| 1 | code_original - Sean's code and sample output - 23/03/07
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| 2 |
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| 3 | ancil - N96 HadGEM1 orography field - retrieved from NEC - 23/03/07
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| 4 |
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| 5 | Missing data - REAL, PARAMETER :: RMDI = -9999.0 - 23/03/07
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| 6 |
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| 7 | ------------------------------------------------------------------------
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| 8 |
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| 9 | Running the code - email from Sean, 23/03/07
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| 10 | ------------------------------------------------------------------------
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| 11 |
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| 12 | Ok, 3 files
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| 13 |
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| 14 | refrac_info.f90
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| 15 |
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| 16 | is just a module containing various definitions.
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| 17 |
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| 18 | gpsro_driver.f90
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| 19 |
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| 20 | is an example of a call to the 1d operator. I have
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| 21 | set the atmospheric parameters up in a simple way, so that it
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| 22 | should be pretty obvious what you have to extract from the UM
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| 23 | model output. Basically, you need the P, T, Q on the (full) model
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| 24 | levels, and the full model level heights.
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| 25 |
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| 26 | gpsro_op.f90
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| 27 |
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| 28 | is the 1d bending angle operator. It is self contained,
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| 29 | so hopefully you should not have to go into it, assuming everything
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| 30 | works!
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| 31 |
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| 32 |
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| 33 | To compile and run
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| 34 |
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| 35 | f90 -c refrac_info.f90
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| 36 |
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| 37 | this should create refrac_info.mod. Then type
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| 38 |
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| 39 | f90 gpsro_driver.f90 gpsro_op.f90 -o gpsro_op
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| 40 |
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| 41 | Then
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| 42 |
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| 43 | gpsro_op
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| 44 |
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| 45 | This will write a profile of bending angles to screen. My results are
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| 46 | given in alpha.out, so you can check its running ok.
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| 47 | -----------------------------------------------------------------------
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| 48 |
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| 49 | UM height levels - from http://www-nwp.metoffice.com/~frcw/UM_Info/ND_levels/ND_levels.html - 16/04/07
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| 50 | -----------------------------------------------------------------------------------------------------------
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| 51 | Blev (=pphead(52) ) contains Zsea , the height of the level over the sea,
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| 52 | bhlev (=pphead(54)) contains C(k) = [ 1 - eta_value(k) / eta_value(first constant rho level) ] ^2,
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| 53 |
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| 54 | so that the height for the level is Z(i,j)= Zsea+ C(k) * orography(i,j) at each point (i,j) in the grid.
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| 55 |
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| 56 | ------------------------------------------------------------------------------------------------------------
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| 57 |
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| 58 | Tangent linear code - 03/07/07
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| 59 | --------------------------------------------------------------------------
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| 60 |
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| 61 |
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| 62 | I have attached the tangent linear code with a driver routine.
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| 63 | To compile and run the driver
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| 64 |
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| 65 | f90 gpsro_drivertl.f90 gpsro_opTL.f90 gpsro_op.f90 -o gpsro_optl
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| 66 |
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| 67 | You always need to compile gpsro_opTL.f90 with gpsro_op.f90 because they
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| 68 | share routines. The interface to the new code is
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| 69 |
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| 70 | SUBROUTINE alpha_optl(nlev, & ! no. of model levs (=38)
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| 71 | nobs, & ! no. of bending angles in profile
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| 72 | roc, & ! radius of curv.
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| 73 | undul, & ! undulation (set to 0.0)
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| 74 | lat, & ! latitude of ob. location (degrees)
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| 75 | pres, & ! pressure on mod levels (hPa)
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| 76 | pres_prime, &
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| 77 | temp, & ! temp on model levels
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| 78 | temp_prime, &
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| 79 | q, & ! specific humidity (g/kg)
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| 80 | q_prime, &
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| 81 | zg, & ! geopotential height of model levels(m)
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| 82 | a, & ! impact parameters
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| 83 | alpha, &
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| 84 | alpha_prime) ! bending angles
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| 85 |
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| 86 | Basically, when you see a "_prime" that means a perturbation. The code
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| 87 | calculates the bending angles (alpha) as before with P,T and Q, but now
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| 88 | also calculates the bending angle perturbations, alpha_prime, caused by
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| 89 | the P, T and Q perturbations, p_prime, t_prime and q_prime, respectively.
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| 90 |
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| 91 | The driver code calculates alpha_prime along with the differences
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| 92 | between 2 calls to the normal operator for a simple profile. The results
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| 93 | are very close.
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| 94 |
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| 95 | The tangent linear code will enable you to look at the relative
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| 96 | contributions of the p_prime, t_prime and q_prime to the alpha_prime.
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| 97 |
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| 98 |
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| 99 | ------------------------------------------------------------------------------------------------------------
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| 100 |
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| 101 | Further calculations - 15/02/08
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| 102 | --------------------------------------------------------------------------
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| 103 |
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| 104 | 1) set q to 0.0 just before refrac_levs is called and
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| 105 | look at the bending angle trends.
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| 106 |
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| 107 | 2) set q to 2000 value just before refrac_levs and
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| 108 | look at trends etc.
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| 109 |
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| 110 | 3) Look at refractivity trend on model levels. One
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| 111 | of the outputs from refrac_levs is refrac. This is
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| 112 | the refractivity on the model levels. (you could
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| 113 | also look at the q = 0 for refrac if you get time.)
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| 114 |
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| 115 | 4) Compare the Tdry and T trends on model levels.
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| 116 | You can calculate Tdry after calling refrac_levs
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| 117 |
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| 118 | Tdry(:) =aval*pres(:)/refrac(:)
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| 119 |
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| 120 | where aval is the refractivity constant defined in
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| 121 | refrac_info.
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| 122 |
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| 123 | Look at error (Tdry(:)-temp(:)) and trend differences.
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| 124 |
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| 125 |
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| 126 |
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| 127 |
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| 128 |
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| 129 |
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| 130 |
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| 131 |
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| 132 |
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| 133 |
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| 134 |
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| 135 |
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| 136 |
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