Upper Air - April 2017


Troposphere

Lower Troposphere

April Lower Troposphere
April Anomaly Rank
(out of 39 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.34 +0.61 Coolest 35th 1984, 1993 -0.33 -0.59 +0.15 +0.27
Warmest 5th 2016 +0.75 +1.35
RSS +0.27 +0.49 Coolest 35th 1985 -0.44 -0.79 +0.14 +0.26
Warmest 5th 1998 +0.74 +1.33
Year-to-Date Lower Troposphere
January–
April
Anomaly Rank
(out of 39 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.41 +0.74 Coolest 36th 1993 -0.36 -0.65 +0.16 +0.28
Warmest 4th 2016 +0.78 +1.40
RSS +0.28 +0.50 Coolest 35th 1985 -0.39 -0.70 +0.14 +0.25
Warmest 4th 2016 +0.72 +1.30
Ties: 2005

Mid-troposphere

April Mid-troposphere
April Anomaly Rank
(out of 39 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.23 +0.41 Coolest 34th 1993 -0.33 -0.59 +0.06 +0.11
Warmest 6th 1998 +0.67 +1.21
RSS +0.21 +0.38 Coolest 33rd 1993 -0.34 -0.61 +0.08 +0.15
Warmest 7th 1998 +0.69 +1.24
STAR +0.22 +0.40 Coolest 33rd 1993 -0.36 -0.65 +0.11 +0.20
Warmest 7th 1998 +0.70 +1.26
UW-UAH +0.31 +0.56 Coolest 35th 1993 -0.40 -0.72 +0.11 +0.20
Warmest 5th 1998 +0.77 +1.39
UW-RSS +0.27 +0.49 Coolest 35th 1993 -0.41 -0.74 +0.13 +0.23
Warmest 5th 1998 +0.77 +1.39
Year-to-Date Mid-troposphere
January–
April
Anomaly Rank
(out of 39 years*)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH +0.25 +0.45 Coolest 35th 1993 -0.30 -0.54 +0.06 +0.11
Warmest 5th 2016 +0.63 +1.13
RSS +0.23 +0.41 Coolest 35th 1993 -0.32 -0.58 +0.09 +0.16
Warmest 4th 2016 +0.62 +1.12
Ties: 2002
STAR +0.23 +0.41 Coolest 32nd 1993 -0.34 -0.61 +0.12 +0.21
Warmest 8th 2016 +0.62 +1.12
UW-RSS +0.31 +0.56 Coolest 36th 1993 -0.41 -0.74 +0.14 +0.25
Warmest 4th 2016 +0.74 +1.33
RATPAC* +0.49 +0.88 Coolest 57th 1965 -0.91 -1.64 +0.16 +0.29
Warmest 4th 2016 +1.09 +1.96

*RATPAC rank is based on 60 years of data

Stratosphere

April Stratosphere
April Anomaly Rank
(out of 39 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.37 -0.67 Coolest 9th 2012, 2016 -0.55 -0.99 -0.29 -0.53
Warmest 30th 1983 +1.06 +1.91
Ties: 2006
RSS -0.26 -0.47 Coolest 11th 2012, 2016 -0.48 -0.86 -0.22 -0.40
Warmest 29th 1992 +1.02 +1.84
STAR -0.24 -0.43 Coolest 13th 1999 -0.45 -0.81 -0.21 -0.38
Warmest 27th 1992 +1.03 +1.85
Year-to-Date Stratosphere
January–
April
Anomaly Rank
(out of 39 years)
Record Years Decadal Trend
°C °F Year °C °F °C °F
UAH -0.39 -0.70 Coolest 8th 2012 -0.59 -1.06 -0.30 -0.55
Warmest 32nd 1983 +1.26 +2.27
RSS -0.32 -0.58 Coolest 9th 2012 -0.54 -0.97 -0.25 -0.45
Warmest 30th 1983 +1.16 +2.09
Ties: 1996
STAR -0.27 -0.49 Coolest 11th 2012 -0.49 -0.88 -0.23 -0.42
Warmest 29th 1983 +1.14 +2.05

Background Information

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time). Global averages from radiosonde data are available from 1958 to present, while satellite measurements date back to 1979.

The mid-troposphere temperatures are centered in the in the atmospheric layer approximately 3–10 km [2–6 miles] above the Earth's surface, which also includes a portion of the lower stratosphere. (The Microwave Sounding Unit [MSU] channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 10 km [6 miles].) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, creates an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCEI's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted by 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) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

References


Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Upper Air for April 2017, published online May 2017, retrieved on May 29, 2017 from https://www.ncdc.noaa.gov/sotc/upper-air/201704.

Metadata