Fig. 2.

Flight strategies employed by a single Twin Otter aircraft in previous aerosol–cloud field investigations (dashed green and purple lines), in contrast to the comprehensive plan for ACTIVATE using a dual-aircraft approach (red lines). Relevant parameters that are typically needed for analysis are shown where they are measured, with some values integrated over cloud depth and others as a function of altitude [i.e., f(z)]: LWP = liquid water path, WVP = water vapor path, ΔZ = cloud thickness, τ = cloud optical depth, CTH = cloud-top height, N_a = subcloud aerosol concentration, w = cloud base updraft velocity, R = rain rate, N_d = cloud droplet concentration, r_e = drop effective radius, σ_a = vertically resolved remote sensing parameters such as aerosol extinction coefficient, T = temperature, q = humidity, u/υ = wind components. Variables in blue and black are measured via remote sensing and in situ techniques, respectively; note though that T(z), q(z), u(z), and υ(z) are measured with dropsondes released from the higher aircraft.