What's new in 2.3.01

Significant changes in 2.3.01

a) Added blkdat variable oneta0. 1+eta is the scale factor from depth to depth + non-steric_SSH. So 1+eta=0.0 is dry land, which isn't allowed. oneta0 sets a minimum on 1+eta. A typical value is 0.1, and there will be entries in the model .log file if oneta is clipped to oneta0.

b) Added blkdat variable lbmont. When HYCOM is run with sshflg=2 the Montgomery potential is offset so that montg1 in an archive file represents steric SSH. This makes tidal analysis easier since non-steric SSH (including tides) is srfhgt-montg1. The Browning & Kreiss barotropic open boundary reads montg1, and it needs to know if this is the original field or the field corrected via sshflg=2. Hence the new blkdat variable lbmont. This only has an effect when lbflag=2, and in all legacy cases lbmont will be 0 (false).

c) Added lmask_rdnest. Mean archives can contain large layer velocities near the bottom because of a mismatch between the p-grid layer thickness mean projected onto cell faces and u-grid and v-grid layer thickness means. These no longer occur for means calculated by the running model, but old in-line means and off-line means (e.g. monthly or annual) still have this issue. To prevent these large velocities effecting the baroclinic nesting, rdnest_in has a compile time parameter, lmask_rdnest, that, when .true., masks nest velocities (sets rmunv to zero) when they are outside the near-surface range. It is .false. unless CPP macro RDNEST_MASK is set.

d) The Browning & Kreiss (latbdt) and Flather (latbdtf) barotropic nesting routines have been overhauled. Flather now uses p-grid nested velocities, [uv]pnst, as in Browning & Kreiss. The Browning & Kreiss normal transport now always has an along port 1-2-1 smoother applied to it. Added a compile time parameter, npline, to control how often pline is updated in latbdt. It is set to 1 unless the CPP macro LATBDT_NPLINE3 sets it to 3.

e) A new variable, sports, has been optionally added to ports.input. It is a scale factor that is applied to all the nested barotropic velocities. Use 1.0 (the default if it is absent) to get the orignal velocities. If present, it is the 1st line of ports.input:

   1.2   'sports' = scale factor for nested velocity (typically 1.0).  
   6     'nports' = number of boundary port sections

f) Added wndflg=-4,-5. When wndflg is set to 4 or 5 U10 winds are read in and wind stress is calculated inside HYCOM using a bulk parameterization. This can be based either on absolute winds (U10) or relative winds (U10-Uocn). Previously, wndflg=4 always used relative winds and wndflg=5 recently used absolute winds (although the original Large & Yeager parameterizion used relative winds, and code for relative winds was included but commented out). Now, wndflg=4,5 uses relative winds and the new options wndflg=-4,-5 use absolute winds. Note that 2.3.00's wndflg=5 becomes 2.3.01's wndflg=-5.