 |
|
|
|
|
|
|
|
|
|
|
|
There are four steps to assimilate SWE observation at a given
time step:
|
|
|
(1)
Forecasting step:
the SWE states evolve nonlinearly
according to model
|
dynamics; its
covariances are propagated linearly with time.
|
|
|
(2)
Updating step: the SWE of each
layer is updated using the Kalman filter
|
|
equations.
|
|
|
(3)
Analysis step:
Snow depth and heat content are calculated using SWE,
|
|
snow density and
snow temperature. When the model predicts no snow and
|
|
the updated SWE
being non-zero, snow density is 150 km/g3 and the air
|
|
temperature at 2
m is assigned to snow temperature.
Otherwise, snow
|
|
density and
temperature predicted by model are used.
|
|
|
(4) Repartition step: At this step, the total snow depth is
evaluated and the
|
|
thickness of each
layer is reassigned to ensure a layer 1 thickness of 5 cm.
|
|
The SWE and heat
content are calculated accordingly.
|
|
