3 ms·

'Glowing' plants could help scientists predict flash drought

49 points by sharpshadow 2y ago

3lit3krew 2y ago
[flagged]
datameta 2y ago
TL;DR: "While the glow is invisible to the naked eye, it can be detected by instruments aboard satellites such as NASA’s Orbiting Carbon Obsevatory-2 (OCO-2). Launched in 2014, OCO-2 has observed the U.S. Midwest aglow during the growing season. The researchers compared years of fluorescence data to an inventory of flash droughts that struck the U.S. between May and July from 2015 to 2020. They found a domino effect: In the weeks and months leading up to a flash drought, vegetation initially thrived as conditions turned warm and dry. The flourishing plants emitted an unusually strong fluorescence signal for the time of year."
ambicapter 2y ago
That's interesting. Could the farmers reduce the impact of the oncoming drought by shading the plants, slowing down their photosynthesis cycle, and reducing the moisture uptake from the soil? Evening out the usage of available water, in a way.
- alice-i-cecile 2y ago
  Generally speaking this will work, yes! Plants use more water during active photosynthesis, and unsurprisingly, water evaporates faster in the open sun. But logistically, on-demand shading of whole fields is quite challenging. And not all crops will be robust to being grown in the shade (for varying levels of shade).
hatthew 2y ago
This topic is mostly new to me so I'm sure this is a dumb question, but what is the benefit here? I would have thought farmers could just manually sample soil moisture levels to get pretty much the same data. The article also mentions the SMAP satellite that can already read soil moisture from space. Is this fluorescence a more reliable early predictor? Is it an easier way to get the data we need?
- bryant 2y ago
  Speculating: Heat (within reason) encourages plant growth provided the other ingredients are there. Plant growth shows up through this luminescence. If a lack of rain can be projected, then the drawdown of ground water can now also be more accurately projected by understanding how much plant growth is taking place. I imagine this can impact emergency prep or other measures e.g around irrigation to get ahead of groundwater depletion resulting in flash crop loss. But that's my take on the value.
- xhkkffbf 2y ago
  Well, if you make satellites like the Orbiting Carbon Observatory, this is a good reason to make another, more sophisticated version. But you're right that cheaper, more local telemetry may be more than adequate. Heck, you can probably think, "I don't remember the last time it rained..."
- dylan604 2y ago
  If you're the government wanting to see the status of the whole country very quickly vs waiting for every single local farmer to report their results to be compiled into a larger view, the satellite view is much more efficient. Food production has somewhat of a strategic value that a government wants to know about.
  - dietr1ch 2y ago
    Well, when the government wanted to monitor earthquakes across the whole world they just deployed sensors. Same thing with Sattelites. I don't understand why it wouldn't deploy weather stations and humidity sensors within its own borders.
    - dylan604 2y ago
      we have the tech to do it from space now with a single sensing platform vs individual sensors on private land. doesn't take much of an imagination to see why one is preferred over the other. USGS can place their sensors on gov't land and get the readings they need. Department of Ag can't really do the same thing.
dylan604 2y ago
from the embedded video, what kind of orbit is that satellite using? it seems strange that it's not a straight down view. the skewed angle gives me the impression it is not geosync, but it's clearly not a polar orbit either. what is the purpose of this skewed view rather than a straight down geosync orbit?
- bagels 2y ago
  https://www.n2yo.com/satellite/?s=40059 https://www.n2yo.com/satellite/?s=40059 Looks like a pretty standard inclination for a sun synchronous roughly circular orbit to me.
  - dylan604 2y ago
    now that you say that, that does make absolute sense. why have a satellite waste time looking at the earth when it's dark? kind of one of those face palm "doh!" moments after the fact. I know polar because that's what ISS uses. I know geosync because that's what communication birds use and was directly beneficial in a former job to know. after that, I am much less familiar with the various other types of orbits. one day, i will take time to learn all of the various orbits and their benefits.
    - mturmon 2y ago
      > ...why have a satellite waste time looking at the earth when it's dark? ... Exactly. Many NASA Earth-observing satellites use the same kind of sun-synchronous orbit (https://en.wikipedia.org/wiki/Sun-synchronous_orbit https://en.wikipedia.org/wiki/Sun-synchronous_orbit). (One of several exceptions are the instruments opportunistically mounted on the ISS, which has its own orbit, as you note.) One of these sequences is called the A-train (https://atrain.nasa.gov https://atrain.nasa.gov) - that's what OCO-2, discussed in OP, is part of. Having it be near noon local time (1:30pm, say) when you pass over every patch of ground has great advantages for some instruments. The sunlight passes through less atmosphere, and does so in "the same way" for most passes. So you're not seeing some places at local dawn and others at local dusk. This makes the observation less sensitive to the difficulties of atmospheric modeling. (Because you need a good atmospheric model to retrieve the solar induced flourescence [SIF] signal.) OTOH, the sun-synchronous orbit does restrict your observations to specific times. The companion instrument, OCO-3 (which is mounted on ISS), plays a special role here. OCO-3 can provide information about the daily cycles of plants that would be undersampled by a consistent 1:30pm arrival. * Separately from orbits: The discovery that you could obtain insights on plant processes at global scales from SIF using the OCO-2 measurement has been a really big deal for Earth science.

