. The number of diameter classes is the same for all PFTs and is set by the parameter '''NCIRC'''. ORCHIDEE-CN, ORCHIDEE-CNP, and ORCHIDEE-MICT are all coded and used for NCIRC = 1. ORCHIDEE-DOFOCO and ORCHIDEE-CN-CAN are coded and tested for NCIRC = 3. Until further testing, three diameter classes are considered sufficient. 
    3532 
    36 The above declaration implies that 9/13th of the trees will always be in the smallest diameter class, 3/13th will be in the medium class and 1 tree out of 13 will be in the largest diameter class. These ratios are kept throughout the simulations and boundaries of the diameter classes are adjusted to respect this constraint. Consequently, an even-aged stand will be simulated with 3 diameter classes where the diameter of the first class may be, for example, 20.3 cm, the diameter of the second class 20.4 cm and the diameter of the third class 20.5 cm. The same code and set-up allows to simulate, in the same simulation, an uneven-aged stand for the same PFT but in a different pixel with, for example, the smallest diameter 7 cm, the medium diameter 25 cm and the largest diameter 45 cm. 
    37   
     33Given earlier choices in ORCHIDEE, we either need to define the boundaries of each diameter class or the diameter distribution. While developing the code, we considered the second approach the most flexible. To allow maximal flexibility, each diameter class needs to be defined separately by the variable '''CIRC_CLASS_DIST_0000X''', where X is the number of the diameter class. The smallest number presents the smallest diameter class. From literature it is known that a truncated exponential distribution is a good first guess:  
     34CIRC_CLASS_DIST_00001=9 
     35CIRC_CLASS_DIST_00002=3 
     36CIRC_CLASS_DIST_00003=1  
    3837 
    39  
    40  
    41  
     38The above declaration implies that 9/13th of the trees will always be in the smallest diameter class, 3/13th will be in the medium class and 1 tree out of 13 will be in the largest diameter class. These ratios are kept throughout the simulations and the boundaries of the diameter classes are adjusted to respect this constraint. Consequently, an even-aged stand will be simulated with three diameter classes where the diameter of the first class may be, for example, 20.3 cm, the diameter of the second class 20.4 cm and the diameter of the third class 20.5 cm. The same code and set-up allows to simulate, in the same simulation, an uneven-aged stand for the same PFT but in a different pixel with, for example, the smallest diameter 7 cm, the medium diameter 25 cm and the largest diameter 45 cm.  
    4239 
    4340=== CWRR vs Choinell ===