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Climate of 2004 - April in Historical Perspective National Climatic Data Center 13 May 2004
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Global Analysis / Global Hazards / United States / U.S. Drought / Extremes
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access detailed analyses of Global and U.S. data.
Global Highlights:
- Based on preliminary data for April 2004, global average combined land and sea surface temperature was third warmest on record
- April temperatures were above average throughout Scandinavia, the western United States, Alaska and India, with below average temperatures in the southern U.S., western Russia and the Carribean
- Precipitation during April was above average across the southern Great Plains of the U.S., western Europe and the United Kingdom with drier than average conditions across Japan, coastal Brazil and the Pacific Northwest of the U.S.
- Near-normal SSTs across the central and eastern equatorial Pacific basin are indicative of neutral ENSO conditions.
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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.
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Introduction
The map below uses anomalies that were calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. This map indicates above average temperatures across eastern Asia, most of Australia, Alaska and the western United States, while cooler than average temperatures occurred in Mexico, portions of Canada and the southeastern U.S.
The mean position of upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500 millibar height anomalies during April 2004) 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
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April |
Anomaly |
Rank |
Warmest Year on Record |
Global
Land
Ocean
Land and Ocean
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+0.84°C (+1.51°F) +0.39°C (+0.70°F)
+0.52°C (+0.94°F)
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5th warmest 3rd warmest 3rd warmest
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1998 (+1.24°C/2.32°F) 1998 (+0.51°C/0.92°F) 1998 (+0.73°C/1.31°F)
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Northern Hemisphere
Land
Ocean
Land and Ocean
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+0.79°C (+1.42°F) +0.47°C (+0.85°F) +0.60°C (+1.08°F)
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9th warmest warmest 3rd warmest
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1998 (+1.26°C/2.27°F)
1998 (+0.78°C/1.40°F)
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Southern Hemisphere
Land
Ocean
Land and Ocean
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+0.74°C (+1.33°F)
+0.35°C (+0.63°F) +0.42°C (+0.76°F)
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4th warmest 7th warmest 5th warmest |
1998 (+1.09°C/1.96°F) 1998 (+0.56°C/1.01°F) 1998 (+0.66°C/1.19°F)
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January-April |
Anomaly |
Rank |
Warmest Year on Record |
Global
Land
Ocean
Land and Ocean |
+1.01°C (+1.82°F)
+0.40°C (+0.72°F)
+0.59°C (+1.06°F)
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3rd warmest 4th warmest 3rd warmest |
2002 (+1.38°C/2.49°F) 1998 (+0.52°C/0.94°F)
1998 (+0.73°C/1.31°F)
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Northern Hemisphere
Land
Ocean
Land and Ocean
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+1.12°C (+2.02°F)
+0.45°C (+0.81°F) +0.72°C (+1.30°F)
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4th warmest 2nd warmest 3rd warmest
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2002 (+1.61°C/2.90°F) 1998 (+0.51°C/0.92°F) 2002 (+0.86°C/1.55°F)
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Southern Hemisphere
Land
Ocean
Land and Ocean
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+0.58°C (+1.04°F)
+0.39°C (+0.70°F) +0.43°C (+0.77°F)
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6th warmest 7th warmest 6th warmest
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1998 (+0.88°C/1.58°F) 1998 (+0.54°C/0.97°F) 1998 (+0.60°C/1.08°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 April 2004, much above average precipitation fell across the southern Great Plains of the U.S., France, southeastern Brazil and Uruguay. Below average precipitation was observed across Malaysia, the southeastern U.S., the northern Great Plains of the U.S. and Japan.
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Troposphere
The tables below contain mid-tropospheric conditions for April 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 April is 0.04°C/decade based on data from the University of Alabama at Huntsville (UAH) and 0.13°C/decade based on data provided by Remote Sensing Systems (RSS). The base period used in both data sets is 1979-1998.
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April |
Anomaly |
Rank |
Warmest Year on Record |
| UAH mid-troposphere
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+0.11°C (+0.20°F)
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6th warmest
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1998 (+0.71°C/1.28°F)
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| RSS mid-troposphere
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+0.32°C (+0.58°F)
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3rd warmest |
1998 (+0.74°C/1.33°F)
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