RADIATION PROGRAM AT TAMANRASSET ALGERIA RESULTS OF RADIATION MEASURE SINCE 1994 By.O.BOUZIANE

Algeria Map

TAMANRASSET Radiation instruments on the roof

MEASURE OF RADIATION -SOLAR RADIATION ( 0.28 µm – 4 µm ) Measure of Downward flux Since September 1994 Direct, Global, Diffuse, RG8 (>=0.69 µm) -ATMOSPHERIC RADIATION ( Long Wave ) : 4 µm -100 µm Measure of Downward flux Since Mars 2000 Since this date, change in measure of diffuse : shade disk in place of shadow band. - Calibration of Instruments : PSP §NIP IN SITU WITH AHF REFERENCE N° 29225

THE TURBIDITY IS VERY LOW IN THE WINTER ( NOV-MARS ) AND VERY HIGH FROM APRIL TO SEPTEMBER : VERY HAZY Measured since january 1995 with Sun photometer ( 500 nm)

THE YEARLY AVERAGE OF THE TURBIDITY CHANGE FROM TO

Measure OF RADIATION AT Tamanrasset

YearDiffus/glb

The Solar Global is maximum in Summer period, with the angle solar Global = Direct*sin (h) +diffuse The low values of direct (cloud ) are compensated by solar elevation and diffuse in summer period. The diffuse are very low in winter period because of clear sky and visibility. In summer period, the diffuse is more important with cover sky and haze. The fraction Diffuse/Global is about 40 % in summer and 25 % in winter. The Global received at surface is % the Extra- Terrestrial Radiation (ETR) on surface horizontal.

OFFSET OF PSP AND NIP Offset of Night from 1 to 2 January 2009 : Winter Period ( cover sky = 3 Ci ) The offset of diffuse stay positive ( > 0 W/m2 ) about 13 mn after sunset. In the Morning the offset become positive 7 mn before sun rise. During the night, the values of offset of NIP and Diffuse are equal around -2 W/m2. Offset of night 5 to 6 june 2009 : Summer period ( haze and cloudly ) The same remark of diffuse offset at sunset and sunrise. The offset of diffuse and global decrease raipdly at 20 TU from -2 W/m2 to -8 W/m2. The NIP offset stay between -1 and -2 W/m2

Radiation in a hazy and cloudly day The day of 05 june 2009 : hazy 4 km of visibility and very cloudly Total daily : PIR (32.91 MJ),Dif (12.31MJ), NIP(8.91 MJ),GLB (19.52MJ) Global = 49 % ETR Dif/Glb = 63 %

Radiation in a clear day with good visibility The day 25 january 2009 : good visibility and no cloud Total daily : PIR( MJ), DIF ( 2.05 MJ), NIP ( MJ), GLB(20.67MJ) GLB = 78 % ETR DIF/GLB = 10 %

Calibration of PSP and NIP Each year, between november to january, the calibration of PSP and NIP is made in situ at Tamanrasset with AHF N° For PSP, we use the mehod : shade and unshade G=direct*sinh + D Knew= (G-D)/(direct*sinh) mv/wm-2 For NIP, the direct comparison between AHF and NIP

The coefficients of global and diffuse decrease regulary since year 2000 with the an average of 1.7 %, the coefficient of global vary from 8.54 to 7.22 µv/wm-2 and for the diffuse from 8.34 to 7.01 µv/wm-2 in 10 years. The coefficient of NIP vary in the interval 7.74 to 7.80, the original value is 7.77 µv/wm-2. It decrease to 7.74 and increase to 7.80 for last years. The variation of coefficient of RG8 is more obscure and not clear : the original value in september 1994 is One year the coefficient decrease and other it increase, in 15 years, the actual value is 8.24 µv/wm-2

INSTALLATION OF AN ALBEDOMETER It is installed last 8 mars 2010, at about 45 meters from Datalogger. It is composed of 02 pyranometers Kipp§Zonnen with the calibration coefficients Upper = 8.16 µv/wm-2 and Lower =7.86 µv/wm-2 This system is connected to the datalogger CR23X. The values of upper PSP can be compared to the value of global BSRN Measure of global reflected and compute of Albedo

Albedometer at Tamanrasset since 8 mars 2010

During the night, the reflected radiation is positive all time : near 0.5 w/m2 from sunset to 2230 tu, increase to 1.6 w/m2 the rest of the night. The BSRN global and new global are nearly equal, except near noon where the BSRN global is higher. The reflected radiation has the same shape with a rate of about 32 %. The Albedo = 0.32

MEASURE OF Aerosol Optical Depth ( AOD) Since October 2006, in collaboration with Spanish Meteorology ( INM) and GAW station of IZANA ( Canaries) Installation of a Cimel Photometer at Tamanrasset for measure of AOD ( AERONET Project). Measure of AOD in 07 longwaves: 1020 nm, 870, 675, 500, 440, 380, 340 nm.

PHOTOMETER CIMEL ON THE ROOF OF METEOROLOGY CENTER TAMANRASSET

The AOD is minimum in winter period and very high in summer period