Clear as mud: Desiccation cracks help reveal the shape of water on Mars

by Geological Society of America and in Geology, April 19,2018 in ScienceDaily


.pdf of the article

In early 2017 scientists announced the discovery of possible desiccation cracks in Gale Crater, which was filled by lakes 3.5 billion years ago. Now, a new study has confirmed that these features are indeed desiccation cracks, and reveals fresh details about Mars’ ancient climate.

“We are now confident that these are mudcracks,” explains lead author Nathaniel Stein, a geologist at the California Institute of Technology in Pasadena. Since desiccation mudcracks form only where wet sediment is exposed to air, their position closer to the center of the ancient lake bed rather than the edge also suggests that lake levels rose and fell dramatically over time.

Reconstructing a Temperature History Using Complete and Partial Data

by Mark Fife, April 19, 2018 in WUWT


In today’s post I am going to go over how I went about creating a reconstruction of the history of temperature from the GHCN data sets using a variable number of stations reporting each year for the years of 1900 to 2011. Before I go into the details of that reconstruction, let me cover how I went about discarding some alternative methods.

I decided to create a test case for reconstruction methods by picking five random, complete station records. I then deleted a portion of one of those records. I mimicked actual record conditions within the GHCN data so my testing would be realistic. In different trials I deleted all but the last 20 years, all but the first 20 years or some number of years in the middle. I tried normalizing each station to its own average and averaging the anomalies. I tried averaging the four complete stations, then normalizing the fourth station by its average distance from the main average. In all cases when I plotted the reconstruction against the true average the errors were quite large.normalizing the fourth station by its average distance from the main average. In all cases when I plotted the reconstruction against the true average the errors were quite large.