Estimation of impulse response of Earth's climate system at short time intervals

A method is described for restoration of the impulse response h(t) of the Earth's climate system (ECS), which is regarded as a time-invariant linear dynamic system whose input is the change in solar constant, and output-the global mean surface temperature anomalies. Search for solution of the ill-posed inverse problem is carried out on a compact set of non-negative, monotonically non-increasing, convex downward functions. This suggests that ECS may be a first-order dynamic system or a set of similar independent subsystems with different time constants. Results of restoration of h(t) at time intervals up to 100 months show that it is a rapidly decreasing function, which does not differ from zero for t > 3 months. An estimate of the equivalent time constant gives the average value of 1.04 +/- 0.17 months. The sensitivity of the ECS to changes in radiative forcing at the top of the atmosphere is equal to 0.41 +/- 0.05 K W-1 m(2). (C) 2012 Elsevier Ltd. All rights reserved.