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Author Topic: Atmospheric connections, structure, and long range weather forecasting  (Read 39091 times)

aslan

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #350 on: August 25, 2020, 02:52:55 PM »
I'm not sure where to post this information, but the QBO is again disrupted with an anomalous interruption of the easterly phase like in 2015 - 2016 :

https://acp.copernicus.org/preprints/acp-2020-791/acp-2020-791.pdf

https://acd-ext.gsfc.nasa.gov/Data_services/met/qbo/qbo_plot.pdf

https://www.essoar.org/doi/10.1002/essoar.10503358.1#.XvEZFtQSp8M.twitter

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #351 on: August 26, 2020, 03:33:18 AM »
Yeah the QBO is definitely on topic

UV levels have been high from all the stratospheric extremes, globally, and been so all summer

https://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/uv_current.shtml
https://acd-ext.gsfc.nasa.gov/Data_services/met/qbo/qbo.html#tomso3latlat

In general if you run analogs against the past 2 years you can't find any synoptic analogs for what has been happening.. it's been getting very clear

Last year, 500mb heights were very anomalously high, the most ever seen in summer.  925mb temps responded a little.  This year, 500mb heights are elevated, especially focused at the North Pole, where a lot of work is being done (loss of PE / friction). but the height anomalies are lower overall vs 2019

Now the poleward transport is taking place from equator to pole almost down to the surface.

warm soup.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #352 on: August 27, 2020, 12:09:31 AM »
Folks, I need a favor.  Can someone please find out if we have atmospheric soundings inside this +4C area and see a height profile of this?

This type of anomaly does not exist in the atmospheric record.  This is the all time greatest anomaly, is dead center at the pole, and has grown over the past 2 years.  This is becoming very suggestive of an unexpected feedback in the dynamics of our atmosphere.

I wonder if we're losing the inversion at the pole.  The various fluxes of planetary atmosphere will be notably impacted by poleward transport taking place at such a low level.  Really, it is looking not only likely, but increasingly so, this isn't just variability on top of climate change.  This is a different gear.

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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #353 on: August 29, 2020, 06:43:39 AM »
May - June air temperatures at 80-90N averaged #1 by a long shot.  In the reanalysis products, we do not see this.  There is no analog.

https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #354 on: August 29, 2020, 10:23:52 AM »
In 2019, we scored the highest ever 500mb geopotential height anomaly at 80-90N, but 925mb air temperatures did not respond to it.  850mb did not respond.  In fact, I think it had been pretty muted in the Arctic after about November of 2016...

we saw excursions of temperature especially in SON and DJF, into March and April but by May it usually calmed down, kinda the new normal, but overall the Arctic had a few recent years with only mild positive temperature anomalies, compared to what we were used to seeing.  flick back through the archive at DMI80N http://ocean.dmi.dk/arctic/meant80n.uk.php and it would seem like the really big anomalies are in 2016 and earlier, at least in terms of duration and power. 

You can also look through the various levels of the atmosphere https://psl.noaa.gov/cgi-bin/data/composites/printpage.pl

Or just chart a time series of the variable in question https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl

So in 2020 it could have appeared that 2019, it's Modoki El Nino, the +IOD, etc had simply forced anticyclones to the pole with various downstream effects.  May of 2020 rolls around and we have yet another dynamic final warming of the stratospheric polar vortex.  Yet again, a barotropic anticyclonic atmosphere briefly attained positioning over the North Pole, but it was less extreme than 2019.
 Geopotential heights 80-90N were elevated but not as much so as the year before.

Sadly, we started seeing in June that 925mb temperatures in the Arctic were sticking out like a sore thumb in the history of the atmosphere.  It blew up.  temps went from like -2C to +3C.  925 millibar height is around 2,500 ft up, or 760m.  there were a lot of soundings.  This is very new activity.

There is nothing published on this yet.

Now, if you look at June-July or May-July of 2020 the picture becomes disappointment.  It is not a trend, this is a ka-booooooom
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #355 on: August 29, 2020, 10:30:52 AM »
What is Omega in the atmosphere?  Rising / falling motion.  It is quasi-geostrophic calculation, a negative omega means rising motion, while a positive omega means subsiding motion. http://snowball.millersville.edu/~adecaria/ESCI342/esci342_lesson10_vertical_motion.pdf

So I'm trying to imagine how the atmosphere is going to redistribute heat in order to derive fossils of Crocodilians and frost intolerant plants on Svalbard at its present position.

