Dueling ITCZs

Guest Post by Willis Eschenbach

Inspired by a comment about modeled rainfall by Dr. Richard Betts over in the Twitterverse, I decided today to look at how well the climate models are able to hindcast historical rainfall amounts and patterns.

I already had the satellite rainfall data from the Tropical Rainfall Measuring Mission (TRMM). So I went over to KNMI and got the Climate Model Intercomparison Project 6 (CMIP6) climate model rainfall results of the 38 different models in their database.

Let me start with a look at the TRMM satellite data. It extends from 40°N to 40°S. The two graphs below are the same, but the top one is Pacific centered and the bottom one is Atlantic centered.

Figure 1. 18-year average, TRMM annual rainfall, Dec. 1997 – Mar 2015

Of interest in this is the line of rain just north of the Equator in both the Pacific and the Atlantic Oceans. This marks the average location of the Inter-Tropical Convergence Zone (ITCZ). It is a line of semi-permanent thunderstorms located where the northern and southern halves of the atmosphere come together. It forms the ascending part of the great Hadley cell circulation, which rises just north of the equator, moves polewards on both sides, descends over the 30° N/S desert belts, and returns to the ITCZ just north of the Equator. Here’s a cross-section of the Hadley cell circulation.

Figure 2. Cross-section of the ITCZ and the northern and southern Hadley cells.

With that as a prologue, consider the following Pacific-centered maps of some of the model results.

Figure 3. Rainfall model output, CMIP6 models

I’m sure you can see the problem. There are two ITCZs in the model output, one above and one below the Equator.

Now, this is not just a huge problem that’s only found in the modern models. It’s been a problem since there have been climate models. It even has its own name. Here is a comment from 2013 in PNAS:

The double-Intertropical Convergence Zone (ITCZ) problem, in which excessive precipitation is produced in the Southern Hemisphere tropics, which resembles a Southern Hemisphere counterpart to the strong Northern Hemisphere ITCZ, is perhaps the most significant and most persistent bias of global climate models.

That was ten years ago, the problem was old and well-recognized back then, and they still haven’t been able to fix it.

And we’re supposed to totally destroy our current energy source and power the world on unicorn methane based on these garbage Tinkertoy™ climate models? Really? They can’t even hindcast the past!

More to the point, they can’t replicate the Hadley cells, a most basic feature of the global circulation, but they are supposed to be able to predict the future a hundred years out?

Laughable, but also tragic in that governments are passing laws and shafting the poor based on this nonsense.

The problems continue. Here are the monthly rainfall observations from the TRMM, along with the modeled monthly rainfall, for the area 40°N to 40°S.

Figure 4. TRMM (red) and modeled (colored) monthly rainfall values, 40°N/S, Dec 1997 – Mar 2015

Again, you can see the problems. Not only is there no overlap between models and observations, but the models are far from agreeing with each other.

Well, how about the trends? There’s a slight upwards trend in the TRMM data, but what about the models? Here’s a “violin plot” of the model trends per decade, along with the TRMM trend over the period.

Figure 5. Violin plot of the model trends in millimeters per decade, along with a yellow/black line representing the TRMM trend. The width of the violet area at any point represents the proportion of models with trends of the value shown on the vertical (Y) axis. For those familiar with a “density plot”, a violin plot is just two of them back to back.

Again, problems. Not only are the various model trends quite different from each other, but they also don’t even agree as to sign. 17% of them are less than zero, the rest above. Also, the TRMM trend is larger than all but two of the model trends.


Anyone who seriously believes one word that the models say about rainfall is either a climate alarmist or a fool … but I repeat myself.

My best to all,


As Always: I ask that when you comment, you quote the exact words you are referring to so we can all be clear about your subject and who said it.

4.9 46 votes
Article Rating
Newest Most Voted
Inline Feedbacks
View all comments
Tom Halla
April 18, 2023 10:08 am

As the models do not do clouds well, it follows they do not do rain well, either.

Reply to  Tom Halla
April 18, 2023 11:53 am

The purpose of climate, or any social science modeling is to obtain support for policy.

