Changes between Version 3 and Version 4 of user/clem/Heat_Flux_air-ice-ocean_interface

Timestamp:

2016-04-15T17:04:22+02:00 (8 years ago)

Author:

clem

Comment:

--

user/clem/Heat_Flux_air-ice-ocean_interface

@@ -4 +4 @@
 It is time to approach the matter from a different angle. I describe below what we are doing in NEMO and what we think the solution should be, and you can comment on that.[[BR]]
 
-So far, the total non-solar flux is imposed by the atmosphere but it excludes (from what I understand) the heat contents of snow precipitation and rain. It also does not take into account the heat content (if any) of evaporated ice and water (already in vapor form) that the atmosphere should receive. The total non-solar (conservative) flux should then write:[[BR]]
+So far, the total non-solar flux (Qns) is imposed by the atmosphere but it excludes (from what I understand) the heat contents of snow precipitation (Qsnow) and rain (Qrain). It also does not take into account the heat content (if any) of evaporated ice and water (Qevap, already in vapor form) that the atmosphere should receive. The total non-solar (conservative) flux should thus be written:[[BR]]
 
 {{{Qns_tot = Qns + Qsnow + Qrain + Qevap}}}
 
-with {{{Qns}}} being the non-solar flux provided by the atmosphere.[[BR]]
 
-Therefore NEMO did a guess on Qsnow, Qrain and Qevap by considering the temperature of falling snow, rain and evaporated water = SST, and temperature of evaporated ice = 0°C. Then,[[BR]]
+So far, as an input from the atmosphere, NEMO only had Qns. Therefore NEMO had to make a guess on Qsnow, Qrain and Qevap by considering the temperature of falling snow, rain and evaporated water = SST, and temperature of evaporated ice = 0°C. Then,[[BR]]
 (''O Marti'' : when it's snowing on sea ice, using the surface temperature (snow/ice) would be a better first guess. But the actual flux from ATM is still needed to be conservative)
 
@@ -26 +25 @@
 
 
-**In order to be really conservative, the atmosphere should provide those fluxes**, or am I completely wrong here?
+My understanding is that **in order to be fully conservative, the atmosphere should provide those fluxes**, or am I completely wrong here?
 O Marti : OK with that. When its rains, some matter is leaving the ATM realm, and an energy is associated with it and given to the OCE realm. 
 
@@ -37 +36 @@
 ''O Marti'' Not exactly. The flux from atmosphere is not 0. But atmosphere doesn't need to compute it. You could diagnose the actual flux by computing the total ATM enthalpy before and after the rains leaves ATM.
 
-2) The atmosphere provides non-zero fluxes and then it is better if NEMO knows how Qsnow is calculated in the atmosphere, which Cp, temperature and Lfus is used (see why below).
+2) The atmosphere (you, from your atmospheric models) provides non-zero fluxes and then it is better if NEMO knows how Qsnow is calculated in the atmosphere, which Cp, temperature and Lfus is used (see why below).
 
 
 **Nota bene**[[BR]]
-The most important flux here (by far) is Qsnow. When snow falls on ice, its heat content adds up with the pre-existing snow and snow temperature is recalculated with this expression:[[BR]]
+The most important flux here (by far) is Qsnow. When snow falls on ice, its heat content adds up with the pre-existing snow to give a total heat content equal to q and snow temperature is recalculated with this expression:[[BR]]
 {{{q =  rho(snow) * ( Cp(snow) * T(snow) - Lfus ) [in J/m3]}}}[[BR]]
 Therefore a large difference between the expressions of Qsnow and q would lead to erroneous snow temperatures. One consequence could be a snow that always melts because its temperature is always positive. The largest difference between Qsnow and q is certainly Lfus which may differ greatly between the atmospheric model and LIM3. [[BR]]
 
+At this point I expect to receive from you the Qsnow, Qevap and Qrain (whether you think it should be zero or a value defined by your atmospheric model calculations). If you do not think this is needed please send me comments based on the above equations so that we can move on in a constructive way.
 
 == LIM3 physical constants ==