2011-05-10 10:31:34Soils of UK and Europe drying out
Daniel Bailey
Daniel Bailey

Soils of UK and Europe drying out

SMOS satellite images showing europe drying out between March and April 2011

As much as we all enjoy the warm weather, some rain would be welcome.

The scale of just how dry the start of 2011 has been is evident in some fascinating data from one of Europe's latest Earth observation satellites.

Smos senses the moisture in the top layers of soil, and it is very clear in these maps that the ground across the UK and much of Europe is now gasping for water.

Last month was the warmest April on record in Britain.

It was also the 11th driest month, with on average just half the usual rainfall. And in parts of south-east England, there was less than 10% of normal precipitation.

Smos artist's impression (Cesbio)  
"Space chopper": The Smos radiometer makes the satellite look like a helicopter

Smos is an experimental mission of the European Space Agency (Esa), and is providing some novel information to meteorologists, hydrologists and other scientists interested in how water moves around the globe.

The 760km-high satellite carries an 8m-wide interferometric radiometer that senses the natural emission of microwaves coming up off the planet's surface.

Variations in the water content of soils will modify this signal.

The maps at the top of this page - which were specially prepared for the BBC - are monthly averages. Blue colours denote wetter earth; yellow colours show drier conditions.

The comparison between the two maps illustrates neatly the process of drying out through March and April.

Data from Smos agrees well with recorded rainfall patterns.

Traditionally, meteorologists have used air temperature readings taken just above the ground to infer soil moisture content. Smos is providing a new means to get at this information.

Rainfall anomaly (Met Office)

Understanding how much water is held in the earth under our feet is a key variable if you want to make weather forecasts.

If soils are wet then much of the energy coming from the Sun will be used to evaporate water from the ground, keeping temperatures cooler than they would otherwise be. Generally speaking, more precipitation would be initiated as well.

But if soils are dry, then the water available for evaporation is limited. As a result, the incoming solar energy will warm the surface, raising the temperatures above it. Over a sustained period, this can lead to drought conditions.

At the European Centre for Medium-Range Weather Forecasts (ECMWF), researchers are experimenting with Smos data.

The ECMWF, which is based at Reading, UK, produces forecasts that look 10 days ahead and more, including making seasonal forecasts.

"We already have soil moisture data in our forecast system which does not use Smos, and our soil moisture data is already quite good. But there is potential to improve it with Smos," said the centre's Dr Patricia de Rosnay. "At the moment we are not sure at what range into the future, Smos data will be most useful to us in making forecasts."


  • 1929 - 57.8mm - Driest (since 1910)
  • 1947 - 258.2mm - Wettest (since 1910)
  • 2011 - 86.5mm - 4th driest (since 1910)

April alone was the 11th driest month (since 1910 for the UK) at 36.7mm


Some studies that were competed after the great European heatwave of summer 2003 showed that if more had been known about the relative dryness of soils in the springtime, meteorologists might have been in a much better position to predict the extreme conditions that followed a few months later. It is an area for ongoing research.

Smos was launched in October 2009. Its radiometer instrument will also measure variations in the saltiness of seawater, a capability which is reflected in the mission's full name: Soil Moisture and Ocean Salinity (Smos) satellite.

The investigation of soil moisture data is led from the Centre for Spatial Studies of the Biosphere (Cesbio) in Toulouse, France.

2011-05-10 10:32:47
Daniel Bailey
Daniel Bailey

Shades of The Dai After Tomorrow...

2011-05-10 13:06:35
Julian Brimelow

Hi Daniel,

Yeah, saw that.  Shades of 2003 perhaps?  Everything could change in a matter of weeks though, so I do not wish to be a pessimist.  With that said, here is what IRI are predicting for Europe in JJA:

No signal, yet, for the precipitation though.  ANyhow, base don the IRI data (and they are a first-rate group), I would not be surprised if there were not a major heat wave this coming summer in Europe.  I would gladly be wrong though, as we sadly know all too well, heat waves kill.


And here is the expected big picture (lots to comment on, but look at Greenland....):


And this is what NASA is expecting:

2011-05-10 13:24:54Invest in Air Conditioning manufactureres, eh?
Daniel Bailey
Daniel Bailey

Thanks, Albie.