Tom Halla
Reply to  dk_
April 18, 2023 11:59 am

Such studies have been called “sagelore” in other situations, and are about as objective as kept professional witnesses for liability lawyers.

April 18, 2023 10:09 am

Catastrophic Anthropogenic Cumulative Error (CACE)

Incomplete or insufficient characterization and an intractable problem set. The very model of chaos… outside of a limited frame of reference.

Javier Vinós
April 18, 2023 11:09 am

Obviously, this is just the tip of a huge iceberg. Nearly just about everything you look at with sufficient detail, including such fundamental climate processes as albedo, cloud nucleation, internal variability, or heat transport, models reproduce it wrongly and/or inconsistently. It is all in the scientific literature. Climate models are unfit for purpose.

All models are wrong, but some are useful (George Box). Climate models are wrong, but they are useful to justify an energy agenda that will make most people poorer.

Javier Vinós
Reply to  Javier Vinós
April 18, 2023 11:23 am

5 days ago I commented to Nick Stokes about the persistent double ITCZ bias in models:

Many models still produce a double intertropical convergence zone in the Pacific.

Samanta, D., Karnauskas, K.B. and Goodkin, N.F., 2019. Tropical Pacific SST and ITCZ biases in climate models: Double trouble for future rainfall projections?Geophysical Research Letters46(4), pp.2242-2252.

“The double Intertropical Convergence Zone bias remains a persistent problem in coupled general circulation model simulations.”

How could you possibly believe that models do a very realistic ENSO with a double ITCZ? Gullibility? Ignorance? Wishful thinking?

His answer:

The splitting of the ITCZ is a fine point which is being solved.

Reply to  Willis Eschenbach
April 18, 2023 12:45 pm

Good stuff Willis. But I would like to change your thoughts about Hadley cells. They exist 95% in the imagination of meteorology professors and 5% in the real world. I seldom see textbook-looking Hadley circulations in my daily looks here, Coriolis patterns often…..have at me…


Reply to  DMacKenzie
April 18, 2023 3:23 pm

Doesnt seem to exist in Indian ocean- at a superficial glance. The difference might be both Pacific and Atlantic extend significantly into both hemispheres , while the Indian doesnt

John Oliver
Reply to  Duker
April 18, 2023 4:21 pm

yes I don’t see it either assuming we are looking for what ? cloud s forming and moving. Seriously I am curious too. Maybe we are not looking at the right satellite imagery.

Reply to  Willis Eschenbach
April 18, 2023 8:33 pm

Thanks for that. helps me understand the desert belts too.

Dave Fair
Reply to  Javier Vinós
April 18, 2023 11:31 am

The UN IPCC owns climate science; trust us.

Reply to  Dave Fair
April 18, 2023 3:24 pm

Its Hollywood/show business for smart people.

Reply to  Duker
April 18, 2023 4:29 pm

smart-arse people?

Dave Fair
Reply to  Duker
April 18, 2023 11:08 pm

I’m sure you meant ‘grifters,’ Duker.

Chris Nisbet
Reply to  Javier Vinós
April 18, 2023 11:37 pm

I presume that fine == fantastic.

Rud Istvan
April 18, 2023 11:17 am

Nice post WE. Hindcast double ITCZ is very serious, but far from the only major known problem in the climate models.

  1. All but one of CMIP6 (INM CM5) produce a tropical troposphere hotspot that does not observationally exist. This is a problem that was first recognized by CMIP3 and AR4. Still not ‘fixed’.
  2. They predict significant Arctic amplification such that summer Arctic sea ice was supposed to have disappeared by about 2014. It hasn’t and is recently increasing.
  3. They predict sea level rise acceleration that observationally does not exist among the vertical land motion corrected long record tide gauges.
  4. They produce a median ECS of about 3.2C when observational EBM says 1.7C
  5. Use of anomalies hides the fact that hindcast actual temperatures disagree model to model by about +/- 3C. Details in essay ‘Models all the way down’ in ebook Blowing Smoke.
Alastair Brickell
Reply to  Willis Eschenbach
April 18, 2023 9:09 pm

Great post. One query…

How actually do you guys do a hindcast? I’m not quite clear. Do you pick an arbitrary starting date and then plug in the latest iteration of one of the many models and see what it predicts for the time after that date? Rinse and repeat for the rest of the models?

