00:02:07 fred huemmrich: Welcome everyone 00:08:49 fred huemmrich: You can place questions in the chat 00:13:47 Ruben Behnke: How much power does this require? 00:16:19 vince: How are the atmospheric corrections applied? 00:19:13 Petya Campbell: What are the difficult cases when it is hard to retrieve fluorescence from FLoX? 00:29:58 Petya Campbell: To Tommi - very interested in the development of the atmospheric correction tools. Can we try to apply the correction to older FLoX data collections from prior years? 00:31:23 Tommaso Julitta: Replying to "How much power does ..." FloX is running 12 V DC. Peak power consumption is 120 W (mostly depends on the cooling. in hot environment the cooling will be typically on most of the time, keeping the spectrometer chanber at 15 degree celsius) 00:36:34 Tommaso Julitta: Replying to "How are the atmosphe..." The 3 retrieval methods we tested are working differently. The main issue is related to the oxygen reabsortpion. So the machine learning method (PLS) is simply skipping Oxygen bands and use information coming from other region (solar absorption lines). The BSF (the one we found to be the most suitable) is decoupling the effect of SIF and expected oxygen reabsorption into the oxygen band. The last one is using atmospheric model to get the actual oxygen transmittance. anyway consider that this effect start to be relevant if you are more than 20 meters above the canopy. if you are interested: https://www.sciencedirect.com/science/article/abs/pii/S0168192322003392?via%3Dihub https://www.sciencedirect.com/science/article/pii/S0034425722004102 00:37:00 Tommaso Julitta: Replying to "To Tommi - very inte..." Yes! 00:37:45 fred huemmrich: Reacted to "Yes!" with 👍 00:38:07 Petya Campbell: Replying to "To Tommi - very inte..." Thanks :) 00:39:11 Tommaso Julitta: Replying to "What are the difficu..." mots of the difficult cases are related to the set up conditions. The assumption of the measurement is that the light measured with the cosine (channel up) is the same reaching the surface. If this is not maintain (ex. shaded area in the canopy) then the measurements will have this error included 00:57:35 Adrian Rocha: Replying to "To Tommi - very inte..." time 00:58:17 Ruben Behnke: Replying to "How much power does ..." Ok, thank you. At what air temps is the cooling required? 00:59:17 Tommaso Julitta: Replying to "How much power does ..." sorry I was writing wrong. 25 degree. so above 25 the cooling will start 01:01:07 Ruben Behnke: Replying to "How much power does ..." Thanks. 01:15:01 Wu Sun: We are not hearing the sound from the video 01:15:37 Christopher Kibler: click share > share sound 01:24:45 Steve Oberbauer: Apogee Instruments sells more robust NDVI sensors than the Decagon model. 01:26:06 Lars Eklundh, Lund University: Replying to "Apogee Instruments s..." Thanks! We tested those with poor results, but I think we were simply unlucky with the sensors we tested. Will give them another try! 01:27:19 Tommaso Julitta: Replying to "Apogee Instruments s..." Bit of JB advertisement...try the RoX :). With it you can get all VIs computed in between 400 and 950 nm 01:28:09 Steve Oberbauer: Replying to "Apogee Instruments s..." I have not tried them myself but their other sensors are quite robust. the decagon sensors failed within months in the everglade wetlands in south florida. 01:29:57 Ran Wang: I’m curious about how much the sharp NDVI increase in the spring was caused by understory phenology and how much was caused by pure snow melting. GPP did not seem to change much and the temperature just went above zero. 01:31:00 fred huemmrich: Is the red chromatic index related to the leaves changing color in the fall? Did the insects remove the leaves, so there was no RCC peak in the fall that year? 01:31:59 José Beltrán: Replying to "Is the red chromatic..." yes 01:32:09 fred huemmrich: Reacted to "yes" with 👍 01:32:10 Lars Eklundh, Lund University: Replying to "I’m curious about ho..." Most NDVI dynamics is caused by snow! So that sharp rise is just when the snow melts 01:32:29 Lars Eklundh, Lund University: Replying to "Is the red chromatic..." Exactly 01:34:50 Ran Wang: Replying to "I’m curious about ho..." Thanks! 01:35:06 Laura Clark: Replying to "Is the red chromatic..." Have you found RCC to be helpful for coniferous forests? Or other ecosystems that don't have such vivid and visible phenophases? Thank you! 01:35:52 Lars Eklundh, Lund University: Replying to "Is the red chromatic..." Good question - we haven't really looked into it but it is worthwhile to check! 01:37:24 Laura Clark: Is it possible to disentangle changing leaf colour from drought responses and phenophases? 01:38:05 Tommaso Julitta: https://lps25.esa.int/ 01:40:47 José Beltrán: Replying to "Is it possible to di..." Great question, I have not yet explored it but I think it is possible only when the drought is not occurring at the same period of the expected senescence 01:41:28 Tommaso Julitta: Hi to everyone, unfortunately I have to leave now. is getting pretty late in EU and have to move home. Many thanks again for the great opportunity! 