49 points by sharpshadow 2y ago

[flagged]

TL;DR: "While the glow is invisible to the naked eye, it can be detected by instruments aboard satellites such as NASA’s Orbiting Carbon Obsevatory-2 (OCO-2). Launched in 2014, OCO-2 has observed the U.S. Midwest aglow during the growing season. The researchers compared years of fluorescence data to an inventory of flash droughts that struck the U.S. between May and July from 2015 to 2020. They found a domino effect: In the weeks and months leading up to a flash drought, vegetation initially thrived as conditions turned warm and dry. The flourishing plants emitted an unusually strong fluorescence signal for the time of year."

ambicapter 2y ago

That's interesting. Could the farmers reduce the impact of the oncoming drought by shading the plants, slowing down their photosynthesis cycle, and reducing the moisture uptake from the soil? Evening out the usage of available water, in a way.

alice-i-cecile 2y ago
Generally speaking this will work, yes! Plants use more water during active photosynthesis, and unsurprisingly, water evaporates faster in the open sun. But logistically, on-demand shading of whole fields is quite challenging. And not all crops will be robust to being grown in the shade (for varying levels of shade).

hatthew 2y ago

This topic is mostly new to me so I'm sure this is a dumb question, but what is the benefit here? I would have thought farmers could just manually sample soil moisture levels to get pretty much the same data. The article also mentions the SMAP satellite that can already read soil moisture from space. Is this fluorescence a more reliable early predictor? Is it an easier way to get the data we need?

bryant 2y ago
Speculating: Heat (within reason) encourages plant growth provided the other ingredients are there. Plant growth shows up through this luminescence. If a lack of rain can be projected, then the drawdown of ground water can now also be more accurately projected by understanding how much plant growth is taking place. I imagine this can impact emergency prep or other measures e.g around irrigation to get ahead of groundwater depletion resulting in flash crop loss. But that's my take on the value.
xhkkffbf 2y ago
Well, if you make satellites like the Orbiting Carbon Observatory, this is a good reason to make another, more sophisticated version. But you're right that cheaper, more local telemetry may be more than adequate. Heck, you can probably think, "I don't remember the last time it rained..."
dylan604 2y ago
If you're the government wanting to see the status of the whole country very quickly vs waiting for every single local farmer to report their results to be compiled into a larger view, the satellite view is much more efficient. Food production has somewhat of a strategic value that a government wants to know about.
- dietr1ch 2y ago
  Well, when the government wanted to monitor earthquakes across the whole world they just deployed sensors. Same thing with Sattelites. I don't understand why it wouldn't deploy weather stations and humidity sensors within its own borders.
  - dylan604 2y ago
    we have the tech to do it from space now with a single sensing platform vs individual sensors on private land. doesn't take much of an imagination to see why one is preferred over the other. USGS can place their sensors on gov't land and get the readings they need. Department of Ag can't really do the same thing.

dylan604 2y ago

from the embedded video, what kind of orbit is that satellite using? it seems strange that it's not a straight down view. the skewed angle gives me the impression it is not geosync, but it's clearly not a polar orbit either. what is the purpose of this skewed view rather than a straight down geosync orbit?

bagels 2y ago
https://www.n2yo.com/satellite/?s=40059 https://www.n2yo.com/satellite/?s=40059 Looks like a pretty standard inclination for a sun synchronous roughly circular orbit to me.
- dylan604 2y ago
  now that you say that, that does make absolute sense. why have a satellite waste time looking at the earth when it's dark? kind of one of those face palm "doh!" moments after the fact. I know polar because that's what ISS uses. I know geosync because that's what communication birds use and was directly beneficial in a former job to know. after that, I am much less familiar with the various other types of orbits. one day, i will take time to learn all of the various orbits and their benefits.
  - mturmon 2y ago
    > ...why have a satellite waste time looking at the earth when it's dark? ... Exactly. Many NASA Earth-observing satellites use the same kind of sun-synchronous orbit (https://en.wikipedia.org/wiki/Sun-synchronous_orbit https://en.wikipedia.org/wiki/Sun-synchronous_orbit). (One of several exceptions are the instruments opportunistically mounted on the ISS, which has its own orbit, as you note.) One of these sequences is called the A-train (https://atrain.nasa.gov https://atrain.nasa.gov) - that's what OCO-2, discussed in OP, is part of. Having it be near noon local time (1:30pm, say) when you pass over every patch of ground has great advantages for some instruments. The sunlight passes through less atmosphere, and does so in "the same way" for most passes. So you're not seeing some places at local dawn and others at local dusk. This makes the observation less sensitive to the difficulties of atmospheric modeling. (Because you need a good atmospheric model to retrieve the solar induced flourescence [SIF] signal.) OTOH, the sun-synchronous orbit does restrict your observations to specific times. The companion instrument, OCO-3 (which is mounted on ISS), plays a special role here. OCO-3 can provide information about the daily cycles of plants that would be undersampled by a consistent 1:30pm arrival. * Separately from orbits: The discovery that you could obtain insights on plant processes at global scales from SIF using the OCO-2 measurement has been a really big deal for Earth science.