III.2.5.1 Equipment

The MetAir standard equipment includes sensors for:

• fast response and high accuracy air temperature and humidity;
• flow and attitude angles resulting in a fast 3-d wind and turbulence measurements;
• ozone (two methods; one accurate, one fast);
• NO₂, NO_x, NO_y, HNO₃, PAN, O_x;
• CO (5 Hz with a precision of 2 ppb);
• CO₂ and H₂O (open- and closed cell IRGA - one fast, the other accurate to 0.2 ppm);
• particle counter for 0.3 and 0.5 micrometer aerosols;
• many "housekeeping parameters", including GPS-position and distance to ground (radar).
• Remote sensing with Hyperspectral Scanner.

III.2.5.2 Flight plans

Dimona will contribute to 5 to 6 days of measurements, with one or two flights per day (3 to 4.5 hours each). With two flights per day, they will be from about 9 to 12 h, and 14 to 18 h LT, or with one extended flight per day between 11 and 16 h LT.

In the following, the basic flight pattern is discussed with different aspects on different graphics.

MA1 is the ferry flight to some "center point, MA2+MA3 are the transsect for westerly winds, and MA2+MA4 for southwesterly winds. They are not not necessarily flown together with the Aztec, but, taking the same tracks might ease the permission, and there might be occasions, where the flights are quasi-synchronous. The same is true for the leg MA1, which is on one of the "SkyArrow tracks" (not shown here).

However, in contrast to Aztec and SkyArrows which fly on different constant altitudes, our task can only be fulfilled, when we can change altitude on these legs between near surface (minimum save flight altitude, see below), and about 2500 m AMSL (8000 ft) quite frequently. The ascents will be made in 8-shaped turns perpendicular to the wind, with the turns against the wind (see details on the last figure below).

Then, we descend to the lowest point of the next profile. The separation between the profiles is depending from the wind speed. We try to move with the air mass (lagrangian measurement). Since ascents are made with about 2 to 3 m/s vertical speed (130 km/h horizontal speed), and descents with about –4 m/s (200 km/h), one ascent/descent cycle over 2500 m takes about half an hour. With an average wind speed of 10 m/s (20 kt or 36 km/h) in the boundary layer, this would result in distances between profiles of about 20 km (or less with lower wind speed as in figure III.2.5.2-d). Also the top of the profiles could be adjusted according to the actual height of the boundary layer. Especially during flights before noon, 1500 m MSL might be enough.

Considering the limitations of the air spaces with their complex vertical structure and temporal activity (see figure III.2.5.2-c), not every profile might be possible to the desired altitude at any time. However, we hope, that for the benefit of the project, most will be possible. Before each ascent, we will request the clearance from the relevant ATC. It is no problem to wait a few minutes when the actual traffic situation does not allow to continue, but, it's possible later (a delay or a divert to another position is less a problem than a "no go"). Our altitude is always visible on the radars, since we have Transponder-C, which is encoding height. Perhaps it would be practical, when we could get a "squawk" (transponder code) for each active measuring day, or even for the campaign?

When flying from LFCS via WP1 to the coast, we will fly on constant altitude about 300 m GND (which is about on 1000 ft MSL). In principle, each of these legs could be flown on this altitude for flights in parallel with the SkyArrows, or for transfers.

The dark blue air spaces on the bottom graph are Aquitaine TMA Sectors 2 and 4 (class D and E), and the red ones are all special use (restricted) air spaces from Cazaux, Biscarosse, Landes West, Captieux, Mont-de-Marsan. We will have to find out, under what conditions we will be allowed to enter them. The blue flight tracks on the map are as in figure III.2.5.2-a (MA1 to MA5). In the vertical cross section (bottom graph), the black track is the upper envelope (top of the profiles).

We do not know yet, if MA3 will be possible (the leg from WP1 in figure III.2.5.2-c to the east, and back to WP3), because it crosses several restricted air spaces (see also figure III.2.5.2-d). Especially during days with southwesterly winds, MA4 (from WP1 to the NE) might be an alternative which crosses less restricted air spaces. However, for wind directions between 260 and 300^°, it would be most desirable to use MA3.

Technical remark:

Safety remark:

On this map, more details of the pattern for westerly winds (MA2+MA3) are shown, together with a better identification of the air spaces. The cross-legs (short north-south-legs of 3 to 5 km length) are the vertical profiles as discussed with figure III.2.5.2-b, with an average horizontal separation of 15 km in this example (suitable for a wind speed of about 30 km/h). These cross legs will be flown as 8-shaped ascending "zig-zag" perpendicular to the wind, with all the turns against the wind (this is to avoid crossing the own exhaust gases which could happen when circling).