01:41:46 Lars Eklundh, Lund University: Replying to "Is it possible to di..." Yes, most broadleaf trees respond visibly to drought, however, not necessarily coniferous trees. The responses in coniferous trees are more complex and not so easily seen from simple vegetation indices. Hyperspectral data may help here. 01:41:58 Sergio Vargas: Apologies about the audio issue, here is the demo video you missed from my slides. Please feel free to reach out with questions/comments/suggestions! Sergio Vargas- savargas@utep.edu 01:43:02 Sergio Vargas: Link to ASTRAL: https://prodgis02.utep.edu/ASTRAL_Viewer/ 01:54:08 Wu Sun: I may have missed the intro, but what unique physiological insights do we gain from nighttime LEDIF measurements that are not available from daytime SIF and PAM measurements? 02:00:53 Petya Campbell: Or insights not available from night time PAM measurements? 02:06:48 Laura Clark: Replying to "Is it possible to di..." thank you! 02:11:54 Petya Campbell: Thanks for the opportunity, I need to leave due to the late time in Sofia. 02:12:09 Albert, Loren: Replying to "Thanks for the oppor..." Thanks Petya! 02:12:59 Chris Wong: Replying to "I may have missed th..." LEDIF serves as a low cost alternative to tease out pure chlorophyll fluorescence signal. Compared to SIF, its closer to Fo wheras SIF is Fs Compared to PAM, its much lower cost and can get canopy scale fluorescence 02:14:40 Chris Wong: Replying to "Or insights not avai..." we were seeking to explore an alternative to PAM, with lower cost, but also the ability to scale to canopy. And with spectrometer, can get the full fluorescence signal such as R:FR ratio 02:16:04 Ran Wang: For the tower based thermal measurements, how was emissivity calculated at pixel level? 02:16:41 Albert, Loren: Replying to "Or insights not avai..." Thanks Chris! I’m curious how much we know about the change in the ‘shape’ of SIF between daytime and nighttime. If aspects of the shape do not change much (like red/far-red ratio perhaps) then could the nighttime LEDIF help validate daytime SIF retrieval? 02:16:59 Wu Sun: Replying to "I may have missed th..." Is it easy to do LEDIF scan over a canopy? Seems spatial mapping would be a great advantage over PAM 02:17:26 fred huemmrich: Replying to "Or insights not avai..." I sometimes take out a blue flashlight at night to show people the red F from leaves. I’m surprised (since I can easily see the red F with my eyes) that you show such small F emissions in your spectral data. 02:18:05 Wu Sun: Reacted to "LEDIF serves as a lo..." with 👍 02:21:34 Chris Wong: Replying to "I may have missed th..." I think it would be feasible. Another group Romero et al 2021. set up a similar system on a tractor to scan a field. Our experiment was fixed spot. The limitation right now, is sensor to canopy distance. Need stronger light source for increased distance. Then vehicle or person to scan a canopy. maybe drone... 02:21:58 Erica Edwards (she/her): Reacted to "LEDIF serves as a lo..." with 👍 02:25:29 Chris Wong: Replying to "Or insights not avai..." @Albert, Loren I think this is a good direction to go with this type of system when complementing daytime SIF. That paper I mentioned near the end gets into that a bit 02:26:02 Albert, Loren: Reacted to "@Albert, Loren I thi..." with 👍 02:28:13 Chris Wong: Replying to "Or insights not avai..." @fred huemmrich Yeah, we tried to keep the light intensity on the weaker side to avoid light acclimation. I can't recall the strength off the top of my head. With the photodiodes, we weren't able to adjut integration time to maximize signal. So lots of room for improvement to optimize signal detection 02:29:43 fred huemmrich: Replying to "Or insights not avai..." Yes, there is a big difference between just messing around with a flashlight and trying to get quantiitative measurements 😀 02:35:49 Wu Sun: Reacted to "I think it would be ..." with 👍 02:36:43 José Beltrán: Replying to "Or insights not avai..." Can you share your presentation screen 02:36:58 José Beltrán: Replying to "Or insights not avai..." it is to small to see your presentation 02:37:49 José Beltrán: Replying to "Or insights not avai..." you are sharing the presenters view not the presentation view 02:38:54 José Beltrán: Replying to "Or insights not avai..." thank you 02:49:26 Ran Wang: I have a question for Koong: For the tower based thermal measurements, how was emissivity calculated at pixel level? 03:00:39 Wu Sun: A follow-up question for Chris, is it possible to use lidar for LEDIF measurements? NASA has been experimenting with lidar for nighttime greenhouse gas measurements 03:02:17 Ingo Ensminger: Great presentations! Thanks a lot! 03:02:26 abaresch: Thank you very much! 03:02:39 sophieruehr: Thank you! 03:02:49 Cynthia Gerlein-Safdi: Thanks all!