Detecting Lee and Barrage clouds using Meteosat 8 Contact person: Jarno Schipper Version August 2005 Folie 2 Example I Lee clouds over Norway: Folie 3 Meteosat 8 IR10.8: 28 June 2005: 0200UTC Folie 4 Meteosat 8 IR10.8: 28 June 2005: 0230UTC Folie 5 Meteosat 8 IR10.8: 28 June 2005: 0300UTC Folie 6 Meteosat 8 IR10.8: 28 June 2005: 0330UTC Folie 7 Meteosat 8 IR10.8: 28 June 2005: 0400UTC Folie 8 Meteosat 8 IR10.8: 28 June 2005: 0430UTC Folie 9 Meteosat 8 IR10.8: 28 June 2005: 0500UTC Folie 10 Meteosat 8 IR10.8: 28 June 2005: 0530UTC Folie 11 Meteosat 8 IR10.8: 28 June 2005: 0600UTC The development of the lee clouds (green arrows) behind the mountain ridge can clearly be seen. Click back and forth! Lee clouds appear white in IR imagery and can sometimes be confused with MCSs. An animation, or satellite loop however is decisive Folie 12 Meteosat 8 RGB: HRVis +HRVis + IR10.8: 28 June 2005: 0600UTC The HRVis RGB is build of two times HRVis channel on Red and Green and the IR10.8 on Blue. The last channel gives the additional temperature profile information. The lee clouds are consistant of blue and darkblue colors which thus means that the contribution of the IR channels is high, thus the lee clouds here are consistant of multilayered to highreaching clouds consistant of iceparticles. Slightly above the upper arrow Lee waves can be spotted. Folie 13 Meteosat 8 RGB: NIR1.6 +VIS0.8 + VIS0.6: 28 June 2005: 0600UTC A final RGB made of NIR1.6 on Red, VIS0.8 on Green and VIS0..6 on blue indicates that the lee clouds found over Norway are blue. This means that the clouds are consistant of multilayered highreaching ice clouds. Folie 14 Example II Lee clouds over Norway and UK: Folie 15 Meteosat 8 IR10.8: 11 April 2005: 2000UTC Folie 16 Meteosat 8 IR10.8: 11 April 2005: 2030UTC Folie 17 Meteosat 8 IR10.8: 11 April 2005: 2100UTC Folie 18 Meteosat 8 IR10.8: 11 April 2005: 2130UTC Folie 19 Meteosat 8 IR10.8: 11 April 2005: 2200UTC Folie 20 Meteosat 8 IR10.8: 11 April 2005: 2230UTC Folie 21 Meteosat 8 IR10.8: 11 April 2005: 2300UTC Folie 22 Meteosat 8 IR10.8: 11 April 2005: 2330UTC Folie 23 Meteosat 8 IR10.8: 12 April 2005: 0000UTC The green arrows mark the positions of interest. Two seperate areas developing lee clouds were identified. Again one over Norway, but now also over Scotland. A closer look over Scotland even reaveals Lee Waves ( red arrow). Folie 24 Example III Lee clouds over UK and Austria: Folie 25 Meteosat 8 IR10.8: 18 March 2005: 0200UTC Folie 26 Meteosat 8 IR10.8: 18 March 2005: 0230UTC Folie 27 Meteosat 8 IR10.8: 18 March 2005: 0300UTC Folie 28 Meteosat 8 IR10.8: 18 March 2005: 03300UTC The red arrow indicates lee waves. Normally these are better seen in HRVis Folie 29 Meteosat 8 IR10.8: 18 March 2005: 0400UTC Folie 30 Meteosat 8 IR10.8: 18 March 2005: 0430UTC Folie 31 Meteosat 8 IR10.8: 18 March 2005: 0500UTC Folie 32 Meteosat 8 IR10.8: 18 March 2005: 0530UTC Folie 33 Meteosat 8 IR10.8: 18 March 2005: 0600UTC The green arrows mark the positions of interest. Especially around the Alps in Austria and Swiss Lee clouds and Barrage clouds often occur. The sharp border in the cloudiness caused by the mountainbarrier can nicely be seen. Folie 34 Meteosat 8 RGB: HRVis + HRVis + IR10.8: 18 March 2005: 0730UTC The HRVis RGB indicates the lee clouds as blue and darkblue. This is a sign that the lee clouds are consisting of highreaching iceclouds. The lee waves are indicated here with the red arrows. Especially in this RGB they are easily picked up. Folie 35 Example IV Lee clouds over Sardinia: Folie 36 Meteosat 8 IR10.8: 8 May 2005: 0800UTC Folie 37 Meteosat 8 IR10.8: 8 May 2005: 0830UTC Folie 38 Meteosat 8 IR10.8: 8 May 2005: 0900UTC Folie 39 Meteosat 8 IR10.8: 8 May 2005: 0930UTC Folie 40 Meteosat 8 IR10.8: 8 May 2005: 1000UTC Folie 41 Meteosat 8 IR10.8: 8 May 2005: 1030UTC Folie 42 Meteosat 8 IR10.8: 8 May 2005: 1100UTC Folie 43 Meteosat 8 IR10.8: 8 May 2005: 1130UTC Folie 44 Meteosat 8 IR10.8: 8 May 2005: 1200UTC The green arrows mark the positions of interest. In this example the stationary position of the lee clouds are very nice visible. Folie 45 Meteosat 8 RGB: HRVis + HRVis + IR10.8: 8 May 2005: 1200UTC In this HRVis RGB the lee clouds are pictured in blue. The contribution blue by the IR10.8 channel is high. This correlates to the fact that the lee clouds are consistant of high cirrus (iceclouds). Folie 46 Meteosat 8 RGB: NIR1.6 + VIS0.8 + VIS0.6: 8 May 2005: 1200UTC In this RGB the lee clouds appear as lightblue. They indicate multilayered high reaching iceclouds. Folie 47 Example V Barrage clouds over Pyrenees: Folie 48 Meteosat 8 IR10.8: 11 November 2004: 0200UTC Folie 49 Meteosat 8 IR10.8: 11 November 2004: 0230UTC Folie 50 Meteosat 8 IR10.8: 11 November 2004: 0300UTC Folie 51 Meteosat 8 IR10.8: 11 November 2004: 0330UTC Folie 52 Meteosat 8 IR10.8: 11 November 2004: 0400UTC Folie 53 Meteosat 8 IR10.8: 11 November 2004: 0430UTC Folie 54 Meteosat 8 IR10.8: 11 November 2004: 0500UTC Folie 55 Meteosat 8 IR10.8: 11 November 2004: 0530UTC Folie 56 Meteosat 8 IR10.8: 11 November 2004: 0600UTC The green arrow marks the location of interest. In this example the stationary position of the Barrage clouds is very nice visible. Unlike the Lee clouds, Barrage clouds appear more greyish in IR imagery. The nearer to the the mountainridge, the more the clouds are being pushed to hiherg levels and thus appear whiter (colder) in IR10.8. Allthough not shown here Lee clouds also occur over this mountainridge quite often. Folie 57 Meteosat 8 WV6.2: 11 November 2004: 0600UTC The red arrow indicates the position where sinking of dry air is observed. Especially with Barrage clouds it is important to study the WV6.2 image as well. On the lee side of the mountain barriage sinking of dry air is often observed. Folie 58 Meteosat 8 RGB:HRVis + HRVis + IR10.8: 11 November 2004: 0900UTC A scala of colours can be seen in this large Barrage cloud over France. Up north it consists of khaki colours (orange arrow) which indicate lowlevel water clouds. The more to the south the mountainous barriage forces air to rise which changes the colour in this RGB to blue (indicated by the pink arrow). The blue color indicates that the air here is supercooled and consists of highlevel and multilayered iceclouds. Folie 59 Example VI Barrage clouds over Alps: Folie 60 Meteosat 8 IR10.8: 8 August 2005: 0200UTC Folie 61 Meteosat 8 IR10.8: 8 August 2005: 0230UTC Folie 62 Meteosat 8 IR10.8: 8 August 2005: 0300UTC Folie 63 Meteosat 8 IR10.8: 8 August 2005: 0330UTC Folie 64 Meteosat 8 IR10.8: 8 August 2005: 0400UTC Folie 65 Meteosat 8 IR10.8: 8 August 2005: 0430UTC Folie 66 Meteosat 8 IR10.8: 8 August 2005: 0500UTC Folie 67 Meteosat 8 IR10.8: 8 August 2005: 0530UTC Folie 68 Meteosat 8 IR10.8: 8 August 2005: 0600UTC The green arrows marks the position of the Barrage clouds. Folie 69 Meteosat 8 IR10.8: 8 August 2005: 0600UTC The green arrows marks the position of the Barrage clouds. In this IR image the wind fields at 850 hPa is projected. The winddirection is according to the priciple of Barrage cloud development. Folie 70 Meteosat 8 IR10.8: 8 August 2005: 0600UTC The darkgreen arrows marks the position of the Barrage clouds. The lighter green arrows indicate the windfield at 500 hPa. In comparison to 850 hPa (previous image) the windfields does seem to be less affected by the Alps at this height. Folie 71 Meteosat 8 IR10.8: 8 August 2005: 0600UTC The green arrows marks the position of the Barrage clouds. The magenta arrows indicate the windfield withint he upper-troposphere at 300 hPa. The windfield follows the synoptic scale systems and does not seem to be affected by the Alps. Wind is a good indication to observe Lee and Barrage clouds, however at what height differs from case to case. Folie 72 Meteosat 8 RGB: HRVis + HRVis + IR10.8: 8 August 2005: 0600UTC In this HRVis RGB image the different clouds can easily be discriminated. The Barrage clouds consist of multilayered high reaching iceclouds. On the lee side (here the southside) of the Alps the dark blue color represents high thin cirrus- clouds (red arrow). Folie 73 Meteosat 8 RGB: NIR1.6 + VIS0.8 +VIS0.6: 8 August 2005: 0600UTC In this image the lightblue color indicates the multilayered clouds which are consistent of ice- particles.