Alastair Brickell
Reply to  Willis Eschenbach
April 19, 2023 1:05 am

OK thanks…that’s not what I was expecting.

Don’t the modellers check how badly their wonderful creations work…or don’t they actually care?

Mark BLR
Reply to  Alastair Brickell
April 19, 2023 10:10 am

Don’t the modellers check how badly their wonderful creations work…

Yes they do.

From the AR6 WG-I report, starting with Box SPM.1, “Scenarios, Climate Models and Projections”, in the “Box SPM.1.2” paragraph (on page 12) :

Some differences from observations remain, for example in regional precipitation patterns.

NB : This got through the “line-by-line checking by governmental representatives” part of the IPCC process.

In the “Executive Summary” for Chapter 8, “Water Cycle Changes” (on page 1059) :

Natural climate variability will continue to be a major source of uncertainty in near-term (2021–2040) water cycle projections (high confidence).

Section is focussed on “Inter-tropical Convergence Zone and Tropical Rain Belts” (!), and includes (on page 1093) :

The AR5 concluded it is likely that the tropical belt, as delimited by the Hadley circulation, has widened since the 1970s. Observations in the satellite era indicate precipitation increases in the core of the Pacific Inter-tropical Convergence Zone (ITCZ) and decreases on the ITCZ margins (Gu et al., 2016; Su et al., 2017). As the satellite period has lengthened, observations have increasingly been used to assess trends in the ITCZ and tropical rain belt.

However, CMIP5 and CMIP6 models still exhibit strong biases in representing the ITCZ, such as the simulation of a double ITCZ

See also the penultimate paragraph of section, “In Situ and Remote-sensing Data” (on page 1383) :

Satellite measurements are also used to evaluate climate model performance, as well as to develop new parametrizations. As a demonstration of the utility of these products in studying model bias, a subtropical cumulus congestus regime has been identified that may be implicated in the unrealistic double Inter-tropical Convergence Zone (ITCZ) found in some climate models …

– – – – –

…or don’t they actually care?

No they don’t.

The start of SPM paragraph B.2.4 (at the top of page 16) :

It is very likely that heavy precipitation events will intensify and become more frequent in most regions with additional global warming. At the global scale, extreme daily precipitation events are projected to intensify by about 7% for each 1°C of global warming (high confidence).

The Technical Summary pulled together various strands from individual chapters of the main report and came up with panel d of Figure TS.7 (on page 64), for example.

See attached screenshot.

Rud Istvan
Reply to  Alastair Brickell
April 19, 2023 7:21 am

AB, the CMIP manual is quite explicit. The first run submitted is a 30 year hindcast from a specific Dec31/Jan 1 initialization. In stead of running forward in time, the model is simply run backwards in time. The model parameters are tuned to make this run as accurate as possible compared to actual history. The CMIP presumption then is, the forward projections will then also be ‘accurate’. This is obviously NOT the case.

Alastair Brickell
Reply to  Rud Istvan
April 19, 2023 2:59 pm

Thanks guys…much appreciated.

Joel O’Bryan
Reply to  Rud Istvan
April 18, 2023 8:15 pm

The hot spot prediction problem, the modelled ECS of 2X to 3X fold over the observed ECS, and the models’ double ITCZ are all symptoms of the same underlying need to push the model predicted ECS into the thermageddon, boogeyman realm of scaremongering. They have to use water vapor condensation in the tropical mid-troposphere to get the amplification needed.
It’s like trying to push on a water ballon to give it the shape one thinks it needs to have, it just bulges out somewhere else. The modellers are just hoping the “somewhere else” is where folks won’t notice.

