[ad_1]
Norel Rimbu attended courses at the Faculty of Physics at AI Cuza University in Iaşi, after which he specialized in the field of atmospheric and globe physics at the Faculty of Physics at the University of Bucharest. After graduating from this specialization course, the equivalent of the current master’s degree, in 1987, according to the legislation of the time, he was assigned to the National Institute of Meteorology and Hydrology (INMH) in Bucharest.
He worked at the INMH for a period of three years (1988-1991). For a relatively long period of time, from 1992 to 2015, he was an assistant and then a university professor at the Faculty of Physics at the University of Bucharest. During this period he also held various temporary positions in international research institutions in the field, such as the Max Planck Institute for Meteorology (MPI), Hamburg, Germany, the University of Bremen (UB), Germany or the Laboratoire de Mereorilogie Dinamique (LMD) . ), Paris France. Rimbu currently holds a permanent position as Principal Investigator at the Alfred Wegener Institute for Polar and Marine Research (AWI), Bremerhaven, Germany.
“Adevărul” spoke with Norel Rimbu about what awaits us this winter, how often it will snow, and what predictions exist for spring 2021.
Truth: Everyone talks about the weather and climate, but very few differentiate between the two. How would the specialist explain what one means and what the other means?
Norel Rîmbu: Climate describes the state of the atmosphere at a given moment. The phenomena that determine the variations in meteorological variables, such as the air temperature at a certain point, the daily amount of precipitation, etc., evolve in a few days to a week or two. Examples of this are atmospheric fronts, cyclones, anticyclones, etc.
Climatic variables are statistical quantities determined by meteorological variables. For example, the monthly average air temperature at a given point is a climatic variable. Variations in climatic variables are determined by processes with a time scale greater than those of climate. Examples of this are Madden-Jullian Oscillation (MJO), El Niño-South Oscillation (ENSO), North Atlantic Oscillation, etc. So up to two weeks we are talking about weather, more than two weeks of weather, although this limit is not precisely defined.
– We are used to being told that almost every winter, before each winter, we will have the coldest winter in recent years, and before the arrival of summer they will tell us that we will have the hottest summer. However, most of the time these predictions do not come true. What else are they made for and why do they make such big mistakes?
Medium and long-term climate forecasts, and I am referring here to those forecasts with an anticipation period of more than two weeks, are especially useful for various sectors of activity such as agriculture, the energy industry, tourism and many other socio-economic areas . Unfortunately these forecasts are not extremely accurate and I will explain why. On the one hand, the climate system is particularly complex, so that not all processes within it can be included in mathematical prediction models, models known as climate models. On the other hand, the mathematical equations that make up these models are non-linear, so they must be solved numerically with the help of a computer. During the iterative, step-by-step solution of these equations, the initial errors are amplified, due to errors inherent in the initial data. As the forecast interval increases, the errors increase, and obviously the precision of the predicted values decreases. These two causes, that is, the non-inclusion of all physical, chemical, biological processes, etc. in climate models and the non-linearity of the equations are associated with errors in medium and long-term climate predictions.
Where can we find the weather?
– Are there other alternatives for a forecast to be as close as possible to reality?
An alternative to numerical prediction, that is, based on climate models, is statistical prediction. Mainly, some mathematical relationships are established between predictors (variables that are predicted) of a given time point and predictors (variables used for prediction) of previous time points. These relationships are established using measurement data. And these forecasts have their limitations.
Both numerical and statistical forecasts are now accurate enough to provide clear benefits to those who use them. I will continue to refer to numerical forecasts.
As I said before, numerical predictions have complex mathematical equations behind them, inaccessible to people without proper mathematical training. We can only describe what these models predict and try to understand these predictions qualitatively. There are several centers in the world that provide long, medium and long-term climate forecasts.
“Could you give us some examples of this?”
I will refer to some centers whose forecasts for the coming weeks and months will be compared. The first is METEOBLUE. Provides weather forecasts (7 to 14 days in advance) and climate (monthly and seasonal). It is interesting that the text can be translated into different languages, including Romanian (https://www.meteoblue.com/ro/vreme/current/bucure%c8%99ti_rom%c3%a2nia_683506). I highly recommend the site.
