State of the Climate
Global Analysis
July 2004
National Oceanic and Atmospheric Administration
National Climatic Data Center
Use the form below to access monthly reports.
Global Highlights:
- Based on preliminary data for July 2004, global average
combined land and sea surface temperature was sixth warmest on
record
- July temperatures were above average throughout Alaska, the
western half of North America and Scandinavia, with below average
temperatures in the Great Plains of the U.S. and adjoining parts of
Canada as well as the United Kingdom
- Precipitation during July was above average across the Great
Plains of the U.S., the majority of Europe and much of South
America, with drier than average conditions in Alaska, India and
Japan
- Near-neutral SSTs across the central equatorial Pacific basin
prompted forecasts of a developing El Niño.
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Contents of this Section:
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| The data presented in this
report are preliminary. Ranks and anomalies may change as more
complete data are received and processed. The most current data may
be accessed via the Global Surface
Temperature Anomalies page. |
 Introduction
The two maps below utilize different base periods and may reflect
different anomaly values of land surface temperatures. The dot map
on the left uses anomalies that were calculated from the Global
Historical Climatology Network (GHCN) data set of land surface
stations using a 1961-1990 base period. The map on the right is a
blended product
which uses satellite and surface anomaly values of measured land
and ocean temperatures as well as SSTs with the base period of
1988-2004. Both maps reflect conditions during July 2004,
indicating above average temperatures in Alaska, the majority of
Canada, the eastern half of Russia and Saudi Arabia, with cooler
than average temperatures in the Great Plains of the US, parts of
southern Australia, Mali and southern Brazil.
The mean position of upper level ridges of high pressure and
troughs of low pressure (depicted by positive and negative 500
millibar height anomalies on the July 2004 map)
are generally reflected by areas of positive and negative
temperature anomalies at the surface, respectively. For other
Global products see the Climate Monitoring
Global Products page. |
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Temperature Rankings and Graphics
Current Month / Year-to-date
| July |
Anomaly |
Rank |
Warmest Year on
Record |
Global
Land
Ocean
Land and Ocean |
+0.46°C (+0.83°F)
+0.38°C (+0.68°F)
+0.40°C (+0.72°F) |
7th warmest
4th warmest
6th warmest |
1998
(+0.98°C/1.76°F)
1998 (+0.52°C/0.94°F)
1998 (+0.66°C/1.19°F) |
Northern Hemisphere
Land
Ocean
Land and Ocean |
+0.49°C (+0.88°F)
+0.53°C (+0.95°F)
+0.51°C (+0.92°F) |
10th warmest
2nd warmest
5th warmest |
2002
(+0.93°C/1.67°F)
1998 (+0.57°C/1.03°F)
1998 (+0.70°C/1.26°F) |
Southern Hemisphere
Land
Ocean
Land and Ocean |
+0.36°C (+0.65°F)
+0.28°C (+0.50°F)
+0.29°C (+0.52°F) |
17th warmest
10th warmest
11th warmest |
1998
(+1.15°C/2.07°F)
1998 (+0.50°C/1.00°F)
1998 (+0.62°C/1.12°F) |
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| January-July |
Anomaly |
Rank |
Warmest Year on
Record |
Global
Land
Ocean
Land and Ocean |
+0.85°C (+1.53°F)
+0.38°C (+0.68°F)
+0.52°C (+0.94°F) |
3rd warmest
4th warmest
4th warmest |
2002
(+1.15°C/2.07°F)
1998 (+0.51°C/0.92°F)
1998 (+0.70°C/1.26°F) |
Northern Hemisphere
Land
Ocean
Land and Ocean |
+0.93°C (+1.67°F)
+0.44°C (+0.80°F)
+0.64°C (+1.15°F) |
4th warmest
2nd warmest
3rd warmest |
2002
(+1.29°C/2.32°F)
1998 (+0.52°C/0.94°F)
1998 (+0.77°C/1.39°F) |
Southern Hemisphere
Land
Ocean
Land and Ocean |
+0.49°C (+0.88°F)
+0.35°C (+0.63°F)
+0.38°C (+0.68°F) |
8th warmest
7th warmest
6th warmest |
1998
(+0.89°C/1.60°F)
1998 (+0.52°C/0.94°F)
1998 (+0.59°C/1.06°F) |
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The most current data may be accessed via the Global Surface
Temperature Anomalies page.
