The equation used to calculate the eastward and northward water-vapour flux (kg m-1 s-1) respectively in the ERA-Interim (The ERA-Interim Archive document version 2.0):
where:
η : the model level coordinate, eta,
∂p : partial delta pressure,
u: eastward wind speed
v: northward wind speed
q: specific humidity
g: acceleration due to gravity
∂η : partial delta eta,
dη : Integration is performed with respect to eta.
The top model level is at 0.1hPa, which is in the middle of the top model layer.