Another center is the European Forest Fire Information System (EFFIS) (https://effis.jrc.ec.europa.eu/about-effis/)/ Here you will find real-time monthly and seasonal forecasts for Europe. Another center is the European Center for Medium-Range Forecasts (https://climate.copernicus.eu/seasonal-forecasts), where you can find global seasonal forecasts. Another example is the CPC of the Center for Climate Prediction in the United States (https://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml).
There are also forecast centers specialized in extreme events, such as SEVERE WEATHER EUROPE SWE (https://www.severe-weather.eu/), whose detailed information can be found on these sites.
A mild winter awaits us
– How would your forecasts be in Germany, what do you think awaits us for the early winter holidays?
Developing medium and long-term climate forecasts requires significant human and material resources. For this reason, there are a limited number of climate research centers in Europe, including Germany, and around the world that are operationally developing such forecasts.
As for the forecast for the winter holidays, it should be noted that it refers to the weather, not the weather. Because it’s about what happens, from a meteorological point of view, on a given day. Most of the forecasts in the mentioned sites point to higher temperatures in the Christmas area of our country. A low pressure center will dominate central and eastern Europe. The wind will be predominantly from the southwest so the warm air will reach the area of our country causing high temperatures. For the following days, information can be obtained from SWE (https://www.severe-weather.eu/#) –
– Are we risking a freezing winter or do current data indicate a mild winter?
The temperature forecast for January and February 2021 prepared in most forecast centers indicates positive thermal anomalies in the area of our country. Temperatures above normal values will be recorded in the coming months. For more information, visit the sites listed above. So to answer your question, we expect a warmer than normal winter in Romania.
– Lovers of winter sports, and not only them, are curious to know if we will have snow. What could you tell them?
The amount of precipitation is more difficult to predict. The centers mentioned above indicate negligible precipitation anomalies in January and February 2021 in Eastern Europe. This means that, in our area, we will have rainfall close to normal in these winter months. Visit the sites mentioned above for more details. But not just for details. These forecasts are constantly updated and it is a good idea to use the updated forecasts, which are probably the closest to reality.
– Maybe it’s premature, but I’m still asking you what data you currently have about spring 2021.
Based on the data we have at the moment, we expect spring to arrive with higher temperatures than usual.
Why extreme weather events have multiplied
– In recent years there has been more and more talk about severe weather phenomena and the fact that they seem to be more and more, from year to year. What would be the main causes?
There are a multitude of causes. I will refer to a phenomenon that could occur in early January 2021. Sudden stratospheric warming (SSD) can be related to severe weather events. Such a phenomenon is expected early next month. (Https://www.severe-weather.eu/global-weather/stratophere-major-winter-warming-watch-january-2021-fă/).
I will briefly explain what that means.
The atmosphere has several layers. The layer that extends from the surface to 8-16 kilometers if we speak of the polar or equatorial region, is called the troposphere. Above is the stratosphere, which extends for about 50 kilometers. During winter, in the stratosphere, the so-called polar vortex (polar vortex) is formed. It is an air circulation from west to east (cyclonic direction) that surrounds the north pole. The stratospheric vortex extends downward vertically and becomes less and less defined, due to surface disturbances: mountains, oceans, etc. As seen in the image below.
Under certain conditions, the stratospheric vortex weakens or even “collapses” being temporarily replaced by another type of circulation, including an “anti-vortex”, in which the circulation is from east to west. So opposite to the one shown in the previous figure. Cold air descends rapidly into the polar region, leading to a rapid rise in stratospheric temperature of up to 50 ° C in just a few days. Hence the term sudden stratospheric warming. Cold air in the stratosphere disperses and reaches the troposphere and affects the jet stream. The change in the jet stream causes severe weather disturbances, including severe weather events.
SSWs are often associated with blockade movements in the North Atlantic and Scandinavia. This meant that in England the climate would be cold and dry, and in southern Europe it would be hot and humid.
This phenomenon is scheduled for early January 2021. Of course, this is not in contradiction to a warm winter in Eastern Europe, as most models predict.
I want to be clear that weather forecasts are not as accurate as weather. That is why you should always consult the latest forecasts developed by prestigious (credible) climate research centers in Europe and beyond. Compare these forecasts and take the risk by making decisions based on the information these forecasts provide. As I mentioned, the forecasts are not perfect, but statistically speaking, they certainly provide substantial benefits to those who use them.
We also recommend:
If you like this article, we hope you will join the community of readers on our Facebook page, by liking it below:
[ad_2]