This sort of planetary atmospheres exercise means I need a cross section analysis of the atmosphere to understand the structure, the stratification, etc.  Or I can look at a map of Omega.  So I'm just running anomalies and I see this pop up about a month ago.  Himalayan Plateau
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #356 on: August 29, 2020, 10:37:56 AM »
Tropopause pressure anomaly?  I don't fully understand this measurement and the chart does not read complete so this would need another method...

but what I'm starting to feel is there is a rising motion at the pole and a sinking motion near mountains.  Certainly, frictional torque / mountain torque has been remarkable this year.  What I really came for though is the air at the pole, so I look at that next
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #357 on: August 29, 2020, 10:53:22 AM »
Ok, there is a negative omega anomaly at 80-90N May - July, or June & July if you prefer, and it exists from 1000mb all the way up to about 300mb. 

What have we seen?  Anticyclones.  High SLP.  Pushing up on the tropopause, and lowering the pressure where it stands.

negative omega at the pole.

So we're seeing poleward transport of heat and high height atmosphere flooding from equator to pole at low levels.  The airmass converges at the pole and collides, uplifts.  Pushing down through the Arctic inversion and up through the tropopause, tihs poleward transport will find equatorward return at mid and upper levels of the atmosphere.

This is a different structure than we had for the past 10,000 years.  This is how you can account for Crocodilians and frost-intolerant plant fossils on Svalbard formed at its present location, but during the PETM.  Probably.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #358 on: August 29, 2020, 12:21:39 PM »
Negative omega at the poles
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uniquorn

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #359 on: August 29, 2020, 12:33:03 PM »
Thanks for this 'step by step' exploration sark

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #360 on: August 29, 2020, 08:50:46 PM »
The last data point on these classic AAM budget charts is always a preliminary, as it can change the next day, so the depth of the negative mountain torque excursion at the very end is only a possibility.  We will see tomorrow how it played out.

https://journals.ametsoc.org/mwr/article/131/11/2608/67169/Mountains-the-Global-Frictional-Torque-and-the

I would think the AAM budget begins to redistribute next, so I'm watching it, but I haven't looked into the data archive for identifiable trends.  It is a very noisy record.  Some qualified observatoins of the AAM budget and forecast are maintained on a wx mapwall here: https://atlas.niu.edu/gwo/
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oren

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #361 on: August 30, 2020, 01:14:19 AM »
The bbr post has been split to a separate thread.

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #362 on: August 30, 2020, 05:34:49 AM »
All the poleward transport at low level becomes convergence at the poles.  This causes updraft.  Equatorward transport must take place at mid and high levels, to my view

https://en.wikipedia.org/wiki/Brewer%E2%80%93Dobson_circulation

to my view, I would think this polar negative omega would build and build atmosphere over the pole and spread out at different levels, dumping stratosphere toward the surface in a suddenly blocked circulation.  We're losing the stratosphere by seeing mixing accelerate wildly

Think blowtorch on ice, permafrost, and everything if this keeps going

anyway, this is a geopotential height anomaly profile from 500mb to high altitude stratosphere at the north pole.  The scale is locked here, thus the blown out ink.  From low to high altitude there is a rising column, largely anticyclonic spin, but like a negative polar vortex is threatening to reverse mean flows, or at least add so much turbulence that it all mixes together

James G. Anderson of Harvard would probably correct a lot of this
« Last Edit: August 30, 2020, 05:47:00 AM by sark »
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #363 on: August 30, 2020, 07:32:26 PM »
I just really expected this to turn around today
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #364 on: August 30, 2020, 11:05:56 PM »
Here is an Omega height profile for June-July 2020 from low to high altitude.  I've locked the scale on this series.  Also, the average surface height of the Tibetan Plateau is 570 millibars.  These tools typically interpolate below terrain (how do you get sea level pressure in Nepal)

500 millibars & up deserve more weight here...

I'm not sure if I should adjust the extent of the mapping in order to apply time series to the area to see the true and total flux of this.. blob.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #365 on: August 31, 2020, 05:25:29 AM »
Sea level pressure for the region is high in the reanalysis, which is interesting because GFS paints it deep blue and has a marked low locked in this area.  The Euro is a mottled high pressure.  There's a lot of model variance even on what the conditions are here

Here is the stark difference at first verification, GFS vs ECMWF

not sure where to look https://www.emc.ncep.noaa.gov/index.php?branch=modelperf
« Last Edit: August 31, 2020, 05:55:44 AM by sark »
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #366 on: August 31, 2020, 04:14:53 PM »
Top image is a gif (click to run) composite images from every year, 1990-2020, 600mb omega anomaly, now including May June July - YTD.  Simply to lock the scale and run through the archive, you can easily get a context for a blob of interest.