From Wayne Davidson's blog, 3-26-2011 entry:

This leaves the problem of seeing how fast El-Nino will be back.  Arctic Low pressures have huge consequences elsewhere.  If this continues,  Europe in particular Western Russia, will be in the same predicament as last summers great heat wave,  but first they will feel chillier by the very cold stratosphere just above, once the vortex finally expires the reverse will strike.

He has more, later entries which foretell less issues for Russia than last year, but leave the spectre of 2003 conditions for Europe, as you mention.  He's of the opinion El Nino will be back, possibly before the end of the Arctic melt season.

To mix metaphors, gonna be a dicey crapshoot...

2011-05-10 13:38:12
Julian Brimelow

Yes, the dice are loaded.

I must check out Wyane's blog, sounds intriguing.

Most modelling groups are predicting neutral conditions by the end of May or in early June, with possibly even El Nino conditions by late summer.  GMAO (NASA model) is by far the most aggressive, and probably an outlier.  However, the SOI has decreased markedly in recent weeks, and that suggests that the current La Nina may be almost over, although its affects will linger for another 5 months or so.  People like johnd hoping for a redevelopment of a La Nina are showing their desperation.....

Anyways, barring a huge equatorial strato volcano blowing its top, 2012 could be very toasty, especially with a little help from the sun.

2011-05-10 16:27:11
Paul D


It has certainly has been dry. We had 3 trees planted along a public path in the winter near where I live (1 oak and 2 field maples), paid for by my tree group and I was getting worried. Trouble is, the recent short bursts of heavy rain do not get deep down in the soil. You can see that despite a heavy rainfall the ground is dry again after a few hours, as the heat evaporates the water.
Fortunately the trees do have foliage although the Oak was late in developing foliage. Will have to monitor them over the summer.

2011-05-10 16:48:31
Rob Painting

Ville, we had a bad drought last year in northern NZ (El Nino typically induces a cool/dry trend where I live). A few of our smaller trees carked it. Wasn't something I was aware of before, but the drought caused the soil to form a crust, when you began watering it would run off with very little moisture being absorbed into the soil. Of course, now we're in La Nina it's warm and won't stop raining. Trees, and our small patch of forest, are great though!.

Yooper/Alby, not looking good for Europe, definite heatwave potential developing. That Iberian Peninsula in particular seems in dire straits, given trends over the last couple of decades.

2011-05-10 20:55:41
Daniel Bailey
Daniel Bailey

It might be nice to write up a blog post on this.  A combination of "this is what the science says, this is what the models are predicting, so this is what to keep an eye on in these areas" type of thing.  A kind of SkS "Seasonal Forecast" segment.

Something that could be revisited later to see how projections panned out (that would be a skeptical thing to do).

2011-05-10 21:06:46


Here in Norway we also have very, very dry conditions for the season. Very little snow which meltet away in a hurry - April was a record high in temperatures (last 100 years of recorded history). We had forrest fires late in April - never heard of here in Norway as far as I know. The forrest fires are continuing now in may.

A bit further north at Hopen Radio (Svalbard) they now have had 30 days with a daily average of 7.4 degrees C above normal. But they have a heliport, so I guess thats the reason ;-)

2011-05-10 22:43:43
Rob Painting

Yooper - sounds like a splendid idea!.

Oslo - yeah, yeah, record events happen all the time! (just joshin')

2011-05-11 01:47:38
Paul D


As it happens I was at a tree warden meeting today and the issue of caring for newly planted trees was mentioned. I mentioned this satellite research in the meeting.
For most species in the UK apparently the amount of watering (by humans) is crucial. To little and the trees roots aim for the surface whcih can lead to death. We were advised that either a lot of watering or none at all is best. With a lot of water, the water goes deeper and the roots act normally, same really with no watering.

I decided being a novice, I would leave our newly planted trees alone, just in case I got the amount wrong.

2011-05-11 02:00:17
Julian Brimelow

The Ville,

Where I live it is by nature quite dry.  We use a root feeder every spring to help give the shrubs and trees a start.  Getting the moisture down to the root-zone is critical.  This is what we use.  Not sure if they are available across the pond.


2011-05-11 04:34:08
Paul D


These trees are in a public space Albatross, so such gizmos are not practical. They would be vandalised.
They used to plant the trees with a pipe buried in the root ball, the water could be poured down the pipe.

But they don't seem to bother now. Probably the cost of regular watering was to much.

A contractor planted the trees. We found the funding for them.