Developing a Research-Grade Historic Mount Washington Summit Temperature Dataset

• To produce homogenous hourly and daily maximum and minimum temperature data records for January 1935 to present from which MWO can derive several official research-grade analyses/products, such as a mean annual temperature time series and trend, to support MWO research and education programs.
• To produce a document allowing external researchers the ability to apply the methods developed here to other historic datasets.
• To create a digital archive of the paper records by scanning or photographing them.

MWO research and education, two of the three core missions of MWO, depend upon having the best climatological data available. In a rapidly warming world, our understanding of how temperature is changing at the summit of Mount Washington relative to the lower elevations of the Northeastern US and other locations globally is critical to accurate temperature trend projections during the 21st century and understanding the processes driving the spatial variability of temperature change (Diaz and Bradley 1997; Rangwala and Miller 2012; Pepin et al. 2015). MWO Research feeds its output to the Education program, which reaches thousands of students and adults each year. Having the most accurate temperature data and their interpretation to share with the public is critical for their learning and understanding of related scientific information and ultimately, motivating them to make well-informed decisions.

MWO Observers have observed temperature, humidity and other variables every hour since 1 January 1935, with few exceptions. However, over this timeframe, the Standard Operating Procedure (SOP) to record temperature and humidity, in particular the daily maximum and minimum temperatures, has changed. These changes open multiple ways these values can be analyzed for temperature trends (see Grant et al. 2005). In addition, a brief scan of our paper records, the WB 1001 and WB 1014 forms, reveals numerous differences in maximum and minimum temperatures, largely during the 1930s-40s. Several non-systematic erroneous values were found in our digital database as well. Because seasonal interns performed the majority of the digitization of our paper records, these erroneous values are probably a result of disinterest/fatigue and/or lack of training/supervision of interns.

The paper records, which consist of several types of hourly, 6-hourly, and monthly forms, are the original and ultimate record of Mount Washington summit weather observations. These paper records reside at the summit and are highly vulnerable to fire and water damage. Only some of the forms have been scanned or photographed. The records must be scanned for redundancy and to support the integrity of the >84-year Mount Washington climate record.

A renewed look at the Mount Washington temperature record with a focus on research is needed to produce a research-grade temperature record. Under MWO staff oversight, staff and outside experts will train and oversee MWO Observers to create this research-grade temperature record. This project will require the use of our paper records located at the summit, SOPs from 1935-present located at the summit, and the pre-existing digital database. Most of the inconsistencies in SOPs for temperature exist pre-1949 and is the period of record for which most effort is required.

The scientific community will benefit from this work by the realization of the full value of this long-term dataset. Furthermore, the procedures developed through this work may be of significant value to other historic climate records that have similar past changes in atmospheric measurement procedures and/or missing data. To maximize the value of this project, a document will be produced that will detail the decisions and procedures taken through the examination of the SOPs and data records. The document may include numeric and/or decision-tree algorithms to apply to other records. It will be made publicly available.

Diaz, H.F., and R.S. Bradley, 1997: Temperature variations during the last century at high elevation sites. Climatic change at high elevation sites, Springer, Dordrecht, pp. 21-47.

Pepin, N., R.S. Bradley, H.F. Diaz, M. Baraër, E.B. Caceres, N. Forsythe, H. Fowler, G. Greenwood, M.Z. Hashmi, X.D. Liu, and J.R. Miller, 2015: Elevation-dependent warming in mountain regions of the world. Nature Climate Change, 5, 5, 424.

Rangwala, I., and J.R. Miller, 2012: Climate change in mountains: a review of elevation-dependent warming and its possible causes. Climatic Change, 114, 3-4, 527-547.

Brian Fitzgerald, Director of Science & Education

(603) 356-2137 ext. 225

Email (link: mailto: bfitzgerald@mountwashington)