Precipitation
The maps below represent anomaly values based on the GHCN data set
of land surface stations using a base period of 1961-1990. The map
to the left is precipitation anomalies measured in millimeters, the
map to the right is the percentage of average (1961-1990)
precipitation. During July 2004, much above average precipitation
fell across the northeastern U.S., southeastern Asia, eastern
Europe and Argentina. Below average precipitation was observed in
the eastern half of Australia, India, Norway and Mongolia. |
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The satellite images below were acquired from SSM/I satellite data
using a base period of 1988-2004. The map on the left reflects
surface liquid wetness conditions, while the map on the right
reflects snow cover conditions for the month. Snow covered areas
that are normally snow-free during this month will appear drier
than average on the wetness image since a wetness value cannot be
determined for regions that are snow covered. Data in these areas
that are normally snow covered are displayed as missing. This is
due to the snow crystalline structure which produces a considerable
amount of scatter and makes it difficult for the SSM/I to
accurately detect the surface conditions. The SSM/I products are
experimental and are under continuing review and development.
Additional data and information can be found on the SSM/I Browser. |
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ENSO SST Analysis
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- Warming in the central equatorial Pacific prompted forecasts of
a developing El Niño (as shown in the adjacent animation of
weekly sea surface temperature anomalies). A consensus of indices
suggests near-neutral ENSO conditions. A comprehensive summary of
July 2004 ENSO conditions can be found on the ENSO monitoring
page. For the latest advisory on ENSO conditions go to NOAA's Climate Prediction
Center (CPC) and the CPC ENSO Diagnostic
Discussion
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- Images of sea surface temperature conditions are available for
all months to date during 2004
at the weekly SST page
Troposphere
The table below summarizes mid-tropospheric conditions for July
2004. These temperatures are for the atmospheric layer centered in
the mid-troposphere (approximately 2-6 miles above the Earth's
surface) which also includes a portion of the lower stratosphere.
(The MSU channel used to measure mid-tropospheric temperatures
receives about 25 percent of its signal above 6 miles.) Analysis of
the satellite record that began in 1979 indicates that global
temperatures are increasing in the mid-troposphere, but the
magnitude of the trend differs based on the analysis methods used
in adjusting for factors such as orbital decay and inter-satellite
differences. The 1979-2004 trend for July is 0.05°C/decade
based on data from the University of Alabama at Huntsville (UAH).
Based on data provided by Remote Sensing Systems (RSS) the trend
for July is 0.12°C/decade. The base period used in both data
sets is 1979-1998.
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July |
Anomaly |
Rank |
Warmest Year on
Record |
| UAH mid-troposphere |
-0.17°C (-0.31°F) |
6th coolest |
1998
(+0.47°C/0.85°F) |
| RSS mid-troposphere |
+0.04°C (+0.07°F) |
13th warmest |
1998
(+0.54°C/0.97°F) |
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Stratosphere
The table below summarizes stratospheric conditions for July 2004.
The stratosphere is located between 10-14 miles above the Earth's
surface. Over the last decade, stratospheric temperatures have been
below average in large part due to the depletion of ozone. The large
increase in temperature in 1982 was caused by the volcanic eruption
of El Chichon in Mexico, and the increase in 1991 was a result of
the eruption of Mt. Pinatubo in the Philippines. Therefore the base
period used in both data sets is 1984-1990 which was chosen to
avoid contamination by these eruptions. |
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July |
Anomaly |
Rank |
Warmest Year on
Record |
| UAH stratosphere |
-0.32°C (-0.58°F) |
9th coolest |
1982
(+0.91°C/1.64°F) |
| RSS stratosphere |
-0.13°C (-0.23°F) |
13th coolest |
1982
(+0.85°C/1.53°F) |
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| Mid-tropospheric and lower stratospheric temperature data are
collected by NOAA's TIROS-N polar-orbiting satellites and adjusted
for time-dependent biases by NASA and the Global
Hydrology and Climate Center at the University of Alabama in
Huntsville (UAH). An independent analysis is also performed by
Remote Sensing Systems
(RSS). |
| For additional details on precipitation and temperatures in
July, see the Global Hazards page . |
References:
Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global
Historical Climatology Network Database. Bull. Amer. Meteorol.
Soc., 78, 2837-2849.
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