Early stages of the recovery Early stages of the recovery of Portuguese of Portuguese

historical meteorological datahistorical meteorological data  

Maria Antónia Valente (1), Ricardo Trigo (2), Manuel Barros(3), Luís Filipe Nunes(4), Eduardo Ivo Alves(5), Elisângela Pinhal (1), Fátima Espírito Santo Coelho(4), Manuel Mendes(4), Jorge Miguel

Miranda (1,2)

  

((1) Instituto Geofísico do Infante D. Luiz, CGUL, IDL, Rua da Escola Politécnica, 58, 1250-102 Lisboa, mavalente@fc.ul.pt;

(2) Centro de Geofísica da Universidade de Lisboa, IDL; (3) Instituto Geofísico da Universidade do Porto;

(4) Instituto de Meteorologia, IP;(5) Instituto Geofísico da Universidade de Coimbra

SIGN (Signatures of environmental change in

the observations of the Geophysical Institutes)

WHO: This project combines the joint efforts of the 3 Portuguese Geophysical Institutes (Lisbon, Porto and Coimbra) and the Portuguese Meteorology Institute to convert to a digital database the historical meteorology data, recorded since 1856 until 1940.

WHAT: Sets of historical data contain monthly, daily and sub-daily (hourly or bi-hourly) records of pressure, temperature, precipitation, humidity, wind speed and direction, cloud cover, evaporation, sunshine hours and ozone.

WHERE: The published data cover several stations in mainland Portugal, the Azores and Madeira islands and in former Portuguese African and Asian colonies.

Project SIGN

Instituto Geofísico do Infante D. Luís

Universidade de Lisboa

Instituto Geofísico daUniversidade do Porto

Instituto Geofísico da Universidade de Coimbra

Lisbon Geophysical Institute (IGIDL) (1856-1940) Includes Lisbon and other meteorological stations in mainland Portugal, Azores and Madeira islands, and former colonies data

Porto – Escola Médico-Cirúrgica (1860-1898)

Coimbra Geophysical Institute (1864-1940)

Digital Recovery Process

Annales pages transformed into digital image (TIFF files)

(Work performed by a hired company, SCN – Sistemas)

Manual typing of table data (2 students)

Corrected OCR techniques applied to tables:

Performed at IGIDL (with Fine Reader ABBYY)

Performed by a hired company, SCN – Sistemas, with OmniPage

Data Published in Annales before 1940

Digital historical records of Lisbon temperature, relative humidity, precipitation, cloud cover, evaporation, and ozone data have been obtained through corrected OCR techniques applied to hourly or bi-hourly tables.

Lisbon/Geofísico 1

Temperature September 1868, bi-hourly data

OCR produces Excel tables. Decadal and monthly averages are used to correct the tables

Excel tables are saved in ASCII files

These files are used as input in a Fortan program that produces long time series and applies several tests.

Lisbon/Geofísico 2 Period 1856-1863 – Essentially monthly data(Manual typing)

MonthlySurface Pressure

Monthly data also digitised: Temperature, relative humidity, wind speed, ozone, cloud cover

Daily Tmax, Tmed and Tmin data

Lisbon/Geofísico 3 Period 1864-1940 – Daily, hourly or bi-hourly data(Corrected OCR)

Digitised so far 1864-1879

Temperature Wind Direction

Cloud Cover

Daily data also digitised: Tmax, Tmed and Tmin, relative humidity, precipitation, evaporation, wind speed, ozone

Daily observations of pressure for Lisbon for the 1864-1940 period were prioritised and have been manually digitised and subject to quality control tests (data after 1940 was supplied by the Portuguese Meteorological Institute)

Lisbon/Geofísico 4 Surface Pressure Long Historical Series 1864-2006

Station Level Pressure, other times available: 12 a.m., 6 p.m.

Problems

1. Gravity correction was applied intermitently after 1938 (series shown here have no gravity correction).

2. Pressure read in mmHg from 1856 to 1993, after 1994 in hPa. Pressure published in mb or hPa after 1938.

3. There are at least two documented jumps: 1895 (+0.25 mmHg) and December 1993 (-1.14 hPa).

4. Observations changed from local time (-37min) to GMT in 1947.

Preliminary digital results are also available for several stations in mainland Portugal, and in the islands of the Azores, Madeira, Cape Vert and São Tomé .

Other stations 1

Porto

Guarda

Campo Maior

Évora

Lagos

LisbonFunchal

P. DelgadaAngra

Cidade da Praia

Azores

Madeira

Cape Vert

Coimbra

Period 1864-1872 – Decadal (10 days) and monthly data (Manual typing)

Period 1873-1946 – Daily data (Corrected OCR)

Already digitised - 1864-1879 – stations marked in red on map + São Tomé

Coimbra daily data 1864-1940 (published in their annales) being done by Coimbra Geophysical Institute

Porto daily data: Escola Médico-Cirúrgica 1860-1898 completed; Serra do Pilar 1888-1940 being done by Porto Geophysical Institute.

Priority stations shown in map plus blue stations (Faro, Moncorvo, Montalegre, Sagres and Serra da Estrela)

Other stations 2 Porto Escola Médico-Cirúrgica 1860-1898, sub-daily data (manually typed)

Data subjected to preliminary tests, gross errors have been corrected.

Other fields: rel. humidity, wind direction and speed, ozone, cloud cover

• Other tests are being applied to detect more typing mistakes and errors

Other stations 3 1864-1872 monthly data (from daily averages)

Summary

Lisbon/Geofísico records from 1856-1874 have been digitised through manual typing and corrected OCR techniques.

Lisbon/Geofísico station level pressure for 1864-1940 (direct observations) and Porto – Escola Médico-Cirúrgica 1860-1898 have been digitised (typing). Both sent to 20th Cent. Reanalysis (Gil Compo) and ACRE (Rob Allan)

Data from other stations in mainland Portugal, isles and former colonies (1864-1874) have been digitised through manual typing and corrected OCR techniques.

Digital images of the IGIDL annales are available for the 1856-1912 period

Ministry of Colonies annales for 1910-1946 are being considered for digitisation also, contents tables have been produced

Future Work

Proceed with the digitisation process until 1940 and merge the pre-1941 digitised data with the post-1941 sets stored in the Meteorology Institute digital database.

Apply error detecting tests and, if possible, correct the errors

Apply homogeneity test to all series of digitised data and, if possible, correct the heterogeneities

Use the long historical data series to study the changes that have taken place during the last 150 years, particularly those related with extremes.

Adapt a synoptic weather type (WT) classification scheme for Portugal (Trigo and Dacamara, 2000) to recently available daily SLP fields reconstructed for Europe since 1850 (Ansell et al., 2006). This daily WT classification will be useful to evaluate climatic trends and extremes of precipitation and temperature over Portugal between 1850 and the present time.