# Campaign logbook

```{admonition}
    Contact
    Cyril Crevoisier, LMD
    Véronique Piou, CNES
```

(20251013)=
## Monday 13th October

A new early start for today in Francazal, with hangar opened at 4:45 to start heating CHARM-F and Picarro instruments. ATR42 was taken out at 6:45 for refueling and crew boarding at 7:00. Take-off happened at 8:00 in light fog.

![ATR_morning](/images/AB2CD_ATR42_earlymorning-131025.jpg)

**SAFIRE ATR42 going out the hangar at Francazal airport and waiting while the sun rises © C. Crevoisier 2025**

Flight to Bilbao was the occasion to enjoy the Basque coast under a steady sun… that did not last while arriving at Bilbao. Decision was rapidly taken to discard the envisioned southern legs where clouds were persistent. The first legs over the oceans and the harbour went well.

![basque](/images/AB2CD_ATR42_Bilbao_131025.jpg)

**Views from the ATR42 over the French Basque coast (left), over Bilbao and the LNG terminal (middle) and over the mountains above Bilbao (right) © C. Pietras and E. Wolkiewiez, 2025**

But clouds decided to keep moving in. The aircraft found itself stuck between two layers of clouds, with light ice crystals even forming on the windows. Unfortunately, changing altitude from FL170 to FL160 did not restore good measurement conditions for the lidars, whose signal was too weak to provide relevant measurements.

After an hour on site, the decision was therefore made to leave the area and return to Francazal early. On the return journey, the ATR42 was able to fly over Lacq, but once again the clouds played their part and a low cloud formed just above the industrial site.

![crystal](/images/AB2CD_ATR42_Bilbao_clouds.jpg)

**Two layers of clouds and even crystal droplets call a shift in the flight legs above Bilbao © E. Wolkiewiez and C. Pietras, 2025**

Meanwhile in Madrid, the weather conditions improved and Gerfaut was able to take-off and perform a new survey.  

![gerfaut](/images/AB2CD_Gerfaut_Madrid_131025.jpg)

**Views from Gerfaut Dynamic WT9 flying at 3 km around Madrid ©P. Laulhere, 2025**

However, the very weak wind above the city prevented the formation of a plume and created a kind of stationary blob above the city. A straight path cutting through this blob was therefore chosen. Measurements taken by the Picarro instrument on board the Dynamic WT9 revealed a very clear increase in **CO2 (~5ppm)** and **CH4 (~70ppb)** above the city.


![gerfaut](/images/AB2CD_Gerfaut_Madrid_131025_co2ch4.jpg)

**CO2 (left) and CH4 (right) mixing ratios measured by the Picarro onboard Gerfaut Dynamic WT9 over Madrid.**

In addition to providing very interested information on Madrid anthropogenic emissions, this result confirms that this type of trajectory is preferable for the ATR42 in the event of very low winds in order to test CHARM-F's ability to capture such a signal. To be tested in the coming days...