I Has A Question

[sammie]

Ok so this if from last years past paper for my exam, and the answers arn't up (because thats helpful) and I am completely scuppered on one question.

"Temperature inferred from infra red satellite imagery are used to estimate the altitude of volcanic eruption clouds which can reach up to 30KM altitude. How might this be done and what are potential problems?” [5 Marks]

[Coast]

Is this any help Sammie? http://www.nwas.org/committees/rs/volcano/ash.htm

By the late 1980’s it was learned that the temperature difference in two longwave IR bands could be used effectively in observing thin ash clouds (Prata 1989).Known as the "split-window" or "reverse absorption" technique, it has become a benchmark for observing ash globally, and for measuring the effectiveness of improved multi-spectral techniques.

The altitude of the ash cloud top is critical for aviation advisories and to accurately predict the future locations of the ash by means of trajectory models such as PUFF or HYSPLIT. The simplest method involves the comparison of IR cloud top temperatures (CTT) to radiosonde or numerical model first guess temperature-height profiles. Since volcanic ash is usually semi-transparent, the CTT method usually underestimates the actual cloud top height. An approach currently in use at some VAACs is to match the drift of the ash cloud with an upper level wind vector from radiosonde, satellite cloud drift, or numerical model data. New research techniques under development show considerable promise in providing more accurate ash cloud top estimates by means of radiative transfer techniques.

Edited October 29, 2008 by Coast

[sammie]

Fantastic thanks Coast.

[Coast]

5 marks for me then?