Part I Status of BSRN database and FTP

Part I Status of BSRN: database and FTP file archive April 27, 2005 CEOS/ WGCV/Land Product Validation Workshop on Albedo Products, Vienna Andreas Roeschreas Institute for Atmospheric and Climate Research, ETH Zurich

• Current status of the database • Synop/ Radiosounding • Albedo (reflected SW radiation) • UV/AOD (Aerosol optical depth) • FTP file archive

37 operational BSRN stations

Operational BSRN stations (North America)

Operational BSRN stations (Europe)

Status of BSRN database NOAA ARM SURFRAD

Status, ff.

13 BSRN stations with SYNOP measurements (logical record 1000, tables STA_SYNOPBAS_YEAR and STA_SYNOPEXT_YEAR) Station State/ Country Acronym Period of record Barrow Alaska BAR 1992 -2003 Bermuda CO, USA BER 1992 -2003 Boulder USA BOU 1992 -2003 De Aar South Africa DAA 2000 -2004 Georg v. Neumayer Antarctica GVN 1992 -2002 Kwajalein Marshall Islands, USA KWA 1992 -2003 Ny Alesund Spitsbergen, Norway NYA 1992 -2002 Payerne Switzerland PAY 1992 -2003 Sede Boqer Israel SBO 2003 South Pole Antarctica SPO 1992 -2003 Syowa Antarctica SYO 1994 -2001 Tamanrasset Algerie TAM 2000 -2001 Tateno Japan TAT 1996 -2004

18 BSRN stations with radiosonde measurements 1992 -2002: BAR, BER, BOU, GVN, KWA, NYA, SPO 1994 -2004: BIL 1995 -2003: BON, BOS 1996 -2003: PAY 1996 -2004: TAT 1997 -2004: E 13, MAN 1998 -2003: DRA 1998 -2004: NAU 2000 -2004: DAA 2003: SBO

BSRN stations reporting 10 m-observation to BSRN (logical record 3010, table „STA_RMH 1000_YEAR“) Station State/ Country Acronym Organisation Period of record Bondville IL, USA BON SURFRAD 1995 -2003 Boulder CO, USA BOS SURFRAD 1995 -2003 Desert Rock NV, USA DRA SURFRAD 1998 -2003 E 13 USA E 13 ARM 1997 -2004 Fort Peck MT, USA FPE SURFRAD 1995 -2003 Goodwin Creek MS, USA GCR SURFRAD 1995 -2003 Payerne Switzerland PAY Swiss meteo 1994 -2003 Rock Springs PA, USA PSU SURFRAD 1998 -2003 All these stations provide reflected SW radiation and thus surface albedo

BSRN stations reporting reflected SW radiation (at standard height) Station State/ Country Acronym Organisation Period of record Barrow Alaska, USA BAR NOAA/ CMDL 01/1992 - 11/1993 Ny Alesund Spitsbergen, Norway NYA AWI, Germany 08/1992 - 12/2003 South Pole Antarctica SPO NOAA/ CMDL 01/1992 - 12/2003 Georg v. Neumayer Antarctica GVN AWI, Germany 04/1992 -12/2003 Syowa Antarctica SYO NIPR, Japan 04/1998 - 01/2002 Payerne Switzerland PAY Meteo Swiss 03/1992 - 04/2004 Toravere Estonia TOR Est. Met. Inst. 01/1999 - 03/2004 Tateno Japan TAT Jap. Met. Agency 02/1996 - 01/2004

BSRN stations reporting UV to BSRN (logical record 500, table „STA_RMUV_YEAR“) Boulder State/ Country CO, USA Goodwin Creek MS, USA GCR SURFRAD 1995 -2003 Fort Peck MT, USA FPE SURFRAD 1995 -2003 Bondville Rock Springs Desert Rock Momote, Manus Is. IL, USA PA, USA NV, USA Papua New Guinea Tropical Western Pacific Switzerland Estonia BON PSU DRA SURFRAD 1995 -2003 1998 -2003 MAN ARM 1996 -2004 NAU ARM 1998 -2004 PAY TOR Swiss meteo EMHI 1998 -2003 2000 -2001 Station Nauru Island Payerne Toravere Acronym Organisation Period of record BOS SURFRAD 1995 -2003 Payerne provides both direct and diffuse UV-a and UV-b, all others only provide total UV-b

BSRN stations measuring UV, not reporting to BSRN Station State/ Country Acronym Organisation Tateno Japan TAT From 1990 Syowa Antarctica SYO From 1991 Alice Springs Australia ASP Bo. M Chesapeake Virginia, USA CHL NASA Tamanrasset Algerie TAM From 1997 Georg von Neumayer Antarctica GVN From 1992 Lauder New Zealand LAU NIWA Period of record From 1993 From 1991 From B. Forgan, based on information from station scientists (at the request of Ohmura/ Roesch)

