legraLeGraMay 18, 2024

Finally my paper looking at #AtmosphericRivers is out!

"How River-like ARE Atmospheric Rivers?”

VERY-- they take moisture from 1000's km and 10deg equatorward than your average storm.

#NASA #CYGNSS - GPS array that looks at how choppy the ocean surface is to determine surface wind speed and heat fluxes compares well w simulations from the #NASAGISS climate model w include a tracer suite that identifies where moisture in the atmosphere originally evaporated from.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023GL105828

Show threadlegraLeGraMay 18, 2024

#CYGNSS #NASAGISS
We use the CMIP6 version of the #NASA GISS model with MERRA2 (~observed) winds, then apply an automated routine (Guan&Waliser 2019) to identify the atmospheric rivers based on the integrated water vapor transport…

(We identify all the 1000s km long filament like tendrils of moisture…)

There is LESS heat flux from the ocean into the atmosphere under #AtmosphericRivers

Show threadlegraLeGraMay 18, 2024

#CYGNSS #NASAGISS #NASA #AtmosphericRivers

Now... here is the cool part.

If it isn't heat flux from below the atmospheric rivers fueling these storms,
How DO you know WHERE fuel (moisture) came from?

We have pretty awesome tracers in the GISS model…

Back in the day, folks would “paint" / tag the Atlantic Blue, the Pacific red and check for how Purple the resulting rain was...
but the tracers we have now are able to distinguish MUCH finer detail for moisture source.

Show threadlegraLeGraMay 18, 2024

#CYGNSS #NASAGISS #NASA #AtmosphericRivers

It turns out that these tracers are able to identify the fact that #AtmosphericRivers source moisture from on average 10degrees equator-ward and 1000km further away that other kinds of rain. (!!) That is pretty amazing!

(Dear mastodon advanced users... I have some video gifs I'd like to share, but Ivory wont let me post... help.)

Show threadlegraLeGraMay 18, 2024

Trying to show how cool atmospheric rivers are...

I find looking at atmospheric rivers mesmerizing ...

Show threadlegraLeGraMay 18, 2024
I put a really fascinating case study into this paper about the January 2021 #AtmosphericRiver Related floods that happened in #Chile... during the dry season.
Show threadlegraLeGra

My student, Carlos Ordaz (whom I co-advise with Jimmy Booth at #CCNY) has had his FIRST paper published. Its about #AtmosphericRiver and #ClimateChange

🎉

Specifically, we looked at what will happen in the future to these storms (and what happened in the past)... and not just the easy answer either (easy= warmer air holds more moisture and thus bigger storms)... dynamics, too.

"Assessing the Impact of Climate Change on Atmospheric Rivers: A Modeling Perspective”

https://dx.doi.org/10.1029/2023JD040074

Jun 30, 2024 at 6:09pmWeb
Show threadlegraLeGraJun 30, 2024

#AtmosphericRiver #ClimateChange

Okay… so first up, the experiment design… we looked at Present Day (you can see that in my paper / posts above), and then I used some old GISS simulations of the Last Glacial Maximum (21000 years ago-- COLD) and projections (year 2095 using RCP8.5) ... then did simplified + and - 3degC for thoroughness…

And then we begin the process of doing the high temporal resolution simulations to look at past/future #AtmosphericRivers

Show threadlegraLeGraJun 30, 2024

#AtmosphericRiver #ClimateChange

Whew. So... We have a good idea of what atmospheric rivers look like today…

Is a little tough to define an AR in a changing climate... you know it when you see it, but if you search for the 85th% Integrated Vapor transport, then the whole signal is our old friend CC.

But that's thermodynamic stuff... or "Clausius Clapeyron” aka 7% more moisture in the atmosphere per deg C temperature change means "of course" storm footprints by modern definitions are bigger.

Show threadlegraLeGraJun 30, 2024

#AtmosphericRiver #ClimateChange

So naturally, the GISS-E2.1 model follows this same thermodynamic pattern.

Carlos looked at the FULL signal, then decomposed it into the
THERMODYNAMIC (=clausius clapeyron) part and the
DYNAMIC (=residual) part.

We do this by changing the threshold of our algorithm for detecting AR's (Guan and Waliser 2019). (See PWV figure below)

Show threadEveryday.Human DerekJun 30, 2024
@atthenius 😳 I wonder if that speeds up the glacial melt…if there’s more water moving around of higher temp?
Show threadlegraLeGraJun 30, 2024

@EVDHmn

Atmospheric rivers don't just deliver moisture, they deliver heat as well.

Whether they make for more positive or more negative mass balance will depend on which effect dominates in the future.

So... I have had some students checking this out... I think there is a different impact on Greenland (energy more important) versus West Antarctica (moisture more important).

But... not quite ready to publish that yet. :-)

Show threadEveryday.Human DerekJun 30, 2024
@atthenius I was thinking a warmer world would amp all the effects. In theory. Cooler world cut down.
Show threadlegraLeGraJun 30, 2024

@EVDHmn

Mostly …

but some places on the world are super cold. And even when they get a bit warmer, they’re still not warm enough quite to melt. — but those warmer temperatures do mean that the air can deliver more moisture.

Show threadEveryday.Human DerekJun 30, 2024
@atthenius fascinating 🧐 thanks for the explanations super neat. 🥰