The time series graph of the area is impressive, but it doesn't take much zooming out to lose the signal.  The overall flux or whatever is localized.  2003 might be an analog?

hope this is worth the graphics
« Last Edit: August 31, 2020, 04:21:39 PM by sark »
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #367 on: August 31, 2020, 04:50:16 PM »
Mountain torques what is you doin

You know, a lot of things are like normal oscillations or whatever, but in 2019-2020 they're so exaggerated
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #368 on: September 02, 2020, 09:18:05 AM »
By setting the interval to a large value and centering the scale on 273.15K (0°C) the blue area shows the average air temperature that is freezing for the 4 month period of May through August.

1999 through 2020

925mb is 2,500ft or 760m

(click to run)
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FishOutofWater

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #369 on: September 02, 2020, 11:48:11 AM »
You have it backwards. There has been subsidence in the stratosphere this summer at the pole. There has been subsidence in the troposphere as well. That's why the surface pressure has been high and the air column has been warm and thick. There has been an enormous amount of uplift and rain in China which has had bad floods on major rivers.

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #370 on: September 02, 2020, 12:51:24 PM »
The flooding is just downstream, in China, of what is certainly a stand out anomaly over the Tibetan Plateau...

I'll ask around about PSL's omega
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uniquorn

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #371 on: September 02, 2020, 12:55:07 PM »
You have it backwards.
That makes more sense with my basic knowledge of hadley cells. So is this correct?
« Last Edit: September 02, 2020, 01:42:30 PM by uniquorn »

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #372 on: September 02, 2020, 03:51:26 PM »
With these wild atmospheric gyrations, could we be watching the atmosphere actually trying to obliterate the Hadley cell with intrusions into the Arctic?

I know. It belongs in the Stupid Questions thread.

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #373 on: September 02, 2020, 04:06:13 PM »
With these wild atmospheric gyrations, could we be watching the atmosphere actually trying to obliterate the Hadley cell with intrusions into the Arctic?

I know. It belongs in the Stupid Questions thread.

This is the thread for that question.
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bbr2315

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #374 on: September 02, 2020, 04:21:45 PM »
With these wild atmospheric gyrations, could we be watching the atmosphere actually trying to obliterate the Hadley cell with intrusions into the Arctic?

I know. It belongs in the Stupid Questions thread.
I may be wrong but I understand it to be the other way around / I think it is the Hadley Cell encompassing the entire NHEM and residual vortices remaining based on elevation / geography, albedo, and oceanic heat content?

So the Hadley Cell is obliterating the Ferrell / Polar Cells (or maybe just Polar Cell and what I am describing above is "remnant" or continental Ferrell Cells? )

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #375 on: September 02, 2020, 05:29:53 PM »
Here is the NCEP/NCAR R1 reference for the parameter

https://psl.noaa.gov/data/gridded/data.ncep.reanalysis.derived.pressure.html

https://psl.noaa.gov/thredds/dodsC/Datasets/ncep.reanalysis.derived/pressure/omega.mon.mean.nc.html

long_name: Monthly Mean of Omega
units: Pascal/s
precision: 3
least_significant_digit: 3
var_desc: Omega (dp/dt)
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #376 on: September 02, 2020, 07:39:47 PM »
Top is a gif with a locked scale of mean omega +/- .12 (click to run)

bottom is the anomaly for 2019.  I needed to see that positive/negative anomaly was positive/negative the mean.
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bbr2315

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #377 on: September 02, 2020, 08:02:37 PM »
Pretty dramatic shift since 2012...

Really illustrates that "WACC-y-ness" is visible from peak warming but less so from 1981-2010 means for now.

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #378 on: September 02, 2020, 08:46:58 PM »
I'm not going to argue with a basic atmospheric physics text. I'll go with that textbook definition of omega.

We need to be very careful in our analyses to examine summer and winter polar dynamics separately because of the importance of the stratospheric polar vortex in the dark months.

There is a paper on that weather phenomenon that produces heavy rain in China and snow in Tibet. The warm and the cold are coupled dynamically. I'm not going to look for it now, but it's out there in the met. journals.