BSRN stations planning to measure UV radiation State/ Country Acronym Organisation Camborne UK CAM Met. Office Lervick UK LER Met. Office From B. Forgan, based on information from station scientists

Aerosol optical depth (AOD) in BSRN Current status: No station provides spectral shortwave radiation (record 200 or 400) Only GVN and NYA includes record 1300 (but provides missing values for spectral AODs) Future plan: Database: Insertion of computed AOD values (for 3 wavelengths) into record 1300 only after transmission data have passed several consistency checks. -> No change in the database schema is required. -> Block 1300 is excluded from the instrument consistency checks. File archive: All measured and calculated data (at all wavelengths) are included in the ftp file archive, including QC/ QA

FTP file archive (ftp: //ezksun 3. ethz. ch) Motivation • Most scientists are more familiar with file archives than with databases • The web interface does not allow the retrieval of all data • Access and download via file archive is simple and fast • Can be easily modified (value-added data) Current status The file archive is automatically updated (cron-job) every night -> The database and the file archive generally contain identical data. Differences between the database and the file archive • Improved quality check flags (recommended by Ells Dutton and Chuck Long) • Global radiation „global 1“ added (sum diffuse plus direct SW radiation) Format Compressed ASCII-files (use „gunzip“ to uncompress data)

FTP file archive - some details to the format Format is the same as described in the „Update of the Technical plan for data management (1998)“ but with the following extensions: • Logical record 100 line 1: X, I 1, X, I 1 Global radiation: Physically possible, extremely rare Direct radiation: Physically possible, extremely rare line 2: X, I 1, X, I 1, X, I 1 Diffuse radiation: Physically possible, extremely rare Longwave downward rad. : Physically possible, extremely rare Global radiation: Comparison between „global 1“ and „global 2“ Comparison between diffuse and direct radiation Comparison of longwave downward and 2 m- temperature

FTP file archive - some details to the format (ff) • Logical record 300 Extension to each line: X, I 1, X, I 1, X, I 1 LW upward radiation: Physically possible, extremely rare Reflected SW radiation : Physically possible, extremely rare Global radiation: Comparison between reflected SW and global radiation Comparison of LW up to air temperature LW up to LW down comparison Meaning of the quality flags 2 -> suspected to be erronous 5 -> cannot be performed 9 -> passed the procedure

Conclusions (Part I) • The BSRN database currently contains 37 operating stations with a total of approximately 2950 monthly data files. • Number of stations which report SYNOP: 13 Radiosounding: 18 UV: 10 Albedo: 15 • More and more scientists prefer to download data from the FTP file archive. • The FTP file archive is automatically updated from files that have been successfully inserted into the BSRN database. • The FTP file archive includes the quality flags according to E. Dutton and C. Long as well as „global 1“ (computed from direct and diffuse measurements). • Data in the FTP file archive can be easily modified/ extended.

Part II Some applications of MODIS/ BRDF data

Validation of seasonal cycles of surface albedo in ECHAM 4 and ECHAM 5

Masks

Annual cycles of surface albedo

Sub-grid scale variability and how representative are point measurements?

Correlation of MODIS 0. 05 x 0. 05 surface albedo with PAY pixel (2000 -2003)

BS ZH PAY

BON

MODIS versus ground truth from BSRN

Surface albedo: MODIS vs. BSRN

Data from Greenland summit have been kindly provided by Sebastian Hoch, ETH Zurich

Zenith angle dependence of surface albedo

Black sky albedo, 6 -21 March 2002, Resolution: 0. 5 o

MODIS white sky albedo minus black sky albedo VIS: blue NIR: red Solar angle at local solar noon

Conclusions (Part II) • MODIS/ BRDF provides high-quality data for validation of GCMs and improving their parameterizations • MODIS (at 0. 05 resolution) agrees well with ground truth from BSRN sites during snow-free periods. Under snow conditions, deviations are significant due to differing vegetation cover (-> snow masking of forest). • MODIS Version 4 differs from Version 3 (in both the mean and the variability) • MODIS Version 3 is too low over pure snow such as Greenland (Version 4 provides improved data). • ECHAM 4 surface albedo is too high over boreal forests and the Himalayas/ Tibetan Plateau. • ECHAM 5 is closer to the observations over the Himalayas than ECHAM 4, but positive albedo biases over snow-covered boreal forests are even more pronounced in ECHAM 5.

Conclusions (ff) • MODIS & BSRN clearly show that neglecting the zenith angle dependence leads to significant errors in the net shortwave radiation. The approach of Briegleb et al. (1986) is suggested for land surface albedo models. • Intracell variability of surface albedo is largest in snow-covered areas and deserts. Normalized intracell variances are largest in mountainous regions. • Intracell variability in the VIS spectrum is much higher than in the NIR band over (partially) snow covered regions (difference asnow - a, no snow is also higher in the VIS) • Surface albedo at specific sites are generally representative for a limited area only.

Correlation of MODIS surface albedo with 0 N/65 W pixel (rain forest)