≧2s),
it is considered an abnormally high temperature. Meanwhile, when
monthly mean air temperature anomaly is below or equal to negative two times of
standard deviations (D
≦-2s),
it is considered an abnormally low temperature.INSTRUCTION
1.
Global real time surface temperature, precipitation data are originated from
CLIMAT report (CS report) via Global
Telecommunications System (GTS)
and part of the data of China’s stations are
originated from AB report.
2.
Global historical surface temperature and precipitation data are from National
Meteorological Information Center (NMIC) of CMA and National Climate Data Center
(NCDC) of USA and there are totally 3285 stations over the world in the data
set. The base period for normals is from 1971 to 2000.
3.
Global real-time upper air data are the 12Z reanalysis data from National
Meteorological Center (NMC), CMA, and then changed into grid data in 2.5°´2.5°.
4.
Global historical upper air data are National Centers for Environmental
Prediction (NCEP) reanalysis grid data, in 2.5°´2.5°
and the base period for normals is from 1971 to 2000.
5.
Real-time and historical SST data are NCEP grid data in 1°´1°,
and the base period for normals is from 1971 to 2000.
6.
Real-time and historical subsurface ocean temperatures are from NCEP, and the
base period for normals is from 1980 to 1997.
7.
Monthly mean OLR are NCEP grid data in 2.5°´2.5°,
and the base period for normals is from 1979 to 2001.
8.
Sunspot number is from Belgium Solar Influences Data analysis Center.
9.
Historical Darwin and Tahiti sea-level pressures are from National Climate
Center, Bureau of Meteorology, Australia, and the base period for normals is
from 1971 to 2000. Meanwhile, the real-time data are from ES40 real-time
database of NMIC, CMA.
10.
Snow cover data are from NOAA (National Oceanic and Atmospheric Administration)
/NESDIS, and the base period for normals is from 1973 to 2002.
1.
Defining Season and Year
Defining
Season is referred to the Northern Hemisphere. Winter, Spring, Summer and Autumn
are from last December to February, from March to May, from June to August and
from September to November, respectively. Year is from last December to
November.
2.
According to WMO’s standards, defining abnormal climate is as following:
Air
temperature: When monthly mean air temperature anomaly is greater than or equal
to two times of standard deviations (D
≧2s),
it is considered an abnormally high temperature. Meanwhile, when
monthly mean air temperature anomaly is below or equal to negative two times of
standard deviations (D
≦-2s),
it is considered an abnormally low temperature.
Precipitation:
When precipitation total is below or equal to the minimum for the
base period, it is considered an abnormally dry condition. Meanwhile, when
precipitation total is above or equal to the maximum for the
base period, it is considered an abnormally wet condition.
3.
For the 500hPa circulation indices
Eurasia
and Asia circulation indices: The regions are 45°N~60°N,
0°~150°E
and 45°N~60°N，60°E~150°E.
The calculation methods are introduced in 《Articles
of Meteorological Science Research Institute, CMA》,
1965. 9.
Polar
Vortex area index: The regions for Asia, the Pacific and the Northern Hemisphere
are between 60°E~150°E,
150°E~120°W
and 0°~360°,
respectively. The calculation methods are introduced in 《Reports
of Jilin Province Meteorological Research Institute》,
No. 2, 1989.
The area indices of the Northern Hemisphere and the Northwestern Pacific subtropical highs are the numbers of grids where geopotential height is greater than or equal to 588 dam over regions between 0°~360° and 110°E~180°, respectively. Intensity index is the accumulation of the difference between geopotential height and 587 dam for each of the above grids in a certain region.
The
Qinghai-Tibet Plateau index is defined as the accumulation of the difference
between geopotential height and 500 dam for every grid in a certain region.
There are two different indices for different regions: region A is 25°N~35°N，80°E~100°E,
and region B is 30°N~40°N,
75°E~105°E.
The Qinghai-Tibet Plateau index in fig.3.12 is that for region B.
India-Burma
trough index is defined as the accumulation of the difference between
geopotential height and 580 dam for every grid in the region of 15°N~20°N，80°E~100°E.
4.
Other indices
SST indices are
defined as the averages of SST and SSTA for a certain region. There are several
different regions, where the composite NINO region ( NINO Z) is composed of
three regions: NINO 1+2, NINO 3 and NINO 4, and the NINO Z index is
area-weighted average of the three different indices. Details refer to 《Acta
Meteorological Sinica》,
2000,Vol. 58, No. 1: 102~109.
Warm Pool Intensity
Index is defined as the standardization of the series of the accumulation for a
certain region of the difference between SST and 28℃
for a grid where SST is greater than 28℃.
There are two different regions:
the Western Pacific warm pool region is 30°N~30°S,
120°E~180°
and the Indian Ocean warm pool region is composed of 30°N~8°S,
41°E~98°E
and 8°S～30°S，41°E~120°E.
Southern
Oscillation Index (SOI) is defined as the standardization of the series of the
difference between standardized Tahiti and Darwin sea-level pressures. For the
SLP in Table 4.1, the upper value is the difference between actual values of SLP
and 1000hPa, while the lower value is SLP anomaly.
Convection
Oscillation Index (COI) is defined as the standardization of the series of the
difference between the standardized the certral and eastern equatorial Pacific
OLR and the western equatorial Pacific OLR. Details refer to 《Quarterly
Journal of Applied Meteorology》,
1998, Vol. 9, No. 2: 169~177.
Wind Index is
defined as the standardized area-mean zonal (or meridional) wind for a certain
region.
The definitions of
Meiyu start and end dates refer to 《Acta
Meteorological Sinica》,
1965，Vol.
35, No. 4: 509~518.
The key region of
South China Sea monsoon is composed of 10°N
~20°N,
110°E
~120°E.
5.
Graphics
Contour
values in Figs for 100hPa geopotential height are the differences between the
actual values and 1600dam.
In
Figures 3.9~3.12, solid lines with the mark “ｏ”
represent actual values of the month, while dashed lines represent normals.
Figure
4.3, Figure 4.12, Figure 4.13 and Figure 4.17 are for the average in a belt
between 5°N~5°S.
In
Figure 4.8 and Figure 4.13, column represents actual value of the month, while
line represents five-month running mean.
Distribution
of the SST monitoring regions is shown in the map in page 2.