Direct comparisons of measurements from surface based sensors and remote sensors like the more recent Moderate Resolution Imaging Spectroradiometer (MODIS) on the TERRA and AQUA satellite platforms show that cloud cover can bias infra red Arctic surface temperature measurements low, for example see Hall 2004 on MODIS Sea Ice Surface Temperature, Scambos 2006 on validation of AVHRR and MODIS ice surface temperature, Randriamampianina 2009 on assimilating ATOVs data in Polar regions, and Koenig 2010 on MODIS data compared with high accuracy surface-based thermochron sensor data on Greenland). It is well documented that annual average Arctic air temperatures have increased over the past few decades, at a rate around twice the global average. The full coverage AVHRR decadal trend from 1981 to 2005 is 0.61 degrees/decade above 60 degrees N, but 0.72 degrees C/decade inside the Arctic Circle (around 66 N) whilst the IABP polar buoy data set gives 0.88 degrees C/decade between 1979 and 1999 for measurements which are (mostly) well inside 80N. Select Parameter. Comparing the results with GISS over the same grid area over dates where the recent ice station and buoy data is used, the correlation is just as high. See current data from the National Snow and Ice Data Centre (NSIDC). Show one image . In such a case (warm water + ice), the water will cool to zero in proportion to the amount of ice that melts (energy equivalence), and then the ice/water mix will remain at 0C. Its primary usefulness is as a constantly updated indicator of global or large scale regional surface temperature changes. Absolute values show less seasonal variation than at the surface, whilst the annual average temperatures are a few degrees colder.

Why does land warm up faster than the oceans? This is indicated both by the GISS, DMI data and other high latitude data sets. Microwave “sounders” (see Waters 1975) measure microwave radiation at multiple characteristic frequencies, each emitted from specific components (eg Oxygen molecules) of the atmosphere which are present in different relatively broad vertical “profiles” within the overall atmospheric column. Though this can reduce slightly in the Summer between the coast and ice covered areas. It appears that the overall seasonal cycle is riding on a gradually warming average value, but peak positive excursions are being limited by the ice melt temperature in Summer. Please, stop measuring temperatures during the melt season! A recent WUWT article by Frank Lansner, August 5th 2010 has the heading “DMI polar data shows cooler Arctic temperature since 1958”. ...and during that period, knowing temperature is useful. This output is an average of all model points at 2m height, currently on a 0.5 degree grid over the most northerly part of the Arctic, above 80N. While summer maximums have showed little trend, the annual average Arctic temperature has risen sharply in recent decades. Enter a term in the search box to find its definition. Figure 2: 30 day rolling average DMI temperatures, averaged over two decadal periods showing increasing average seasonal temperatures over the DMI record. Frank Lansnser goes on to show data from GISS July polar views (where individual grid cells show large variability) and compares this with graphics of DMI data for July 2010 to cast doubt on the validity of the GISS gridded values in the polar regions. Thus the reality is that the annual average temperature as indicated by DMI has risen at rates around twice the global average over the past 50 years, which is entirely consistent with other Arctic data sets, including the data from GISS. You should seriously sit back and ponder the possibilty that people who have been studying these things for centuries actually might know a few things that you do not know. This means that the DMI Arctic temperature data has had several changes in its history. THE ESCALATOR This chart is therefore highly misleading.

Many diagrams or charts only show a slight result. The daily mean temperature of the Arctic area north of the 80th northern parallel is estimated from the average of the 00z and 12z analysis for all model grid points inside that area. Despite this, the DMI data has been used as a reference for comparison. Every kilo of melted ice cools 80 liter water with 1 degree C. An,  no Frank, melting ice does not cool the environment.

Comments Policy... You need to be logged in to post a comment. Link to this page. This maximum temperature “clipping” effect is clearly seen on the following chart which shows measured 2m air temperature data from former USSR Polar Stations NP-6 and NP-30 from positions above 80N (see Lindsay 1998 for more detail). The Goddard Institute of Space Science (GISS) global surface temperature anomaly series is based on observations rather than models. These longer time series from equivalent satellite sensors are themselves made up of data from several (not necessarily overlapping) satellite missions, so care must be taken when analyzing long term trends (see analysis of calibration of TOVS data for some visual representations and context). From DMI we learn, that Arctic 80N-90N temperatures in the melt season this year is colder than average. The Arctic Today: Climate and Weather - Mean temperatures North of 80N - Arctic weather North of 60N - Ice Extent in the Northern Hemisphere - Minimum Ice Extent since 1979 - Monthly mean Sea Ice Extent since 1979: Satellite Products - Sea ice drift and- sea ice concentration - Sea Surface temp.

All of these data sets should be used with caution when making comparisons at high latitudes, as they do not have identical coverage. This is why the Summer air temperatures have not varied much over the entire instrumental period. Thus conclusions from an objective analysis of available data, and recent peer reviewed work, whether based on updated independent observations at various resolutions, or state of the art high resolution climate modeling using all available data sources, is that the Arctic is experiencing strong warming, roughly double the global average, and showing increasing surface temperature trends with higher latitude. Printable Version  |  Whilst some caution is advised by GISS in using the interpolated data in the Arctic region, it appears that GISS trends in the Arctic region as a whole are consistent with other high latitude data sets, and show similar trends (in terms of annual averaged values) with other data sets which cover the region above 80N. This, I suppose, begets the idea of the necessity of responsible leadership. A study using data from stations and Polar drifting ice buoys showed that near surface air temperatures over the pack ice are relatively homogenous, with a CLS (correlation length scale) of 900-1000 km (Rigor 2000). Ah, OK: I suppose I am making the general point about document shock making people sick of reading documents properly. Care is also advised in the use of MSU data at high latitudes due to MSU sensor scanning geometry, for example the standard zonal “polar” data from RSS covers from 60N to 82.5N. Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off). Several attempts have been made to homogenize and assimilate these data sets into a common Arctic time series. In general the satellite data has almost full polar coverage and very high spatial resolution, but lower absolute accuracy over ice. These changes could be linked to minor differences in the apparent Summer melt temperature, (there are small differences between the ERA-40 and the T511 outputs in the overlap period in 2002).

What Lansner (and others) have effectively done is to pick one of the peak monthly GISS values (light blue) and compared the average DMI value for that month.