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #379 on: September 02, 2020, 10:16:49 PM »
August is in the monthly NCEP/NCAR R1

temps at 925mb for the entire Arctic over the past 4 months have been the most extreme ever observed.  Hard to reckon with this signal over the past two years.

Second is gif of 1999-2020 925mb air temperature anomaly vs the 1981-2010 average (click to run)
« Last Edit: September 03, 2020, 11:33:38 PM by sark »
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #380 on: September 03, 2020, 05:22:11 AM »
Tropopause pressure over the entire Arctic gained 25mb of height for 4 months.   Same response in the SH

Plot is tropopause pressure over the entire Arctic for MJJA from 1948 to 2020
« Last Edit: September 03, 2020, 06:16:19 AM by sark »
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vox_mundi

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #381 on: September 03, 2020, 10:19:54 AM »
Arctic sea-ice loss intensifies aerosol transport to the Tibetan Plateau
https://www.nature.com/articles/s41558-020-0881-2

Abstract:

The Tibetan Plateau (TP) has recently been polluted by anthropogenic emissions transported from South Asia, but the mechanisms conducive to this aerosol delivery are poorly understood.

Here we show that winter loss of Arctic sea ice over the subpolar North Atlantic boosts aerosol transport toward the TP in April, when the aerosol loading is at its climatological maximum and preceding the Indian summer monsoon onset.

 Low sea ice in February weakens the polar jet, causing decreased Ural snowpack via reduced transport of warm, moist oceanic air into the high-latitude Eurasian interior.

This diminished snowpack persists through April, reinforcing the Ural pressure ridge and East Asian trough, segments of a quasi-stationary Rossby wave train extending across Eurasia.

These conditions facilitate an enhanced subtropical westerly jet at the southern edge of the TP, invigorating upslope winds that combine with mesoscale updrafts to waft emissions over the Himalayas onto the TP.
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #382 on: September 03, 2020, 08:49:18 PM »
https://www.olcf.ornl.gov/2020/08/28/reaching-new-heights-in-weather-forecastings-exascale-future/

Quote
REACHING NEW HEIGHTS IN WEATHER FORECASTING’S EXASCALE FUTURE

ECMWF and ORNL researchers use the power of Summit to simulate the Earth’s atmosphere for a full season at 1-square-kilometer grid-spacing
Using the Oak Ridge Leadership Computing Facility’s (OLCF’s) IBM AC922 Summit—the nation’s most powerful supercomputer devoted to open science, located at the US Department of Energy’s (DOE’s) Oak Ridge National Laboratory (ORNL)—a team of researchers from the European Centre for Medium-Range Weather Forecasts (ECMWF) and ORNL achieved a computational first: a global simulation of the Earth’s atmosphere at a 1-square-kilometer average grid-spacing for a full 4-month season.

Completed in June, the milestone marks a big improvement in resolution for the Integrated Forecasting System (IFS) code, also known as the “European Model,” which currently operates at 9-kilometer grid-spacing for routine weather forecast operations. It also serves as the first step in an effort to create multi-season atmospheric simulations at high resolution, pointing toward the future of weather forecasting—one powered by exascale supercomputers.

“In this project, we have now shown for the first time that simulations at this resolution can be sustained over a long time span—a full season—and that the large amount of data that are produced can be handled on a supercomputer such as Summit,” said Nils Wedi, head of Earth System Modelling at ECMWF. “We provide factual numbers for what it takes to realize these simulations, and what one may expect both in terms of data volumes and scientific results. We therefore provide a baseline against which future research may be evaluated.”

Established in 1975, the ECMWF is an intergovernmental organization composed of 34 member and cooperating countries, providing numerical weather predictions to its members while also selling forecast data to commercial weather services. The original IFS code was written some 30 years ago and has been one of the leading global weather-forecast systems in the world, continually updated and optimized for use on many generations of supercomputers at ECMWF. However, to advance its performance and scalability, ECMWF researchers also test their code on external high-performance computing systems, including the OLCF’s decommissioned Titan and now on Summit.

Armed with a 2020 allocation of compute time from the DOE’s Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program, Wedi and his team aim to deliver a “quantum leap” forward in simulating and understanding the Earth’s weather and climate. Although results from the 4 months of simulated weather are currently being analyzed, the team expects a bounty of information leading to more precise forecasting.

