Introduction

This report covers my trip to the US, the primary purpose of which was the presentation of a paper at the inaugural CLOUDSAT science meeting in LA. My paper summarized validation opportunities in Australia, namely, Cape Grim and Jabiru. The unique opportunities for validation work in the northern part of Australia are related to the fact that a high variety of clouds (convective, boundary layer and cirrus clouds) and biomass burning aerosol can be observed there, provided that a strategic location for observations is chosen. Our group at CAR believes that Jabiru fits the most important selection criteria: good access, good infrastructure and a manned location.

Cloudsat Program

Cloudsat will put a radar and A-band passive radiometer in space. The key scientific issues on which the Cloudsat mission is based are:

1. Quantitatively evaluate the representation of clouds and cloud processes in global atmospheric circulation models
2. Quantitatively evaluate the relationship between the vertical profiles of cloud liquid water and ice content and the radiative heating by clouds
3. Compare and validate cloud and aerosol information derived from other satellite systems, in particular EOS-PM.
4. Investigate the indirect effect of aerosols on clouds

Cloudsat (space-borne radar) will be launched in March 2003, using the same rocket on which the PICASSO space-borne lidar will be launched. Once in space, PICASSO will be released first, then CLOUDSAT. This means that both the lidar and the radar will fly in close formation, with the result that there can be earth co-location of footprint of both instruments.

Approximately 70 scientists and engineers attended the meeting. Most were from the continental USA, with a small contingent from Canada, France, Germany and Japan and myself from Australia. About 40% of those involved were engineers and associated staff (JPL was heavily represented). The meeting was well run (Graeme Stephens is PI) and consisted largely of detailed discussions on the science plan, engineering requirements, a summary of participation of others (such as the Canadians and the French), a section on validation studies associated with remote sensing instruments, and validation opportunities in the USA and around the globe. It was in this last section that I gave my presentation.

Strategic issues

1. Both Canada (through Cloudsat) and France (through Picasso) have a very large involvement in the US cloud satellite missions. At the same time Canada is a team member of ESA and, of course, France is as well. The Earth Radiation Mission (ERM) proposed by ESA is a mission with goals that are similar to Cloudsat /Picasso. ESA now faces an interesting dilemma: Either chop the ERM mission and be left out on important remote sensing work, or approve it and wonder why two of their own contributing countries are double dipping (or rather double pouring). A final decision on ERM is apparently due later this year, which we look forward to with some interest.
2. There is some justifiable push to align some of the ARM (Atmospheric Radiation Measurement) work with those of Cloudsat and Picasso. The proposed CRYSTAL program (2002), which will study high cirrus in the tropics, is seen as a forerunner for Cloudsat / Picasso, and is due to take place at Manus and Nauru in the west Pacific. A big problem with those two stations is access and logistics. I made the point in my talk that according to the definition of ‘West-pacific’ as used by ARM, Jabiru just falls in the south-western corner, and that there is a lot of high cirrus there. In other words: Jabiru, with its good access, could be used for some CRYSTAL studies as well.
3. Japan also wants to put radar in space, but just as the Europeans are somewhat late in decision-making. Because of the Cloudsat decision Japan will have to re-justify their work and re-create their objectives. Their radar is still in the design phase and is now due to be launched in 2005.