Isentropic Cold Airmass Analysis Tool

Introduction

This is a software package to calculate cold airmass below threshold potential temperature surfaces. This package is useful for any study related to cold airmass budget, cold air outbreaks, and polar warming. Several parameters such as cold airmass amount, negative heat content, their horizontal fluxes, and their diabatic change rates can be derived from conventional gridded meteorological data, like reanalysis data. Derivation and formulation of isentropic cold airmass are documented in Iwasaki et al. (2014).

Examples (based on JRA-55 reanalysis)

The following figure shows climatolgy of cold airmass below a potential temperature of 280 K in boreal and austral winters. From top to bottom: cold airmass amount, cold airmass flux, and diabatic genesis/loss rates.