With the higher resolution of 1-kilometer grid-spacing—enabled partly by special adaptations of the I/O scheme exploiting Summit’s memory hierarchy and network, and further accelerated by recoding IFS to use Summit’s GPU accelerators—the team’s simulations are able to represent variations in topography with finer detail. For example, IFS’s current operational modeling simulates the Himalayan mountains at heights of about 6,000 meters; its elevations are averaged out over the 9-square-kilometer grids, resulting in “smoothed out” peaks. By zooming into smaller areas with 1-square-kilometer grids, the averaged topography is much closer to reality—the Himalayas’ peaks are now presented near their true heights of 8,000 meters with much better resolved gradients representing the slopes. This increased detail results in better airflow characteristics that help determine global circulation patterns.

What’s more, the 1-kilometer grid-spacing also enables the representation of processes in the atmosphere that were previously too small to be accounted for with the 9-kilometer spacing. Now, tropical thunderstorms—which can move warm, moist air into the upper atmosphere in a process called deep convection—can be simulated explicitly in the models, providing a better look at tropical atmospheric motions, which in turn affect the circulation patterns in the rest of the world.

“We are not simply looking at whether we can make an improvement at any given locality, but ideally all these things should translate into a global circulation system,” said Val Anantharaj, an ORNL computational scientist who serves as data liaison on the project. “If we can resolve the global atmospheric circulation pattern better, then we should be able to produce better forecasts.”

Once their paper is published, the team will make the simulation’s data available to the international science community. By eliminating some of the fundamental modelling assumptions prevalent in conventional simulations, the high-resolution data may help to improve model simulations at coarser resolutions.



Anantharaj said the project’s long-term goal is to simulate the remaining seasons in order to have one full year modeled—or to least cover an Atlantic hurricane season. But the ECMWF team also has an eye on the future of weather itself, as well as its forecasting. Such high-resolution models can provide virtual laboratories to further our understanding on how the climate is evolving and how weather may look in such a future climate.

The output and compute rate of these simulations can also be used to predict the impact of future high-resolution models employed on emerging HPC platforms as scientific computing enters the exascale era with new systems, such as the upcoming 1.5 exaflops Frontier, on track to be deployed in 2021 at the OLCF, a DOE Office of Science User Facility.

“The handling and data challenges that we have overcome during this project are still very large, and our simulations are at the edge of what is achievable today,” Wedi said. “However, I believe that it will be possible to run simulations with 1-kilometer grid-spacing routinely in the future—in the same way we are running simulations with 9-kilometer grid-spacing today. To continue to push these boundaries is important.”

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #383 on: September 04, 2020, 11:41:36 PM »
1990-2020 May - August 6000 thickness.  I can't find a reference for this parameter but it seems to simply be 1000-500mb geopotential height difference.

"Recall from Chapter 8 that thickness is the geopotential height difference between two pressure levels, in practice most commonly 1000 and 500 hPa. Larger (smaller) 1000–500-hPa thickness indicates: A larger (smaller) distance between the 1000- and 500-hPa height surfaces."

https://www.sciencedirect.com/book/9780128092477/synoptic-analysis-and-forecasting

(click to run)
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #384 on: September 11, 2020, 01:33:53 AM »
click to run gif

925mb (2,500ft / 760m) air temperature anomaly vs 1981-2010.  I believe the airmass at this level has now thawed permanently in the May - August period, and is responsible for amplification of extremes over the midlatitudes in the past two years.
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FishOutofWater

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #385 on: September 11, 2020, 03:00:53 AM »
" Tropopause pressure over the entire Arctic gained 25mb of height for 4 months.   Same response in the SH "

Millibars are units of pressure. In meteorology height is measured in meters and so is thickness. The polar troposphere may have expanded upwards in response to warming but it did not expand by 25mb. That does not compute, nor does it make any sense at all.

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #386 on: September 11, 2020, 03:05:35 AM »
here's the 925mb temp anomaly vs 1979-2000 first gif (click to run)

the chart is from the reanalysis but is "rudimentary"
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #387 on: September 11, 2020, 03:12:29 AM »
I think the way it computes for me is that the tropopause height was elevated by 75ish meters from May-August, which is around 30 millibars lower in pressure.  there's clearly been a giant column of warm air geolocated over the pole, mildly anticyclonic, with anomalous uplift, no?  That's what we've seen in May-August for the past 2 summers after dynamic final warmings of the winter strat PV.

