Liquid Water Path and Ice Water Path

The ice water path (IWP), defined as the integral of the ice water content (IWC) through the depth of an ice cloud layer, is a quantity of considerable importance in climate studies because it is critical for determining cloud absorption, optical depth (Platt and Harshvardhan 1988), albedo, and emissivity (Stephens 1980)


Liquid water path – in units of [kg/m²] is a measure of the total amount of liquid water present between two points in the atmosphere.[1]

LWP is an important quantity in understanding radiative transfer in the atmosphere. It is defined as the integral of liquid water content between two points in the atmosphere.

GFS Documentation

The details of the model are presented in the ncep office notes at

Click to access on442.pdf

The GFS model, formerly known as the Medium Range Forecast model (MRF) was initially developed by J. Sela(1980,1982).

The introduction of gocart aerosol module is described in the ncep technical note

Click to access on472.pdf

It clearly mentions that the model is incapable of carrying advection and other dynamics and operates similar to an offine model coupled with the physics module through a coupler.

The introduction of sigma hybrid pressure levels into the gfs

Click to access on461.pdf

Understanding Spectral Modelling

The COLA-Atmosphere-Biosphere General Circulation Model

Click to access The%20COLA%20Atmosphere.pdf

Recent Changes into the Global Forecast System

The NCEP Climate Forecast System Version 2

Changes to the NCEP GFS by Srinivas Moorthy

Click to access 484.pdf

The NCEP Climate Forecast System