Dave Fair
April 18, 2023 11:26 am

Willis, you are nothing but a damned right-wing climate denier, denying the double ITZ that is clearly shown in the state-of-the-art UN IPCC climate models. There are multiple lines of evidence showing that our climate is seriously out of balance and careening into chaos if we don’t get to Net Zero by 2050 at the latest. The UN has declared a climate Code Red that demands immediate action by all peoples on the planet.

Reply to  Dave Fair
April 18, 2023 10:28 pm

I reckon that the entire Code Red could be mitigated just by changing a single parameter. Isn’t that a public service worth doing?

April 18, 2023 11:44 am

Notes on Greenhouse Atmosphere:

1) Greenhouse Effect is Real (IR active gases)

2) Greenhouse Effect builds until critical Rayleigh threshold is met.

3) Rayleigh threshold is that critical difference between “top” and “bottom” temperature at which fluid dynamic motions kick in.

4) Fluid dynamic motions limit the difference between “bottom” and “top” temperature of atmosphere.

5) The Rayleigh threshold is determined by the adiabatic atmospheric density profile & hydrodynamic freedom (phase changes).

6) Atmosphere cannot violate the Rayleigh threshold. Once settled into exchange equilibrium, Top and Bottom temperature are in fixed proportion irrespective of IR forcing.

7) Greenhouse effect builds until the critical point of instability (i.e. the difference between top and bottom temperature set by atmospheric material properties).

8) Under such constraints in the fluid atmosphere, atmospheric radiative imbalance, and atmospheric-surface imbalance, is immediately compensated by non-radiative flux.

9) Atmosphere absorbed flux = Downward emitted flux, including between atmosphere and surface. This, because of riding the Rayleigh threshold.

10) Surface-Atmosphere flux discontinuity is imaginary.

In conclusion: Greenhouse effect is real, while at the same time there is no net radiative flux within surface-atmosphere system.

This, because the Earth is already riding the critical point of hydrodynamic instability. The greenhouse effect builds until reaching the Rayleigh threshold, at which point the greenhouse effect becomes fixed. This “natural” greenhouse effect can no longer be perturbed by trace gas emission.

Greenhouse Climate Models will never function correctly until this is understood. The boundary condition flux proportion is fixed (top and bottom). Those who argue that because there is no net flux between surface and atmosphere that therefore there can be no greenhouse effect are wrong. The greenhouse effect is real, but it cannot be enhanced by trace gas emission. The atmosphere is already fully dynamic.

The boundary conditions are in fixed proportion, but internal dynamics are free to change.

Reference: “On Convection Currents in a Horizontal Layer of Fluid, when the hotter Temperature is on the Under Side. By Lord Rayleigh 1916”

Last edited 1 month ago by JCM
Reply to  JCM
April 18, 2023 1:26 pm

observational global fixed greenhouse boundary proportion is 3 units atmosphere absorbed (bottom) to 2 units outgoing flux (top).

Frank from NoVA
Reply to  JCM
April 18, 2023 4:29 pm

Much to think about. Would it be fair to say that Earth attained max Greenhouse, i.e., became insensitive to further changes in GHG concentrations, a gazillion years ago, and that since then AST (average surface temperature) has simply been a function of plate tectonics, orbital mechanics, etc.?

Reply to  Frank from NoVA
April 18, 2023 6:11 pm

hi Frank,

you could assume ‘max greenhouse’ is achieved once you have a moist condensing atmosphere.

With unlimited water in all its phases the critical threshold for max greenhouse is relatively low.

April 18, 2023 11:55 am

It is disgusting, I loathe liars and cheats. I view everybody in the climate alarmist crowd as a liar and a cheat.

April 18, 2023 1:20 pm

Years ago, climate catastrophists were predicting warming at the top of the tropopause and would be THE PROOF of the anthropogenic fingerprint etc etc, That warming never happened and the catastrophists then forgot all about it. Now they are back on the tropopause: They have discovered that the top of the tropopause has risen about 50 to 60 meters per decade over the past 20 years. So that’s about 100 to 120 meters in twenty years.

The tropopause is 7 to 20 km (4 to 12 miles) above sea level.

I had a look through my telescope, and there it was: High up in the sky. It says: END OF THE TROPOPAUSE.

Last edited 1 month ago by Sceptic-Al
John Oliver
Reply to  Sceptic-Al
April 18, 2023 3:52 pm

Al Gore told the children “way way up high above the Earth there is a dome”

Clyde Spencer
Reply to  John Oliver
April 18, 2023 8:05 pm

I think that it was also revealed in “The Truman Story,” starring Jim Carrey.

April 18, 2023 1:29 pm

story tip https://twitter.com/AFP/status/1647520201850896384
the nutters want to ban rice growing

Last edited 1 month ago by HB
Henry Pool
April 18, 2023 1:38 pm

Ja. Ja. I say it again. I told you. The current drought on the pampas of ARG.
The Summer drought now coming to the USA and EU.
It is all because of the GB cycle. I predicted it all back in 2019.
Pity that nobody believes me.

April 18, 2023 2:32 pm

There is only one ITCZ and it moves back and forwards across the equator as each hemisphere transitions from winter to summer and then back to winter.
In the 1990’s I was based in Central Kalimantan about the same distance south of Balikpapan as north of Banjarmasin where I recorded the rainfall on a daily basis and graphed the results. I found that the rainfall reached a peak towards the end of the calendar year then fell away before reaching an even higher peak in about April when the major flooding of the rivers occurred. Each peak coincided with the ITCZ transitioning over the equator. During the middle of the year it became very dry, even no rain at all for a couple of months in one year.

Kelanis rainfall graph 1.png
April 18, 2023 5:07 pm

An alternative view:


NASA’s QuikSCAT satellite has confirmed a 30-year old largely unproven theory that there are two areas near the equator where the winds converge year after year and drive ocean circulation south of the equator. By analyzing winds, QuikSCAT has found a year-round southern and northern Intertropical Convergence Zone. This find is important to climate modelers and weather forecasters because it provides more detail on how the oceans and atmosphere interact near the equator.

Clyde Spencer
Reply to  Willis Eschenbach
April 18, 2023 8:10 pm

SCAT is a word commonly used by biologists in polite company to describe animal feces. Perhaps that provides some insight on the quality of the data from QuickSCAT.

April 18, 2023 5:43 pm

Consider the positioning of the ITCZS as shown in Figure 1 then superimpose the ocean circulation patterns, it is apparent that the regions of high rainfall are associated with warm surface currents running mostly from west to east in the Atlantic and Pacific Oceans. There is an exception in the region over Indonesia but there is a warm current in the Indian ocean that flows from east to west towards Indonesia. You will see this in the following map.

comment image

It would seem to me that the models have not taken ocean circulation into account.

Rud Istvan
Reply to  tmatsci
April 19, 2023 7:26 am

You are generally correct. The ocean layers are generally just slabs.

Joel O’Bryan
April 18, 2023 7:59 pm

Precipitation is the result of the heat transport process of convection and condensation. It happens because latent heat of vaporization is converted to sensible heat as the water condenses out high in the troposphere into precip, and thus the converted energy can be released to space.
The reason the CMIP modellers have to force their hindcasts have more precip than observation is so to match the surface temperature reconstructions, otherwise the models would run far too hot in the past and would be glaringly wrong to the casual observer. So to cool the models (so as not to elicit much non-expert scrutiny), they fudge-in via parameterization the needed precip to transport heat to the tropopause in the equatorial regions to match the surface temperature history.

The entire CMIP modelling effort to justify a great restructuring of Western economics (the Great Reset) is just based on nested lies on top of nested lies, it’s lies all the way down through the climate scam onion.

April 18, 2023 9:49 pm

WOW ! Richard Betts ? He’s sticking his head up above the parapet again ? Never mind, with that level of BS it’ll be trimmed off again. 🙂

Last edited 1 month ago by Streetcred
April 19, 2023 10:13 am

Thank you Willis Another great rebuttal line.

%d bloggers like this:
Verified by MonsterInsights