You can reverse the color bar on the PSL site and see how closely it tracks, but now red = lower pressure at the tropopause boundary

How do you feel about "negative polar vortex"
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #388 on: September 11, 2020, 03:28:23 AM »
anticyclonic uplift is the snag?
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #389 on: September 11, 2020, 11:39:38 AM »
Tropopause pressure 85-90N for May through August

Whatever is the full and lucid explanation of all this, the anomaly rips right through some charts
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #390 on: October 19, 2020, 05:40:55 AM »
La Nina hasn't changed anything.  Now this is scary.
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #391 on: October 19, 2020, 09:38:32 AM »
Apologies for my lack of knowledge, but why is this bad and what are the implied consequences?

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #392 on: October 20, 2020, 04:18:10 AM »
We are in year two of explosive atmospheric height growth over the poles.  It was trending up and up for 20 years, noisy, but rising.  Now it is as if something broke and is generating upwelling at the pole, not just high pressure at the lower levels, but high pressure at upper levels also, pushing up on the tropopause greatly.

All of this comes with splits in the raw geopotential heights across the Arctic suddenly occurring frequently, yielding a brief period where two circulations, of side by side co-rotating vortex columns, shearing at the interaction between them.   The polar cell "splits" in the troposphere and even as high as 100mb.

The giant ridging across the Arctic and North Pole in the majority of 2019-2020 now is the most extreme two years of variability on record.  It's not El Nino or La Nina or summer or winter or QBO-E or W that is correlated with this behavior, we've seen it under vastly different seasonal influences

There is some evidence of solar minimum amplification of high latitude blocking / ridging.  That's probably my last hope, that sunspots will appear and the average geopotential heights will go back to rising gradually from this sharp excursion of the past two years.

Whatever the causes and future, what we have in the books are two years with an unexpected and sudden increase in the power of poleward transport, it keeps splitting the polar cell, lots of jet is piling up in the Arctic and it doesn't look a whole lot better than last year, which was an El Nino

The tropics have been suppressed in terms of zonal pushes through progression of the MJO which spent the most time in phases 1&2 this past summer.

There's not really a good explanation for it yet
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #393 on: October 20, 2020, 06:51:50 AM »
x-post from freezing thread, but the clouds forming up there seem like a bunch of the methane is pushing up the cap, and forcing the water vapor to stay in the lower atmo?

https://forum.arctic-sea-ice.net/index.php/topic,3299.350.html

 (yes, meant noctilucent clouds.

Looks like someone did a study in Alaska this year, and reported 50% of days in "season" (may til august) had NLCs, and that they were getting lower, and showed some "growth sedimentation mechinism"

http://ffden-2.phys.uaf.edu/atm/atm/theses/2020/Alspach,%20Jennifer_Thesis.pdf

looks like the sattelite is still operational

http://aim.hamptonu.edu/mission/status.php

http://aim.hamptonu.edu/

"The season continues to be a strong one, as shown in the figure. Throughout the 2020 season, daily PMC frequencies have exceeded frequencies in all or most previous years. Although not shown, this is consistent with lower-than-typical temperatures and higher-than-typical water vapor mixing ratios, as measured by the NASA Microwave Limb Sounder. These conditions are consistent with low solar activity, but definitive attribution is still under investigation."

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #394 on: October 20, 2020, 07:15:28 AM »
Sark thanks for that excellent explanation!

Morganism, I read the theisis you linked to with interest, learning a lot of new stuff. I had no idea that this phenomenon existed, nor that it was linked to methane. And according to the author of the thesis, they have been on the increased.

However it was not clear to me whether this would count as a postive or a negative feedback. Water vapor is a greenhouse gas, and thin clouds have an insulating effect. But methane is a very strong greenhouse gas so it is not clear what converting it into water vapor and clouds will do.
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #395 on: October 20, 2020, 08:03:17 AM »
While the anomalies are definitely relevant, I see no split in the polar cell.

Spot the difference: 100mb geopotential height 1960-1990 winter vs 2019-20

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #396 on: October 20, 2020, 08:33:21 AM »
El Cid is who inspired me to watch the raw geopotential heights, which are splitting  frequently at 500mb in the NH.  Even with +AAM and +AO as in January.

Or even December- January.
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #397 on: October 20, 2020, 08:47:14 AM »
It happens frequently now
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #398 on: October 20, 2020, 10:06:42 AM »
The first picture is an anomaly chart. The second shows no split. The third shows a split but as there is no comparison to previous years, we can not draw a conclusion. How many times was there a "split" in previous years vs 2019 or 2020? That is the relevant question. Maybe there also were splits previously as well, I don't know.

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #399 on: October 20, 2020, 10:11:26 AM »
I did not need to search long, there also were many splits in the "good old days", like this one: