zzzChanghengChen-MatlabResults

=Basic parts:=

1. Download and read...
My language code files for making the below figures are linked below. I started from scratch. Question 2: Question 3: Question 4: Question 5:

===2. Calculate zonally averaged P and v over longitude, and plot the resulting latitude-time series.===

Here is the latitude-time sections of P in the zonal mean, and at 91.25°W:



Zonally averaged precipitation shows higher value along the equator from January through April. During this period of time, precipitation is unevenly distributed between around 91.25°W and the other parts of the world. In other words, a deficit of precipitation around 91.25°W comes along with a surplus somewhere else. While in the following months, there is no big difference between the precipitation in zonal mean and at 91.25°W. However, this does not necessarily indicate evenly distributed precipitation.

Here is the latitude-time sections of v in the zonal mean, and at 90°W:



Generally speaking, meridional wind at 90°W is stronger than that in the zonal mean along the equator and south of 60°S. While a comparison of the meridional extension of the meridional wind reaches an interesting conclusion: the meridional wind "bands" along the equator and south of 60°S are wider in the zonal mean.

===3. Average air temperature over both lat and lon, to make a 12-month time series. Which season has the warmest global mean surface temperature? Can you understand why?===

Global mean surface temperature has a mild annual cycle:

Two main reasons lead to the "bell" shape distribution with a peak in July of the globally averaged air surface temperature. (1) There is an unequal distribution of land and water between the Northern and Southern hemispheres. (Northern Hemisphere : 60.7% land, 39.3% water; Southern Hemisphere: 80.9% water, 19.1% land) (2) For several reasons, including a low heat capacity compared with ocean, the land will heat up more quickly and cool off more rapidly as well. During Northern summer, a dominant portion of solar radiation comes to the Northern Hemisphere. The 60.7% land warms up fast and causes a significant increase in surface air temperature. While during Southern summer a relative low surface air temperature is expected.

===4. Make a map of the temporal (i.e. seasonal) standard deviation of precipitation, expressed as a percentage of the annual mean precipitation. This might be one definition of a "monsoonal" climate.=== Here is a map expressing the seasonality of precipitation:

Places with intensely seasonal rainfall tend to be Sahara desert, western Middle East and central Asia, Australia, southern Africa and over Pacific cold tongue.

5. What is the space-time standard deviation of 'air' (temperature)?
The total space-time standard deviation of temperature is 15.22°C. The challenge of computing it is that we want area averages over the Earth, but we started with lat-lon grids. A simple call of stdev(air array) gives 21.78°C, which is too large. It is mainly because without taking latitudinally-weighted average, the space-time standard deviation of the surface air temperature at high latitudes from the mean is exaggerated.