Introduction

Table 4.2.0.7 contains an entry for Storm Relative Helicity (SRH) [J/kg], code number 8. The storm relative helicity is storm-motion dependent and can be calculated separately for the mean flow, right-moving and left-moving storms. The unit in the existing entry 8 doesn’t look quite right and should therefore be deprecated. We propose to add three additional parameters for the right-moving and left-moving case as well as for the mean flow. Effective Storm-Relative Helicity is a refined version of standard SRH (Thompson, R. L. et al., 2003). The Effective Storm Relative Helicity (ESRH) is calculated over a vertical layer, the effective inflow layer, for which we propose to add 2 new types of level to code table 4.5.

Amendment details

ADD to code table 4.2: Product discipline 0 - Meteorological products, parameter category 7: thermodynamic stability indices.

ADD to code table 4.5 Type of fixed surface

Note: The effective inflow layer base and top forms the "effective inflow layer". The layer is characterized when several critiria on the value of CAPE and CIN are met. A common threshold is when CAPE ≥ 100 J kg-1 and CIN ≥ −250 J kg-1 at the same time. The exact definition and thresholds can vary across the models so it is left to each producer to document how their "effective inflow layer" is defined.

Requestor(s)

Sebastien Villaume (ECMWF)
Robert Osinski (ECMWF)
Ivan Tsonevsky (ECMWF)

Stakeholder(s)

ECMWF

Expected impact of change

None

Consultations

No response

Data exchange plans

No response

Comments

No response