Hansen’s downward adjustments of Peruvian temperature records by as much as 3 deg C is based on the presumptive quality of Peruvian “rural” sites. If one even spends 40 minutes examining the locations of these sites, any resemblance to rural USHCN sites disappears.
In addition, the failure of NOAA and NASA to update their records is notable. In some case, NOAA maintains up-to-the-hour records of sites which GHCN and NASA have not updated in decades. I counted 13 Hansen-rural sites in Peru.
Brief comments on each one follow. Online versions at NOAA are mentioned – see this source citing NOAA (I haven’t sourced the data at NOAA directly at present).
Iquitos: This record is current to 2008. Wikipedia says:
Iquitos is the largest city in the Peruvian rainforest, with a population of around 400000
Yurimaguas: This record ends in 2003. Online at NOAA PR84425. Wikipedia:
Yurimaguas is a thriving port-town in the Loreto Region of northeastern Peruvian Amazonia. Historically associated with Maynas(Pais de los Maynas), the culturally diverse town is affectionately known as the “Pearl of the Huallaga” (“Perla del Huallaga”). Yurimaguas is located at the confluence of rachel the majestic Huallaga and Paranapura Rivers in the steamy rainforests of northeastern Peru,. It is the capital of both Alto Amazonas Province and Yurimaguas District, and had a population estimated at about 64,000 inhabitants (2002).
Moyobamba This record ends in 1988, but is online at NOAA Station Id: PR84435.
Moyobamba is a city and capital of the San Martín Region in northern Peru. There are about 50 thousand inhabitants.
Chachapoyas: This ends in 2001, but is online at NOAA as Station Id: PR84444.
Chachapoyas is a city in northern Peru at an elevation of 2,235 meters (7,657 feet). The city has a population of approximately 20,279 people.
Lambayeque: This record ends in 1961.
Lambayeque is a city in the Lambayeque region in northern Peru. It is notable for its exceptional museums featuring artefacts from local archaeological sites.
Tarapoto This record is current to 2008 and is online at NOAA Station Id: PR84455
Tarapoto known as The Palm Tree City is a thriving commercial city in northern Peru, an hour by plane from Lima, situated in the San Martín Province of the San Martín Region, located to the east in what is known as the selva baja. Although Moyobamba is the capital of the region, Tarapoto is its largest city, and is linked to the Upper Amazon and the historic city of Yurimaguas by now a maintained transandean road. The city is 350 meters above sea level and has a population of over 120,000 inhabitants.
Cajamarca: This ends in 2001.
Cajamarca is located in the northern highlands of Peru, and is the capital of the Cajamarca region. It is approximately 2,700 m (8,900 ft) above sea level and has a population of about 135,000 people.
Juanjui: This record ends in 2001. It is located in northern Peru and is described as a town.
Tingo Maria: This ends in 2001.
Tingo María is the capital of Leoncio Prado Province in the Huánuco Region in central Peru. It has a urban population of around 55,000 (June 2007)
Jauja. This record ends in 1975.
Jauja is a town of 25,000 people in central Peru, capital of a province with a population of 105,000. It is situated in the fertile Mantaro Valley, 45 kilometers to the north of Huancayo (the capital of Junín Region), at an altitude of 3,400 m.
San Juan (de Marcona) This record ends in 1997, but is online at NOAA http://www.climate-charts.com/Locations/p/PR84701.html. It is mentioned as having a population of 11570.
Quince Mil : This is a very high airport in Peru in the Cuzco region. I didn’t locate any population information in a quick look. Record ends in 1985.
El Alto I didn’t locate any population information in a quick look. The record is very short – from 1951 to only 1971.
Hansen’s Population Data
It’s hard to figure out why Hansen would classify (for example) the city of Iquitos (population 400,000) as “rural”. Hansen et al 1999 provided the following definitions for “rural”, “small” and “urban”:
We use the definition of Peterson et al 1997 for these categories: that is, rural areas have a recent population of less than 10,000, small towns between 10,000 and 50,000 and urban areas more than 50,000. These populations refer to approximately 1980.
Peterson et al 1997 is presumably Peterson and Vose (BAMS 1997), An overview of the GHCN temperature database. Here’s how Peterson and Vose 1997 introduced their population data set:
Given the popularity of GHCN, researchers at NCDC, CDIAC, and Arizona State University have prepared an enhanced database to serve the ever increasing demand for these data. This archive, GHCN version 2, breaks considerable new ground in the field of global climate databases. Enhancements include 5) detailed metadata (e.g., population, vegetation, topography) that allow more detailed analyses to be conducted; …
Wherever possible, we used population data from the then-current United Nations Demographic Yearbook (United Nations 1993). Unfortunately, only cities of 100 000 or more inhabitants were listed in the yearbook. For smaller cities we used population data from several recent atlases. Again, although the atlases were recent, we do not know the date of source of the data that went into creating the atlases. Additionally, this represents only one moment in time; an urban station of today may have been on a farm 50 years ago, though it is probably valid to assume that if a station is designated rural now, it was most likely rural 50 years ago. Knowing the importance of avoiding the effect of urban warming by preferring rural stations in climate analysis, these population metadata have been used as one of the criteria in the initial selection of the Global Climate Observing System (GCOS) Surface Network (Peterson et al. 1997a).
These cities have been growing quickly, but it’s hard to believe that atlases in use in 1997 would have classified Iquitos as rural. It’s questionable whether any of these stations are actually “rural” within the proposed definition of Hansen et al 1999. Many of the sites even seem to be “urban” (rather than “small town”) under the definitions of Hansen et al 1999.
If the supposedly “rural” comparanda are actually “urban” or “small” within the Hansen definitions, then the GISS “adjustment” ends up being an almost completely meaningless adjustment of one set of urban values by another set of urban values. No wonder these adjustments seem so random.
Yeah, yeah, Hansen et al 1999 was written 8 years ago, but the same crappy population database is used in adjustments being done as we speak.
And by the way, I didn’t search through the database and pick out Peru as a lurid example. I’ve been to Peru though I haven’t traveled extensively through Peru and it didn’t have too many stations to look at so I could do a quick first cut analysis. So it’s not like I examined Ecuador and it was great and I’m only showing Peru because it’s bad. It just happened to be what I looked at. Maybe Hansen’s done a terrific job on every other country.
Update: This post is criticized by Tamino here where he describes my criticism of NASA’s population data as “Despicable”